♻️ remove unnecessary if

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

.github/workflows/check_amalgamation.yml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Harden Runner
-        uses: step-security/harden-runner@a5ad31d6a139d249332a2605b85202e8c0b78450 # v2.19.1
+        uses: step-security/harden-runner@9ca718d3bf646d6534007c269a635b3e54cadf99 # v2.19.2
         with:
           egress-policy: audit
 
@@ -34,7 +34,7 @@ jobs:
 
     steps:
       - name: Harden Runner
-        uses: step-security/harden-runner@a5ad31d6a139d249332a2605b85202e8c0b78450 # v2.19.1
+        uses: step-security/harden-runner@9ca718d3bf646d6534007c269a635b3e54cadf99 # v2.19.2
         with:
           egress-policy: audit
 

.github/workflows/cifuzz.yml

@@ -9,7 +9,7 @@ jobs:
     runs-on: ubuntu-22.04
     steps:
     - name: Harden Runner
-      uses: step-security/harden-runner@a5ad31d6a139d249332a2605b85202e8c0b78450 # v2.19.1
+      uses: step-security/harden-runner@9ca718d3bf646d6534007c269a635b3e54cadf99 # v2.19.2
       with:
         egress-policy: audit
 

.github/workflows/codeql-analysis.yml

@@ -27,7 +27,7 @@ jobs:
 
     steps:
     - name: Harden Runner
-      uses: step-security/harden-runner@a5ad31d6a139d249332a2605b85202e8c0b78450 # v2.19.1
+      uses: step-security/harden-runner@9ca718d3bf646d6534007c269a635b3e54cadf99 # v2.19.2
       with:
         egress-policy: audit
 

.github/workflows/comment_check_amalgamation.yml

@@ -19,7 +19,7 @@ jobs:
       pull-requests: write
     steps:
       - name: Harden Runner
-        uses: step-security/harden-runner@a5ad31d6a139d249332a2605b85202e8c0b78450 # v2.19.1
+        uses: step-security/harden-runner@9ca718d3bf646d6534007c269a635b3e54cadf99 # v2.19.2
         with:
           egress-policy: audit
 

.github/workflows/dependency-review.yml

@@ -17,11 +17,11 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Harden Runner
-        uses: step-security/harden-runner@a5ad31d6a139d249332a2605b85202e8c0b78450 # v2.19.1
+        uses: step-security/harden-runner@9ca718d3bf646d6534007c269a635b3e54cadf99 # v2.19.2
         with:
           egress-policy: audit
 
       - name: 'Checkout Repository'
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
       - name: 'Dependency Review'
-        uses: actions/dependency-review-action@2031cfc080254a8a887f58cffee85186f0e49e48 # v4.9.0
+        uses: actions/dependency-review-action@a1d282b36b6f3519aa1f3fc636f609c47dddb294 # v5.0.0

.github/workflows/flawfinder.yml

@@ -27,7 +27,7 @@ jobs:
       security-events: write
     steps:
       - name: Harden Runner
-        uses: step-security/harden-runner@a5ad31d6a139d249332a2605b85202e8c0b78450 # v2.19.1
+        uses: step-security/harden-runner@9ca718d3bf646d6534007c269a635b3e54cadf99 # v2.19.2
         with:
           egress-policy: audit
 

.github/workflows/labeler.yml

@@ -17,7 +17,7 @@ jobs:
 
     steps:
       - name: Harden Runner
-        uses: step-security/harden-runner@a5ad31d6a139d249332a2605b85202e8c0b78450 # v2.19.1
+        uses: step-security/harden-runner@9ca718d3bf646d6534007c269a635b3e54cadf99 # v2.19.2
         with:
           egress-policy: audit
 

.github/workflows/publish_documentation.yml

@@ -27,7 +27,7 @@ jobs:
     runs-on: ubuntu-22.04
     steps:
       - name: Harden Runner
-        uses: step-security/harden-runner@a5ad31d6a139d249332a2605b85202e8c0b78450 # v2.19.1
+        uses: step-security/harden-runner@9ca718d3bf646d6534007c269a635b3e54cadf99 # v2.19.2
         with:
           egress-policy: audit
 
