diff --git a/.gitignore b/.gitignore
index eb880af..55f29f8 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,6 +1,8 @@
 compile_commands.json
 .clang-format
-.ccls-cache/*
+.clang-tidy
+.ccls-cache/
+.cache/
 experiment/
 build/
 hbuild/
diff --git a/include/ss/common.hpp b/include/ss/common.hpp
index c70230e..e507994 100644
--- a/include/ss/common.hpp
+++ b/include/ss/common.hpp
@@ -1,11 +1,15 @@
 #pragma once
 #include <cerrno>
-#include <cstdint>
 #include <cstdio>
 #include <cstdlib>
 #include <cstring>
 #include <vector>
 
+#if !__unix__
+#include <array>
+#include <cstdint>
+#endif
+
 namespace ss {
 
 struct none {};
@@ -17,18 +21,18 @@ constexpr inline auto default_delimiter = ",";
 constexpr inline auto get_line_initial_buffer_size = 128;
 
 template <bool StringError>
-inline void assert_string_error_defined() {
+void assert_string_error_defined() {
     static_assert(StringError,
                   "'string_error' needs to be enabled to use 'error_msg'");
 }
 
 template <bool ThrowOnError>
-inline void assert_throw_on_error_not_defined() {
+void assert_throw_on_error_not_defined() {
     static_assert(!ThrowOnError, "cannot handle errors manually if "
                                  "'throw_on_error' is enabled");
 }
 
-inline void* strict_realloc(void* ptr, size_t size) {
+[[nodiscard]] inline void* strict_realloc(void* ptr, size_t size) {
     ptr = std::realloc(ptr, size);
     if (!ptr) {
         throw std::bad_alloc{};
@@ -38,18 +42,20 @@ inline void* strict_realloc(void* ptr, size_t size) {
 }
 
 #if __unix__
-inline ssize_t get_line_file(char*& lineptr, size_t& n, FILE* file) {
+[[nodiscard]] inline ssize_t get_line_file(char*& lineptr, size_t& n,
+                                           FILE* file) {
     return getline(&lineptr, &n, file);
 }
 #else
 
 using ssize_t = intptr_t;
 
-ssize_t get_line_file(char*& lineptr, size_t& n, FILE* file) {
-    char buff[get_line_initial_buffer_size];
+[[nodiscard]] inline ssize_t get_line_file(char*& lineptr, size_t& n,
+                                           FILE* file) {
+    std::array<char, get_line_initial_buffer_size> buff;
 
     if (lineptr == nullptr || n < sizeof(buff)) {
-        size_t new_n = sizeof(buff);
+        const size_t new_n = sizeof(buff);
         lineptr = static_cast<char*>(strict_realloc(lineptr, new_n));
         n = new_n;
     }
@@ -57,17 +63,17 @@ ssize_t get_line_file(char*& lineptr, size_t& n, FILE* file) {
     lineptr[0] = '\0';
 
     size_t line_used = 0;
-    while (std::fgets(buff, sizeof(buff), file) != nullptr) {
+    while (std::fgets(buff.data(), sizeof(buff), file) != nullptr) {
         line_used = std::strlen(lineptr);
-        size_t buff_used = std::strlen(buff);
+        size_t buff_used = std::strlen(buff.data());
 
         if (n <= buff_used + line_used) {
-            size_t new_n = n * 2;
+            const size_t new_n = n * 2;
             lineptr = static_cast<char*>(strict_realloc(lineptr, new_n));
             n = new_n;
         }
 
-        std::memcpy(lineptr + line_used, buff, buff_used);
+        std::memcpy(lineptr + line_used, buff.data(), buff_used);
         line_used += buff_used;
         lineptr[line_used] = '\0';
 
@@ -81,15 +87,16 @@ ssize_t get_line_file(char*& lineptr, size_t& n, FILE* file) {
 
 #endif
 
-ssize_t get_line_buffer(char*& lineptr, size_t& n,
-                        const char* const csv_data_buffer, size_t csv_data_size,
-                        size_t& curr_char) {
+[[nodiscard]] inline ssize_t get_line_buffer(char*& lineptr, size_t& n,
+                                             const char* const csv_data_buffer,
+                                             size_t csv_data_size,
+                                             size_t& curr_char) {
     if (curr_char >= csv_data_size) {
         return -1;
     }
 
     if (lineptr == nullptr || n < get_line_initial_buffer_size) {
-        auto new_lineptr = static_cast<char*>(
+        auto* new_lineptr = static_cast<char*>(
             strict_realloc(lineptr, get_line_initial_buffer_size));
         lineptr = new_lineptr;
         n = get_line_initial_buffer_size;
@@ -98,7 +105,7 @@ ssize_t get_line_buffer(char*& lineptr, size_t& n,
     size_t line_used = 0;
     while (curr_char < csv_data_size) {
         if (line_used + 1 >= n) {
-            size_t new_n = n * 2;
+            const size_t new_n = n * 2;
 
             char* new_lineptr =
                 static_cast<char*>(strict_realloc(lineptr, new_n));
@@ -114,19 +121,15 @@ ssize_t get_line_buffer(char*& lineptr, size_t& n,
         }
     }
 
-    if (line_used != 0) {
-        lineptr[line_used] = '\0';
-        return line_used;
-    }
-
-    return -1;
+    lineptr[line_used] = '\0';
+    return line_used;
 }
 
-std::tuple<ssize_t, bool> get_line(char*& buffer, size_t& buffer_size,
-                                   FILE* file,
-                                   const char* const csv_data_buffer,
-                                   size_t csv_data_size, size_t& curr_char) {
-    ssize_t ssize;
+[[nodiscard]] inline std::tuple<ssize_t, bool> get_line(
+    char*& buffer, size_t& buffer_size, FILE* file,
+    const char* const csv_data_buffer, size_t csv_data_size,
+    size_t& curr_char) {
+    ssize_t ssize = 0;
     if (file) {
         ssize = get_line_file(buffer, buffer_size, file);
         curr_char += ssize;
@@ -145,4 +148,4 @@ std::tuple<ssize_t, bool> get_line(char*& buffer, size_t& buffer_size,
     return {ssize, false};
 }
 
-} /* ss */
+} /* namespace ss */
diff --git a/include/ss/converter.hpp b/include/ss/converter.hpp
index 5058df5..06e67d2 100644
--- a/include/ss/converter.hpp
+++ b/include/ss/converter.hpp
@@ -110,19 +110,19 @@ public:
     // parses line with given delimiter, returns a 'T' object created with
     // extracted values of type 'Ts'
     template <typename T, typename... Ts>
-    T convert_object(line_ptr_type line,
-                     const std::string& delim = default_delimiter) {
+    [[nodiscard]] T convert_object(
+        line_ptr_type line, const std::string& delim = default_delimiter) {
         return to_object<T>(convert<Ts...>(line, delim));
     }
 
     // parses line with given delimiter, returns tuple of objects with
     // extracted values of type 'Ts'
     template <typename... Ts>
-    no_void_validator_tup_t<Ts...> convert(
+    [[nodiscard]] no_void_validator_tup_t<Ts...> convert(
         line_ptr_type line, const std::string& delim = default_delimiter) {
         split(line, delim);
         if (splitter_.valid()) {
-            return convert<Ts...>(splitter_.split_data_);
+            return convert<Ts...>(splitter_.get_split_data());
         } else {
             handle_error_bad_split();
             return {};
@@ -131,13 +131,13 @@ public:
 
     // parses already split line, returns 'T' object with extracted values
     template <typename T, typename... Ts>
-    T convert_object(const split_data& elems) {
+    [[nodiscard]] T convert_object(const split_data& elems) {
         return to_object<T>(convert<Ts...>(elems));
     }
 
     // same as above, but uses cached split line
     template <typename T, typename... Ts>
-    T convert_object() {
+    [[nodiscard]] T convert_object() {
         return to_object<T>(convert<Ts...>());
     }
 
@@ -146,7 +146,8 @@ public:
     // one argument is given which is a class which has a tied
     // method which returns a tuple, returns that type
     template <typename T, typename... Ts>
-    no_void_validator_tup_t<T, Ts...> convert(const split_data& elems) {
+    [[nodiscard]] no_void_validator_tup_t<T, Ts...> convert(
+        const split_data& elems) {
         if constexpr (sizeof...(Ts) == 0 && is_instance_of_v<std::tuple, T>) {
             return convert_impl(elems, static_cast<T*>(nullptr));
         } else if constexpr (tied_class_v<T, Ts...>) {
@@ -162,11 +163,11 @@ public:
 
     // same as above, but uses cached split line
     template <typename T, typename... Ts>
-    no_void_validator_tup_t<T, Ts...> convert() {
-        return convert<T, Ts...>(splitter_.split_data_);
+    [[nodiscard]] no_void_validator_tup_t<T, Ts...> convert() {
+        return convert<T, Ts...>(splitter_.get_split_data());
     }
 
-    bool valid() const {
+    [[nodiscard]] bool valid() const {
         if constexpr (string_error) {
             return error_.empty();
         } else if constexpr (throw_on_error) {
@@ -176,12 +177,12 @@ public:
         }
     }
 
-    const std::string& error_msg() const {
+    [[nodiscard]] const std::string& error_msg() const {
         assert_string_error_defined<string_error>();
         return error_;
     }
 
-    bool unterminated_quote() const {
+    [[nodiscard]] bool unterminated_quote() const {
         return splitter_.unterminated_quote();
     }
 
@@ -189,9 +190,9 @@ public:
     // contain the beginnings and the ends of each column of the string
     const split_data& split(line_ptr_type line,
                             const std::string& delim = default_delimiter) {
-        splitter_.split_data_.clear();
+        splitter_.clear_split_data();
         if (line[0] == '\0') {
-            return splitter_.split_data_;
+            return splitter_.get_split_data();
         }
 
         return splitter_.split(line, delim);
@@ -207,7 +208,7 @@ private:
         return splitter_.resplit(new_line, new_size, delim);
     }
 
-    size_t size_shifted() {
+    [[nodiscard]] size_t size_shifted() {
         return splitter_.size_shifted();
     }
 
@@ -223,9 +224,11 @@ private:
         }
     }
 
-    std::string error_sufix(const string_range msg, size_t pos) const {
+    [[nodiscard]] std::string error_sufix(const string_range msg,
+                                          size_t pos) const {
+        constexpr static auto reserve_size = 32;
         std::string error;
-        error.reserve(32);
+        error.reserve(reserve_size);
         error.append("at column ")
             .append(std::to_string(pos + 1))
             .append(": \'")
@@ -350,7 +353,8 @@ private:
     ////////////////
 
     template <typename... Ts>
-    no_void_validator_tup_t<Ts...> convert_impl(const split_data& elems) {
+    [[nodiscard]] no_void_validator_tup_t<Ts...> convert_impl(
+        const split_data& elems) {
         clear_error();
 
         if (!splitter_.valid()) {
@@ -381,7 +385,7 @@ private:
     }
 
     template <typename... Ts>
-    no_void_validator_tup_t<std::tuple<Ts...>> convert_impl(
+    [[nodiscard]] no_void_validator_tup_t<std::tuple<Ts...>> convert_impl(
         const split_data& elems, const std::tuple<Ts...>*) {
         return convert_impl<Ts...>(elems);
     }
@@ -390,11 +394,11 @@ private:
     // column mapping
     ////////////////
 
-    bool columns_mapped() const {
-        return column_mappings_.size() != 0;
+    [[nodiscard]] bool columns_mapped() const {
+        return !column_mappings_.empty();
     }
 
-    size_t column_position(size_t tuple_position) const {
+    [[nodiscard]] size_t column_position(size_t tuple_position) const {
         if (!columns_mapped()) {
             return tuple_position;
         }
@@ -404,7 +408,7 @@ private:
     // assumes positions are valid and the vector is not empty
     void set_column_mapping(std::vector<size_t> positions,
                             size_t number_of_columns) {
-        column_mappings_ = positions;
+        column_mappings_ = std::move(positions);
         number_of_columns_ = number_of_columns;
     }
 
@@ -425,7 +429,7 @@ private:
         }
 
         if constexpr (std::is_same_v<T, std::string>) {
-            extract(msg.first, msg.second, dst);
+            static_cast<void>(extract(msg.first, msg.second, dst));
             return;
         }
 
@@ -471,7 +475,8 @@ private:
     }
 
     template <typename... Ts>
-    no_void_validator_tup_t<Ts...> extract_tuple(const split_data& elems) {
+    [[nodiscard]] no_void_validator_tup_t<Ts...> extract_tuple(
+        const split_data& elems) {
         static_assert(!all_of_v<std::is_void, Ts...>,
                       "at least one parameter must be non void");
         no_void_validator_tup_t<Ts...> ret{};
@@ -490,7 +495,7 @@ private:
     friend class parser;
 
     std::vector<size_t> column_mappings_;
-    size_t number_of_columns_;
+    size_t number_of_columns_{0};
 };
 
-} /* ss */
+} /* namespace ss */
diff --git a/include/ss/exception.hpp b/include/ss/exception.hpp
index 97c714a..90f1441 100644
--- a/include/ss/exception.hpp
+++ b/include/ss/exception.hpp
@@ -12,12 +12,12 @@ class exception : public std::exception {
     std::string msg_;
 
 public:
-    exception(const std::string& msg): msg_{msg} {
+    exception(std::string msg) : msg_{std::move(msg)} {
     }
 
-    virtual char const* what() const noexcept {
+    [[nodiscard]] char const* what() const noexcept override {
         return msg_.c_str();
     }
 };
 
-} /* ss */
+} /* namespace ss */
diff --git a/include/ss/extract.hpp b/include/ss/extract.hpp
index 64b6b1b..58cea4e 100644
--- a/include/ss/extract.hpp
+++ b/include/ss/extract.hpp
@@ -2,8 +2,8 @@
 
 #include "type_traits.hpp"
 #include <charconv>
+#include <cstdint>
 #include <cstring>
-#include <functional>
 #include <optional>
 #include <string>
 #include <string_view>
@@ -13,6 +13,7 @@
 #include <fast_float/fast_float.h>
 #else
 #include <algorithm>
+#include <array>
 #include <cstdlib>
 #endif
 
@@ -25,8 +26,8 @@ namespace ss {
 #ifndef SSP_DISABLE_FAST_FLOAT
 
 template <typename T>
-std::enable_if_t<std::is_floating_point_v<T>, std::optional<T>> to_num(
-    const char* const begin, const char* const end) {
+[[nodiscard]] std::enable_if_t<std::is_floating_point_v<T>, std::optional<T>>
+to_num(const char* const begin, const char* const end) {
     T ret;
     auto [ptr, ec] = fast_float::from_chars(begin, end, ret);
 
@@ -39,22 +40,23 @@ std::enable_if_t<std::is_floating_point_v<T>, std::optional<T>> to_num(
 #else
 
 template <typename T>
-std::enable_if_t<std::is_floating_point_v<T>, std::optional<T>> to_num(
-    const char* const begin, const char* const end) {
+[[nodiscard]] std::enable_if_t<std::is_floating_point_v<T>, std::optional<T>>
+to_num(const char* const begin, const char* const end) {
     static_assert(!std::is_same_v<T, long double>,
                   "Conversion to long double is disabled");
 
     constexpr static auto buff_max = 64;
-    char short_buff[buff_max];
-    size_t string_range = std::distance(begin, end);
+    std::array<char, buff_max> short_buff;
+
+    const size_t string_range = std::distance(begin, end);
     std::string long_buff;
 
-    char* buff;
+    char* buff = nullptr;
     if (string_range > buff_max) {
         long_buff = std::string{begin, end};
         buff = long_buff.data();
     } else {
-        buff = short_buff;
+        buff = short_buff.data();
         buff[string_range] = '\0';
         std::copy_n(begin, string_range, buff);
     }
@@ -86,12 +88,14 @@ struct numeric_wrapper {
     using type = T;
 
     numeric_wrapper() = default;
-    numeric_wrapper(numeric_wrapper&&) = default;
+    numeric_wrapper(numeric_wrapper&&) noexcept = default;
     numeric_wrapper(const numeric_wrapper&) = default;
 
-    numeric_wrapper& operator=(numeric_wrapper&&) = default;
+    numeric_wrapper& operator=(numeric_wrapper&&) noexcept = default;
     numeric_wrapper& operator=(const numeric_wrapper&) = default;
 
+    ~numeric_wrapper() = default;
+
     numeric_wrapper(T other) : value{other} {
     }
 
@@ -110,7 +114,7 @@ using int8 = numeric_wrapper<int8_t>;
 using uint8 = numeric_wrapper<uint8_t>;
 
 template <typename T>
-std::enable_if_t<std::is_integral_v<T>, std::optional<T>> to_num(
+[[nodiscard]] std::enable_if_t<std::is_integral_v<T>, std::optional<T>> to_num(
     const char* const begin, const char* const end) {
     T ret;
     auto [ptr, ec] = std::from_chars(begin, end, ret);
@@ -122,8 +126,9 @@ std::enable_if_t<std::is_integral_v<T>, std::optional<T>> to_num(
 }
 
 template <typename T>
-std::enable_if_t<is_instance_of_v<numeric_wrapper, T>, std::optional<T>> to_num(
-    const char* const begin, const char* const end) {
+[[nodiscard]] std::enable_if_t<is_instance_of_v<numeric_wrapper, T>,
+                               std::optional<T>>
+to_num(const char* const begin, const char* const end) {
     T ret;
     auto [ptr, ec] = std::from_chars(begin, end, ret.value);
 
@@ -142,14 +147,15 @@ template <typename T>
 struct unsupported_type {
     constexpr static bool value = false;
 };
-} /* namespace */
+} /* namespace errors */
 
 template <typename T>
-std::enable_if_t<!std::is_integral_v<T> && !std::is_floating_point_v<T> &&
-                     !is_instance_of_v<std::optional, T> &&
-                     !is_instance_of_v<std::variant, T> &&
-                     !is_instance_of_v<numeric_wrapper, T>,
-                 bool>
+[[nodiscard]] std::enable_if_t<!std::is_integral_v<T> &&
+                                   !std::is_floating_point_v<T> &&
+                                   !is_instance_of_v<std::optional, T> &&
+                                   !is_instance_of_v<std::variant, T> &&
+                                   !is_instance_of_v<numeric_wrapper, T>,
+                               bool>
 extract(const char*, const char*, T&) {
     static_assert(error::unsupported_type<T>::value,
                   "Conversion for given type is not defined, an "
@@ -157,9 +163,10 @@ extract(const char*, const char*, T&) {
 }
 
 template <typename T>
-std::enable_if_t<std::is_integral_v<T> || std::is_floating_point_v<T> ||
-                     is_instance_of_v<numeric_wrapper, T>,
-                 bool>
+[[nodiscard]] std::enable_if_t<std::is_integral_v<T> ||
+                                   std::is_floating_point_v<T> ||
+                                   is_instance_of_v<numeric_wrapper, T>,
+                               bool>
 extract(const char* begin, const char* end, T& value) {
     auto optional_value = to_num<T>(begin, end);
     if (!optional_value) {
@@ -170,8 +177,8 @@ extract(const char* begin, const char* end, T& value) {
 }
 
 template <typename T>
-std::enable_if_t<is_instance_of_v<std::optional, T>, bool> extract(
-    const char* begin, const char* end, T& value) {
+[[nodiscard]] std::enable_if_t<is_instance_of_v<std::optional, T>, bool>
+extract(const char* begin, const char* end, T& value) {
     typename T::value_type raw_value;
     if (extract(begin, end, raw_value)) {
         value = raw_value;
@@ -182,7 +189,8 @@ std::enable_if_t<is_instance_of_v<std::optional, T>, bool> extract(
 }
 
 template <typename T, size_t I>
-bool extract_variant(const char* begin, const char* end, T& value) {
+[[nodiscard]] bool extract_variant(const char* begin, const char* end,
+                                   T& value) {
     using IthType = std::variant_alternative_t<I, std::decay_t<T>>;
     IthType ithValue;
     if (extract<IthType>(begin, end, ithValue)) {
@@ -195,7 +203,7 @@ bool extract_variant(const char* begin, const char* end, T& value) {
 }
 
 template <typename T>
-std::enable_if_t<is_instance_of_v<std::variant, T>, bool> extract(
+[[nodiscard]] std::enable_if_t<is_instance_of_v<std::variant, T>, bool> extract(
     const char* begin, const char* end, T& value) {
     return extract_variant<T, 0>(begin, end, value);
 }
@@ -205,7 +213,8 @@ std::enable_if_t<is_instance_of_v<std::variant, T>, bool> extract(
 ////////////////
 
 template <>
-inline bool extract(const char* begin, const char* end, bool& value) {
+[[nodiscard]] inline bool extract(const char* begin, const char* end,
+                                  bool& value) {
     if (end == begin + 1) {
         if (*begin == '1') {
             value = true;
@@ -215,10 +224,13 @@ inline bool extract(const char* begin, const char* end, bool& value) {
             return false;
         }
     } else {
-        size_t size = end - begin;
-        if (size == 4 && std::strncmp(begin, "true", size) == 0) {
+        constexpr static auto true_size = 4;
+        constexpr static auto false_size = 5;
+        const size_t size = end - begin;
+        if (size == true_size && std::strncmp(begin, "true", size) == 0) {
             value = true;
-        } else if (size == 5 && std::strncmp(begin, "false", size) == 0) {
+        } else if (size == false_size &&
+                   std::strncmp(begin, "false", size) == 0) {
             value = false;
         } else {
             return false;
@@ -229,22 +241,24 @@ inline bool extract(const char* begin, const char* end, bool& value) {
 }
 
 template <>
-inline bool extract(const char* begin, const char* end, char& value) {
+[[nodiscard]] inline bool extract(const char* begin, const char* end,
+                                  char& value) {
     value = *begin;
     return (end == begin + 1);
 }
 
 template <>
-inline bool extract(const char* begin, const char* end, std::string& value) {
+[[nodiscard]] inline bool extract(const char* begin, const char* end,
+                                  std::string& value) {
     value = std::string{begin, end};
     return true;
 }
 
 template <>
-inline bool extract(const char* begin, const char* end,
-                    std::string_view& value) {
+[[nodiscard]] inline bool extract(const char* begin, const char* end,
+                                  std::string_view& value) {
     value = std::string_view{begin, static_cast<size_t>(end - begin)};
     return true;
 }
 
