add possibility to iterate with the parser, update unit tests, update README

README.md

@@ -35,13 +35,8 @@ Bill (Heath) Gates,65,3.3
 
 int main() {
     ss::parser p{"students.csv"};
-    if (!p.valid()) {
-        exit(EXIT_FAILURE);
-    }
-
-    while (!p.eof()) {
-        auto [name, age, grade] = p.get_next<std::string, int, double>();
 
+    for(auto& [name, age, grade] : p.iterate<std::string, int, double>()) {
         if (p.valid()) {
             std::cout << name << ' ' << age << ' ' << grade << std::endl;
         }
@@ -88,7 +83,17 @@ The library supports [CMake](#Cmake) and [meson](#Meson) build systems
 # Usage
 
 ## Conversions
-The above example will be used to show some of the features of the library. As seen above, the **get_next** method returns a tuple of objects specified inside the template type list.
+An alternate loop to the example above would look like: 
+```cpp
+while(!p.eof()) {
+    auto [name, age, grade] = p.get_next<std::string, int, double>();
+    if (p.valid()) {
+        std::cout << name << ' ' << age << ' ' << grade << std::endl;
+    }
+}
+```
+
+The alternate example will be used to show some of the features of the library. The **get_next** method returns a tuple of objects specified inside the template type list.
 
 If a conversion could not be applied, the method would return a tuple of default constructed objects, and the **valid** method would return **false**, for example if the third (grade) column in our csv could not be converted to a double the conversion would fail. 
 
