Merge branch 'do-not-require-default-ctor-108'

fix #108.

tests/test_utility.cpp

@@ -9,27 +9,24 @@
 #include <vector>
 #include <array>
 
-BOOST_AUTO_TEST_CASE(test_resize)
+BOOST_AUTO_TEST_CASE(test_try_reserve)
 {
     {
-        typedef std::vector<int>  resizable_type;
-        typedef std::array<int,1> non_resizable_type;
-        BOOST_TEST(toml::detail::has_resize_method<resizable_type>::value);
-        BOOST_TEST(!toml::detail::has_resize_method<non_resizable_type>::value);
+        // since BOOST_TEST is a macro, it cannot handle commas correctly.
+        // When toml::detail::has_reserve_method<std::array<int, 1>>::value
+        // is passed to a macro, C preprocessor considers
+        // toml::detail::has_reserve_method<std::array<int as the first argument
+        // and 1>>::value as the second argument. We need an alias to avoid
+        // this problem.
+        using reservable_type    = std::vector<int>  ;
+        using nonreservable_type = std::array<int, 1>;
+        BOOST_TEST( toml::detail::has_reserve_method<reservable_type   >::value);
+        BOOST_TEST(!toml::detail::has_reserve_method<nonreservable_type>::value);
     }
     {
         std::vector<int> v;
-        toml::resize(v, 10);
-        BOOST_TEST(v.size() == 10u);
-    }
-    {
-        std::array<int, 15> a;
-        toml::resize(a, 10);
-        BOOST_TEST(a.size() == 15u);
-    }
-    {
-        std::array<int, 15> a;
-        BOOST_CHECK_THROW(toml::resize(a, 20), std::invalid_argument);
+        toml::try_reserve(v, 100);
+        BOOST_TEST(v.capacity() == 100u);
     }
 }
 

toml/get.hpp

@@ -198,23 +198,23 @@ get(const basic_value<C, M, V>& v)
 // ============================================================================
 // forward declaration to use this recursively. ignore this and go ahead.
 
-// array-like type with resize(N) method
+// array-like type with push_back(value) method
 template<typename T, typename C,
          template<typename ...> class M, template<typename ...> class V>
 detail::enable_if_t<detail::conjunction<
-    detail::is_container<T>,      // T is container
-    detail::has_resize_method<T>, // T::resize(N) works
+    detail::is_container<T>,         // T is a container
+    detail::has_push_back_method<T>, // T::push_back(value) works
     detail::negation<                // but not toml::array
         detail::is_exact_toml_type<T, basic_value<C, M, V>>>
     >::value, T>
 get(const basic_value<C, M, V>&);
 
-// array-like type with resize(N) method
+// array-like type without push_back(value) method
 template<typename T, typename C,
          template<typename ...> class M, template<typename ...> class V>
 detail::enable_if_t<detail::conjunction<
-    detail::is_container<T>,                        // T is container
-    detail::negation<detail::has_resize_method<T>>, // no T::resize() exists
+    detail::is_container<T>,                           // T is a container
+    detail::negation<detail::has_push_back_method<T>>, // w/o push_back(...)
     detail::negation<                                  // not toml::array
         detail::is_exact_toml_type<T, basic_value<C, M, V>>>
     >::value, T>
@@ -274,31 +274,54 @@ get(const basic_value<C, M, V>&);
 template<typename T, typename C,
          template<typename ...> class M, template<typename ...> class V>
 detail::enable_if_t<detail::conjunction<
-    detail::is_container<T>,      // T is container
-    detail::has_resize_method<T>, // T::resize(N) works
+    detail::is_container<T>,         // T is a container
+    detail::has_push_back_method<T>, // container.push_back(elem) works
     detail::negation<                // but not toml::array
         detail::is_exact_toml_type<T, basic_value<C, M, V>>>
     >::value, T>
 get(const basic_value<C, M, V>& v)
 {
     using value_type = typename T::value_type;
-    const auto& ar = v.as_array();
+    const auto& ary = v.as_array();
+
     T container;
-    container.resize(ar.size());
-    std::transform(ar.cbegin(), ar.cend(), container.begin(),
-                   [](const value& x){return ::toml::get<value_type>(x);});
+    try_reserve(container, ary.size());
+
+    for(const auto& elem : ary)
+    {
+        container.push_back(get<value_type>(elem));
+    }
     return container;
 }
 
 // ============================================================================
-// array-like types; but does not have resize(); most likely std::array.
+// std::forward_list does not have push_back, insert, or emplace.
+// It has insert_after, emplace_after, push_front.
+
+template<typename T, typename C,
+         template<typename ...> class M, template<typename ...> class V>
+detail::enable_if_t<detail::is_std_forward_list<T>::value, T>
+get(const basic_value<C, M, V>& v)
+{
+    using value_type = typename T::value_type;
+    T container;
+    for(const auto& elem : v.as_array())
+    {
+        container.push_front(get<value_type>(elem));
+    }
+    container.reverse();
+    return container;
+}
+
+// ============================================================================
+// array-like types, without push_back(). most likely [std|boost]::array.
 