-} /* ss */
+} /* namespace ss */
diff --git a/include/ss/function_traits.hpp b/include/ss/function_traits.hpp
index c22a936..b71df1b 100644
--- a/include/ss/function_traits.hpp
+++ b/include/ss/function_traits.hpp
@@ -2,7 +2,6 @@
 
 #include <cstdlib>
 #include <functional>
-#include <tuple>
 
 namespace ss {
 
@@ -77,4 +76,4 @@ struct member_wrapper<R T::*> {
     template <typename T>                                                      \
     constexpr bool has_m_##method##_t = has_m_##method<T>::value;
 
-} /* trait */
+} /* namespace ss */
diff --git a/include/ss/parser.hpp b/include/ss/parser.hpp
index e800593..b054328 100644
--- a/include/ss/parser.hpp
+++ b/include/ss/parser.hpp
@@ -5,7 +5,6 @@
 #include "exception.hpp"
 #include "extract.hpp"
 #include "restrictions.hpp"
-#include <cerrno>
 #include <cstdlib>
 #include <cstring>
 #include <optional>
@@ -32,10 +31,12 @@ class parser {
 
     constexpr static bool ignore_empty = setup<Options...>::ignore_empty;
 
+    using header_splitter = ss::splitter<
+        ss::filter_not_t<ss::is_instance_of_multiline, Options...>>;
+
 public:
-    parser(const std::string& file_name,
-           const std::string& delim = ss::default_delimiter)
-        : file_name_{file_name}, reader_{file_name_, delim} {
+    parser(std::string file_name, std::string delim = ss::default_delimiter)
+        : file_name_{std::move(file_name)}, reader_{file_name_, delim} {
         if (reader_.file_) {
             read_line();
             if constexpr (ignore_header) {
@@ -51,7 +52,7 @@ public:
 
     parser(const char* const csv_data_buffer, size_t csv_data_size,
            const std::string& delim = ss::default_delimiter)
-        : file_name_{"buffer line"},
+        : file_name_{"CSV data buffer"},
           reader_{csv_data_buffer, csv_data_size, delim} {
         if (csv_data_buffer) {
             read_line();
@@ -66,14 +67,15 @@ public:
         }
     }
 
-    parser(parser&& other) = default;
-    parser& operator=(parser&& other) = default;
+    parser(parser&& other) noexcept = default;
+    parser& operator=(parser&& other) noexcept = default;
+    ~parser() = default;
 
     parser() = delete;
     parser(const parser& other) = delete;
     parser& operator=(const parser& other) = delete;
 
-    bool valid() const {
+    [[nodiscard]] bool valid() const {
         if constexpr (string_error) {
             return error_.empty();
         } else if constexpr (throw_on_error) {
@@ -83,12 +85,12 @@ public:
         }
     }
 
-    const std::string& error_msg() const {
+    [[nodiscard]] const std::string& error_msg() const {
         assert_string_error_defined<string_error>();
         return error_;
     }
 
-    bool eof() const {
+    [[nodiscard]] bool eof() const {
         return eof_;
     }
 
@@ -97,23 +99,21 @@ public:
     }
 
     template <typename T, typename... Ts>
-    T get_object() {
+    [[nodiscard]] T get_object() {
         return to_object<T>(get_next<Ts...>());
     }
 
-    size_t line() const {
+    [[nodiscard]] size_t line() const {
         return reader_.line_number_ > 0 ? reader_.line_number_ - 1
                                         : reader_.line_number_;
     }
 
-    size_t position() const {
+    [[nodiscard]] size_t position() const {
         return reader_.chars_read_;
     }
 
     template <typename T, typename... Ts>
-    no_void_validator_tup_t<T, Ts...> get_next() {
-        std::optional<std::string> error;
-
+    [[nodiscard]] no_void_validator_tup_t<T, Ts...> get_next() {
         if (!eof_) {
             if constexpr (throw_on_error) {
                 try {
@@ -162,20 +162,49 @@ public:
         return value;
     }
 
-    bool field_exists(const std::string& field) {
+    [[nodiscard]] std::string raw_header() const {
+        assert_ignore_header_not_defined();
+        return raw_header_;
+    }
+
+    [[nodiscard]] std::vector<std::string> header() {
+        assert_ignore_header_not_defined();
+        clear_error();
+
+        header_splitter splitter;
+        std::string raw_header_copy = raw_header_;
+
+        if (!strict_split(splitter, raw_header_copy)) {
+            return {};
+        }
+
+        std::vector<std::string> split_header;
+        for (const auto& [begin, end] : splitter.get_split_data()) {
+            split_header.emplace_back(begin, end);
+        }
+
+        return split_header;
+    }
+
+    [[nodiscard]] bool field_exists(const std::string& field) {
+        assert_ignore_header_not_defined();
+        clear_error();
+
         if (header_.empty()) {
             split_header_data();
         }
 
+        if (!valid()) {
+            return false;
+        }
+
         return header_index(field).has_value();
     }
 
     template <typename... Ts>
     void use_fields(const Ts&... fields_args) {
-        if constexpr (ignore_header) {
-            handle_error_header_ignored();
-            return;
-        }
+        assert_ignore_header_not_defined();
+        clear_error();
 
         if (header_.empty() && !eof()) {
             split_header_data();
@@ -188,7 +217,7 @@ public:
         auto fields = std::vector<std::string>{fields_args...};
 
         if (fields.empty()) {
-            handle_error_empty_mapping();
+            handle_error_invalid_use_fields_argument();
             return;
         }
 
@@ -236,13 +265,17 @@ public:
             }
 
             iterator(const iterator& other) = default;
-            iterator(iterator&& other) = default;
+            iterator(iterator&& other) noexcept = default;
+            ~iterator() = default;
 
-            value& operator*() {
+            iterator& operator=(const iterator& other) = delete;
+            iterator& operator=(iterator&& other) noexcept = delete;
+
+            [[nodiscard]] value& operator*() {
                 return value_;
             }
 
-            value* operator->() {
+            [[nodiscard]] value* operator->() {
                 return &value_;
             }
 
@@ -261,17 +294,21 @@ public:
                 return *this;
             }
 
-            iterator& operator++(int) {
-                return ++*this;
+            iterator operator++(int) {
+                auto result = *this;
+                ++*this;
+                return result;
             }
 
-            friend bool operator==(const iterator& lhs, const iterator& rhs) {
+            [[nodiscard]] friend bool operator==(const iterator& lhs,
+                                                 const iterator& rhs) {
                 return (lhs.parser_ == nullptr && rhs.parser_ == nullptr) ||
                        (lhs.parser_ == rhs.parser_ &&
                         &lhs.value_ == &rhs.value_);
             }
 
-            friend bool operator!=(const iterator& lhs, const iterator& rhs) {
+            [[nodiscard]] friend bool operator!=(const iterator& lhs,
+                                                 const iterator& rhs) {
                 return !(lhs == rhs);
             }
 
@@ -283,11 +320,11 @@ public:
         iterable(parser<Options...>* parser) : parser_{parser} {
         }
 
-        iterator begin() {
+        [[nodiscard]] iterator begin() {
             return ++iterator{parser_};
         }
 
-        iterator end() {
+        [[nodiscard]] iterator end() {
             return iterator{};
         }
 
@@ -296,12 +333,12 @@ public:
     };
 
     template <typename... Ts>
-    auto iterate() {
+    [[nodiscard]] auto iterate() {
         return iterable<false, Ts...>{this};
     }
 
     template <typename... Ts>
-    auto iterate_object() {
+    [[nodiscard]] auto iterate_object() {
         return iterable<true, Ts...>{this};
     }
 
@@ -326,7 +363,7 @@ public:
             Fun&& fun = none{}) {
             using Value = no_void_validator_tup_t<Us...>;
             std::optional<Value> value;
-            try_convert_and_invoke<Value, Us...>(value, fun);
+            try_convert_and_invoke<Value, Us...>(value, std::forward<Fun>(fun));
             return composite_with(std::move(value));
         }
 
@@ -335,11 +372,11 @@ public:
         template <typename U, typename... Us, typename Fun = none>
         composite<Ts..., std::optional<U>> or_object(Fun&& fun = none{}) {
             std::optional<U> value;
-            try_convert_and_invoke<U, Us...>(value, fun);
+            try_convert_and_invoke<U, Us...>(value, std::forward<Fun>(fun));
             return composite_with(std::move(value));
         }
 
-        std::tuple<Ts...> values() {
+        [[nodiscard]] std::tuple<Ts...> values() {
             return values_;
         }
 
@@ -362,7 +399,7 @@ public:
 
     private:
         template <typename T>
-        composite<Ts..., T> composite_with(T&& new_value) {
+        [[nodiscard]] composite<Ts..., T> composite_with(T&& new_value) {
             auto merged_values =
                 std::tuple_cat(std::move(values_),
                                std::tuple<T>{parser_.valid()
@@ -392,7 +429,7 @@ public:
         }
 
         template <typename U, typename... Us>
-        no_void_validator_tup_t<U, Us...> try_same() {
+        [[nodiscard]] no_void_validator_tup_t<U, Us...> try_same() {
             parser_.clear_error();
             auto value =
                 parser_.reader_.converter_.template convert<U, Us...>();
@@ -413,8 +450,8 @@ public:
     // tries to convert a line and returns a composite which is
     // able to try additional conversions in case of failure
     template <typename... Ts, typename Fun = none>
-    composite<std::optional<no_void_validator_tup_t<Ts...>>> try_next(
-        Fun&& fun = none{}) {
+    [[nodiscard]] composite<std::optional<no_void_validator_tup_t<Ts...>>>
+    try_next(Fun&& fun = none{}) {
         assert_throw_on_error_not_defined<throw_on_error>();
         using Ret = no_void_validator_tup_t<Ts...>;
         return try_invoke_and_make_composite<
@@ -424,7 +461,7 @@ public:
     // identical to try_next but returns composite with object instead of a
     // tuple
     template <typename T, typename... Ts, typename Fun = none>
-    composite<std::optional<T>> try_object(Fun&& fun = none{}) {
+    [[nodiscard]] composite<std::optional<T>> try_object(Fun&& fun = none{}) {
         assert_throw_on_error_not_defined<throw_on_error>();
         return try_invoke_and_make_composite<
             std::optional<T>>(get_object<T, Ts...>(), std::forward<Fun>(fun));
@@ -443,7 +480,8 @@ private:
             using Ret = decltype(try_invoke_impl(arg, std::forward<Fun>(fun)));
             constexpr bool returns_void = std::is_same_v<Ret, void>;
             if constexpr (!returns_void) {
-                if (!try_invoke_impl(arg, std::forward<Fun>(fun))) {
+                if (!try_invoke_impl(std::forward<Arg>(arg),
+                                     std::forward<Fun>(fun))) {
                     handle_error_failed_check();
                 }
             } else {
@@ -474,26 +512,55 @@ private:
     }
 
     template <typename T, typename Fun = none>
-    composite<T> try_invoke_and_make_composite(T&& value, Fun&& fun) {
+    [[nodiscard]] composite<T> try_invoke_and_make_composite(T&& value,
+                                                             Fun&& fun) {
         if (valid()) {
             try_invoke(*value, std::forward<Fun>(fun));
         }
-        return {valid() ? std::move(value) : std::nullopt, *this};
+        return {valid() ? std::forward<T>(value) : std::nullopt, *this};
     }
 
     ////////////////
     // header
     ////////////////
 
+    void assert_ignore_header_not_defined() const {
+        static_assert(!ignore_header,
+                      "cannot use this method when 'ignore_header' is defined");
+    }
+
+    [[nodiscard]] bool strict_split(header_splitter& splitter,
+                                    std::string& header) {
+        if constexpr (throw_on_error) {
+            try {
+                splitter.split(header.data(), reader_.delim_);
+            } catch (const ss::exception& e) {
+                decorate_rethrow_invalid_header_split(e);
+            }
+        } else {
+            splitter.split(header.data(), reader_.delim_);
+            if (!splitter.valid()) {
+                handle_error_invalid_header_split(splitter);
+                return false;
+            }
+        }
+
+        return true;
+    }
+
     void split_header_data() {
-        ss::splitter<Options...> splitter;
+        header_splitter splitter;
         std::string raw_header_copy = raw_header_;
-        splitter.split(raw_header_copy.data(), reader_.delim_);
-        for (const auto& [begin, end] : splitter.split_data_) {
+
+        if (!strict_split(splitter, raw_header_copy)) {
+            return;
+        }
+
+        for (const auto& [begin, end] : splitter.get_split_data()) {
             std::string field{begin, end};
             if (std::find(header_.begin(), header_.end(), field) !=
                 header_.end()) {
-                handle_error_invalid_header(field);
+                handle_error_duplicate_header_field(field);
                 header_.clear();
                 return;
             }
@@ -501,7 +568,7 @@ private:
         }
     }
 
-    std::optional<size_t> header_index(const std::string& field) {
+    [[nodiscard]] std::optional<size_t> header_index(const std::string& field) {
         auto it = std::find(header_.begin(), header_.end(), field);
 
         if (it == header_.end()) {
@@ -524,7 +591,7 @@ private:
     }
 
     void handle_error_failed_check() {
-        constexpr static auto error_msg = " failed check";
+        constexpr static auto error_msg = ": failed check";
 
         if constexpr (string_error) {
             error_.clear();
@@ -537,7 +604,7 @@ private:
     }
 
     void handle_error_null_buffer() {
-        constexpr static auto error_msg = " received null data buffer";
+        constexpr static auto error_msg = ": received null data buffer";
 
         if constexpr (string_error) {
             error_.clear();
@@ -550,7 +617,7 @@ private:
     }
 
     void handle_error_file_not_open() {
-        constexpr static auto error_msg = " could not be opened";
+        constexpr static auto error_msg = ": could not be opened";
 
         if constexpr (string_error) {
             error_.clear();
@@ -563,7 +630,7 @@ private:
     }
 
     void handle_error_eof_reached() {
-        constexpr static auto error_msg = " read on end of file";
+        constexpr static auto error_msg = ": read on end of file";
 
         if constexpr (string_error) {
             error_.clear();
@@ -588,20 +655,6 @@ private:
         }
     }
 
-    void handle_error_header_ignored() {
-        constexpr static auto error_msg =
-            ": the header row is ignored within the setup it cannot be used";
-
-        if constexpr (string_error) {
-            error_.clear();
-            error_.append(file_name_).append(error_msg);
-        } else if constexpr (throw_on_error) {
-            throw ss::exception{file_name_ + error_msg};
-        } else {
-            error_ = true;
-        }
-    }
-
     void handle_error_invalid_field(const std::string& field) {
         constexpr static auto error_msg =
             ": header does not contain given field: ";
@@ -629,8 +682,9 @@ private:
         }
     }
 
-    void handle_error_empty_mapping() {
-        constexpr static auto error_msg = "received empty mapping";
+    void handle_error_invalid_use_fields_argument() {
+        constexpr static auto error_msg =
+            "received invalid argument for 'use_fields'";
 
         if constexpr (string_error) {
             error_.clear();
@@ -642,19 +696,53 @@ private:
         }
     }
 
-    void handle_error_invalid_header(const std::string& field) {
-        constexpr static auto error_msg = "header contains duplicates: ";
+    void handle_error_invalid_header_field() {
+        constexpr static auto error_msg = ": header contains empty field";
 
         if constexpr (string_error) {
             error_.clear();
-            error_.append(error_msg).append(error_msg);
+            error_.append(file_name_).append(error_msg);
         } else if constexpr (throw_on_error) {
-            throw ss::exception{error_msg + field};
+            throw ss::exception{file_name_ + error_msg};
         } else {
             error_ = true;
         }
     }
 
+    void handle_error_duplicate_header_field(const std::string& field) {
+        constexpr static auto error_msg = ": header contains duplicate: ";
+
+        if constexpr (string_error) {
+            error_.clear();
+            error_.append(file_name_).append(error_msg).append(field);
+        } else if constexpr (throw_on_error) {
+            throw ss::exception{file_name_ + error_msg + field};
+        } else {
+            error_ = true;
+        }
+    }
+
+    void handle_error_invalid_header_split(const header_splitter& splitter) {
+        constexpr static auto error_msg = ": failed header parsing: ";
+
+        if constexpr (string_error) {
+            error_.clear();
+            error_.append(file_name_)
+                .append(error_msg)
+                .append(splitter.error_msg());
+        } else {
+            error_ = true;
+        }
+    }
+
+    void decorate_rethrow_invalid_header_split(const ss::exception& e) const {
+        static_assert(throw_on_error,
+                      "throw_on_error needs to be enabled to use this method");
+        throw ss::exception{std::string{file_name_}
+                                .append(": failed header parsing: ")
+                                .append(e.what())};
+    }
+
     void decorate_rethrow(const ss::exception& e) const {
         static_assert(throw_on_error,
                       "throw_on_error needs to be enabled to use this method");
@@ -674,17 +762,18 @@ private:
     }
 
     struct reader {
-        reader(const std::string& file_name_, const std::string& delim)
-            : delim_{delim}, file_{std::fopen(file_name_.c_str(), "rb")} {
+        reader(const std::string& file_name_, std::string delim)
+            : delim_{std::move(delim)},
+              file_{std::fopen(file_name_.c_str(), "rb")} {
         }
 
         reader(const char* const buffer, size_t csv_data_size,
-               const std::string& delim)
-            : delim_{delim}, csv_data_buffer_{buffer},
+               std::string delim)
+            : delim_{std::move(delim)}, csv_data_buffer_{buffer},
               csv_data_size_{csv_data_size} {
         }
 
-        reader(reader&& other)
+        reader(reader&& other) noexcept
             : buffer_{other.buffer_},
               next_line_buffer_{other.next_line_buffer_},
               helper_buffer_{other.helper_buffer_},
@@ -705,7 +794,7 @@ private:
             other.file_ = nullptr;
         }
 
-        reader& operator=(reader&& other) {
+        reader& operator=(reader&& other) noexcept {
             if (this != &other) {
                 buffer_ = other.buffer_;
                 next_line_buffer_ = other.next_line_buffer_;
@@ -741,7 +830,7 @@ private:
             std::free(helper_buffer_);
 
             if (file_) {
-                std::fclose(file_);
+                std::ignore = std::fclose(file_);
             }
         }
 
@@ -750,7 +839,7 @@ private:
         reader& operator=(const reader& other) = delete;
 
         // read next line each time in order to set eof_
-        bool read_next() {
+        [[nodiscard]] bool read_next() {
             next_line_converter_.clear_error();
             size_t size = 0;
             while (size == 0) {
@@ -842,7 +931,7 @@ private:
             std::swap(converter_, next_line_converter_);
         }
 
-        bool multiline_limit_reached(size_t& limit) {
+        [[nodiscard]] bool multiline_limit_reached(size_t& limit) {
             if constexpr (multiline::size > 0) {
                 if (limit++ >= multiline::size) {
                     next_line_converter_.handle_error_multiline_limit_reached();
@@ -852,8 +941,8 @@ private:
             return false;
         }
 
-        bool escaped_eol(size_t size) {
-            const char* curr;
+        [[nodiscard]] bool escaped_eol(size_t size) {
+            const char* curr = nullptr;
             for (curr = next_line_buffer_ + size - 1;
                  curr >= next_line_buffer_ &&
                  setup<Options...>::escape::match(*curr);
@@ -862,7 +951,7 @@ private:
             return (next_line_buffer_ - curr + size) % 2 == 0;
         }
 
-        bool unterminated_quote() {
+        [[nodiscard]] bool unterminated_quote() {
             return next_line_converter_.unterminated_quote();
         }
 
@@ -877,7 +966,7 @@ private:
             }
         }
 
-        size_t remove_eol(char*& buffer, size_t ssize) {
+        [[nodiscard]] size_t remove_eol(char*& buffer, size_t ssize) {
             if (buffer[ssize - 1] != '\n') {
                 crlf_ = false;
                 return ssize;
@@ -899,7 +988,7 @@ private:
                             size_t& buffer_size, const char* const second,
                             size_t second_size) {
             buffer_size = first_size + second_size + 3;
-            auto new_first = static_cast<char*>(
+            auto* new_first = static_cast<char*>(
                 strict_realloc(static_cast<void*>(first), buffer_size));
 
             first = new_first;
@@ -907,8 +996,9 @@ private:
             first_size += second_size;
         }
 
-        bool append_next_line_to_buffer(char*& buffer, size_t& line_size,
-                                        size_t buffer_size) {
+        [[nodiscard]] bool append_next_line_to_buffer(char*& buffer,
+                                                      size_t& line_size,
+                                                      size_t buffer_size) {
             undo_remove_eol(buffer, line_size, buffer_size);
 
             chars_read_ = curr_char_;
@@ -927,8 +1017,8 @@ private:
             return true;
         }
 
-        std::string get_buffer() {
-            return std::string{next_line_buffer_, next_line_buffer_size_};
+        [[nodiscard]] std::string get_buffer() {
+            return std::string{next_line_buffer_, next_line_size_};
         }
 