@@ -119,6 +124,12 @@ This works with any object if the constructor could be invoked using the templat
 auto vec = p.get_object<std::vector<std::string>, std::string, std::string, 
                         std::string>();
 ```
+An iteration loop as in the first example which returns objects would look like:
+```cpp
+for(auto& student : p.iterate_object<student, std::string, int, double>()) {
+// ...
+}
+```
 And finally, using something I personally like to do, a struct (class) with a **tied** method which returns a tuple of references to to the members of the struct.
 ```cpp
 struct student {
@@ -134,6 +145,7 @@ The method can be used to compare the object, serialize it, deserialize it, etc.
 // returns student
 auto s = p.get_next<student>();
 ```
+This works with the iteration loop too.
 *Note, the order in which the members of the tied method are returned must match the order of the elements in the csv*.
 
 ## Setup

include/ss/common.hpp

@@ -1,4 +1,7 @@
 #pragma once
+#include <cstdint>
+#include <cstdio>
+#include <cstdlib>
 #include <vector>
 
 namespace ss {
@@ -21,7 +24,6 @@ inline ssize_t get_line(char** lineptr, size_t* n, FILE* stream) {
     return getline(lineptr, n, stream);
 }
 #else
-#include <cstdint>
 using ssize_t = int64_t;
 inline ssize_t get_line(char** lineptr, size_t* n, FILE* stream) {
     size_t pos;

include/ss/parser.hpp

@@ -85,6 +85,73 @@ public:
         return value;
     }
 
+    ////////////////
+    // iterator
+    ////////////////
+
+    template <bool get_object, typename T, typename... Ts>
+    struct iterable {
+        struct iterator {
+            using value =
+                ss::ternary_t<get_object, T, no_void_validator_tup_t<T, Ts...>>;
+
+            iterator() : parser_{nullptr} {}
+            iterator(parser<Matchers...>* parser) : parser_{parser} {}
+
+            value& operator*() { return value_; }
+            value* operator->() { return &value_; }
+
+            iterator& operator++() {
+                if (parser_->eof()) {
+                    parser_ = nullptr;
+                } else {
+                    if constexpr (get_object) {
+                        value_ =
+                            std::move(parser_->template get_object<T, Ts...>());
+                    } else {
+                        value_ =
+                            std::move(parser_->template get_next<T, Ts...>());
+                    }
+                }
+                return *this;
+            }
+
+            iterator& operator++(int) { return ++*this; }
+
+            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) {
+                return !(lhs == rhs);
+            }
+
+        private:
+            value value_;
+            parser<Matchers...>* parser_;
+        };
+
+        iterable(parser<Matchers...>* parser) : parser_{parser} {}
+
+        iterator begin() { return ++iterator{parser_}; }
+        iterator end() { return iterator{}; }
+
+    private:
+        parser<Matchers...>* parser_;
+    };
+
+    template <typename... Ts>
+    auto iterate() {
+        return iterable<false, Ts...>{this};
+    }
+
+    template <typename... Ts>
+    auto iterate_object() {
+        return iterable<true, Ts...>{this};
+    }
+
     ////////////////
     // composite conversion
     ////////////////

include/ss/type_traits.hpp

@@ -388,7 +388,7 @@ T to_object_impl(std::index_sequence<Is...>, U&& data) {
 
 template <class T, class U>
 T to_object(U&& data) {
-    using NoRefU = std::remove_reference_t<U>;
+    using NoRefU = std::decay_t<U>;
     if constexpr (is_instance_of_v<std::tuple, NoRefU>) {
         return to_object_impl<
             T>(std::make_index_sequence<std::tuple_size<NoRefU>{}>{},

test/test_parser.cpp

@@ -21,12 +21,9 @@ struct unique_file_name {
 
     unique_file_name()
         : name{"random_" + std::to_string(i++) + time_now_rand() +
-               "_file.csv"} {
+               "_file.csv"} {}
-    }
 
-    ~unique_file_name() {
+    ~unique_file_name() { std::filesystem::remove(name); }
-        std::filesystem::remove(name);
-    }
 };
 
 void replace_all(std::string& s, const std::string& from,
@@ -60,9 +57,7 @@ struct X {
             .append(delim)
             .append(s);
     }
-    auto tied() const {
+    auto tied() const { return std::tie(i, d, s); }
-        return std::tie(i, d, s);
-    }
 };
 
 template <typename T>
@@ -98,40 +93,85 @@ TEST_CASE("parser test various cases") {
         ss::parser<ss::string_error> p{f.name, ","};
         ss::parser p0{std::move(p)};
         p = std::move(p0);
-
         std::vector<X> i;
 
+        ss::parser<ss::string_error> p2{f.name, ","};
+        std::vector<X> i2;
+
         while (!p.eof()) {
             auto a = p.get_next<int, double, std::string>();
             i.emplace_back(ss::to_object<X>(a));
         }
 
+        for (const auto& a : p2.iterate<int, double, std::string>()) {
+            i2.emplace_back(ss::to_object<X>(a));
+        }
+
         CHECK_EQ(i, data);
+        CHECK_EQ(i2, data);
     }
 
     {
         ss::parser p{f.name, ","};
         std::vector<X> i;
+
+        ss::parser p2{f.name, ","};
+        std::vector<X> i2;
+
+        ss::parser p3{f.name, ","};
+        std::vector<X> i3;
+
         std::vector<X> expected = {std::begin(data) + 1, std::end(data)};
+        using tup = std::tuple<int, double, std::string>;
 
         p.ignore_next();
         while (!p.eof()) {
-            using tup = std::tuple<int, double, std::string>;