@@ -40,7 +40,7 @@ jobs:
         run: make build -C docs/mkdocs
 
       - name: Deploy documentation
-        uses: peaceiris/actions-gh-pages@4f9cc6602d3f66b9c108549d475ec49e8ef4d45e # v4.0.0
+        uses: peaceiris/actions-gh-pages@84c30a85c19949d7eee79c4ff27748b70285e453 # v4.1.0
         with:
           github_token: ${{ secrets.GITHUB_TOKEN }}
           publish_dir: ./docs/mkdocs/site

.github/workflows/scorecards.yml

@@ -36,7 +36,7 @@ jobs:
 
     steps:
       - name: Harden Runner
-        uses: step-security/harden-runner@a5ad31d6a139d249332a2605b85202e8c0b78450 # v2.19.1
+        uses: step-security/harden-runner@9ca718d3bf646d6534007c269a635b3e54cadf99 # v2.19.2
         with:
           egress-policy: audit
 

.github/workflows/semgrep.yml

@@ -32,7 +32,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Harden Runner
-        uses: step-security/harden-runner@a5ad31d6a139d249332a2605b85202e8c0b78450 # v2.19.1
+        uses: step-security/harden-runner@9ca718d3bf646d6534007c269a635b3e54cadf99 # v2.19.2
         with:
           egress-policy: audit
 

.github/workflows/stale.yml

@@ -16,7 +16,7 @@ jobs:
 
     steps:
       - name: Harden Runner
-        uses: step-security/harden-runner@a5ad31d6a139d249332a2605b85202e8c0b78450 # v2.19.1
+        uses: step-security/harden-runner@9ca718d3bf646d6534007c269a635b3e54cadf99 # v2.19.2
         with:
           egress-policy: audit
 

.github/workflows/ubuntu.yml

@@ -46,7 +46,7 @@ jobs:
         target: [ci_test_amalgamation, ci_test_single_header, ci_cppcheck, ci_cpplint, ci_reproducible_tests, ci_non_git_tests, ci_offline_testdata, ci_reuse_compliance, ci_test_valgrind]
     steps:
       - name: Harden Runner
-        uses: step-security/harden-runner@a5ad31d6a139d249332a2605b85202e8c0b78450 # v2.19.1
+        uses: step-security/harden-runner@9ca718d3bf646d6534007c269a635b3e54cadf99 # v2.19.2
         with:
           egress-policy: audit
 
@@ -98,7 +98,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Harden Runner
-        uses: step-security/harden-runner@a5ad31d6a139d249332a2605b85202e8c0b78450 # v2.19.1
+        uses: step-security/harden-runner@9ca718d3bf646d6534007c269a635b3e54cadf99 # v2.19.2
         with:
           egress-policy: audit
 
@@ -251,7 +251,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Harden Runner
-        uses: step-security/harden-runner@a5ad31d6a139d249332a2605b85202e8c0b78450 # v2.19.1
+        uses: step-security/harden-runner@9ca718d3bf646d6534007c269a635b3e54cadf99 # v2.19.2
         with:
           egress-policy: audit
 
@@ -272,7 +272,7 @@ jobs:
         target: [ci_test_examples, ci_test_build_documentation]
     steps:
       - name: Harden Runner
-        uses: step-security/harden-runner@a5ad31d6a139d249332a2605b85202e8c0b78450 # v2.19.1
+        uses: step-security/harden-runner@9ca718d3bf646d6534007c269a635b3e54cadf99 # v2.19.2
         with:
           egress-policy: audit
 

cmake/requirements/requirements-cppcheck.txt

@@ -1 +1 @@
-cppcheck==1.5.0
+cppcheck==1.5.1

docs/mkdocs/docs/api/json_pointer/front.md

@@ -0,0 +1,37 @@
+# <small>nlohmann::json_pointer::</small>front
+
+```cpp
+const string_t& front() const;
+```
+
+Return the first reference token.
+
+## Return value
+
+First reference token.
+
+## Exceptions
+
+Throws [out_of_range.405](../../home/exceptions.md#jsonexceptionout_of_range405) if the JSON pointer has no parent.
+
+## Complexity
+
+Constant.
+
+## Examples
+
+??? example
+
+    The example shows the usage of `front`.
+     
+    ```cpp
+    --8<-- "examples/json_pointer__front.cpp"
+    ```
+    
+    Output:
+    
+    ```json
+    --8<-- "examples/json_pointer__front.output"
+    ```
+
+## Version history