         ////////////////
@@ -971,4 +1061,4 @@ private:
     bool eof_{false};
 };
 
-} /* ss */
+} /* namespace ss */
diff --git a/include/ss/restrictions.hpp b/include/ss/restrictions.hpp
index e72611e..bcd8335 100644
--- a/include/ss/restrictions.hpp
+++ b/include/ss/restrictions.hpp
@@ -10,7 +10,7 @@ template <typename T, auto... Values>
 struct ax {
 private:
     template <auto X, auto... Xs>
-    bool ss_valid_impl(const T& x) const {
+    [[nodiscard]] bool ss_valid_impl(const T& x) const {
         if constexpr (sizeof...(Xs) != 0) {
             return x != X && ss_valid_impl<Xs...>(x);
         }
@@ -18,11 +18,11 @@ private:
     }
 
 public:
-    bool ss_valid(const T& value) const {
+    [[nodiscard]] bool ss_valid(const T& value) const {
         return ss_valid_impl<Values...>(value);
     }
 
-    const char* error() const {
+    [[nodiscard]] const char* error() const {
         return "value excluded";
     }
 };
@@ -35,7 +35,7 @@ template <typename T, auto... Values>
 struct nx {
 private:
     template <auto X, auto... Xs>
-    bool ss_valid_impl(const T& x) const {
+    [[nodiscard]] bool ss_valid_impl(const T& x) const {
         if constexpr (sizeof...(Xs) != 0) {
             return x == X || ss_valid_impl<Xs...>(x);
         }
@@ -43,11 +43,11 @@ private:
     }
 
 public:
-    bool ss_valid(const T& value) const {
+    [[nodiscard]] bool ss_valid(const T& value) const {
         return ss_valid_impl<Values...>(value);
     }
 
-    const char* error() const {
+    [[nodiscard]] const char* error() const {
         return "value excluded";
     }
 };
@@ -61,28 +61,28 @@ public:
 
 template <typename T, auto N>
 struct gt {
-    bool ss_valid(const T& value) const {
+    [[nodiscard]] bool ss_valid(const T& value) const {
         return value > N;
     }
 };
 
 template <typename T, auto N>
 struct gte {
-    bool ss_valid(const T& value) const {
+    [[nodiscard]] bool ss_valid(const T& value) const {
         return value >= N;
     }
 };
 
 template <typename T, auto N>
 struct lt {
-    bool ss_valid(const T& value) const {
+    [[nodiscard]] bool ss_valid(const T& value) const {
         return value < N;
     }
 };
 
 template <typename T, auto N>
 struct lte {
-    bool ss_valid(const T& value) const {
+    [[nodiscard]] bool ss_valid(const T& value) const {
         return value <= N;
     }
 };
@@ -93,7 +93,7 @@ struct lte {
 
 template <typename T, auto Min, auto Max>
 struct ir {
-    bool ss_valid(const T& value) const {
+    [[nodiscard]] bool ss_valid(const T& value) const {
         return value >= Min && value <= Max;
     }
 };
@@ -104,7 +104,7 @@ struct ir {
 
 template <typename T, auto Min, auto Max>
 struct oor {
-    bool ss_valid(const T& value) const {
+    [[nodiscard]] bool ss_valid(const T& value) const {
         return value < Min || value > Max;
     }
 };
@@ -115,13 +115,13 @@ struct oor {
 
 template <typename T>
 struct ne {
-    bool ss_valid(const T& value) const {
+    [[nodiscard]] bool ss_valid(const T& value) const {
         return !value.empty();
     }
 
-    const char* error() const {
+    [[nodiscard]] const char* error() const {
         return "empty field";
     }
 };
 
-} /* ss */
+} /* namespace ss */
diff --git a/include/ss/setup.hpp b/include/ss/setup.hpp
index 2f298fc..d0172ba 100644
--- a/include/ss/setup.hpp
+++ b/include/ss/setup.hpp
@@ -293,4 +293,7 @@ private:
 template <typename... Options>
 struct setup<setup<Options...>> : setup<Options...> {};
 
-} /* ss */
+template <typename... Options>
+struct setup<std::tuple<Options...>> : setup<Options...> {};
+
+} /* namespace ss */
diff --git a/include/ss/splitter.hpp b/include/ss/splitter.hpp
index d974e83..0f06499 100644
--- a/include/ss/splitter.hpp
+++ b/include/ss/splitter.hpp
@@ -2,11 +2,9 @@
 #include "common.hpp"
 #include "exception.hpp"
 #include "setup.hpp"
-#include "type_traits.hpp"
 #include <algorithm>
 #include <cstdlib>
 #include <cstring>
-#include <memory>
 #include <string>
 #include <vector>
 
@@ -30,7 +28,7 @@ private:
 public:
     using line_ptr_type = std::conditional_t<is_const_line, const char*, char*>;
 
-    bool valid() const {
+    [[nodiscard]] bool valid() const {
         if constexpr (string_error) {
             return error_.empty();
         } else if constexpr (throw_on_error) {
@@ -40,12 +38,12 @@ public:
         }
     }
 
-    const std::string& error_msg() const {
+    [[nodiscard]] const std::string& error_msg() const {
         assert_string_error_defined<string_error>();
         return error_;
     }
 
-    bool unterminated_quote() const {
+    [[nodiscard]] bool unterminated_quote() const {
         return unterminated_quote_;
     }
 
@@ -57,13 +55,21 @@ public:
         return split_impl_select_delim(delimiter);
     }
 
+    [[nodiscard]] const split_data& get_split_data() const {
+        return split_data_;
+    }
+
+    void clear_split_data() {
+        split_data_.clear();
+    }
+
 private:
     ////////////////
     // resplit
     ////////////////
 
     // number of characters the end of line is shifted backwards
-    size_t size_shifted() const {
+    [[nodiscard]] size_t size_shifted() const {
         return escaped_;
     }
 
@@ -86,7 +92,7 @@ private:
         }
 
         const auto [old_line, old_begin] = *std::prev(split_data_.end());
-        size_t begin = old_begin - old_line - 1;
+        const size_t begin = old_begin - old_line - 1;
 
         // safety measure
         if (new_size != -1 && static_cast<size_t>(new_size) < begin) {
@@ -194,19 +200,19 @@ private:
     // matching
     ////////////////
 
-    bool match(const char* const curr, char delim) {
+    [[nodiscard]] bool match(const char* const curr, char delim) {
         return *curr == delim;
     };
 
-    bool match(const char* const curr, const std::string& delim) {
+    [[nodiscard]] bool match(const char* const curr, const std::string& delim) {
         return std::strncmp(curr, delim.c_str(), delim.size()) == 0;
     };
 
-    size_t delimiter_size(char) {
+    [[nodiscard]] size_t delimiter_size(char) {
         return 1;
     }
 
-    size_t delimiter_size(const std::string& delim) {
+    [[nodiscard]] size_t delimiter_size(const std::string& delim) {
         return delim.size();
     }
 
@@ -227,8 +233,8 @@ private:
     }
 
     template <typename Delim>
-    std::tuple<size_t, bool> match_delimiter(line_ptr_type begin,
-                                             const Delim& delim) {
+    [[nodiscard]] std::tuple<size_t, bool> match_delimiter(line_ptr_type begin,
+                                                           const Delim& delim) {
         line_ptr_type end = begin;
 
         trim_right_if_enabled(end);
@@ -322,8 +328,9 @@ private:
 
         trim_left_if_enabled(begin_);
 
-        for (done_ = false; !done_; read(delim))
-            ;
+        for (done_ = false; !done_;) {
+            read(delim);
+        }
 
         return split_data_;
     }
@@ -462,7 +469,6 @@ private:
     // members
     ////////////////
 
-public:
     error_type error_{};
     bool unterminated_quote_{false};
     bool done_{true};
@@ -479,4 +485,4 @@ public:
     friend class converter;
 };
 
-} /* ss */
+} /* namespace ss */
diff --git a/include/ss/type_traits.hpp b/include/ss/type_traits.hpp
index 294b8bb..0f8a776 100644
--- a/include/ss/type_traits.hpp
+++ b/include/ss/type_traits.hpp
@@ -34,7 +34,11 @@ struct left_of_impl;
 
 template <size_t N, typename T, typename... Ts>
 struct left_of_impl {
-    static_assert(N < 128, "recursion limit reached");
+private:
+    constexpr static auto recursion_limit = 128;
+
+public:
+    static_assert(N < recursion_limit, "recursion limit reached");
     static_assert(N != 0, "cannot take the whole tuple");
     using type = tup_cat_t<T, typename left_of_impl<N - 1, Ts...>::type>;
 };
@@ -362,12 +366,12 @@ constexpr bool is_instance_of_v = is_instance_of<Template, Ts...>::value;
 ////////////////
 
 template <class T, std::size_t... Is, class U>
-T to_object_impl(std::index_sequence<Is...>, U&& data) {
+[[nodiscard]] T to_object_impl(std::index_sequence<Is...>, U&& data) {
     return {std::get<Is>(std::forward<U>(data))...};
 }
 
 template <class T, class U>
-T to_object(U&& data) {
+[[nodiscard]] T to_object(U&& data) {
     using NoRefU = std::decay_t<U>;
     if constexpr (is_instance_of_v<std::tuple, NoRefU>) {
         return to_object_impl<
@@ -378,4 +382,4 @@ T to_object(U&& data) {
     }
 }
 
-} /* trait */
+} /* namespace ss */
diff --git a/script/single_header_generator.py b/script/single_header_generator.py
index 91c9dcc..7aa9bfc 100755
--- a/script/single_header_generator.py
+++ b/script/single_header_generator.py
@@ -14,14 +14,21 @@ headers = ['type_traits.hpp',
 
 combined_file = []
 includes = []
+in_pp_block = False
 
 for header in headers:
     with open(headers_dir + header) as f:
         for line in f.read().splitlines():
+            if '#if ' in line:
+                in_pp_block = True
+
+            if '#endif' in line:
+                in_pp_block = False
+
             if '#include "' in line or '#include <fast_float' in line:
                 continue
 
-            if '#include <' in line:
+            if '#include <' in line and not in_pp_block:
                 includes.append(line)
                 continue
 
@@ -30,6 +37,7 @@ for header in headers:
 
 includes = sorted(set(includes))
 
+print('#pragma once')
 print('\n'.join(includes))
 print('#define SSP_DISABLE_FAST_FLOAT')
 print('\n'.join(combined_file))
diff --git a/ssp.hpp b/ssp.hpp
index 811a490..0fc4cd3 100644
--- a/ssp.hpp
+++ b/ssp.hpp
@@ -1,3 +1,4 @@
+#pragma once
 #include <algorithm>
 #include <array>
 #include <cerrno>
@@ -8,7 +9,6 @@
 #include <cstring>
 #include <exception>
 #include <functional>
-#include <memory>
 #include <optional>
 #include <string>
 #include <string_view>
@@ -50,7 +50,11 @@ struct left_of_impl;
 
 template <size_t N, typename T, typename... Ts>
 struct left_of_impl {
-    static_assert(N < 128, "recursion limit reached");
+private:
+    constexpr static auto recursion_limit = 128;
+
+public:
+    static_assert(N < recursion_limit, "recursion limit reached");
     static_assert(N != 0, "cannot take the whole tuple");
     using type = tup_cat_t<T, typename left_of_impl<N - 1, Ts...>::type>;
 };
@@ -378,12 +382,12 @@ constexpr bool is_instance_of_v = is_instance_of<Template, Ts...>::value;
 ////////////////
 
 template <class T, std::size_t... Is, class U>
-T to_object_impl(std::index_sequence<Is...>, U&& data) {
+[[nodiscard]] T to_object_impl(std::index_sequence<Is...>, U&& data) {
     return {std::get<Is>(std::forward<U>(data))...};
 }
 
 template <class T, class U>
-T to_object(U&& data) {
+[[nodiscard]] T to_object(U&& data) {
     using NoRefU = std::decay_t<U>;
     if constexpr (is_instance_of_v<std::tuple, NoRefU>) {
         return to_object_impl<
@@ -394,7 +398,7 @@ T to_object(U&& data) {
     }
 }
 
-} /* trait */
+} /* namespace ss */
 
 namespace ss {
 
@@ -406,15 +410,15 @@ class exception : public std::exception {
     std::string msg_;
 
 public:
-    exception(const std::string& msg): msg_{msg} {
+    exception(std::string msg) : msg_{std::move(msg)} {
     }
 
-    virtual char const* what() const noexcept {
+    [[nodiscard]] char const* what() const noexcept override {
         return msg_.c_str();
     }
 };
 
-} /* ss */
+} /* namespace ss */
 
 
 namespace ss {
@@ -490,7 +494,7 @@ struct member_wrapper<R T::*> {
     template <typename T>                                                      \
     constexpr bool has_m_##method##_t = has_m_##method<T>::value;
 
-} /* trait */
+} /* namespace ss */
 
 namespace ss {
 
@@ -502,7 +506,7 @@ template <typename T, auto... Values>
 struct ax {
 private:
     template <auto X, auto... Xs>
-    bool ss_valid_impl(const T& x) const {
+    [[nodiscard]] bool ss_valid_impl(const T& x) const {
         if constexpr (sizeof...(Xs) != 0) {
             return x != X && ss_valid_impl<Xs...>(x);
         }
@@ -510,11 +514,11 @@ private:
     }
 
 public:
-    bool ss_valid(const T& value) const {
+    [[nodiscard]] bool ss_valid(const T& value) const {
         return ss_valid_impl<Values...>(value);
     }
 
-    const char* error() const {
+    [[nodiscard]] const char* error() const {
         return "value excluded";
     }
 };
@@ -527,7 +531,7 @@ template <typename T, auto... Values>
 struct nx {
 private:
     template <auto X, auto... Xs>
-    bool ss_valid_impl(const T& x) const {
+    [[nodiscard]] bool ss_valid_impl(const T& x) const {
         if constexpr (sizeof...(Xs) != 0) {
             return x == X || ss_valid_impl<Xs...>(x);
         }
@@ -535,11 +539,11 @@ private:
     }
 
 public:
-    bool ss_valid(const T& value) const {
+    [[nodiscard]] bool ss_valid(const T& value) const {
         return ss_valid_impl<Values...>(value);
     }
 
-    const char* error() const {
+    [[nodiscard]] const char* error() const {
         return "value excluded";
     }
 };
@@ -553,28 +557,28 @@ public:
 
 template <typename T, auto N>
 struct gt {
-    bool ss_valid(const T& value) const {
+    [[nodiscard]] bool ss_valid(const T& value) const {
         return value > N;
     }
 };
 
 template <typename T, auto N>
 struct gte {
-    bool ss_valid(const T& value) const {
+    [[nodiscard]] bool ss_valid(const T& value) const {
         return value >= N;
     }
 };
 
 template <typename T, auto N>
 struct lt {
-    bool ss_valid(const T& value) const {
+    [[nodiscard]] bool ss_valid(const T& value) const {
         return value < N;
     }
 };
 
 template <typename T, auto N>
 struct lte {
-    bool ss_valid(const T& value) const {
+    [[nodiscard]] bool ss_valid(const T& value) const {
         return value <= N;
     }
 };
@@ -585,7 +589,7 @@ struct lte {
 
 template <typename T, auto Min, auto Max>
 struct ir {
-    bool ss_valid(const T& value) const {
+    [[nodiscard]] bool ss_valid(const T& value) const {
         return value >= Min && value <= Max;
     }
 };
@@ -596,7 +600,7 @@ struct ir {
 
 template <typename T, auto Min, auto Max>
 struct oor {
-    bool ss_valid(const T& value) const {
+    [[nodiscard]] bool ss_valid(const T& value) const {
         return value < Min || value > Max;
     }
 };
@@ -607,16 +611,21 @@ struct oor {
 
 template <typename T>
 struct ne {
-    bool ss_valid(const T& value) const {
+    [[nodiscard]] bool ss_valid(const T& value) const {
         return !value.empty();
     }
 
-    const char* error() const {
+    [[nodiscard]] const char* error() const {
         return "empty field";
     }
 };
 
-} /* ss */
+} /* namespace ss */
+
+#if !__unix__
+#include <array>
+#include <cstdint>
+#endif
 
 namespace ss {
 
@@ -629,18 +638,18 @@ constexpr inline auto default_delimiter = ",";
 constexpr inline auto get_line_initial_buffer_size = 128;
 
 template <bool StringError>
-inline void assert_string_error_defined() {
+void assert_string_error_defined() {
     static_assert(StringError,
                   "'string_error' needs to be enabled to use 'error_msg'");
 }
 
 template <bool ThrowOnError>
-inline void assert_throw_on_error_not_defined() {
+void assert_throw_on_error_not_defined() {
     static_assert(!ThrowOnError, "cannot handle errors manually if "
                                  "'throw_on_error' is enabled");
 }
 
-inline void* strict_realloc(void* ptr, size_t size) {
+[[nodiscard]] inline void* strict_realloc(void* ptr, size_t size) {
     ptr = std::realloc(ptr, size);
     if (!ptr) {
         throw std::bad_alloc{};
@@ -650,18 +659,20 @@ inline void* strict_realloc(void* ptr, size_t size) {
 }
 
 #if __unix__
-inline ssize_t get_line_file(char*& lineptr, size_t& n, FILE* file) {
+[[nodiscard]] inline ssize_t get_line_file(char*& lineptr, size_t& n,
+                                           FILE* file) {
     return getline(&lineptr, &n, file);
 }
 #else
 
 using ssize_t = intptr_t;
 
-ssize_t get_line_file(char*& lineptr, size_t& n, FILE* file) {
-    char buff[get_line_initial_buffer_size];
+[[nodiscard]] inline ssize_t get_line_file(char*& lineptr, size_t& n,
+                                           FILE* file) {
+    std::array<char, get_line_initial_buffer_size> buff;
 
     if (lineptr == nullptr || n < sizeof(buff)) {
-        size_t new_n = sizeof(buff);
+        const size_t new_n = sizeof(buff);
         lineptr = static_cast<char*>(strict_realloc(lineptr, new_n));
         n = new_n;
     }
@@ -669,17 +680,17 @@ ssize_t get_line_file(char*& lineptr, size_t& n, FILE* file) {
     lineptr[0] = '\0';
 
     size_t line_used = 0;
-    while (std::fgets(buff, sizeof(buff), file) != nullptr) {
+    while (std::fgets(buff.data(), sizeof(buff), file) != nullptr) {
         line_used = std::strlen(lineptr);
-        size_t buff_used = std::strlen(buff);
+        size_t buff_used = std::strlen(buff.data());
 
         if (n <= buff_used + line_used) {
-            size_t new_n = n * 2;
+            const size_t new_n = n * 2;
             lineptr = static_cast<char*>(strict_realloc(lineptr, new_n));
             n = new_n;
         }
 
-        std::memcpy(lineptr + line_used, buff, buff_used);
+        std::memcpy(lineptr + line_used, buff.data(), buff_used);
         line_used += buff_used;
         lineptr[line_used] = '\0';
 
@@ -693,15 +704,16 @@ ssize_t get_line_file(char*& lineptr, size_t& n, FILE* file) {
 
 #endif
 
-ssize_t get_line_buffer(char*& lineptr, size_t& n,
-                        const char* const csv_data_buffer, size_t csv_data_size,
-                        size_t& curr_char) {
+[[nodiscard]] inline ssize_t get_line_buffer(char*& lineptr, size_t& n,
+                                             const char* const csv_data_buffer,
+                                             size_t csv_data_size,
+                                             size_t& curr_char) {
     if (curr_char >= csv_data_size) {
         return -1;
     }
 
     if (lineptr == nullptr || n < get_line_initial_buffer_size) {
-        auto new_lineptr = static_cast<char*>(
+        auto* new_lineptr = static_cast<char*>(
             strict_realloc(lineptr, get_line_initial_buffer_size));
         lineptr = new_lineptr;
         n = get_line_initial_buffer_size;
@@ -710,7 +722,7 @@ ssize_t get_line_buffer(char*& lineptr, size_t& n,
     size_t line_used = 0;
     while (curr_char < csv_data_size) {
         if (line_used + 1 >= n) {
-            size_t new_n = n * 2;
+            const size_t new_n = n * 2;
 
             char* new_lineptr =
                 static_cast<char*>(strict_realloc(lineptr, new_n));
@@ -726,19 +738,15 @@ ssize_t get_line_buffer(char*& lineptr, size_t& n,
         }
     }
 
-    if (line_used != 0) {
-        lineptr[line_used] = '\0';
-        return line_used;
-    }
-
-    return -1;
+    lineptr[line_used] = '\0';
+    return line_used;
 }
 
-std::tuple<ssize_t, bool> get_line(char*& buffer, size_t& buffer_size,
-                                   FILE* file,
-                                   const char* const csv_data_buffer,
-                                   size_t csv_data_size, size_t& curr_char) {
-    ssize_t ssize;
+[[nodiscard]] inline std::tuple<ssize_t, bool> get_line(
+    char*& buffer, size_t& buffer_size, FILE* file,
+    const char* const csv_data_buffer, size_t csv_data_size,
+    size_t& curr_char) {
+    ssize_t ssize = 0;
     if (file) {
         ssize = get_line_file(buffer, buffer_size, file);
         curr_char += ssize;
@@ -757,7 +765,7 @@ std::tuple<ssize_t, bool> get_line(char*& buffer, size_t& buffer_size,
     return {ssize, false};
 }
 
-} /* ss */
+} /* namespace ss */
 
 namespace ss {
 
@@ -1050,7 +1058,10 @@ private:
 template <typename... Options>
 struct setup<setup<Options...>> : setup<Options...> {};
 
