implement the try_object method, update unit tests, update documentation

README.md

@@ -245,3 +245,28 @@ struct even {
 auto [name, age] = p.get_next<std::string, even<int>, void>();
 ```
 ## Custom conversions
+
+Custom types can be used when converting values. An override of the **ss::extract**  
+function needs to be made and you are good to go. Custom conversion for an enum  
+would look like this: 
+```cpp
+enum class shape { circle, rectangle, triangle };
+
+template <>
+inline bool ss::extract(const char* begin, const char* end, shape& dst) {
+    const static std::unordered_map<std::string, shape>
+        shapes{{"circle", shape::circle},
+               {"rectangle", shape::rectangle},
+               {"triangle", shape::triangle}};
+
+    if (auto it = shapes.find(std::string(begin, end)); it != shapes.end()) {
+        dst = it->second;
+        return true;
+    }
+    return false;
+}
+```
+The shape enum will be in an example below. The **inline** is there just to prevent   
+multiple definition errors. The function returns **true** if the conversion was  
+a success, and **false** otherwise. The function uses **const char*** begin and end  
+for performance reasons.

include/ss/parser.hpp

@@ -184,6 +184,19 @@ public:
         return {std::move(value), *this};
     };
 
+    // 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{}) {
+        std::optional<T> value;
+        auto new_value = get_object<T, Ts...>();
+        if (valid()) {
+            value = std::move(new_value);
+            try_invoke(*value, std::forward<Fun>(fun));
+        }
+        return {std::move(value), *this};
+    };
+
 private:
     template <typename...>
     friend class composite;
@@ -327,7 +340,7 @@ private:
     const std::string file_name_;
     const std::string delim_;
     std::string string_error_;
-    bool bool_error_;
+    bool bool_error_{false};
     error_mode error_mode_{error_mode::error_bool};
     converter converter_;
     converter::split_input split_input_;

test/test_parser.cpp

@@ -179,8 +179,9 @@ TEST_CASE("testing composite conversion") {
     unique_file_name f;
     {
         std::ofstream out{f.name};
-        for (auto& i : {"10,a,11.1", "10,20,11.1", "junk", "10,11.1",
-                        "1,11.1,a", "junk", "10,junk", "11,junk"}) {
+        for (auto& i :
+             {"10,a,11.1", "10,20,11.1", "junk", "10,11.1", "1,11.1,a", "junk",
+              "10,junk", "11,junk", "10,11.1,c"}) {
             out << i << std::endl;
         }
     }
@@ -241,9 +242,9 @@ TEST_CASE("testing composite conversion") {
         REQUIRE(!p.eof());
 
         auto [d1, d2, d3, d4, d5] =
-            p.try_next<int, int, double>(fail)
+            p.try_object<test_struct, int, double, char>(fail)
                 .on_error(expect_error)
-                .or_else_object<test_struct, int, double, char>(fail)
+                .or_else<int, char, char>(fail)
                 .or_else<test_struct>(fail)
                 .or_else<test_tuple>(fail)
                 .or_else<int, char, double>(fail)
@@ -334,6 +335,20 @@ TEST_CASE("testing composite conversion") {
         REQUIRE(!d2);
         CHECK(*d1 == std::tuple{11, std::variant<int, std::string>{"junk"}});
     }
+
+    {
+        REQUIRE(!p.eof());
+
+        auto [d1, d2] = p.try_object<test_struct, int, double, char>()
+                            .or_else<int>(fail)
+                            .values();
+        REQUIRE(p.valid());
+        REQUIRE(d1);
+        REQUIRE(!d2);
+        CHECK(d1->tied() == std::tuple{10, 11.1, 'c'});
+    }
+
+    CHECK(p.eof());
 }
 
 size_t move_called = 0;