docs/mkdocs/docs/api/json_pointer/index.md

@@ -37,6 +37,9 @@ are the base for JSON patches.
 - [**pop_back**](pop_back.md) - remove the last reference token
 - [**back**](back.md) - return last reference token
 - [**push_back**](push_back.md) - append an unescaped token at the end of the pointer
+- [**pop_front**](pop_front.md) - remove the first reference token
+- [**front**](front.md) - return first reference token
+- [**push_front**](push_front.md) - append an unescaped token at the start of the pointer
 - [**empty**](empty.md) - return whether the pointer points to the root document
 
 ## Literals

docs/mkdocs/docs/api/json_pointer/pop_front.md

@@ -0,0 +1,33 @@
+# <small>nlohmann::json_pointer::</small>pop_front
+
+```cpp
+void pop_front();
+```
+
+Remove the first reference token.
+
+## Exceptions
+
+Throws [out_of_range.405](../../home/exceptions.md#jsonexceptionout_of_range405) if the JSON pointer has no parent.
+
+## Complexity
+
+Linear in the number of reference tokens in the `json_pointer`.
+
+## Examples
+
+??? example
+
+    The example shows the usage of `pop_front`.
+     
+    ```cpp
+    --8<-- "examples/json_pointer__pop_front.cpp"
+    ```
+    
+    Output:
+    
+    ```json
+    --8<-- "examples/json_pointer__pop_front.output"
+    ```
+
+## Version history

docs/mkdocs/docs/api/json_pointer/push_front.md

@@ -0,0 +1,36 @@
+# <small>nlohmann::json_pointer::</small>push_front
+
+```cpp
+void push_front(const string_t& token);
+
+void push_front(string_t&& token);
+```
+
+Append an unescaped token at the start of the reference pointer.
+
+## Parameters
+
+`token` (in)
+:   token to add
+
+## Complexity
+
+Linear in the number of reference tokens in the `json_pointer`.
+
+## Examples
+
+??? example
+
+    The example shows the result of `push_front` for different JSON Pointers.
+     
+    ```cpp
+    --8<-- "examples/json_pointer__push_front.cpp"
+    ```
+    
+    Output:
+    
+    ```json
+    --8<-- "examples/json_pointer__push_front.output"
+    ```
+
+## Version history

docs/mkdocs/docs/examples/json_pointer__front.cpp

@@ -0,0 +1,15 @@
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+using json = nlohmann::json;
+
+int main()
+{
+    // different JSON Pointers
+    json::json_pointer ptr1("/foo");
+    json::json_pointer ptr2("/foo/0");
+
+    // call empty()
+    std::cout << "first reference token of \"" << ptr1 << "\" is \"" << ptr1.front() << "\"\n"
+              << "first reference token of \"" << ptr2 << "\" is \"" << ptr2.front() << "\"" << std::endl;
+}

docs/mkdocs/docs/examples/json_pointer__front.output

@@ -0,0 +1,2 @@
+first reference token of "/foo" is "foo"
+first reference token of "/foo/0" is "foo"

docs/mkdocs/docs/examples/json_pointer__pop_front.cpp

@@ -0,0 +1,21 @@
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+using json = nlohmann::json;
+
+int main()
+{
+    // create empty JSON Pointer
+    json::json_pointer ptr("/foo/bar/baz");
+    std::cout << "\"" << ptr << "\"\n";
+
+    // call pop_front()
+    ptr.pop_front();
+    std::cout << "\"" << ptr << "\"\n";
+
+    ptr.pop_front();
+    std::cout << "\"" << ptr << "\"\n";
+
+    ptr.pop_front();
+    std::cout << "\"" << ptr << "\"\n";
+}

