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⚡ keys are now returned as const reference #1098

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Niels Lohmann 2018-05-26 13:26:40 +02:00
parent 4639bb2c8f
commit 90eb0a91e0
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GPG key ID: 7F3CEA63AE251B69
3 changed files with 30 additions and 10 deletions
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2
include/nlohmann/detail/iterators/iter_impl.hpp
View file

@ -583,7 +583,7 @@ class iter_impl
@brief return the key of an object iterator
@pre The iterator is initialized; i.e. `m_object != nullptr`.
*/
typename object_t::key_type key() const
const typename object_t::key_type& key() const
{
assert(m_object != nullptr);

18
include/nlohmann/detail/iterators/iteration_proxy.hpp
View file

@ -21,6 +21,10 @@ template<typename IteratorType> class iteration_proxy
IteratorType anchor;
/// an index for arrays (used to create key names)
std::size_t array_index = 0;
/// a string representation of the array index
std::string array_index_str = "0";
/// an empty string (to return a reference for primitive values)
const std::string empty_str = "";
public:
explicit iteration_proxy_internal(IteratorType it) noexcept : anchor(it) {}
@ -35,7 +39,13 @@ template<typename IteratorType> class iteration_proxy
iteration_proxy_internal& operator++()
{
++anchor;
++array_index;
assert(anchor.m_object != nullptr);
if (anchor.m_object->is_array())
{
// update array index and string representation
array_index_str = std::to_string(++array_index);
}
return *this;
}
@ -47,7 +57,7 @@ template<typename IteratorType> class iteration_proxy
}
/// return key of the iterator
std::string key() const
const std::string& key() const
{
assert(anchor.m_object != nullptr);
@ -55,7 +65,7 @@ template<typename IteratorType> class iteration_proxy
{
// use integer array index as key
case value_t::array:
return std::to_string(array_index);
return array_index_str;
// use key from the object
case value_t::object:
@ -63,7 +73,7 @@ template<typename IteratorType> class iteration_proxy
// use an empty key for all primitive types
default:
return "";
return empty_str;
}
}

20
single_include/nlohmann/json.hpp
View file

@ -4636,7 +4636,7 @@ class iter_impl
@brief return the key of an object iterator
@pre The iterator is initialized; i.e. `m_object != nullptr`.
*/
typename object_t::key_type key() const
const typename object_t::key_type& key() const
{
assert(m_object != nullptr);
@ -4691,6 +4691,10 @@ template<typename IteratorType> class iteration_proxy
IteratorType anchor;
/// an index for arrays (used to create key names)
std::size_t array_index = 0;
/// a string representation of the array index
std::string array_index_str = "0";
/// an empty string (to return a reference for primitive values)
const std::string empty_str = "";
public:
explicit iteration_proxy_internal(IteratorType it) noexcept : anchor(it) {}
@ -4705,7 +4709,13 @@ template<typename IteratorType> class iteration_proxy
iteration_proxy_internal& operator++()
{
++anchor;
++array_index;
assert(anchor.m_object != nullptr);
if (anchor.m_object->is_array())
{
// update array index and string representation
array_index_str = std::to_string(++array_index);
}
return *this;
}
@ -4717,7 +4727,7 @@ template<typename IteratorType> class iteration_proxy
}
/// return key of the iterator
std::string key() const
const std::string& key() const
{
assert(anchor.m_object != nullptr);
@ -4725,7 +4735,7 @@ template<typename IteratorType> class iteration_proxy
{
// use integer array index as key
case value_t::array:
return std::to_string(array_index);
return array_index_str;
// use key from the object
case value_t::object:
@ -4733,7 +4743,7 @@ template<typename IteratorType> class iteration_proxy
// use an empty key for all primitive types
default:
return "";
return empty_str;
}
}