-} /* ss */
+template <typename... Options>
+struct setup<std::tuple<Options...>> : setup<Options...> {};
+
+} /* namespace ss */
 
 namespace ss {
 
@@ -1072,7 +1083,7 @@ private:
 public:
     using line_ptr_type = std::conditional_t<is_const_line, const char*, char*>;
 
-    bool valid() const {
+    [[nodiscard]] bool valid() const {
         if constexpr (string_error) {
             return error_.empty();
         } else if constexpr (throw_on_error) {
@@ -1082,12 +1093,12 @@ public:
         }
     }
 
-    const std::string& error_msg() const {
+    [[nodiscard]] const std::string& error_msg() const {
         assert_string_error_defined<string_error>();
         return error_;
     }
 
-    bool unterminated_quote() const {
+    [[nodiscard]] bool unterminated_quote() const {
         return unterminated_quote_;
     }
 
@@ -1099,13 +1110,21 @@ public:
         return split_impl_select_delim(delimiter);
     }
 
+    [[nodiscard]] const split_data& get_split_data() const {
+        return split_data_;
+    }
+
+    void clear_split_data() {
+        split_data_.clear();
+    }
+
 private:
     ////////////////
     // resplit
     ////////////////
 
     // number of characters the end of line is shifted backwards
-    size_t size_shifted() const {
+    [[nodiscard]] size_t size_shifted() const {
         return escaped_;
     }
 
@@ -1128,7 +1147,7 @@ private:
         }
 
         const auto [old_line, old_begin] = *std::prev(split_data_.end());
-        size_t begin = old_begin - old_line - 1;
+        const size_t begin = old_begin - old_line - 1;
 
         // safety measure
         if (new_size != -1 && static_cast<size_t>(new_size) < begin) {
@@ -1236,19 +1255,19 @@ private:
     // matching
     ////////////////
 
-    bool match(const char* const curr, char delim) {
+    [[nodiscard]] bool match(const char* const curr, char delim) {
         return *curr == delim;
     };
 
-    bool match(const char* const curr, const std::string& delim) {
+    [[nodiscard]] bool match(const char* const curr, const std::string& delim) {
         return std::strncmp(curr, delim.c_str(), delim.size()) == 0;
     };
 
-    size_t delimiter_size(char) {
+    [[nodiscard]] size_t delimiter_size(char) {
         return 1;
     }
 
-    size_t delimiter_size(const std::string& delim) {
+    [[nodiscard]] size_t delimiter_size(const std::string& delim) {
         return delim.size();
     }
 
@@ -1269,8 +1288,8 @@ private:
     }
 
     template <typename Delim>
-    std::tuple<size_t, bool> match_delimiter(line_ptr_type begin,
-                                             const Delim& delim) {
+    [[nodiscard]] std::tuple<size_t, bool> match_delimiter(line_ptr_type begin,
+                                                           const Delim& delim) {
         line_ptr_type end = begin;
 
         trim_right_if_enabled(end);
@@ -1364,8 +1383,9 @@ private:
 
         trim_left_if_enabled(begin_);
 
-        for (done_ = false; !done_; read(delim))
-            ;
+        for (done_ = false; !done_;) {
+            read(delim);
+        }
 
         return split_data_;
     }
@@ -1504,7 +1524,6 @@ private:
     // members
     ////////////////
 
-public:
     error_type error_{};
     bool unterminated_quote_{false};
     bool done_{true};
@@ -1521,7 +1540,7 @@ public:
     friend class converter;
 };
 
-} /* ss */
+} /* namespace ss */
 
 
 #ifndef SSP_DISABLE_FAST_FLOAT
@@ -1537,8 +1556,8 @@ namespace ss {
 #ifndef SSP_DISABLE_FAST_FLOAT
 
 template <typename T>
-std::enable_if_t<std::is_floating_point_v<T>, std::optional<T>> to_num(
-    const char* const begin, const char* const end) {
+[[nodiscard]] std::enable_if_t<std::is_floating_point_v<T>, std::optional<T>>
+to_num(const char* const begin, const char* const end) {
     T ret;
     auto [ptr, ec] = fast_float::from_chars(begin, end, ret);
 
@@ -1551,22 +1570,23 @@ std::enable_if_t<std::is_floating_point_v<T>, std::optional<T>> to_num(
 #else
 
 template <typename T>
-std::enable_if_t<std::is_floating_point_v<T>, std::optional<T>> to_num(
-    const char* const begin, const char* const end) {
+[[nodiscard]] std::enable_if_t<std::is_floating_point_v<T>, std::optional<T>>
+to_num(const char* const begin, const char* const end) {
     static_assert(!std::is_same_v<T, long double>,
                   "Conversion to long double is disabled");
 
     constexpr static auto buff_max = 64;
-    char short_buff[buff_max];
-    size_t string_range = std::distance(begin, end);
+    std::array<char, buff_max> short_buff;
+
+    const size_t string_range = std::distance(begin, end);
     std::string long_buff;
 
-    char* buff;
+    char* buff = nullptr;
     if (string_range > buff_max) {
         long_buff = std::string{begin, end};
         buff = long_buff.data();
     } else {
-        buff = short_buff;
+        buff = short_buff.data();
         buff[string_range] = '\0';
         std::copy_n(begin, string_range, buff);
     }
@@ -1598,12 +1618,14 @@ struct numeric_wrapper {
     using type = T;
 
     numeric_wrapper() = default;
-    numeric_wrapper(numeric_wrapper&&) = default;
+    numeric_wrapper(numeric_wrapper&&) noexcept = default;
     numeric_wrapper(const numeric_wrapper&) = default;
 
-    numeric_wrapper& operator=(numeric_wrapper&&) = default;
+    numeric_wrapper& operator=(numeric_wrapper&&) noexcept = default;
     numeric_wrapper& operator=(const numeric_wrapper&) = default;
 
+    ~numeric_wrapper() = default;
+
     numeric_wrapper(T other) : value{other} {
     }
 
@@ -1622,7 +1644,7 @@ using int8 = numeric_wrapper<int8_t>;
 using uint8 = numeric_wrapper<uint8_t>;
 
 template <typename T>
-std::enable_if_t<std::is_integral_v<T>, std::optional<T>> to_num(
+[[nodiscard]] std::enable_if_t<std::is_integral_v<T>, std::optional<T>> to_num(
     const char* const begin, const char* const end) {
     T ret;
     auto [ptr, ec] = std::from_chars(begin, end, ret);
@@ -1634,8 +1656,9 @@ std::enable_if_t<std::is_integral_v<T>, std::optional<T>> to_num(
 }
 
 template <typename T>
-std::enable_if_t<is_instance_of_v<numeric_wrapper, T>, std::optional<T>> to_num(
-    const char* const begin, const char* const end) {
+[[nodiscard]] std::enable_if_t<is_instance_of_v<numeric_wrapper, T>,
+                               std::optional<T>>
+to_num(const char* const begin, const char* const end) {
     T ret;
     auto [ptr, ec] = std::from_chars(begin, end, ret.value);
 
@@ -1654,14 +1677,15 @@ template <typename T>
 struct unsupported_type {
     constexpr static bool value = false;
 };
-} /* namespace */
+} /* namespace errors */
 
 template <typename T>
-std::enable_if_t<!std::is_integral_v<T> && !std::is_floating_point_v<T> &&
-                     !is_instance_of_v<std::optional, T> &&
-                     !is_instance_of_v<std::variant, T> &&
-                     !is_instance_of_v<numeric_wrapper, T>,
-                 bool>
+[[nodiscard]] std::enable_if_t<!std::is_integral_v<T> &&
+                                   !std::is_floating_point_v<T> &&
+                                   !is_instance_of_v<std::optional, T> &&
+                                   !is_instance_of_v<std::variant, T> &&
+                                   !is_instance_of_v<numeric_wrapper, T>,
+                               bool>
 extract(const char*, const char*, T&) {
     static_assert(error::unsupported_type<T>::value,
                   "Conversion for given type is not defined, an "
@@ -1669,9 +1693,10 @@ extract(const char*, const char*, T&) {
 }
 
 template <typename T>
-std::enable_if_t<std::is_integral_v<T> || std::is_floating_point_v<T> ||
-                     is_instance_of_v<numeric_wrapper, T>,
-                 bool>
+[[nodiscard]] std::enable_if_t<std::is_integral_v<T> ||
+                                   std::is_floating_point_v<T> ||
+                                   is_instance_of_v<numeric_wrapper, T>,
+                               bool>
 extract(const char* begin, const char* end, T& value) {
     auto optional_value = to_num<T>(begin, end);
     if (!optional_value) {
@@ -1682,8 +1707,8 @@ extract(const char* begin, const char* end, T& value) {
 }
 
 template <typename T>
-std::enable_if_t<is_instance_of_v<std::optional, T>, bool> extract(
-    const char* begin, const char* end, T& value) {
+[[nodiscard]] std::enable_if_t<is_instance_of_v<std::optional, T>, bool>
+extract(const char* begin, const char* end, T& value) {
     typename T::value_type raw_value;
     if (extract(begin, end, raw_value)) {
         value = raw_value;
@@ -1694,7 +1719,8 @@ std::enable_if_t<is_instance_of_v<std::optional, T>, bool> extract(
 }
 
 template <typename T, size_t I>
-bool extract_variant(const char* begin, const char* end, T& value) {
+[[nodiscard]] bool extract_variant(const char* begin, const char* end,
+                                   T& value) {
     using IthType = std::variant_alternative_t<I, std::decay_t<T>>;
     IthType ithValue;
     if (extract<IthType>(begin, end, ithValue)) {
@@ -1707,7 +1733,7 @@ bool extract_variant(const char* begin, const char* end, T& value) {
 }
 
 template <typename T>
-std::enable_if_t<is_instance_of_v<std::variant, T>, bool> extract(
+[[nodiscard]] std::enable_if_t<is_instance_of_v<std::variant, T>, bool> extract(
     const char* begin, const char* end, T& value) {
     return extract_variant<T, 0>(begin, end, value);
 }
@@ -1717,7 +1743,8 @@ std::enable_if_t<is_instance_of_v<std::variant, T>, bool> extract(
 ////////////////
 
 template <>
-inline bool extract(const char* begin, const char* end, bool& value) {
+[[nodiscard]] inline bool extract(const char* begin, const char* end,
+                                  bool& value) {
     if (end == begin + 1) {
         if (*begin == '1') {
             value = true;
@@ -1727,10 +1754,13 @@ inline bool extract(const char* begin, const char* end, bool& value) {
             return false;
         }
     } else {
-        size_t size = end - begin;
-        if (size == 4 && std::strncmp(begin, "true", size) == 0) {
+        constexpr static auto true_size = 4;
+        constexpr static auto false_size = 5;
+        const size_t size = end - begin;
+        if (size == true_size && std::strncmp(begin, "true", size) == 0) {
             value = true;
-        } else if (size == 5 && std::strncmp(begin, "false", size) == 0) {
+        } else if (size == false_size &&
+                   std::strncmp(begin, "false", size) == 0) {
             value = false;
         } else {
             return false;
@@ -1741,25 +1771,27 @@ inline bool extract(const char* begin, const char* end, bool& value) {
 }
 
 template <>
-inline bool extract(const char* begin, const char* end, char& value) {
+[[nodiscard]] inline bool extract(const char* begin, const char* end,
+                                  char& value) {
     value = *begin;
     return (end == begin + 1);
 }
 
 template <>
-inline bool extract(const char* begin, const char* end, std::string& value) {
+[[nodiscard]] inline bool extract(const char* begin, const char* end,
+                                  std::string& value) {
     value = std::string{begin, end};
     return true;
 }
 
 template <>
-inline bool extract(const char* begin, const char* end,
-                    std::string_view& value) {
+[[nodiscard]] inline bool extract(const char* begin, const char* end,
+                                  std::string_view& value) {
     value = std::string_view{begin, static_cast<size_t>(end - begin)};
     return true;
 }
 
-} /* ss */
+} /* namespace ss */
 
 namespace ss {
 INIT_HAS_METHOD(tied)
@@ -1862,19 +1894,19 @@ public:
     // parses line with given delimiter, returns a 'T' object created with
     // extracted values of type 'Ts'
     template <typename T, typename... Ts>
-    T convert_object(line_ptr_type line,
-                     const std::string& delim = default_delimiter) {
+    [[nodiscard]] T convert_object(
+        line_ptr_type line, const std::string& delim = default_delimiter) {
         return to_object<T>(convert<Ts...>(line, delim));
     }
 
     // parses line with given delimiter, returns tuple of objects with
     // extracted values of type 'Ts'
     template <typename... Ts>
-    no_void_validator_tup_t<Ts...> convert(
+    [[nodiscard]] no_void_validator_tup_t<Ts...> convert(
         line_ptr_type line, const std::string& delim = default_delimiter) {
         split(line, delim);
         if (splitter_.valid()) {
-            return convert<Ts...>(splitter_.split_data_);
+            return convert<Ts...>(splitter_.get_split_data());
         } else {
             handle_error_bad_split();
             return {};
@@ -1883,13 +1915,13 @@ public:
 
     // parses already split line, returns 'T' object with extracted values
     template <typename T, typename... Ts>
-    T convert_object(const split_data& elems) {
+    [[nodiscard]] T convert_object(const split_data& elems) {
         return to_object<T>(convert<Ts...>(elems));
     }
 
     // same as above, but uses cached split line
     template <typename T, typename... Ts>
-    T convert_object() {
+    [[nodiscard]] T convert_object() {
         return to_object<T>(convert<Ts...>());
     }
 
@@ -1898,7 +1930,8 @@ public:
     // one argument is given which is a class which has a tied
     // method which returns a tuple, returns that type
     template <typename T, typename... Ts>
-    no_void_validator_tup_t<T, Ts...> convert(const split_data& elems) {
+    [[nodiscard]] no_void_validator_tup_t<T, Ts...> convert(
+        const split_data& elems) {
         if constexpr (sizeof...(Ts) == 0 && is_instance_of_v<std::tuple, T>) {
             return convert_impl(elems, static_cast<T*>(nullptr));
         } else if constexpr (tied_class_v<T, Ts...>) {
@@ -1914,11 +1947,11 @@ public:
 
     // same as above, but uses cached split line
     template <typename T, typename... Ts>
-    no_void_validator_tup_t<T, Ts...> convert() {
-        return convert<T, Ts...>(splitter_.split_data_);
+    [[nodiscard]] no_void_validator_tup_t<T, Ts...> convert() {
+        return convert<T, Ts...>(splitter_.get_split_data());
     }
 
-    bool valid() const {
+    [[nodiscard]] bool valid() const {
         if constexpr (string_error) {
             return error_.empty();
         } else if constexpr (throw_on_error) {
@@ -1928,12 +1961,12 @@ public:
         }
     }
 
-    const std::string& error_msg() const {
+    [[nodiscard]] const std::string& error_msg() const {
         assert_string_error_defined<string_error>();
         return error_;
     }
 
-    bool unterminated_quote() const {
+    [[nodiscard]] bool unterminated_quote() const {
         return splitter_.unterminated_quote();
     }
 
@@ -1941,9 +1974,9 @@ public:
     // contain the beginnings and the ends of each column of the string
     const split_data& split(line_ptr_type line,
                             const std::string& delim = default_delimiter) {
-        splitter_.split_data_.clear();
+        splitter_.clear_split_data();
         if (line[0] == '\0') {
-            return splitter_.split_data_;
+            return splitter_.get_split_data();
         }
 
         return splitter_.split(line, delim);
@@ -1959,7 +1992,7 @@ private:
         return splitter_.resplit(new_line, new_size, delim);
     }
 
-    size_t size_shifted() {
+    [[nodiscard]] size_t size_shifted() {
         return splitter_.size_shifted();
     }
 
@@ -1975,9 +2008,11 @@ private:
         }
     }
 
-    std::string error_sufix(const string_range msg, size_t pos) const {
+    [[nodiscard]] std::string error_sufix(const string_range msg,
+                                          size_t pos) const {
+        constexpr static auto reserve_size = 32;
         std::string error;
-        error.reserve(32);
+        error.reserve(reserve_size);
         error.append("at column ")
             .append(std::to_string(pos + 1))
             .append(": \'")
@@ -2102,7 +2137,8 @@ private:
     ////////////////
 
     template <typename... Ts>
-    no_void_validator_tup_t<Ts...> convert_impl(const split_data& elems) {
+    [[nodiscard]] no_void_validator_tup_t<Ts...> convert_impl(
+        const split_data& elems) {
         clear_error();
 
         if (!splitter_.valid()) {
@@ -2133,7 +2169,7 @@ private:
     }
 
     template <typename... Ts>
-    no_void_validator_tup_t<std::tuple<Ts...>> convert_impl(
+    [[nodiscard]] no_void_validator_tup_t<std::tuple<Ts...>> convert_impl(
         const split_data& elems, const std::tuple<Ts...>*) {
         return convert_impl<Ts...>(elems);
     }
@@ -2142,11 +2178,11 @@ private:
     // column mapping
     ////////////////
 
-    bool columns_mapped() const {
-        return column_mappings_.size() != 0;
+    [[nodiscard]] bool columns_mapped() const {
+        return !column_mappings_.empty();
     }
 
-    size_t column_position(size_t tuple_position) const {
+    [[nodiscard]] size_t column_position(size_t tuple_position) const {
         if (!columns_mapped()) {
             return tuple_position;
         }
@@ -2156,7 +2192,7 @@ private:
     // assumes positions are valid and the vector is not empty
     void set_column_mapping(std::vector<size_t> positions,
                             size_t number_of_columns) {
-        column_mappings_ = positions;
+        column_mappings_ = std::move(positions);
         number_of_columns_ = number_of_columns;
     }
 
@@ -2177,7 +2213,7 @@ private:
         }
 
         if constexpr (std::is_same_v<T, std::string>) {
-            extract(msg.first, msg.second, dst);
+            static_cast<void>(extract(msg.first, msg.second, dst));
             return;
         }
 
@@ -2223,7 +2259,8 @@ private:
     }
 
     template <typename... Ts>
-    no_void_validator_tup_t<Ts...> extract_tuple(const split_data& elems) {
+    [[nodiscard]] no_void_validator_tup_t<Ts...> extract_tuple(
+        const split_data& elems) {
         static_assert(!all_of_v<std::is_void, Ts...>,
                       "at least one parameter must be non void");
         no_void_validator_tup_t<Ts...> ret{};
@@ -2242,10 +2279,10 @@ private:
     friend class parser;
 
     std::vector<size_t> column_mappings_;
-    size_t number_of_columns_;
+    size_t number_of_columns_{0};
 };
 
-} /* ss */
+} /* namespace ss */
 
 
 namespace ss {
@@ -2268,10 +2305,12 @@ class parser {
 
     constexpr static bool ignore_empty = setup<Options...>::ignore_empty;
 
+    using header_splitter = ss::splitter<
+        ss::filter_not_t<ss::is_instance_of_multiline, Options...>>;
+
 public:
-    parser(const std::string& file_name,
-           const std::string& delim = ss::default_delimiter)
-        : file_name_{file_name}, reader_{file_name_, delim} {
+    parser(std::string file_name, std::string delim = ss::default_delimiter)
+        : file_name_{std::move(file_name)}, reader_{file_name_, delim} {
         if (reader_.file_) {
             read_line();
             if constexpr (ignore_header) {
@@ -2287,7 +2326,7 @@ public:
 
     parser(const char* const csv_data_buffer, size_t csv_data_size,
            const std::string& delim = ss::default_delimiter)
-        : file_name_{"buffer line"},
+        : file_name_{"CSV data buffer"},
           reader_{csv_data_buffer, csv_data_size, delim} {
         if (csv_data_buffer) {
             read_line();
@@ -2302,14 +2341,15 @@ public:
         }
     }
 
-    parser(parser&& other) = default;
-    parser& operator=(parser&& other) = default;
+    parser(parser&& other) noexcept = default;
+    parser& operator=(parser&& other) noexcept = default;
+    ~parser() = default;
 
     parser() = delete;
     parser(const parser& other) = delete;
     parser& operator=(const parser& other) = delete;
 
-    bool valid() const {
+    [[nodiscard]] bool valid() const {
         if constexpr (string_error) {
             return error_.empty();
         } else if constexpr (throw_on_error) {
@@ -2319,12 +2359,12 @@ public:
         }
     }
 
-    const std::string& error_msg() const {
+    [[nodiscard]] const std::string& error_msg() const {
         assert_string_error_defined<string_error>();
         return error_;
     }
 
-    bool eof() const {
+    [[nodiscard]] bool eof() const {
         return eof_;
     }
 
@@ -2333,23 +2373,21 @@ public:
     }
 
     template <typename T, typename... Ts>
-    T get_object() {
+    [[nodiscard]] T get_object() {
         return to_object<T>(get_next<Ts...>());
     }
 
-    size_t line() const {
+    [[nodiscard]] size_t line() const {
         return reader_.line_number_ > 0 ? reader_.line_number_ - 1
                                         : reader_.line_number_;
     }
 
-    size_t position() const {
+    [[nodiscard]] size_t position() const {
         return reader_.chars_read_;
     }
 
     template <typename T, typename... Ts>
-    no_void_validator_tup_t<T, Ts...> get_next() {
-        std::optional<std::string> error;
-
+    [[nodiscard]] no_void_validator_tup_t<T, Ts...> get_next() {
         if (!eof_) {
             if constexpr (throw_on_error) {
                 try {
@@ -2398,20 +2436,49 @@ public:
         return value;
     }
 