 template<typename T, typename C,
          template<typename ...> class M, template<typename ...> class V>
 detail::enable_if_t<detail::conjunction<
-    detail::is_container<T>,                        // T is container
-    detail::negation<detail::has_resize_method<T>>, // no T::resize() exists
-    detail::negation<                              // but not toml::array
+    detail::is_container<T>,                           // T is a container
+    detail::negation<detail::has_push_back_method<T>>, // w/o push_back
+    detail::negation<                                  // T is not toml::array
         detail::is_exact_toml_type<T, basic_value<C, M, V>>>
     >::value, T>
 get(const basic_value<C, M, V>& v)

toml/traits.hpp

@@ -7,6 +7,7 @@
 #include <chrono>
 #include <tuple>
 #include <string>
+#include <forward_list>
 #if __cplusplus >= 201703L
 #if __has_include(<string_view>)
 #include <string_view>
@@ -43,17 +44,23 @@ struct has_mapped_type_impl
     template<typename T> static std::true_type  check(typename T::mapped_type*);
     template<typename T> static std::false_type check(...);
 };
-struct has_resize_method_impl
+struct has_reserve_method_impl
 {
-    constexpr static std::size_t dummy=0;
-    template<typename T> static std::true_type  check(decltype(std::declval<T>().resize(dummy))*);
     template<typename T> static std::false_type check(...);
+    template<typename T> static std::true_type  check(
+        decltype(std::declval<T>().reserve(std::declval<std::size_t>()))*);
+};
+struct has_push_back_method_impl
+{
+    template<typename T> static std::false_type check(...);
+    template<typename T> static std::true_type  check(
+        decltype(std::declval<T>().push_back(std::declval<typename T::value_type>()))*);
 };
-
 struct is_comparable_impl
 {
-    template<typename T> static std::true_type  check(decltype(std::declval<T>() < std::declval<T>())*);
     template<typename T> static std::false_type check(...);
+    template<typename T> static std::true_type  check(
+        decltype(std::declval<T>() < std::declval<T>())*);
 };
 
 struct has_from_toml_method_impl
@@ -91,7 +98,9 @@ struct has_key_type    : decltype(has_key_type_impl::check<T>(nullptr)){};
 template<typename T>
 struct has_mapped_type : decltype(has_mapped_type_impl::check<T>(nullptr)){};
 template<typename T>
-struct has_resize_method : decltype(has_resize_method_impl::check<T>(nullptr)){};
+struct has_reserve_method : decltype(has_reserve_method_impl::check<T>(nullptr)){};
+template<typename T>
+struct has_push_back_method : decltype(has_push_back_method_impl::check<T>(nullptr)){};
 template<typename T>
 struct is_comparable : decltype(is_comparable_impl::check<T>(nullptr)){};
 
@@ -149,6 +158,10 @@ template<typename T> struct is_std_tuple : std::false_type{};
 template<typename ... Ts>
 struct is_std_tuple<std::tuple<Ts...>> : std::true_type{};
 
+template<typename T> struct is_std_forward_list : std::false_type{};
+template<typename T>
+struct is_std_forward_list<std::forward_list<T>> : std::true_type{};
+
 template<typename T> struct is_chrono_duration: std::false_type{};
 template<typename Rep, typename Period>
 struct is_chrono_duration<std::chrono::duration<Rep, Period>>: std::true_type{};

toml/utility.hpp

@@ -36,30 +36,25 @@ inline std::unique_ptr<T> make_unique(Ts&& ... args)
 
 namespace detail
 {
-
-template<typename T>
-inline void resize_impl(T& container, std::size_t N, std::true_type)
+template<typename Container>
+void try_reserve_impl(Container& container, std::size_t N, std::true_type)
 {
-    container.resize(N);
-    return ;
+    container.reserve(N);
+    return;
 }
-
-template<typename T>
-inline void resize_impl(T& container, std::size_t N, std::false_type)
+template<typename Container>
+void try_reserve_impl(Container&, std::size_t, std::false_type) noexcept
 {
-    if(container.size() >= N) {return;}
-
-    throw std::invalid_argument("not resizable type");
+    return;
 }
-
 } // detail
 
-template<typename T>
-inline void resize(T& container, std::size_t N)
+template<typename Container>
+void try_reserve(Container& container, std::size_t N)
 {
-    if(container.size() == N) {return;}
-
-    return detail::resize_impl(container, N, detail::has_resize_method<T>());
+    if(N <= container.size()) {return;}
+    detail::try_reserve_impl(container, N, detail::has_reserve_method<Container>{});
+    return;
 }
 
 namespace detail