             auto a = p.get_next<tup>();
             i.emplace_back(ss::to_object<X>(a));
         }
 
+        p2.ignore_next();
+        for (const auto& a : p2.iterate<tup>()) {
+            i2.emplace_back(ss::to_object<X>(a));
+        }
+
+        p3.ignore_next();
+        for (auto it = p3.iterate<tup>().begin(); it != p3.iterate<tup>().end();
+             ++it) {
+            i3.emplace_back(ss::to_object<X>(*it));
+        }
+
         CHECK_EQ(i, expected);
+        CHECK_EQ(i2, expected);
+        CHECK_EQ(i3, expected);
     }
 
     {
         ss::parser p{f.name, ","};
         std::vector<X> i;
+        ss::parser p2{f.name, ","};
+        std::vector<X> i2;
 
         while (!p.eof()) {
             i.push_back(p.get_object<X, int, double, std::string>());
         }
 
+        for (auto&& a : p2.iterate_object<X, int, double, std::string>()) {
+            i2.push_back(std::move(a));
+        }
+
+        CHECK_EQ(i, data);
+        CHECK_EQ(i2, data);
+    }
+
+    {
+        ss::parser p{f.name, ","};
+        std::vector<X> i;
+
+        for (auto&& a : p.iterate_object<X, int, double, std::string>()) {
+            i.push_back(std::move(a));
+        }
+
         CHECK_EQ(i, data);
     }
 
@@ -139,11 +179,32 @@ TEST_CASE("parser test various cases") {
         ss::parser p{f.name, ","};
         std::vector<X> i;
 
-        while (!p.eof()) {
+        ss::parser p2{f.name, ","};
+        std::vector<X> i2;
+
         using tup = std::tuple<int, double, std::string>;
+        while (!p.eof()) {
             i.push_back(p.get_object<X, tup>());
         }
 
+        for (auto it = p2.iterate_object<X, tup>().begin();
+             it != p2.iterate_object<X, tup>().end(); it++) {
+            i2.push_back({it->i, it->d, it->s});
+        }
+
+        CHECK_EQ(i, data);
+        CHECK_EQ(i2, data);
+    }
+
+    {
+        ss::parser p{f.name, ","};
+        std::vector<X> i;
+
+        using tup = std::tuple<int, double, std::string>;
+        for (auto&& a : p.iterate_object<X, tup>()) {
+            i.push_back(std::move(a));
+        }
+
         CHECK_EQ(i, data);
     }
 
@@ -158,11 +219,25 @@ TEST_CASE("parser test various cases") {
         CHECK_EQ(i, data);
     }
 
+    {
+        ss::parser p{f.name, ","};
+        std::vector<X> i;
+
+        for (auto&& a : p.iterate<X>()) {
+            i.push_back(std::move(a));
+        }
+
+        CHECK_EQ(i, data);
+    }
+
     {
         constexpr int excluded = 3;
         ss::parser p{f.name, ","};
         std::vector<X> i;
 
+        ss::parser p2{f.name, ","};
+        std::vector<X> i2;
+
         while (!p.eof()) {
             auto a =
                 p.get_object<X, ss::ax<int, excluded>, double, std::string>();
@@ -171,6 +246,13 @@ TEST_CASE("parser test various cases") {
             }
         }
 
+        for (auto&& a : p2.iterate_object<X, ss::ax<int, excluded>, double,
+                                          std::string>()) {
+            if (p2.valid()) {
+                i2.push_back(std::move(a));
+            }
+        }
+
         std::vector<X> expected;
         for (auto& x : data) {
             if (x.i != excluded) {
@@ -181,34 +263,57 @@ TEST_CASE("parser test various cases") {
         std::copy_if(data.begin(), data.end(), expected.begin(),
                      [](const X& x) { return x.i != excluded; });
         CHECK_EQ(i, expected);
+        CHECK_EQ(i2, expected);
     }
 
     {
         ss::parser p{f.name, ","};
         std::vector<X> i;
 
+        ss::parser p2{f.name, ","};
+        std::vector<X> i2;
+
         while (!p.eof()) {
             auto a = p.get_object<X, ss::nx<int, 3>, double, std::string>();
             if (p.valid()) {
                 i.push_back(a);
             }
         }
+
+        for (auto&& a :
+             p2.iterate_object<X, ss::nx<int, 3>, double, std::string>()) {
+            if (p2.valid()) {
+                i2.push_back(std::move(a));
+            }
+        }
+
         std::vector<X> expected = {{3, 4, "y"}};
         CHECK_EQ(i, expected);
+        CHECK_EQ(i2, expected);
     }
 
     {
         unique_file_name empty_f;
         std::vector<X> empty_data = {};
+
         make_and_write(empty_f.name, empty_data);
 
         ss::parser p{empty_f.name, ","};
         std::vector<X> i;
 
+        ss::parser p2{empty_f.name, ","};
+        std::vector<X> i2;
+
         while (!p.eof()) {
             i.push_back(p.get_next<X>());
         }
+
+        for (auto&& a : p2.iterate<X>()) {
+            i2.push_back(std::move(a));
+        }
+
         CHECK(i.empty());
+        CHECK(i2.empty());
     }
 }
 
@@ -217,13 +322,10 @@ struct test_struct {
     int i;
     double d;
     char c;
-    auto tied() {
+    auto tied() { return std::tie(i, d, c); }
-        return std::tie(i, d, c);
-    }
 };
 
-void expect_test_struct(const test_struct&) {
+void expect_test_struct(const test_struct&) {}
-}
 
 // various scenarios
 TEST_CASE("parser test composite conversion") {
@@ -444,9 +546,7 @@ struct my_string {
 
     my_string() = default;
 
-    ~my_string() {
+    ~my_string() { delete[] data; }
-        delete[] data;
-    }
 
     // make sure no object is copied
     my_string(const my_string&) = delete;
@@ -477,9 +577,7 @@ struct xyz {
     my_string x;
     my_string y;
     my_string z;
-    auto tied() {
+    auto tied() { return std::tie(x, y, z); }
-        return std::tie(x, y, z);
-    }
 };
 
 TEST_CASE("parser test the moving of parsed values") {