-    bool field_exists(const std::string& field) {
+    [[nodiscard]] std::string raw_header() const {
+        assert_ignore_header_not_defined();
+        return raw_header_;
+    }
+
+    [[nodiscard]] std::vector<std::string> header() {
+        assert_ignore_header_not_defined();
+        clear_error();
+
+        header_splitter splitter;
+        std::string raw_header_copy = raw_header_;
+
+        if (!strict_split(splitter, raw_header_copy)) {
+            return {};
+        }
+
+        std::vector<std::string> split_header;
+        for (const auto& [begin, end] : splitter.get_split_data()) {
+            split_header.emplace_back(begin, end);
+        }
+
+        return split_header;
+    }
+
+    [[nodiscard]] bool field_exists(const std::string& field) {
+        assert_ignore_header_not_defined();
+        clear_error();
+
         if (header_.empty()) {
             split_header_data();
         }
 
+        if (!valid()) {
+            return false;
+        }
+
         return header_index(field).has_value();
     }
 
     template <typename... Ts>
     void use_fields(const Ts&... fields_args) {
-        if constexpr (ignore_header) {
-            handle_error_header_ignored();
-            return;
-        }
+        assert_ignore_header_not_defined();
+        clear_error();
 
         if (header_.empty() && !eof()) {
             split_header_data();
@@ -2424,7 +2491,7 @@ public:
         auto fields = std::vector<std::string>{fields_args...};
 
         if (fields.empty()) {
-            handle_error_empty_mapping();
+            handle_error_invalid_use_fields_argument();
             return;
         }
 
@@ -2472,13 +2539,17 @@ public:
             }
 
             iterator(const iterator& other) = default;
-            iterator(iterator&& other) = default;
+            iterator(iterator&& other) noexcept = default;
+            ~iterator() = default;
 
-            value& operator*() {
+            iterator& operator=(const iterator& other) = delete;
+            iterator& operator=(iterator&& other) noexcept = delete;
+
+            [[nodiscard]] value& operator*() {
                 return value_;
             }
 
-            value* operator->() {
+            [[nodiscard]] value* operator->() {
                 return &value_;
             }
 
@@ -2497,17 +2568,21 @@ public:
                 return *this;
             }
 
-            iterator& operator++(int) {
-                return ++*this;
+            iterator operator++(int) {
+                auto result = *this;
+                ++*this;
+                return result;
             }
 
-            friend bool operator==(const iterator& lhs, const iterator& rhs) {
+            [[nodiscard]] friend bool operator==(const iterator& lhs,
+                                                 const iterator& rhs) {
                 return (lhs.parser_ == nullptr && rhs.parser_ == nullptr) ||
                        (lhs.parser_ == rhs.parser_ &&
                         &lhs.value_ == &rhs.value_);
             }
 
-            friend bool operator!=(const iterator& lhs, const iterator& rhs) {
+            [[nodiscard]] friend bool operator!=(const iterator& lhs,
+                                                 const iterator& rhs) {
                 return !(lhs == rhs);
             }
 
@@ -2519,11 +2594,11 @@ public:
         iterable(parser<Options...>* parser) : parser_{parser} {
         }
 
-        iterator begin() {
+        [[nodiscard]] iterator begin() {
             return ++iterator{parser_};
         }
 
-        iterator end() {
+        [[nodiscard]] iterator end() {
             return iterator{};
         }
 
@@ -2532,12 +2607,12 @@ public:
     };
 
     template <typename... Ts>
-    auto iterate() {
+    [[nodiscard]] auto iterate() {
         return iterable<false, Ts...>{this};
     }
 
     template <typename... Ts>
-    auto iterate_object() {
+    [[nodiscard]] auto iterate_object() {
         return iterable<true, Ts...>{this};
     }
 
@@ -2562,7 +2637,7 @@ public:
             Fun&& fun = none{}) {
             using Value = no_void_validator_tup_t<Us...>;
             std::optional<Value> value;
-            try_convert_and_invoke<Value, Us...>(value, fun);
+            try_convert_and_invoke<Value, Us...>(value, std::forward<Fun>(fun));
             return composite_with(std::move(value));
         }
 
@@ -2571,11 +2646,11 @@ public:
         template <typename U, typename... Us, typename Fun = none>
         composite<Ts..., std::optional<U>> or_object(Fun&& fun = none{}) {
             std::optional<U> value;
-            try_convert_and_invoke<U, Us...>(value, fun);
+            try_convert_and_invoke<U, Us...>(value, std::forward<Fun>(fun));
             return composite_with(std::move(value));
         }
 
-        std::tuple<Ts...> values() {
+        [[nodiscard]] std::tuple<Ts...> values() {
             return values_;
         }
 
@@ -2598,7 +2673,7 @@ public:
 
     private:
         template <typename T>
-        composite<Ts..., T> composite_with(T&& new_value) {
+        [[nodiscard]] composite<Ts..., T> composite_with(T&& new_value) {
             auto merged_values =
                 std::tuple_cat(std::move(values_),
                                std::tuple<T>{parser_.valid()
@@ -2628,7 +2703,7 @@ public:
         }
 
         template <typename U, typename... Us>
-        no_void_validator_tup_t<U, Us...> try_same() {
+        [[nodiscard]] no_void_validator_tup_t<U, Us...> try_same() {
             parser_.clear_error();
             auto value =
                 parser_.reader_.converter_.template convert<U, Us...>();
@@ -2649,8 +2724,8 @@ public:
     // tries to convert a line and returns a composite which is
     // able to try additional conversions in case of failure
     template <typename... Ts, typename Fun = none>
-    composite<std::optional<no_void_validator_tup_t<Ts...>>> try_next(
-        Fun&& fun = none{}) {
+    [[nodiscard]] composite<std::optional<no_void_validator_tup_t<Ts...>>>
+    try_next(Fun&& fun = none{}) {
         assert_throw_on_error_not_defined<throw_on_error>();
         using Ret = no_void_validator_tup_t<Ts...>;
         return try_invoke_and_make_composite<
@@ -2660,7 +2735,7 @@ public:
     // identical to try_next but returns composite with object instead of a
     // tuple
     template <typename T, typename... Ts, typename Fun = none>
-    composite<std::optional<T>> try_object(Fun&& fun = none{}) {
+    [[nodiscard]] composite<std::optional<T>> try_object(Fun&& fun = none{}) {
         assert_throw_on_error_not_defined<throw_on_error>();
         return try_invoke_and_make_composite<
             std::optional<T>>(get_object<T, Ts...>(), std::forward<Fun>(fun));
@@ -2679,7 +2754,8 @@ private:
             using Ret = decltype(try_invoke_impl(arg, std::forward<Fun>(fun)));
             constexpr bool returns_void = std::is_same_v<Ret, void>;
             if constexpr (!returns_void) {
-                if (!try_invoke_impl(arg, std::forward<Fun>(fun))) {
+                if (!try_invoke_impl(std::forward<Arg>(arg),
+                                     std::forward<Fun>(fun))) {
                     handle_error_failed_check();
                 }
             } else {
@@ -2710,26 +2786,55 @@ private:
     }
 
     template <typename T, typename Fun = none>
-    composite<T> try_invoke_and_make_composite(T&& value, Fun&& fun) {
+    [[nodiscard]] composite<T> try_invoke_and_make_composite(T&& value,
+                                                             Fun&& fun) {
         if (valid()) {
             try_invoke(*value, std::forward<Fun>(fun));
         }
-        return {valid() ? std::move(value) : std::nullopt, *this};
+        return {valid() ? std::forward<T>(value) : std::nullopt, *this};
     }
 
     ////////////////
     // header
     ////////////////
 
+    void assert_ignore_header_not_defined() const {
+        static_assert(!ignore_header,
+                      "cannot use this method when 'ignore_header' is defined");
+    }
+
+    [[nodiscard]] bool strict_split(header_splitter& splitter,
+                                    std::string& header) {
+        if constexpr (throw_on_error) {
+            try {
+                splitter.split(header.data(), reader_.delim_);
+            } catch (const ss::exception& e) {
+                decorate_rethrow_invalid_header_split(e);
+            }
+        } else {
+            splitter.split(header.data(), reader_.delim_);
+            if (!splitter.valid()) {
+                handle_error_invalid_header_split(splitter);
+                return false;
+            }
+        }
+
+        return true;
+    }
+
     void split_header_data() {
-        ss::splitter<Options...> splitter;
+        header_splitter splitter;
         std::string raw_header_copy = raw_header_;
-        splitter.split(raw_header_copy.data(), reader_.delim_);
-        for (const auto& [begin, end] : splitter.split_data_) {
+
+        if (!strict_split(splitter, raw_header_copy)) {
+            return;
+        }
+
+        for (const auto& [begin, end] : splitter.get_split_data()) {
             std::string field{begin, end};
             if (std::find(header_.begin(), header_.end(), field) !=
                 header_.end()) {
-                handle_error_invalid_header(field);
+                handle_error_duplicate_header_field(field);
                 header_.clear();
                 return;
             }
@@ -2737,7 +2842,7 @@ private:
         }
     }
 
-    std::optional<size_t> header_index(const std::string& field) {
+    [[nodiscard]] std::optional<size_t> header_index(const std::string& field) {
         auto it = std::find(header_.begin(), header_.end(), field);
 
         if (it == header_.end()) {
@@ -2760,7 +2865,7 @@ private:
     }
 
     void handle_error_failed_check() {
-        constexpr static auto error_msg = " failed check";
+        constexpr static auto error_msg = ": failed check";
 
         if constexpr (string_error) {
             error_.clear();
@@ -2773,7 +2878,7 @@ private:
     }
 
     void handle_error_null_buffer() {
-        constexpr static auto error_msg = " received null data buffer";
+        constexpr static auto error_msg = ": received null data buffer";
 
         if constexpr (string_error) {
             error_.clear();
@@ -2786,7 +2891,7 @@ private:
     }
 
     void handle_error_file_not_open() {
-        constexpr static auto error_msg = " could not be opened";
+        constexpr static auto error_msg = ": could not be opened";
 
         if constexpr (string_error) {
             error_.clear();
@@ -2799,7 +2904,7 @@ private:
     }
 
     void handle_error_eof_reached() {
-        constexpr static auto error_msg = " read on end of file";
+        constexpr static auto error_msg = ": read on end of file";
 
         if constexpr (string_error) {
             error_.clear();
@@ -2824,20 +2929,6 @@ private:
         }
     }
 
-    void handle_error_header_ignored() {
-        constexpr static auto error_msg =
-            ": the header row is ignored within the setup it cannot be used";
-
-        if constexpr (string_error) {
-            error_.clear();
-            error_.append(file_name_).append(error_msg);
-        } else if constexpr (throw_on_error) {
-            throw ss::exception{file_name_ + error_msg};
-        } else {
-            error_ = true;
-        }
-    }
-
     void handle_error_invalid_field(const std::string& field) {
         constexpr static auto error_msg =
             ": header does not contain given field: ";
@@ -2865,8 +2956,9 @@ private:
         }
     }
 
-    void handle_error_empty_mapping() {
-        constexpr static auto error_msg = "received empty mapping";
+    void handle_error_invalid_use_fields_argument() {
+        constexpr static auto error_msg =
+            "received invalid argument for 'use_fields'";
 
         if constexpr (string_error) {
             error_.clear();
@@ -2878,19 +2970,53 @@ private:
         }
     }
 
-    void handle_error_invalid_header(const std::string& field) {
-        constexpr static auto error_msg = "header contains duplicates: ";
+    void handle_error_invalid_header_field() {
+        constexpr static auto error_msg = ": header contains empty field";
 
         if constexpr (string_error) {
             error_.clear();
-            error_.append(error_msg).append(error_msg);
+            error_.append(file_name_).append(error_msg);
         } else if constexpr (throw_on_error) {
-            throw ss::exception{error_msg + field};
+            throw ss::exception{file_name_ + error_msg};
         } else {
             error_ = true;
         }
     }
 
+    void handle_error_duplicate_header_field(const std::string& field) {
+        constexpr static auto error_msg = ": header contains duplicate: ";
+
+        if constexpr (string_error) {
+            error_.clear();
+            error_.append(file_name_).append(error_msg).append(field);
+        } else if constexpr (throw_on_error) {
+            throw ss::exception{file_name_ + error_msg + field};
+        } else {
+            error_ = true;
+        }
+    }
+
+    void handle_error_invalid_header_split(const header_splitter& splitter) {
+        constexpr static auto error_msg = ": failed header parsing: ";
+
+        if constexpr (string_error) {
+            error_.clear();
+            error_.append(file_name_)
+                .append(error_msg)
+                .append(splitter.error_msg());
+        } else {
+            error_ = true;
+        }
+    }
+
+    void decorate_rethrow_invalid_header_split(const ss::exception& e) const {
+        static_assert(throw_on_error,
+                      "throw_on_error needs to be enabled to use this method");
+        throw ss::exception{std::string{file_name_}
+                                .append(": failed header parsing: ")
+                                .append(e.what())};
+    }
+
     void decorate_rethrow(const ss::exception& e) const {
         static_assert(throw_on_error,
                       "throw_on_error needs to be enabled to use this method");
@@ -2910,17 +3036,18 @@ private:
     }
 
     struct reader {
-        reader(const std::string& file_name_, const std::string& delim)
-            : delim_{delim}, file_{std::fopen(file_name_.c_str(), "rb")} {
+        reader(const std::string& file_name_, std::string delim)
+            : delim_{std::move(delim)},
+              file_{std::fopen(file_name_.c_str(), "rb")} {
         }
 
         reader(const char* const buffer, size_t csv_data_size,
-               const std::string& delim)
-            : delim_{delim}, csv_data_buffer_{buffer},
+               std::string delim)
+            : delim_{std::move(delim)}, csv_data_buffer_{buffer},
               csv_data_size_{csv_data_size} {
         }
 
-        reader(reader&& other)
+        reader(reader&& other) noexcept
             : buffer_{other.buffer_},
               next_line_buffer_{other.next_line_buffer_},
               helper_buffer_{other.helper_buffer_},
@@ -2941,7 +3068,7 @@ private:
             other.file_ = nullptr;
         }
 
-        reader& operator=(reader&& other) {
+        reader& operator=(reader&& other) noexcept {
             if (this != &other) {
                 buffer_ = other.buffer_;
                 next_line_buffer_ = other.next_line_buffer_;
@@ -2977,7 +3104,7 @@ private:
             std::free(helper_buffer_);
 
             if (file_) {
-                std::fclose(file_);
+                std::ignore = std::fclose(file_);
             }
         }
 
@@ -2986,7 +3113,7 @@ private:
         reader& operator=(const reader& other) = delete;
 
         // read next line each time in order to set eof_
-        bool read_next() {
+        [[nodiscard]] bool read_next() {
             next_line_converter_.clear_error();
             size_t size = 0;
             while (size == 0) {
@@ -3078,7 +3205,7 @@ private:
             std::swap(converter_, next_line_converter_);
         }
 
-        bool multiline_limit_reached(size_t& limit) {
+        [[nodiscard]] bool multiline_limit_reached(size_t& limit) {
             if constexpr (multiline::size > 0) {
                 if (limit++ >= multiline::size) {
                     next_line_converter_.handle_error_multiline_limit_reached();
@@ -3088,8 +3215,8 @@ private:
             return false;
         }
 
-        bool escaped_eol(size_t size) {
-            const char* curr;
+        [[nodiscard]] bool escaped_eol(size_t size) {
+            const char* curr = nullptr;
             for (curr = next_line_buffer_ + size - 1;
                  curr >= next_line_buffer_ &&
                  setup<Options...>::escape::match(*curr);
@@ -3098,7 +3225,7 @@ private:
             return (next_line_buffer_ - curr + size) % 2 == 0;
         }
 
-        bool unterminated_quote() {
+        [[nodiscard]] bool unterminated_quote() {
             return next_line_converter_.unterminated_quote();
         }
 
@@ -3113,7 +3240,7 @@ private:
             }
         }
 
-        size_t remove_eol(char*& buffer, size_t ssize) {
+        [[nodiscard]] size_t remove_eol(char*& buffer, size_t ssize) {
             if (buffer[ssize - 1] != '\n') {
                 crlf_ = false;
                 return ssize;
@@ -3135,7 +3262,7 @@ private:
                             size_t& buffer_size, const char* const second,
                             size_t second_size) {
             buffer_size = first_size + second_size + 3;
-            auto new_first = static_cast<char*>(
+            auto* new_first = static_cast<char*>(
                 strict_realloc(static_cast<void*>(first), buffer_size));
 
             first = new_first;
@@ -3143,8 +3270,9 @@ private:
             first_size += second_size;
         }
 
-        bool append_next_line_to_buffer(char*& buffer, size_t& line_size,
-                                        size_t buffer_size) {
+        [[nodiscard]] bool append_next_line_to_buffer(char*& buffer,
+                                                      size_t& line_size,
+                                                      size_t buffer_size) {
             undo_remove_eol(buffer, line_size, buffer_size);
 
             chars_read_ = curr_char_;
@@ -3163,8 +3291,8 @@ private:
             return true;
         }
 
-        std::string get_buffer() {
-            return std::string{next_line_buffer_, next_line_buffer_size_};
+        [[nodiscard]] std::string get_buffer() {
+            return std::string{next_line_buffer_, next_line_size_};
         }
 
         ////////////////
@@ -3207,4 +3335,4 @@ private:
     bool eof_{false};
 };
 
-} /* ss */
+} /* namespace ss */
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index be399a1..6fd368c 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -33,10 +33,11 @@ set(DOCTEST "${FETCHCONTENT_BASE_DIR}/doctest-src")
 enable_testing()
 
 foreach(name IN ITEMS test_splitter test_parser1_1 test_parser1_2
-                      test_parser1_3 test_parser1_4 test_converter
-                      test_extractions test_parser2_1 test_parser2_2
-                      test_parser2_3 test_parser2_4 test_parser2_5
-                      test_parser2_6 test_extractions_without_fast_float)
+                      test_parser1_3 test_parser1_4 test_parser1_5
+                      test_converter test_extractions test_parser2_1
+                      test_parser2_2 test_parser2_3 test_parser2_4
+                      test_parser2_5 test_parser2_6
+                      test_extractions_without_fast_float)
     add_executable("${name}" "${name}.cpp")
     target_link_libraries("${name}" PRIVATE ssp::ssp fast_float
                                             doctest::doctest)
diff --git a/test/meson.build b/test/meson.build
index f4e6639..6be0f1f 100644
--- a/test/meson.build
+++ b/test/meson.build
@@ -6,6 +6,7 @@ tests = [
   'parser1_2',
   'parser1_3',
   'parser1_4',
+  'parser1_5',
   'splitter',
   'converter',
   'extractions',
diff --git a/test/test_converter.cpp b/test/test_converter.cpp
index 659e78f..e4e0a8c 100644
--- a/test/test_converter.cpp
+++ b/test/test_converter.cpp
@@ -1,17 +1,17 @@
 #include "test_helpers.hpp"
-#include <algorithm>
 #include <ss/converter.hpp>
 
 TEST_CASE("converter test split") {
     ss::converter c;
     for (const auto& [s, expected, delim] :
          // clang-format off
-                {std::make_tuple("a,b,c,d", std::vector{"a", "b", "c", "d"}, ","),
-                {"", {}, " "},
-                {" x x x x | x ", {" x x x x ", " x "}, "|"},
-                {"a::b::c::d", {"a", "b", "c", "d"}, "::"},
-                {"x\t-\ty", {"x", "y"}, "\t-\t"},
-                {"x", {"x"}, ","}} // clang-format on
+        {std::make_tuple("a,b,c,d", std::vector{"a", "b", "c", "d"}, ","),
+        {"", {}, " "},
+        {" x x x x | x ", {" x x x x ", " x "}, "|"},
+        {"a::b::c::d", {"a", "b", "c", "d"}, "::"},
+        {"x\t-\ty", {"x", "y"}, "\t-\t"},
+        {"x", {"x"}, ","}} 
+        // clang-format on
     ) {
         auto split = c.split(s, delim);
         CHECK_EQ(split.size(), expected.size());
@@ -278,37 +278,38 @@ TEST_CASE_TEMPLATE("converter test valid conversions with exceptions", T, int,
 TEST_CASE_TEMPLATE("converter test invalid conversions", T, int, ss::uint8) {
     ss::converter c;
 
-    c.convert<T>("");
+    std::ignore = c.convert<T>("");
     REQUIRE_FALSE(c.valid());
 
-    c.convert<T>("1", "");
+    std::ignore = c.convert<T>("1", "");
     REQUIRE_FALSE(c.valid());
 
-    c.convert<T>("10", "");
+    std::ignore = c.convert<T>("10", "");
     REQUIRE_FALSE(c.valid());
 
-    c.convert<T, void>("");
+    std::ignore = c.convert<T, void>("");
     REQUIRE_FALSE(c.valid());
 
-    c.convert<T, void>(",junk");
+    std::ignore = c.convert<T, void>(",junk");
     REQUIRE_FALSE(c.valid());
 
-    c.convert<void, T>("junk,");
+    std::ignore = c.convert<void, T>("junk,");
     REQUIRE_FALSE(c.valid());
 
-    c.convert<T>("x");
+    std::ignore = c.convert<T>("x");
     REQUIRE_FALSE(c.valid());
 
-    c.convert<T, void>("x");
+    std::ignore = c.convert<T, void>("x");
     REQUIRE_FALSE(c.valid());
 
-    c.convert<T, void>("x,junk");
+    std::ignore = c.convert<T, void>("x,junk");
     REQUIRE_FALSE(c.valid());
 
-    c.convert<void, T>("junk,x");
+    std::ignore = c.convert<void, T>("junk,x");
     REQUIRE_FALSE(c.valid());
 