docs/mkdocs/docs/examples/json_pointer__pop_front.output

@@ -0,0 +1,4 @@
+"/foo/bar/baz"
+"/bar/baz"
+"/baz"
+""

docs/mkdocs/docs/examples/json_pointer__push_front.cpp

@@ -0,0 +1,21 @@
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+using json = nlohmann::json;
+
+int main()
+{
+    // create empty JSON Pointer
+    json::json_pointer ptr;
+    std::cout << "\"" << ptr << "\"\n";
+
+    // call push_front()
+    ptr.push_front("foo");
+    std::cout << "\"" << ptr << "\"\n";
+
+    ptr.push_front("0");
+    std::cout << "\"" << ptr << "\"\n";
+
+    ptr.push_front("bar");
+    std::cout << "\"" << ptr << "\"\n";
+}

docs/mkdocs/docs/examples/json_pointer__push_front.output

@@ -0,0 +1,4 @@
+""
+"/foo"
+"/0/foo"
+"/bar/0/foo"

docs/mkdocs/mkdocs.yml

@@ -233,6 +233,7 @@ nav:
           - '(Constructor)': api/json_pointer/json_pointer.md
           - 'back': api/json_pointer/back.md
           - 'empty': api/json_pointer/empty.md
+          - 'front': api/json_pointer/front.md
           - 'operator string_t': api/json_pointer/operator_string_t.md
           - 'operator==': api/json_pointer/operator_eq.md
           - 'operator!=': api/json_pointer/operator_ne.md
@@ -240,7 +241,9 @@ nav:
           - 'operator/=': api/json_pointer/operator_slasheq.md
           - 'parent_pointer': api/json_pointer/parent_pointer.md
           - 'pop_back': api/json_pointer/pop_back.md
+          - 'pop_front': api/json_pointer/pop_front.md
           - 'push_back': api/json_pointer/push_back.md
+          - 'push_front': api/json_pointer/push_front.md
           - 'string_t': api/json_pointer/string_t.md
           - 'to_string': api/json_pointer/to_string.md
       - json_sax:

docs/mkdocs/requirements.txt

@@ -1,7 +1,7 @@
 wheel==0.47.0
 
 mkdocs==1.6.1                                       # documentation framework
-mkdocs-git-revision-date-localized-plugin==1.5.1    # plugin "git-revision-date-localized"
+mkdocs-git-revision-date-localized-plugin==1.5.2    # plugin "git-revision-date-localized"
 mkdocs-material==9.7.6                             # theme for mkdocs
 mkdocs-material-extensions==1.3.1                   # extensions
 mkdocs-minify-plugin==0.8.0                         # plugin "minify"

include/nlohmann/detail/conversions/from_json.hpp

@@ -388,14 +388,10 @@ inline void from_json(const BasicJsonType& j, ConstructibleObjectType& obj)
 
     ConstructibleObjectType ret;
     const auto* inner_object = j.template get_ptr<const typename BasicJsonType::object_t*>();
-    using value_type = typename ConstructibleObjectType::value_type;
+    for (const auto& p : *inner_object)
-    std::transform(
-        inner_object->begin(), inner_object->end(),
-        std::inserter(ret, ret.begin()),
-        [](typename BasicJsonType::object_t::value_type const & p)
     {
-        return value_type(p.first, p.second.template get<typename ConstructibleObjectType::mapped_type>());
+        ret.emplace(p.first, p.second.template get<typename ConstructibleObjectType::mapped_type>());
-    });
+    }
     obj = std::move(ret);
 }
 

include/nlohmann/detail/conversions/to_json.hpp

@@ -214,10 +214,7 @@ struct external_constructor<value_t::array>
         j.m_data.m_type = value_t::array;
         j.m_data.m_value = value_t::array;
         j.m_data.m_value.array->resize(arr.size());
-        if (arr.size() > 0)
-        {
         std::copy(std::begin(arr), std::end(arr), j.m_data.m_value.array->begin());
-        }
         j.set_parents();
         j.assert_invariant();
     }

include/nlohmann/detail/iterators/iter_impl.hpp

@@ -35,7 +35,7 @@ This class implements a both iterators (iterator and const_iterator) for the
       been set (e.g., by a constructor or a copy assignment). If the iterator is
       default-constructed, it is *uninitialized* and most methods are undefined.
       **The library uses assertions to detect calls on uninitialized iterators.**
-@requirement The class satisfies the following concept requirements:
+@requirement REQ-JSON-01 The class satisfies the following concept requirements:
 -
 [BidirectionalIterator](https://en.cppreference.com/w/cpp/named_req/BidirectionalIterator):
   The iterator that can be moved can be moved in both directions (i.e.

