From 90eb0a91e0caffdf9b33939760880a92ec132aba Mon Sep 17 00:00:00 2001
From: Niels Lohmann <mail@nlohmann.me>
Date: Sat, 26 May 2018 13:26:40 +0200
Subject: [PATCH] :zap: keys are now returned as const reference #1098
---
.../nlohmann/detail/iterators/iter_impl.hpp | 2 +-
.../detail/iterators/iteration_proxy.hpp | 18 +++++++++++++----
single_include/nlohmann/json.hpp | 20 ++++++++++++++-----
3 files changed, 30 insertions(+), 10 deletions(-)
diff --git a/include/nlohmann/detail/iterators/iter_impl.hpp b/include/nlohmann/detail/iterators/iter_impl.hpp
index 52ede17b..08108a22 100644
--- a/include/nlohmann/detail/iterators/iter_impl.hpp
+++ b/include/nlohmann/detail/iterators/iter_impl.hpp
@@ -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);
diff --git a/include/nlohmann/detail/iterators/iteration_proxy.hpp b/include/nlohmann/detail/iterators/iteration_proxy.hpp
index 7547d038..39c35a2e 100644
--- a/include/nlohmann/detail/iterators/iteration_proxy.hpp
+++ b/include/nlohmann/detail/iterators/iteration_proxy.hpp
@@ -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;
}
}
diff --git a/single_include/nlohmann/json.hpp b/single_include/nlohmann/json.hpp
index 8c9942bb..0b2e055c 100644
--- a/single_include/nlohmann/json.hpp
+++ b/single_include/nlohmann/json.hpp
@@ -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;
}
}