-    c.convert<void, std::variant<T, double>, double>("junk;.5.5;6", ";");
+    std::ignore =
+        c.convert<void, std::variant<T, double>, double>("junk;.5.5;6", ";");
     REQUIRE_FALSE(c.valid());
 }
 
@@ -316,34 +317,36 @@ TEST_CASE_TEMPLATE("converter test invalid conversions with exceptions", T, int,
                    ss::uint8) {
     ss::converter<ss::throw_on_error> c;
 
-    REQUIRE_EXCEPTION(c.convert<T>(""));
-    REQUIRE_EXCEPTION(c.convert<T>("1", ""));
-    REQUIRE_EXCEPTION(c.convert<T>("10", ""));
-    REQUIRE_EXCEPTION(c.convert<T, void>(""));
-    REQUIRE_EXCEPTION(c.convert<T, void>(",junk"));
-    REQUIRE_EXCEPTION(c.convert<void, T>("junk,"));
-    REQUIRE_EXCEPTION(c.convert<T>("x"));
-    REQUIRE_EXCEPTION(c.convert<T, void>("x"));
-    REQUIRE_EXCEPTION(c.convert<T, void>("x,junk"));
-    REQUIRE_EXCEPTION(c.convert<void, T>("junk,x"));
+    REQUIRE_EXCEPTION(std::ignore = c.convert<T>(""));
+    REQUIRE_EXCEPTION(std::ignore = c.convert<T>("1", ""));
+    REQUIRE_EXCEPTION(std::ignore = c.convert<T>("10", ""));
+    REQUIRE_EXCEPTION(std::ignore = c.convert<T, void>(""));
+    REQUIRE_EXCEPTION(std::ignore = c.convert<T, void>(",junk"));
+    REQUIRE_EXCEPTION(std::ignore = c.convert<void, T>("junk,"));
+    REQUIRE_EXCEPTION(std::ignore = c.convert<T>("x"));
+    REQUIRE_EXCEPTION(std::ignore = c.convert<T, void>("x"));
+    REQUIRE_EXCEPTION(std::ignore = c.convert<T, void>("x,junk"));
+    REQUIRE_EXCEPTION(std::ignore = c.convert<void, T>("junk,x"));
     REQUIRE_EXCEPTION(
-        c.convert<void, std::variant<T, double>, double>("junk;.5.5;6", ";"));
+        std::ignore =
+            c.convert<void, std::variant<T, double>, double>("junk;.5.5;6",
+                                                             ";"));
 }
 
 TEST_CASE_TEMPLATE("converter test ss:ax restriction (all except)", T, int,
                    ss::uint8) {
     ss::converter c;
 
-    c.convert<ss::ax<T, 0>>("0");
+    std::ignore = c.convert<ss::ax<T, 0>>("0");
     REQUIRE_FALSE(c.valid());
 
-    c.convert<ss::ax<T, 0, 1, 2>>("1");
+    std::ignore = c.convert<ss::ax<T, 0, 1, 2>>("1");
     REQUIRE_FALSE(c.valid());
 
-    c.convert<void, char, ss::ax<T, 0, 1, 2>>("junk,c,1");
+    std::ignore = c.convert<void, char, ss::ax<T, 0, 1, 2>>("junk,c,1");
     REQUIRE_FALSE(c.valid());
 
-    c.convert<ss::ax<T, 1>, char>("1,c");
+    std::ignore = c.convert<ss::ax<T, 1>, char>("1,c");
     REQUIRE_FALSE(c.valid());
     {
         T tup = c.convert<ss::ax<T, 1>>("3");
@@ -367,10 +370,11 @@ TEST_CASE_TEMPLATE(
     ss::uint8) {
     ss::converter<ss::throw_on_error> c;
 
-    REQUIRE_EXCEPTION(c.convert<ss::ax<T, 0>>("0"));
-    REQUIRE_EXCEPTION(c.convert<ss::ax<T, 0, 1, 2>>("1"));
-    REQUIRE_EXCEPTION(c.convert<void, char, ss::ax<T, 0, 1, 2>>("junk,c,1"));
-    REQUIRE_EXCEPTION(c.convert<ss::ax<T, 1>, char>("1,c"));
+    REQUIRE_EXCEPTION(std::ignore = c.convert<ss::ax<T, 0>>("0"));
+    REQUIRE_EXCEPTION(std::ignore = c.convert<ss::ax<T, 0, 1, 2>>("1"));
+    REQUIRE_EXCEPTION(
+        std::ignore = c.convert<void, char, ss::ax<T, 0, 1, 2>>("junk,c,1"));
+    REQUIRE_EXCEPTION(std::ignore = c.convert<ss::ax<T, 1>, char>("1,c"));
 
     try {
         {
@@ -393,13 +397,13 @@ TEST_CASE_TEMPLATE(
 TEST_CASE("converter test ss:nx restriction (none except)") {
     ss::converter c;
 
-    c.convert<ss::nx<int, 1>>("3");
+    std::ignore = c.convert<ss::nx<int, 1>>("3");
     REQUIRE_FALSE(c.valid());
 
-    c.convert<char, ss::nx<int, 1, 2, 69>>("c,3");
+    std::ignore = c.convert<char, ss::nx<int, 1, 2, 69>>("c,3");
     REQUIRE_FALSE(c.valid());
 
-    c.convert<ss::nx<int, 1>, char>("3,c");
+    std::ignore = c.convert<ss::nx<int, 1>, char>("3,c");
     REQUIRE_FALSE(c.valid());
 
     {
@@ -427,9 +431,10 @@ TEST_CASE("converter test ss:nx restriction (none except)") {
 TEST_CASE("converter test ss:nx restriction (none except) with exceptions") {
     ss::converter<ss::throw_on_error> c;
 
-    REQUIRE_EXCEPTION(c.convert<ss::nx<int, 1>>("3"));
-    REQUIRE_EXCEPTION(c.convert<char, ss::nx<int, 1, 2, 69>>("c,3"));
-    REQUIRE_EXCEPTION(c.convert<ss::nx<int, 1>, char>("3,c"));
+    REQUIRE_EXCEPTION(std::ignore = c.convert<ss::nx<int, 1>>("3"));
+    REQUIRE_EXCEPTION(std::ignore =
+                          c.convert<char, ss::nx<int, 1, 2, 69>>("c,3"));
+    REQUIRE_EXCEPTION(std::ignore = c.convert<ss::nx<int, 1>, char>("3,c"));
 
     try {
         {
@@ -461,13 +466,13 @@ TEST_CASE_TEMPLATE("converter test ss:ir restriction (in range)", T, int,
                    ss::uint8) {
     ss::converter c;
 
-    c.convert<ss::ir<T, 0, 2>>("3");
+    std::ignore = c.convert<ss::ir<T, 0, 2>>("3");
     REQUIRE_FALSE(c.valid());
 
-    c.convert<char, ss::ir<T, 4, 69>>("c,3");
+    std::ignore = c.convert<char, ss::ir<T, 4, 69>>("c,3");
     REQUIRE_FALSE(c.valid());
 
-    c.convert<ss::ir<T, 1, 2>, char>("3,c");
+    std::ignore = c.convert<ss::ir<T, 1, 2>, char>("3,c");
     REQUIRE_FALSE(c.valid());
 
     {
@@ -497,9 +502,9 @@ TEST_CASE_TEMPLATE(
     ss::uint8) {
     ss::converter<ss::throw_on_error> c;
 
-    REQUIRE_EXCEPTION(c.convert<ss::ir<T, 0, 2>>("3"));
-    REQUIRE_EXCEPTION(c.convert<char, ss::ir<T, 4, 69>>("c,3"));
-    REQUIRE_EXCEPTION(c.convert<ss::ir<T, 1, 2>, char>("3,c"));
+    REQUIRE_EXCEPTION(std::ignore = c.convert<ss::ir<T, 0, 2>>("3"));
+    REQUIRE_EXCEPTION(std::ignore = c.convert<char, ss::ir<T, 4, 69>>("c,3"));
+    REQUIRE_EXCEPTION(std::ignore = c.convert<ss::ir<T, 1, 2>, char>("3,c"));
 
     try {
         {
@@ -530,16 +535,16 @@ TEST_CASE_TEMPLATE(
 TEST_CASE("converter test ss:oor restriction (out of range)") {
     ss::converter c;
 
-    c.convert<ss::oor<int, 1, 5>>("3");
+    std::ignore = c.convert<ss::oor<int, 1, 5>>("3");
     REQUIRE_FALSE(c.valid());
 
-    c.convert<ss::oor<int, 0, 2>>("2");
+    std::ignore = c.convert<ss::oor<int, 0, 2>>("2");
     REQUIRE_FALSE(c.valid());
 
-    c.convert<char, ss::oor<int, 0, 1>, void>("c,1,junk");
+    std::ignore = c.convert<char, ss::oor<int, 0, 1>, void>("c,1,junk");
     REQUIRE_FALSE(c.valid());
 
-    c.convert<ss::oor<int, 1, 20>, char>("1,c");
+    std::ignore = c.convert<ss::oor<int, 1, 20>, char>("1,c");
     REQUIRE_FALSE(c.valid());
 
     {
@@ -564,10 +569,12 @@ TEST_CASE("converter test ss:oor restriction (out of range)") {
 TEST_CASE("converter test ss:oor restriction (out of range) with exceptions") {
     ss::converter<ss::throw_on_error> c;
 
-    REQUIRE_EXCEPTION(c.convert<ss::oor<int, 1, 5>>("3"));
-    REQUIRE_EXCEPTION(c.convert<ss::oor<int, 0, 2>>("2"));
-    REQUIRE_EXCEPTION(c.convert<char, ss::oor<int, 0, 1>, void>("c,1,junk"));
-    REQUIRE_EXCEPTION(c.convert<ss::oor<int, 1, 20>, char>("1,c"));
+    REQUIRE_EXCEPTION(std::ignore = c.convert<ss::oor<int, 1, 5>>("3"));
+    REQUIRE_EXCEPTION(std::ignore = c.convert<ss::oor<int, 0, 2>>("2"));
+    REQUIRE_EXCEPTION(
+        std::ignore = c.convert<char, ss::oor<int, 0, 1>, void>("c,1,junk"));
+    REQUIRE_EXCEPTION(std::ignore =
+                          c.convert<ss::oor<int, 1, 20>, char>("1,c"));
 
     try {
         {
@@ -608,19 +615,19 @@ inline bool ss::extract(const char* begin, const char* end,
 TEST_CASE("converter test ss:ne restriction (not empty)") {
     ss::converter c;
 
-    c.convert<ss::ne<std::string>>("");
+    std::ignore = c.convert<ss::ne<std::string>>("");
     REQUIRE_FALSE(c.valid());
 
-    c.convert<int, ss::ne<std::string>>("3,");
+    std::ignore = c.convert<int, ss::ne<std::string>>("3,");
     REQUIRE_FALSE(c.valid());
 
-    c.convert<ss::ne<std::string>, int>(",3");
+    std::ignore = c.convert<ss::ne<std::string>, int>(",3");
     REQUIRE_FALSE(c.valid());
 
-    c.convert<void, ss::ne<std::string>, int>("junk,,3");
+    std::ignore = c.convert<void, ss::ne<std::string>, int>("junk,,3");
     REQUIRE_FALSE(c.valid());
 
-    c.convert<ss::ne<std::vector<int>>>("");
+    std::ignore = c.convert<ss::ne<std::vector<int>>>("");
     REQUIRE_FALSE(c.valid());
 
     {
@@ -643,11 +650,12 @@ TEST_CASE("converter test ss:ne restriction (not empty)") {
 TEST_CASE("converter test ss:ne restriction (not empty) with exceptions") {
     ss::converter<ss::throw_on_error> c;
 
-    REQUIRE_EXCEPTION(c.convert<ss::ne<std::string>>(""));
-    REQUIRE_EXCEPTION(c.convert<int, ss::ne<std::string>>("3,"));
-    REQUIRE_EXCEPTION(c.convert<ss::ne<std::string>, int>(",3"));
-    REQUIRE_EXCEPTION(c.convert<void, ss::ne<std::string>, int>("junk,,3"));
-    REQUIRE_EXCEPTION(c.convert<ss::ne<std::vector<int>>>(""));
+    REQUIRE_EXCEPTION(std::ignore = c.convert<ss::ne<std::string>>(""));
+    REQUIRE_EXCEPTION(std::ignore = c.convert<int, ss::ne<std::string>>("3,"));
+    REQUIRE_EXCEPTION(std::ignore = c.convert<ss::ne<std::string>, int>(",3"));
+    REQUIRE_EXCEPTION(std::ignore =
+                          c.convert<void, ss::ne<std::string>, int>("junk,,3"));
+    REQUIRE_EXCEPTION(std::ignore = c.convert<ss::ne<std::vector<int>>>(""));
 
     try {
         {
@@ -675,22 +683,22 @@ TEST_CASE(
     "converter test ss:lt ss::lte ss::gt ss::gte restriction (in range)") {
     ss::converter c;
 
-    c.convert<ss::lt<int, 3>>("3");
+    std::ignore = c.convert<ss::lt<int, 3>>("3");
     REQUIRE_FALSE(c.valid());
 
-    c.convert<ss::lt<int, 2>>("3");
+    std::ignore = c.convert<ss::lt<int, 2>>("3");
     REQUIRE_FALSE(c.valid());
 
-    c.convert<ss::gt<int, 3>>("3");
+    std::ignore = c.convert<ss::gt<int, 3>>("3");
     REQUIRE_FALSE(c.valid());
 
-    c.convert<ss::gt<int, 4>>("3");
+    std::ignore = c.convert<ss::gt<int, 4>>("3");
     REQUIRE_FALSE(c.valid());
 
-    c.convert<ss::lte<int, 2>>("3");
+    std::ignore = c.convert<ss::lte<int, 2>>("3");
     REQUIRE_FALSE(c.valid());
 
-    c.convert<ss::gte<int, 4>>("3");
+    std::ignore = c.convert<ss::gte<int, 4>>("3");
     REQUIRE_FALSE(c.valid());
 
     {
@@ -734,12 +742,12 @@ TEST_CASE("converter test ss:lt ss::lte ss::gt ss::gte restriction (in range) "
           "with exception") {
     ss::converter<ss::throw_on_error> c;
 
-    REQUIRE_EXCEPTION(c.convert<ss::lt<int, 3>>("3"));
-    REQUIRE_EXCEPTION(c.convert<ss::lt<int, 2>>("3"));
-    REQUIRE_EXCEPTION(c.convert<ss::gt<int, 3>>("3"));
-    REQUIRE_EXCEPTION(c.convert<ss::gt<int, 4>>("3"));
-    REQUIRE_EXCEPTION(c.convert<ss::lte<int, 2>>("3"));
-    REQUIRE_EXCEPTION(c.convert<ss::gte<int, 4>>("3"));
+    REQUIRE_EXCEPTION(std::ignore = c.convert<ss::lt<int, 3>>("3"));
+    REQUIRE_EXCEPTION(std::ignore = c.convert<ss::lt<int, 2>>("3"));
+    REQUIRE_EXCEPTION(std::ignore = c.convert<ss::gt<int, 3>>("3"));
+    REQUIRE_EXCEPTION(std::ignore = c.convert<ss::gt<int, 4>>("3"));
+    REQUIRE_EXCEPTION(std::ignore = c.convert<ss::lte<int, 2>>("3"));
+    REQUIRE_EXCEPTION(std::ignore = c.convert<ss::gte<int, 4>>("3"));
 
     try {
         {
@@ -784,14 +792,14 @@ TEST_CASE("converter test ss:lt ss::lte ss::gt ss::gte restriction (in range) "
 
 TEST_CASE("converter test error mode") {
     ss::converter<ss::string_error> c;
-    c.convert<int>("junk");
+    std::ignore = c.convert<int>("junk");
     CHECK_FALSE(c.valid());
     CHECK_FALSE(c.error_msg().empty());
 }
 
 TEST_CASE("converter test throw on error mode") {
     ss::converter<ss::throw_on_error> c;
-    REQUIRE_EXCEPTION(c.convert<int>("junk"));
+    REQUIRE_EXCEPTION(std::ignore = c.convert<int>("junk"));
 }
 
 TEST_CASE("converter test converter with quotes spacing and escaping") {
@@ -908,7 +916,7 @@ TEST_CASE("converter test invalid split conversions") {
 
     {
         // mismatched quote
-        c.convert<std::string, std::string, double, char>(
+        std::ignore = c.convert<std::string, std::string, double, char>(
             buff(R"(  "just  , some ,   "12.3","a"  )"));
         CHECK_FALSE(c.valid());
         CHECK_FALSE(c.unterminated_quote());
@@ -917,7 +925,7 @@ TEST_CASE("converter test invalid split conversions") {
 
     {
         // unterminated quote
-        c.convert<std::string, std::string, double, std::string>(
+        std::ignore = c.convert<std::string, std::string, double, std::string>(
             buff(R"(  ju\,st  ,  "so,me"  ,   12.34     ,   "str""ings)"));
         CHECK_FALSE(c.valid());
         CHECK(c.unterminated_quote());
@@ -926,7 +934,7 @@ TEST_CASE("converter test invalid split conversions") {
 
     {
         // unterminated escape
-        c.convert<std::string, std::string, double, std::string>(
+        std::ignore = c.convert<std::string, std::string, double, std::string>(
             buff(R"(just,some,2,strings\)"));
         CHECK_FALSE(c.valid());
         CHECK_FALSE(c.unterminated_quote());
@@ -935,7 +943,7 @@ TEST_CASE("converter test invalid split conversions") {
 
     {
         // unterminated escape while quoting
-        c.convert<std::string, std::string, double, std::string>(
+        std::ignore = c.convert<std::string, std::string, double, std::string>(
             buff(R"(just,some,2,"strings\)"));
         CHECK_FALSE(c.valid());
         CHECK_FALSE(c.unterminated_quote());
@@ -944,7 +952,7 @@ TEST_CASE("converter test invalid split conversions") {
 
     {
         // unterminated escaped quote
-        c.convert<std::string, std::string, double, std::string>(
+        std::ignore = c.convert<std::string, std::string, double, std::string>(
             buff(R"(just,some,2,"strings\")"));
         CHECK_FALSE(c.valid());
         CHECK(c.unterminated_quote());
@@ -958,27 +966,32 @@ TEST_CASE("converter test invalid split conversions with exceptions") {
         c;
 
     // mismatched quote
-    REQUIRE_EXCEPTION(c.convert<std::string, std::string, double, char>(
-        buff(R"(  "just  , some ,   "12.3","a"  )")));
+    REQUIRE_EXCEPTION(std::ignore =
+                          c.convert<std::string, std::string, double, char>(
+                              buff(R"(  "just  , some ,   "12.3","a"  )")));
     CHECK_FALSE(c.unterminated_quote());
 
     // unterminated quote
-    REQUIRE_EXCEPTION(c.convert<std::string, std::string, double, std::string>(
-        buff(R"(  ju\,st  ,  "so,me"  ,   12.34     ,   "str""ings)")));
+    REQUIRE_EXCEPTION(
+        std::ignore = c.convert<std::string, std::string, double, std::string>(
+            buff(R"(  ju\,st  ,  "so,me"  ,   12.34     ,   "str""ings)")));
     CHECK(c.unterminated_quote());
 
     // unterminated escape
-    REQUIRE_EXCEPTION(c.convert<std::string, std::string, double, std::string>(
-        buff(R"(just,some,2,strings\)")));
+    REQUIRE_EXCEPTION(
+        std::ignore = c.convert<std::string, std::string, double, std::string>(
+            buff(R"(just,some,2,strings\)")));
     CHECK_FALSE(c.unterminated_quote());
 
     // unterminated escape while quoting
-    REQUIRE_EXCEPTION(c.convert<std::string, std::string, double, std::string>(
-        buff(R"(just,some,2,"strings\)")));
+    REQUIRE_EXCEPTION(
+        std::ignore = c.convert<std::string, std::string, double, std::string>(
+            buff(R"(just,some,2,"strings\)")));
     CHECK_FALSE(c.unterminated_quote());
 
     // unterminated escaped quote
-    REQUIRE_EXCEPTION(c.convert<std::string, std::string, double, std::string>(
-        buff(R"(just,some,2,"strings\")")));
+    REQUIRE_EXCEPTION(
+        std::ignore = c.convert<std::string, std::string, double, std::string>(
+            buff(R"(just,some,2,"strings\")")));
     CHECK(c.unterminated_quote());
 }
diff --git a/test/test_extractions.cpp b/test/test_extractions.cpp
index 88ec317..6e44196 100644
--- a/test/test_extractions.cpp
+++ b/test/test_extractions.cpp
@@ -23,7 +23,7 @@ struct is_unsigned : public std::is_unsigned<T> {};
 template <>
 struct is_unsigned<ss::uint8> : public std::true_type {};
 
-} /* namespace */
+} /* anonymous namespace */
 
 static_assert(is_signed<ss::int8>::value);
 static_assert(is_unsigned<ss::uint8>::value);
diff --git a/test/test_extractions_without_fast_float.cpp b/test/test_extractions_without_fast_float.cpp
index 2c9a984..7add461 100644
--- a/test/test_extractions_without_fast_float.cpp
+++ b/test/test_extractions_without_fast_float.cpp
@@ -1,5 +1,4 @@
 #include "test_helpers.hpp"
-#include <algorithm>
 
