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Merge pull request #2553 from jasujm/jasujm/input_adapter_custom_container

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Fix compilation of input_adapter(container) in edge cases
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Niels Lohmann 2020-12-29 14:37:20 +01:00 committed by GitHub
commit ff3863dc1d
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3 changed files with 84 additions and 17 deletions
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29
include/nlohmann/detail/input/input_adapters.hpp
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@ -371,15 +371,36 @@ typename iterator_input_adapter_factory<IteratorType>::adapter_type input_adapte
}
// Convenience shorthand from container to iterator
template<typename ContainerType>
auto input_adapter(const ContainerType& container) -> decltype(input_adapter(begin(container), end(container)))
{
// Enable ADL
// Enables ADL on begin(container) and end(container)
// Encloses the using declarations in namespace for not to leak them to outside scope
namespace container_input_adapter_factory_impl {
using std::begin;
using std::end;
template<typename ContainerType, typename Enable = void>
struct container_input_adapter_factory {};
template<typename ContainerType>
struct container_input_adapter_factory< ContainerType,
void_t<decltype(begin(std::declval<ContainerType>()), end(std::declval<ContainerType>()))> >
{
using adapter_type = decltype(input_adapter(begin(std::declval<ContainerType>()), end(std::declval<ContainerType>())));
static adapter_type create(const ContainerType& container)
{
return input_adapter(begin(container), end(container));
}
};
}
template<typename ContainerType>
typename container_input_adapter_factory_impl::container_input_adapter_factory<ContainerType>::adapter_type input_adapter(const ContainerType& container)
{
return container_input_adapter_factory_impl::container_input_adapter_factory<ContainerType>::create(container);
}
// Special cases with fast paths
inline file_input_adapter input_adapter(std::FILE* file)

29
single_include/nlohmann/json.hpp
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@ -5183,15 +5183,36 @@ typename iterator_input_adapter_factory<IteratorType>::adapter_type input_adapte
}
// Convenience shorthand from container to iterator
template<typename ContainerType>
auto input_adapter(const ContainerType& container) -> decltype(input_adapter(begin(container), end(container)))
{
// Enable ADL
// Enables ADL on begin(container) and end(container)
// Encloses the using declarations in namespace for not to leak them to outside scope
namespace container_input_adapter_factory_impl {
using std::begin;
using std::end;
template<typename ContainerType, typename Enable = void>
struct container_input_adapter_factory {};
template<typename ContainerType>
struct container_input_adapter_factory< ContainerType,
void_t<decltype(begin(std::declval<ContainerType>()), end(std::declval<ContainerType>()))> >
{
using adapter_type = decltype(input_adapter(begin(std::declval<ContainerType>()), end(std::declval<ContainerType>())));
static adapter_type create(const ContainerType& container)
{
return input_adapter(begin(container), end(container));
}
};
}
template<typename ContainerType>
typename container_input_adapter_factory_impl::container_input_adapter_factory<ContainerType>::adapter_type input_adapter(const ContainerType& container)
{
return container_input_adapter_factory_impl::container_input_adapter_factory<ContainerType>::create(container);
}
// Special cases with fast paths
inline file_input_adapter input_adapter(std::FILE* file)

27
test/src/unit-user_defined_input.cpp
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@ -63,7 +63,7 @@ const char* end(const MyContainer& c)
return c.data + strlen(c.data);
}
TEST_CASE("Custom container")
TEST_CASE("Custom container non-member begin/end")
{
MyContainer data{"[1,2,3,4]"};
@ -75,6 +75,31 @@ TEST_CASE("Custom container")
}
TEST_CASE("Custom container member begin/end")
{
struct MyContainer2
{
const char* data;
const char* begin() const
{
return data;
}
const char* end() const
{
return data + strlen(data);
}
};
MyContainer2 data{"[1,2,3,4]"};
json as_json = json::parse(data);
CHECK(as_json.at(0) == 1);
CHECK(as_json.at(1) == 2);
CHECK(as_json.at(2) == 3);
CHECK(as_json.at(3) == 4);
}
TEST_CASE("Custom iterator")
{
const char* raw_data = "[1,2,3,4]";