 #define SSP_DISABLE_FAST_FLOAT
 #include <ss/extract.hpp>
diff --git a/test/test_helpers.hpp b/test/test_helpers.hpp
index 188e731..6841d25 100644
--- a/test/test_helpers.hpp
+++ b/test/test_helpers.hpp
@@ -19,7 +19,7 @@
 namespace ss {
 template <typename... Ts>
 class parser;
-} /* ss */
+} /* namespace ss */
 
 namespace {
 
@@ -145,6 +145,17 @@ struct unique_file_name {
         CHECK_FALSE(std::string{e.what()}.empty());                            \
     }
 
+#define CHECK_EQ_ARRAY(first, second)                                          \
+    {                                                                          \
+        const auto& first_ = (first);                                          \
+        const auto& second_ = (second);                                        \
+        CHECK_EQ(first_.size(), second_.size());                               \
+        for (size_t i_ = 0; i_ < std::min(first_.size(), second_.size());      \
+             ++i_) {                                                           \
+            CHECK_EQ(first_[i_], second_[i_]);                                 \
+        }                                                                      \
+    }
+
 template <typename T>
 [[maybe_unused]] std::vector<std::vector<T>> vector_combinations(
     const std::vector<T>& v, size_t n) {
@@ -166,6 +177,22 @@ template <typename T>
     return ret;
 }
 
+[[maybe_unused]] std::string merge_header(
+    const std::vector<std::string>& header,
+    const std::string& delimiter = ss::default_delimiter) {
+    std::string s;
+    if (!header.empty()) {
+        for (const auto& i : header) {
+            s.append(i);
+            s.append(delimiter);
+        }
+        for (size_t i = 0; i < delimiter.size(); ++i) {
+            s.pop_back();
+        }
+    }
+    return s;
+};
+
 [[maybe_unused]] std::string make_buffer(const std::string& file_name) {
     std::ifstream in{file_name, std::ios::binary};
     std::string tmp;
@@ -185,6 +212,7 @@ template <typename T>
         }
     };
 
+    // Evade small string optimization
     out.reserve(sizeof(out) + 1);
 
     copy_if_whitespaces();
@@ -224,4 +252,4 @@ make_parser(const std::string& file_name,
     return make_parser_impl<buffer_mode, Ts...>(file_name, delim);
 }
 
-} /* namespace */
+} /* anonymous namespace */
diff --git a/test/test_parser1.hpp b/test/test_parser1.hpp
index 90267c8..c40bdc3 100644
--- a/test/test_parser1.hpp
+++ b/test/test_parser1.hpp
@@ -12,8 +12,9 @@
 #include <unordered_set>
 
 namespace {
-[[maybe_unused]] void replace_all(std::string& s, const std::string& from,
-                                  const std::string& to) {
+#ifdef _WIN32
+void replace_all(std::string& s, const std::string& from,
+                 const std::string& to) {
     if (from.empty()) return;
     size_t start_pos = 0;
     while ((start_pos = s.find(from, start_pos)) != std::string::npos) {
@@ -21,6 +22,7 @@ namespace {
         start_pos += to.length();
     }
 }
+#endif
 
 template <typename... Ts>
 void expect_error_on_command(ss::parser<Ts...>& p,
@@ -28,6 +30,7 @@ void expect_error_on_command(ss::parser<Ts...>& p,
     if (ss::setup<Ts...>::throw_on_error) {
         try {
             command();
+            FAIL("expected exception");
         } catch (const std::exception& e) {
             CHECK_FALSE(std::string{e.what()}.empty());
         }
@@ -55,7 +58,7 @@ struct X {
     double d;
     std::string s;
 
-    std::string to_string() const {
+    [[nodiscard]] std::string to_string() const {
         if (s == empty) {
             return "";
         }
@@ -66,14 +69,15 @@ struct X {
             .append(delim)
             .append(s);
     }
-    auto tied() const {
+
+    [[nodiscard]] auto tied() const {
         return std::tie(i, d, s);
     }
 };
 
 template <typename T>
-std::enable_if_t<ss::has_m_tied_t<T>, bool> operator==(const T& lhs,
-                                                       const T& rhs) {
+[[nodiscard]] std::enable_if_t<ss::has_m_tied_t<T>, bool> operator==(
+    const T& lhs, const T& rhs) {
     return lhs.tied() == rhs.tied();
 }
 
@@ -109,4 +113,4 @@ static void make_and_write(const std::string& file_name,
     }
 }
 
-} /* namespace */
+} /* anonymous namespace */
diff --git a/test/test_parser1_1.cpp b/test/test_parser1_1.cpp
index 650393b..6338ee8 100644
--- a/test/test_parser1_1.cpp
+++ b/test/test_parser1_1.cpp
@@ -57,7 +57,7 @@ struct Y {
             .append(s3);
     }
 
-    auto tied() const {
+    [[nodiscard]] auto tied() const {
         return std::tie(s1, s2, s3);
     }
 };
@@ -115,7 +115,8 @@ TEST_CASE_TEMPLATE("test line method", T, ParserOptionCombinations) {
     CHECK_EQ(p.line(), expected_line);
 
     while (!p.eof()) {
-        auto _ = p.template get_next<std::string, std::string, std::string>();
+        std::ignore =
+            p.template get_next<std::string, std::string, std::string>();
         ++expected_line;
         CHECK_EQ(p.line(), expected_line);
     }
diff --git a/test/test_parser1_2.cpp b/test/test_parser1_2.cpp
index eaf9516..dffcf17 100644
--- a/test/test_parser1_2.cpp
+++ b/test/test_parser1_2.cpp
@@ -51,14 +51,16 @@ TEST_CASE_TEMPLATE("test moving of parsed composite values", T,
     // to compile is enough
     return;
     auto [p, _] = make_parser<buffer_mode, ErrorMode>("", "");
-    p.template try_next<my_string, my_string, my_string>()
-        .template or_else<my_string, my_string, my_string, my_string>(
-            [](auto&&) {})
-        .template or_else<my_string>([](auto&) {})
-        .template or_else<xyz>([](auto&&) {})
-        .template or_object<xyz, my_string, my_string, my_string>([](auto&&) {})
-        .template or_else<std::tuple<my_string, my_string, my_string>>(
-            [](auto&, auto&, auto&) {});
+    std::ignore =
+        p.template try_next<my_string, my_string, my_string>()
+            .template or_else<my_string, my_string, my_string, my_string>(
+                [](auto&&) {})
+            .template or_else<my_string>([](auto&) {})
+            .template or_else<xyz>([](auto&&) {})
+            .template or_object<xyz, my_string, my_string, my_string>(
+                [](auto&&) {})
+            .template or_else<std::tuple<my_string, my_string, my_string>>(
+                [](auto&, auto&, auto&) {});
 }
 
 TEST_CASE_TEMPLATE("parser test string error mode", BufferMode, std::true_type,
@@ -73,7 +75,7 @@ TEST_CASE_TEMPLATE("parser test string error mode", BufferMode, std::true_type,
     auto [p, _] = make_parser<BufferMode::value, ss::string_error>(f.name, ",");
 
     REQUIRE_FALSE(p.eof());
-    p.template get_next<int>();
+    std::ignore = p.template get_next<int>();
     CHECK_FALSE(p.valid());
     CHECK_FALSE(p.error_msg().empty());
 }
@@ -92,7 +94,7 @@ TEST_CASE_TEMPLATE("parser throw on error mode", BufferMode, std::true_type,
 
     REQUIRE_FALSE(p.eof());
     try {
-        p.template get_next<int>();
+        std::ignore = p.template get_next<int>();
         FAIL("Expected exception...");
     } catch (const std::exception& e) {
         CHECK_FALSE(std::string{e.what()}.empty());
@@ -148,7 +150,8 @@ TEST_CASE_TEMPLATE("test quote multiline", T, ParserOptionCombinations) {
         make_parser<buffer_mode, ErrorMode, ss::quote<'"'>>(f.name, ",");
     while (!p.eof()) {
         auto command = [&p_no_multiline = p_no_multiline] {
-            p_no_multiline.template get_next<int, double, std::string>();
+            std::ignore =
+                p_no_multiline.template get_next<int, double, std::string>();
         };
         expect_error_on_command(p_no_multiline, command);
     }
diff --git a/test/test_parser1_3.cpp b/test/test_parser1_3.cpp
index e1f9b6e..69ddd8e 100644
--- a/test/test_parser1_3.cpp
+++ b/test/test_parser1_3.cpp
@@ -83,7 +83,7 @@ void test_unterminated_line(const std::vector<std::string>& lines,
     size_t line = 0;
     while (!p.eof()) {
         auto command = [&p = p] {
-            p.template get_next<int, double, std::string>();
+            std::ignore = p.template get_next<int, double, std::string>();
         };
 
         if (line == bad_line) {
diff --git a/test/test_parser1_4.cpp b/test/test_parser1_4.cpp
index 993e74b..e6e6966 100644
--- a/test/test_parser1_4.cpp
+++ b/test/test_parser1_4.cpp
@@ -9,6 +9,7 @@ struct has_type<T, std::tuple<Us...>>
 
 template <typename T, typename... Ts>
 static void test_fields(const std::string file_name, const std::vector<X>& data,
+                        const std::vector<std::string>& header,
                         const std::vector<std::string>& fields) {
     constexpr auto buffer_mode = T::BufferMode::value;
     using ErrorMode = typename T::ErrorMode;
@@ -17,9 +18,14 @@ static void test_fields(const std::string file_name, const std::vector<X>& data,
     auto [p, _] = make_parser<buffer_mode, ErrorMode>(file_name, ",");
     CHECK_FALSE(p.field_exists("Unknown"));
     p.use_fields(fields);
+
+    CHECK_EQ_ARRAY(header, p.header());
+    CHECK_EQ(merge_header(p.header(), ","), p.raw_header());
     std::vector<CaseType> i;
 
     for (const auto& a : p.template iterate<CaseType>()) {
+        CHECK_EQ_ARRAY(header, p.header());
+        CHECK_EQ(merge_header(p.header(), ","), p.raw_header());
         i.push_back(a);
     }
 
@@ -40,12 +46,12 @@ static void test_fields(const std::string file_name, const std::vector<X>& data,
 TEST_CASE_TEMPLATE("test various cases with header", T,
                    ParserOptionCombinations) {
     unique_file_name f{"various_cases_with_header"};
+    using str = std::string;
+
     constexpr static auto Int = "Int";
     constexpr static auto Dbl = "Double";
     constexpr static auto Str = "String";
-    using str = std::string;
-
-    std::vector<std::string> header{Int, Dbl, Str};
+    const std::vector<std::string> header{Int, Dbl, Str};
 
     std::vector<X> data = {{1, 2, "x"}, {3, 4, "y"},  {5, 6, "z"},
                            {7, 8, "u"}, {9, 10, "v"}, {11, 12, "w"}};
@@ -59,6 +65,8 @@ TEST_CASE_TEMPLATE("test various cases with header", T,
         std::vector<X> i;
 
         for (const auto& a : p.iterate<int, double, std::string>()) {
+            CHECK_EQ(header, p.header());
+            CHECK_EQ(merge_header(p.header(), ","), p.raw_header());
             i.emplace_back(ss::to_object<X>(a));
         }
 
@@ -71,46 +79,22 @@ TEST_CASE_TEMPLATE("test various cases with header", T,
 
         p.ignore_next();
         for (const auto& a : p.iterate<int, double, std::string>()) {
+            CHECK_EQ(header, p.header());
+            CHECK_EQ(merge_header(p.header(), ","), p.raw_header());
             i.emplace_back(ss::to_object<X>(a));
         }
 
         CHECK_EQ(i, data);
     }
 
-    {
-        ss::parser<ss::ignore_header> p{f.name, ","};
-        std::vector<X> i;
-
-        for (const auto& a : p.iterate<int, double, std::string>()) {
-            i.emplace_back(ss::to_object<X>(a));
-        }
-
-        CHECK_EQ(i, data);
-    }
-
-    {
-        ss::parser<ss::ignore_header, ss::string_error> p{f.name, ","};
-        p.use_fields(Int, Dbl, Str);
-        CHECK_FALSE(p.valid());
-    }
-
-    {
-        ss::parser<ss::ignore_header, ss::string_error> p{f.name, ","};
-        CHECK_FALSE(p.field_exists("Unknown"));
-
-        p.use_fields(Int, "Unknown");
-        CHECK_FALSE(p.valid());
-    }
-
-    {
-        ss::parser<ss::ignore_header, ss::string_error> p{f.name, ","};
-        p.use_fields(Int, Int);
-        CHECK_FALSE(p.valid());
-    }
-
     {
         ss::parser<ss::string_error> p{f.name, ","};
+        CHECK_EQ(header, p.header());
+        CHECK_EQ(merge_header(p.header(), ","), p.raw_header());
+
         p.use_fields(Int, Dbl);
+        CHECK_EQ(header, p.header());
+        CHECK_EQ(merge_header(p.header(), ","), p.raw_header());
 
         {
             auto [int_, double_] = p.get_next<int, double>();
@@ -119,6 +103,8 @@ TEST_CASE_TEMPLATE("test various cases with header", T,
         }
 
         p.use_fields(Dbl, Int);
+        CHECK_EQ(header, p.header());
+        CHECK_EQ(merge_header(p.header(), ","), p.raw_header());
 
         {
             auto [double_, int_] = p.get_next<double, int>();
@@ -163,25 +149,25 @@ TEST_CASE_TEMPLATE("test various cases with header", T,
                     template_params.append(type)
                     arg_params.append(header[type])
                 call = 'testFields<' + ', '.join(template_params) + \
-                    '>(o, d, {' + ', '.join(arg_params) + '});'
+                    '>(o, d, header, {' + ', '.join(arg_params) + '});'
                 print(call)
         */
 
-    test_fields<T, str>(o, d, {Str});
-    test_fields<T, int>(o, d, {Int});
-    test_fields<T, double>(o, d, {Dbl});
-    test_fields<T, str, int>(o, d, {Str, Int});
-    test_fields<T, str, double>(o, d, {Str, Dbl});
-    test_fields<T, int, str>(o, d, {Int, Str});
-    test_fields<T, int, double>(o, d, {Int, Dbl});
-    test_fields<T, double, str>(o, d, {Dbl, Str});
-    test_fields<T, double, int>(o, d, {Dbl, Int});
-    test_fields<T, str, int, double>(o, d, {Str, Int, Dbl});
-    test_fields<T, str, double, int>(o, d, {Str, Dbl, Int});
-    test_fields<T, int, str, double>(o, d, {Int, Str, Dbl});
-    test_fields<T, int, double, str>(o, d, {Int, Dbl, Str});
-    test_fields<T, double, str, int>(o, d, {Dbl, Str, Int});
-    test_fields<T, double, int, str>(o, d, {Dbl, Int, Str});
+    test_fields<T, str>(o, d, header, {Str});
+    test_fields<T, int>(o, d, header, {Int});
+    test_fields<T, double>(o, d, header, {Dbl});
+    test_fields<T, str, int>(o, d, header, {Str, Int});
+    test_fields<T, str, double>(o, d, header, {Str, Dbl});
+    test_fields<T, int, str>(o, d, header, {Int, Str});
+    test_fields<T, int, double>(o, d, header, {Int, Dbl});
+    test_fields<T, double, str>(o, d, header, {Dbl, Str});
+    test_fields<T, double, int>(o, d, header, {Dbl, Int});
+    test_fields<T, str, int, double>(o, d, header, {Str, Int, Dbl});
+    test_fields<T, str, double, int>(o, d, header, {Str, Dbl, Int});
+    test_fields<T, int, str, double>(o, d, header, {Int, Str, Dbl});
+    test_fields<T, int, double, str>(o, d, header, {Int, Dbl, Str});
+    test_fields<T, double, str, int>(o, d, header, {Dbl, Str, Int});
+    test_fields<T, double, int, str>(o, d, header, {Dbl, Int, Str});
 }
 
 template <typename T>
@@ -190,6 +176,18 @@ void test_invalid_fields(const std::vector<std::string>& lines,
     constexpr auto buffer_mode = T::BufferMode::value;
     using ErrorMode = typename T::ErrorMode;
 
+    auto check_header = [&lines](auto& p) {
+        if (lines.empty()) {
+            CHECK_EQ(p.header().size(), 1);
+            CHECK_EQ(p.header().at(0), "");
+            CHECK_EQ(merge_header(p.header(), ","), p.raw_header());
+        } else {
+            CHECK_EQ(lines[0], merge_header(p.header()));
+            CHECK_EQ(merge_header(p.header(), ","), p.raw_header());
+        }
+        CHECK(p.valid());
+    };
+
     unique_file_name f{"invalid_fields"};
     {
         std::ofstream out{f.name};
@@ -203,6 +201,7 @@ void test_invalid_fields(const std::vector<std::string>& lines,
         auto [p, _] = make_parser<buffer_mode, ErrorMode>(f.name, ",");
         auto command = [&p = p] { p.use_fields(); };
         expect_error_on_command(p, command);
+        check_header(p);
     }
 
     {
@@ -210,6 +209,7 @@ void test_invalid_fields(const std::vector<std::string>& lines,
         auto [p, _] = make_parser<buffer_mode, ErrorMode>(f.name, ",");
         auto command = [&p = p] { p.use_fields("Unknown"); };
         expect_error_on_command(p, command);
+        check_header(p);
     }
 
     {
@@ -221,6 +221,7 @@ void test_invalid_fields(const std::vector<std::string>& lines,
         if (!fields.empty()) {
             expect_error_on_command(p, command);
         }
+        check_header(p);
     }
 
     {
@@ -228,17 +229,21 @@ void test_invalid_fields(const std::vector<std::string>& lines,
         auto [p, _] = make_parser<buffer_mode, ErrorMode>(f.name, ",");
         auto command = [&p = p, &fields = fields] {
             p.use_fields(fields.at(0));
-            p.template get_next<std::string, std::string>();
+            std::ignore = p.template get_next<std::string, std::string>();
         };
+        check_header(p);
+
         if (!fields.empty()) {
             expect_error_on_command(p, command);
         }
+        check_header(p);
     }
 
     {
         // Invalid header
         auto [p, _] = make_parser<buffer_mode, ErrorMode>(f.name, ",");
         auto command = [&p = p, &fields = fields] { p.use_fields(fields); };
+        check_header(p);
 
         if (!fields.empty()) {
             // Pass if there are no duplicates, fail otherwise
@@ -255,10 +260,11 @@ void test_invalid_fields(const std::vector<std::string>& lines,
                 }
             }
         }
+        check_header(p);
     }
 }
 
-TEST_CASE_TEMPLATE("test invalid fheader fields usage", T,
+TEST_CASE_TEMPLATE("test invalid header fields usage", T,
                    ParserOptionCombinations) {
     test_invalid_fields<T>({}, {});
 
@@ -289,7 +295,7 @@ TEST_CASE_TEMPLATE("test invalid rows with header", T,
     constexpr auto buffer_mode = T::BufferMode::value;
     using ErrorMode = typename T::ErrorMode;
 
-    unique_file_name f{"invalid rows with header"};
+    unique_file_name f{"invalid_rows_with_header"};
     {
         std::ofstream out{f.name};
         out << "Int,String,Double" << std::endl;
@@ -301,8 +307,12 @@ TEST_CASE_TEMPLATE("test invalid rows with header", T,
         out << "six,line6,10.11" << std::endl;
     }
 
+    std::vector<std::string> header = {"Int", "String", "Double"};
+
     {
         auto [p, _] = make_parser<buffer_mode, ErrorMode>(f.name);
+        CHECK_EQ_ARRAY(header, p.header());
+        CHECK_EQ(merge_header(p.header()), p.raw_header());
 
         p.use_fields("Int", "String", "Double");
         using data = std::tuple<int, std::string, double>;
@@ -325,10 +335,14 @@ TEST_CASE_TEMPLATE("test invalid rows with header", T,
                                       {3, "line3", 67.8},
                                       {5, "line5", 9.10}};
         CHECK_EQ(i, expected);
+        CHECK_EQ_ARRAY(header, p.header());
+        CHECK_EQ(merge_header(p.header()), p.raw_header());
     }
 
     {
         auto [p, _] = make_parser<buffer_mode, ErrorMode>(f.name);
+        CHECK_EQ_ARRAY(header, p.header());
+        CHECK_EQ(merge_header(p.header()), p.raw_header());
 
         p.use_fields("Double", "Int");
         using data = std::tuple<double, int>;
@@ -349,10 +363,14 @@ TEST_CASE_TEMPLATE("test invalid rows with header", T,
 
         std::vector<data> expected = {{2.34, 1}, {67.8, 3}, {9.10, 5}};
         CHECK_EQ(i, expected);
+        CHECK_EQ_ARRAY(header, p.header());
+        CHECK_EQ(merge_header(p.header()), p.raw_header());
     }
 
     {
         auto [p, _] = make_parser<buffer_mode, ErrorMode>(f.name);
+        CHECK_EQ_ARRAY(header, p.header());
+        CHECK_EQ(merge_header(p.header()), p.raw_header());
 
         p.use_fields("String", "Double");
         using data = std::tuple<std::string, double>;
@@ -376,96 +394,7 @@ TEST_CASE_TEMPLATE("test invalid rows with header", T,
                                       {"line5", 9.10},
                                       {"line6", 10.11}};
         CHECK_EQ(i, expected);
+        CHECK_EQ_ARRAY(header, p.header());
+        CHECK_EQ(merge_header(p.header()), p.raw_header());
     }
 }
-
-template <typename T>
-void test_ignore_empty(const std::vector<X>& data) {
-    constexpr auto buffer_mode = T::BufferMode::value;
-    using ErrorMode = typename T::ErrorMode;
-
-    unique_file_name f{"ignore_empty"};
-    make_and_write(f.name, data);
-
-    std::vector<X> expected;
-    for (const auto& d : data) {
-        if (d.s != X::empty) {
-            expected.push_back(d);
-        }
-    }
-
-    {
-        auto [p, _] =
-            make_parser<buffer_mode, ErrorMode, ss::ignore_empty>(f.name, ",");
-
-        std::vector<X> i;
-        for (const auto& a : p.template iterate<X>()) {
-            i.push_back(a);
-        }
-
-        CHECK_EQ(i, expected);
-    }
-
-    {
-        auto [p, _] = make_parser<buffer_mode, ErrorMode>(f.name, ",");
-        std::vector<X> i;
-        size_t n = 0;
-        while (!p.eof()) {
-            try {
-                ++n;
-                const auto& a = p.template get_next<X>();
-                if (data.at(n - 1).s == X::empty) {
-                    CHECK_FALSE(p.valid());
-                    continue;
-                }
-                i.push_back(a);
-            } catch (...) {
-                CHECK_EQ(data.at(n - 1).s, X::empty);
-            }
-        }
-
-        CHECK_EQ(i, expected);
-    }
-}
-
-TEST_CASE_TEMPLATE("test various cases with empty lines", T,
-                   ParserOptionCombinations) {
-    test_ignore_empty<T>(
-        {{1, 2, "x"}, {3, 4, "y"}, {9, 10, "v"}, {11, 12, "w"}});
-
-    test_ignore_empty<T>(
-        {{1, 2, X::empty}, {3, 4, "y"}, {9, 10, "v"}, {11, 12, "w"}});
-
-    test_ignore_empty<T>(
-        {{1, 2, "x"}, {3, 4, "y"}, {9, 10, "v"}, {11, 12, X::empty}});
-
-    test_ignore_empty<T>(
-        {{1, 2, "x"}, {5, 6, X::empty}, {9, 10, "v"}, {11, 12, "w"}});
-
-    test_ignore_empty<T>(
-        {{1, 2, X::empty}, {5, 6, X::empty}, {9, 10, "v"}, {11, 12, "w"}});
-
-    test_ignore_empty<T>(
-        {{1, 2, X::empty}, {3, 4, "y"}, {9, 10, "v"}, {11, 12, X::empty}});
-
-    test_ignore_empty<T>(
-        {{1, 2, "x"}, {3, 4, "y"}, {9, 10, X::empty}, {11, 12, X::empty}});
-
-    test_ignore_empty<T>(
-        {{1, 2, X::empty}, {3, 4, "y"}, {9, 10, X::empty}, {11, 12, X::empty}});
-
-    test_ignore_empty<T>({{1, 2, X::empty},
-                          {3, 4, X::empty},
-                          {9, 10, X::empty},
-                          {11, 12, X::empty}});
-
-    test_ignore_empty<T>(
-        {{1, 2, "x"}, {3, 4, X::empty}, {9, 10, X::empty}, {11, 12, X::empty}});
-
-    test_ignore_empty<T>(
-        {{1, 2, X::empty}, {3, 4, X::empty}, {9, 10, X::empty}, {11, 12, "w"}});
-
-    test_ignore_empty<T>({{11, 12, X::empty}});
-
-    test_ignore_empty<T>({});
-}
diff --git a/test/test_parser1_5.cpp b/test/test_parser1_5.cpp
new file mode 100644
index 0000000..e56a3a2
--- /dev/null
+++ b/test/test_parser1_5.cpp
@@ -0,0 +1,301 @@
+#include "test_parser1.hpp"
+
+TEST_CASE_TEMPLATE("test empty fields header", T, ParserOptionCombinations) {
+    constexpr auto buffer_mode = T::BufferMode::value;
+    using ErrorMode = typename T::ErrorMode;
+
+    unique_file_name f{"empty_fields_header"};
+
+    // Empty header
+    {
+        std::ofstream out{f.name};
+        out << "" << std::endl;
+        out << "1" << std::endl;
+    }
+
+    {
+        std::vector<std::string> expected_header = {""};
+        auto [p, _] = make_parser<buffer_mode, ErrorMode>(f.name);
+        CHECK_EQ_ARRAY(expected_header, p.header());
+        CHECK_EQ("", p.raw_header());
+        CHECK(p.valid());
+    }
+
+    // All empty header fields
+    {
+        std::ofstream out{f.name};
+        out << ",," << std::endl;
+        out << "1,2,3" << std::endl;
+    }
+
+    {
+        std::vector<std::string> expected_header = {"", "", ""};
+        auto [p, _] = make_parser<buffer_mode, ErrorMode>(f.name);
+        CHECK_EQ_ARRAY(expected_header, p.header());
+        CHECK_EQ(",,", p.raw_header());
+        CHECK(p.valid());
+
+        auto command1 = [&p = p] { std::ignore = p.field_exists("Int"); };
+        expect_error_on_command(p, command1);
+
+        auto command2 = [&p = p] { p.use_fields("Int"); };
+        expect_error_on_command(p, command2);
+    }
+
+    // One empty field
+    const std::vector<std::string> valid_fields = {"Int0", "Int1", ""};
+
+    using svec = std::vector<std::string>;
+    const std::vector<std::vector<std::string>> valid_field_combinations =
+        {svec{"Int0"},
+         svec{"Int1"},
+         svec{""},
+         svec{"", "Int0"},
+         svec{"Int0", "Int1"},
+         svec{"Int1", ""},
+         svec{"Int0", "", "Int1"},
+         svec{"", "Int1", "Int0"}};
+
+    // Last header field empty
+    {
+        std::ofstream out{f.name};
+        out << "Int0,Int1," << std::endl;
+        out << "1,2,3" << std::endl;
+    }
+
+    {
+        std::vector<std::string> expected_header = {"Int0", "Int1", ""};
+        auto [p, _] = make_parser<buffer_mode, ErrorMode>(f.name);
+        CHECK_EQ_ARRAY(expected_header, p.header());
+        CHECK_EQ("Int0,Int1,", p.raw_header());
+        CHECK(p.valid());
+
+        for (const auto& field : valid_fields) {
+            CHECK(p.field_exists(field));
+            CHECK(p.valid());
+        }
+
+        for (const auto& fields : valid_field_combinations) {
+            p.use_fields(fields);
+            CHECK(p.valid());
+        }
+    }
+
+    // First header field empty
+    {
+        std::ofstream out{f.name};
+        out << ",Int0,Int1" << std::endl;
+        out << "1,2,3" << std::endl;
+    }
+
+    {
+        std::vector<std::string> expected_header = {"", "Int0", "Int1"};
+        auto [p, _] = make_parser<buffer_mode, ErrorMode>(f.name);
+        CHECK_EQ_ARRAY(expected_header, p.header());
+        CHECK_EQ(",Int0,Int1", p.raw_header());
+        CHECK(p.valid());
+
+        for (const auto& field : valid_fields) {
+            CHECK(p.field_exists(field));
+            CHECK(p.valid());
+        }
+
+        for (const auto& fields : valid_field_combinations) {
+            p.use_fields(fields);
+            CHECK(p.valid());
+        }
+    }
+
+    // Middle header field empty
+    {
+        std::ofstream out{f.name};
+        out << "Int0,,Int1" << std::endl;
+        out << "1,2,3" << std::endl;
+    }
+
+    {
+        std::vector<std::string> expected_header = {"Int0", "", "Int1"};
+        auto [p, _] = make_parser<buffer_mode, ErrorMode>(f.name);
+        CHECK_EQ_ARRAY(expected_header, p.header());
+        CHECK_EQ("Int0,,Int1", p.raw_header());
+        CHECK(p.valid());
+
+        for (const auto& field : valid_fields) {
+            CHECK(p.field_exists(field));
+            CHECK(p.valid());
+        }
+
+        for (const auto& fields : valid_field_combinations) {
+            p.use_fields(fields);
+            CHECK(p.valid());
+        }
+    }
+}
+
+template <typename T, typename... Ts>
+void test_unterminated_quote_header() {
+    constexpr auto buffer_mode = T::BufferMode::value;
+    using ErrorMode = typename T::ErrorMode;
+
+    unique_file_name f{"unterminated_quote_header"};
+
+    {
+        std::ofstream out{f.name};
+        out << "\"Int" << std::endl;
+        out << "1" << std::endl;
+    }
+
+    {
+        auto [p, _] = make_parser<buffer_mode, ErrorMode, Ts...>(f.name);
+
+        auto command0 = [&p = p] { std::ignore = p.header(); };
+        expect_error_on_command(p, command0);
+        CHECK_EQ(p.raw_header(), "\"Int");
+
+        auto command1 = [&p = p] { std::ignore = p.field_exists("Int"); };
+        expect_error_on_command(p, command1);
+
+        auto command2 = [&p = p] { p.use_fields("Int"); };
+        expect_error_on_command(p, command2);
+    }
+}
+
+TEST_CASE_TEMPLATE("test unterminated quote header", T,
+                   ParserOptionCombinations) {
+    using quote = ss::quote<'"'>;
+    using escape = ss::escape<'\\'>;
+    test_unterminated_quote_header<T, quote>();
+    test_unterminated_quote_header<T, quote, ss::multiline>();
+    test_unterminated_quote_header<T, quote, escape>();
+    test_unterminated_quote_header<T, quote, escape, ss::multiline>();
+}
+
+template <typename T, typename... Ts>
+void test_unterminated_escape_header() {
+    constexpr auto buffer_mode = T::BufferMode::value;
+    using ErrorMode = typename T::ErrorMode;
+
+    unique_file_name f{"unterminated_escape_header"};
+
+    // Unterminated escape in header
+    {
+        std::ofstream out{f.name};
+        out << "Int\\" << std::endl;
+        out << "1" << std::endl;
+    }
+
+    {
+        auto [p, _] = make_parser<buffer_mode, ErrorMode, Ts...>(f.name);
+
+        auto command0 = [&p = p] { std::ignore = p.header(); };
+        expect_error_on_command(p, command0);
+        CHECK_EQ(p.raw_header(), "Int\\");
+
+        auto command1 = [&p = p] { std::ignore = p.field_exists("Int"); };
+        expect_error_on_command(p, command1);
+
+        auto command2 = [&p = p] { p.use_fields("Int"); };
+        expect_error_on_command(p, command2);
+    }
+}
+
+TEST_CASE_TEMPLATE("test unterminated escape header", T,
+                   ParserOptionCombinations) {
+    using quote = ss::quote<'"'>;
+    using escape = ss::escape<'\\'>;
+    test_unterminated_escape_header<T, escape>();
+    test_unterminated_escape_header<T, escape, ss::multiline>();
+    test_unterminated_escape_header<T, escape, quote>();
+    test_unterminated_escape_header<T, escape, quote, ss::multiline>();
+}
+
+template <typename T>
+void test_ignore_empty(const std::vector<X>& data) {
+    constexpr auto buffer_mode = T::BufferMode::value;
+    using ErrorMode = typename T::ErrorMode;
+
+    unique_file_name f{"ignore_empty"};
+    make_and_write(f.name, data);
+
+    std::vector<X> expected;
+    for (const auto& d : data) {
+        if (d.s != X::empty) {
+            expected.push_back(d);
+        }
+    }
+
+    {
+        auto [p, _] =
+            make_parser<buffer_mode, ErrorMode, ss::ignore_empty>(f.name, ",");
+
+        std::vector<X> i;
+        for (const auto& a : p.template iterate<X>()) {
+            i.push_back(a);
+        }
+
+        CHECK_EQ(i, expected);
+    }
+
+    {
+        auto [p, _] = make_parser<buffer_mode, ErrorMode>(f.name, ",");
+        std::vector<X> i;
+        size_t n = 0;
+        while (!p.eof()) {
+            try {
+                ++n;
+                const auto& a = p.template get_next<X>();
+                if (data.at(n - 1).s == X::empty) {
+                    CHECK_FALSE(p.valid());
+                    continue;
+                }
+                i.push_back(a);
+            } catch (...) {
+                CHECK_EQ(data.at(n - 1).s, X::empty);
+            }
+        }
+
+        CHECK_EQ(i, expected);
+    }
+}
+
+TEST_CASE_TEMPLATE("test various cases with empty lines", T,
+                   ParserOptionCombinations) {
+    test_ignore_empty<T>(
+        {{1, 2, "x"}, {3, 4, "y"}, {9, 10, "v"}, {11, 12, "w"}});
+
+    test_ignore_empty<T>(
+        {{1, 2, X::empty}, {3, 4, "y"}, {9, 10, "v"}, {11, 12, "w"}});
+
+    test_ignore_empty<T>(
+        {{1, 2, "x"}, {3, 4, "y"}, {9, 10, "v"}, {11, 12, X::empty}});
+
+    test_ignore_empty<T>(
+        {{1, 2, "x"}, {5, 6, X::empty}, {9, 10, "v"}, {11, 12, "w"}});
+
+    test_ignore_empty<T>(
+        {{1, 2, X::empty}, {5, 6, X::empty}, {9, 10, "v"}, {11, 12, "w"}});
+
+    test_ignore_empty<T>(
+        {{1, 2, X::empty}, {3, 4, "y"}, {9, 10, "v"}, {11, 12, X::empty}});
+
+    test_ignore_empty<T>(
+        {{1, 2, "x"}, {3, 4, "y"}, {9, 10, X::empty}, {11, 12, X::empty}});
+
+    test_ignore_empty<T>(
+        {{1, 2, X::empty}, {3, 4, "y"}, {9, 10, X::empty}, {11, 12, X::empty}});
+
+    test_ignore_empty<T>({{1, 2, X::empty},
+                          {3, 4, X::empty},
+                          {9, 10, X::empty},
+                          {11, 12, X::empty}});
+
+    test_ignore_empty<T>(
+        {{1, 2, "x"}, {3, 4, X::empty}, {9, 10, X::empty}, {11, 12, X::empty}});
+
+    test_ignore_empty<T>(
+        {{1, 2, X::empty}, {3, 4, X::empty}, {9, 10, X::empty}, {11, 12, "w"}});
+
+    test_ignore_empty<T>({{11, 12, X::empty}});
+
+    test_ignore_empty<T>({});
+}
diff --git a/test/test_parser2.hpp b/test/test_parser2.hpp
index 6048a33..6e1b9d7 100644
--- a/test/test_parser2.hpp
+++ b/test/test_parser2.hpp
@@ -1,13 +1,7 @@
 #include "test_helpers.hpp"
-#include <algorithm>
-#include <filesystem>
 #include <fstream>
-#include <iomanip>
 #include <iostream>
-#include <regex>
 #include <ss/parser.hpp>
-#include <sstream>
-#include <unordered_map>
 #include <unordered_set>
 
 #ifndef SEGMENT_NAME
@@ -91,8 +85,8 @@ struct column {
 };
 
 template <typename... Ts>
-column make_column(const std::string& input_header,
-                   const std::vector<field>& input_fields) {
+[[nodiscard]] column make_column(const std::string& input_header,
+                                 const std::vector<field>& input_fields) {
     using setup = ss::setup<Ts...>;
     std::vector<field> filtered_fields;
 
@@ -133,8 +127,8 @@ column make_column(const std::string& input_header,
 }
 
 template <typename... Ts>
-std::vector<std::string> generate_csv_data(const std::vector<field>& data,
-                                           const std::string& delim) {
+[[nodiscard]] std::vector<std::string> generate_csv_data(
+    const std::vector<field>& data, const std::string& delim) {
     (void)delim;
     using setup = ss::setup<Ts...>;
     constexpr static auto escape = '\\';
@@ -333,8 +327,10 @@ void test_data_combinations(const std::vector<column>& input_data,
         field_header.push_back(field{el.header});
     }
 
+    std::string header_line;
     if (include_header) {
         auto header_data = generate_csv_data<Ts...>(field_header, delim);
+        header_line = merge_header(header_data, delim);
         if (input_data.size() == 0 && rand() % 10 == 0) {
             write_to_file(header_data, delim, f.name, false);
         } else {
@@ -403,7 +399,9 @@ void test_data_combinations(const std::vector<column>& input_data,
                 fields.push_back(header[index]);
             }
 
-            p.use_fields(fields);
+            if constexpr (!setup::ignore_header) {
+                p.use_fields(fields);
+            }
 
             if (!p.valid()) {
                 if constexpr (setup::string_error) {
@@ -425,8 +423,19 @@ void test_data_combinations(const std::vector<column>& input_data,
             }
         };
 
+        auto check_header = [&p = p, &header = header, include_header,
+                             header_line] {
+            if (include_header) {
+                if constexpr (!setup::ignore_header) {
+                    CHECK_EQ_ARRAY(header, p.header());
+                    CHECK_EQ(header_line, p.raw_header());
+                }
+            }
+        };
+
         int num_columns = layout.size();
         for (size_t i = 0; i < n + 1; ++i) {
+            check_header();
             try {
                 switch (num_columns) {
                 case 1: {
@@ -616,7 +625,7 @@ void test_option_combinations3() {
     test_option_combinations2<Ts..., trim>();
 }
 
-} /* namespace */
+} /* anonymous namespace */
 
 // Tests split into multiple compilation units
 #if 0
diff --git a/test/test_parser2_1.cpp b/test/test_parser2_1.cpp
index 55ec45a..71c3ae1 100644
--- a/test/test_parser2_1.cpp
+++ b/test/test_parser2_1.cpp
@@ -9,4 +9,3 @@ TEST_CASE("parser test various cases version 2 segment 1") {
     test_option_combinations3<escape>();
 #endif
 }
-
diff --git a/test/test_parser2_2.cpp b/test/test_parser2_2.cpp
index ec76aa9..b4721fb 100644
--- a/test/test_parser2_2.cpp
+++ b/test/test_parser2_2.cpp
@@ -10,4 +10,3 @@ TEST_CASE("parser test various cases version 2 segment 2") {
     test_option_combinations3<escape, quote>();
 #endif
 }
-
diff --git a/test/test_parser2_3.cpp b/test/test_parser2_3.cpp
index aab905c..4b8266c 100644
--- a/test/test_parser2_3.cpp
+++ b/test/test_parser2_3.cpp
@@ -11,4 +11,3 @@ TEST_CASE("parser test various cases version 2 segment 3") {
     test_option_combinations3<quote, multiline>();
 #endif
 }
-
diff --git a/test/test_parser2_4.cpp b/test/test_parser2_4.cpp
index ea78aaf..65cc1cb 100644
--- a/test/test_parser2_4.cpp
+++ b/test/test_parser2_4.cpp
@@ -12,4 +12,3 @@ TEST_CASE("parser test various cases version 2 segment 4") {
     test_option_combinations3<escape, quote, multiline_r>();
 #endif
 }
-
diff --git a/test/test_parser2_5.cpp b/test/test_parser2_5.cpp
index 3f345b0..dcb661a 100644
--- a/test/test_parser2_5.cpp
+++ b/test/test_parser2_5.cpp
@@ -13,4 +13,3 @@ TEST_CASE("parser test various cases version 2 segment 5") {
     test_option_combinations<escape, quote, multiline, trimr>();
 #endif
 }
-
diff --git a/test/test_parser2_6.cpp b/test/test_parser2_6.cpp
index d6ec30f..c093143 100644
--- a/test/test_parser2_6.cpp
+++ b/test/test_parser2_6.cpp
@@ -8,4 +8,3 @@ TEST_CASE("parser test various cases version 2 segment 6") {
 
     test_option_combinations3<escape, quote, multiline>();
 }
-
diff --git a/test/test_single_header.sh b/test/test_single_header.sh
index 8a2bb91..bd47386 100755
--- a/test/test_single_header.sh
+++ b/test/test_single_header.sh
@@ -3,12 +3,14 @@
 set -x
 set -e
 
-python3 script/single_header_generator.py > ssp.cpp
+TMP_HDR=test_single_header.hpp
+TMP_SRC=test_single_header.cpp
+TMP_BIN=test_single_header
 
-echo 'int main(){ ss::parser p{""}; p.get_next<int, float>(); return 0; }' \
-    >> ssp.cpp
+python3 script/single_header_generator.py > ${TMP_HDR}
+cat ${TMP_HDR} test/test_single_header_main.txt > ${TMP_SRC}
 
-g++ -std=c++17 ssp.cpp -o ssp.bin -Wall -Wextra
-./ssp.bin
+g++ -std=c++17 ${TMP_SRC} -o ${TMP_BIN} -Wall -Wextra
+./${TMP_BIN}
 
-rm ssp.cpp ssp.bin
+rm ${TMP_HDR} ${TMP_SRC} ${TMP_BIN}
diff --git a/test/test_single_header_main.txt b/test/test_single_header_main.txt
new file mode 100644
index 0000000..77d8c6c
--- /dev/null
+++ b/test/test_single_header_main.txt
@@ -0,0 +1,12 @@
+int main() {
+    using quote = ss::quote<'"'>;
+    using escape = ss::escape<'\\'>;
+    using trim = ss::trim<' '>;
+
+    std::string data = "1,string,2.34,c";
+
+    ss::parser<quote, escape, trim, ss::multiline> p{data.c_str(), data.size()};
+    auto tup = p.get_next<int, std::string, float, std::optional<char>>();
+
+    return 0;
+}
diff --git a/test/test_splitter.cpp b/test/test_splitter.cpp
index 201de9d..5216688 100644
--- a/test/test_splitter.cpp
+++ b/test/test_splitter.cpp
@@ -145,7 +145,7 @@ make_combinations(const std::vector<std::string>& input,
 
     return {std::move(lines), std::move(expectations)};
 }
-} /* namespace */
+} /* anonymous namespace */
 
 /* ********************************** */
 /* ********************************** */
@@ -548,7 +548,7 @@ public:
         return splitter.size_shifted();
     }
 };
-} /* ss */
+} /* namespace ss */
 
 TEST_CASE("splitter test resplit unterminated quote") {