include/nlohmann/detail/iterators/json_reverse_iterator.hpp

@@ -29,7 +29,7 @@ namespace detail
 iterator (to create @ref reverse_iterator) and @ref const_iterator (to
 create @ref const_reverse_iterator).
 
-@requirement The class satisfies the following concept requirements:
+@requirement REQ-JSON-02 The class satisfies the following concept requirements:
 -
 [BidirectionalIterator](https://en.cppreference.com/w/cpp/named_req/BidirectionalIterator):
   The iterator that can be moved can be moved in both directions (i.e.

include/nlohmann/detail/json_pointer.hpp

@@ -154,6 +154,44 @@ class json_pointer
         return res;
     }
 
+    /// @brief remove first reference token
+    /// @sa https://json.nlohmann.me/api/json_pointer/pop_front/
+    void pop_front()
+    {
+        if (JSON_HEDLEY_UNLIKELY(empty()))
+        {
+            JSON_THROW(detail::out_of_range::create(405, "JSON pointer has no parent", nullptr));
+        }
+
+        reference_tokens.erase(reference_tokens.begin());
+    }
+
+    /// @brief return first reference token
+    /// @sa https://json.nlohmann.me/api/json_pointer/front/
+    const string_t& front() const
+    {
+        if (JSON_HEDLEY_UNLIKELY(empty()))
+        {
+            JSON_THROW(detail::out_of_range::create(405, "JSON pointer has no parent", nullptr));
+        }
+
+        return reference_tokens.front();
+    }
+
+    /// @brief append an unescaped token at the start of the reference pointer
+    /// @sa https://json.nlohmann.me/api/json_pointer/push_front/
+    void push_front(const string_t& token)
+    {
+        reference_tokens.insert(reference_tokens.begin(), token);
+    }
+
+    /// @brief append an unescaped token at the start of the reference pointer
+    /// @sa https://json.nlohmann.me/api/json_pointer/push_front/
+    void push_front(string_t&& token)
+    {
+        reference_tokens.insert(reference_tokens.begin(), std::move(token));
+    }
+
     /// @brief remove last reference token
     /// @sa https://json.nlohmann.me/api/json_pointer/pop_back/
     void pop_back()

include/nlohmann/detail/output/serializer.hpp

@@ -825,14 +825,27 @@ class serializer
         o->write_characters(begin, static_cast<size_t>(end - begin));
     }
 
+    JSON_HEDLEY_NON_NULL(1)
+    static int snprintf_float(char* buf, std::size_t size, int d, double x)
+    {
+        // NOLINTNEXTLINE(cppcoreguidelines-pro-type-vararg,hicpp-vararg)
+        return (std::snprintf)(buf, size, "%.*g", d, x);
+    }
+
+    JSON_HEDLEY_NON_NULL(1)
+    static int snprintf_float(char* buf, std::size_t size, int d, long double x)
+    {
+        // NOLINTNEXTLINE(cppcoreguidelines-pro-type-vararg,hicpp-vararg)
+        return (std::snprintf)(buf, size, "%.*lg", d, x);
+    }
+
     void dump_float(number_float_t x, std::false_type /*is_ieee_single_or_double*/)
     {
         // get the number of digits for a float -> text -> float round-trip
         static constexpr auto d = std::numeric_limits<number_float_t>::max_digits10;
 
         // the actual conversion
-        // NOLINTNEXTLINE(cppcoreguidelines-pro-type-vararg,hicpp-vararg)
+        std::ptrdiff_t len = snprintf_float(number_buffer.data(), number_buffer.size(), d, x);
-        std::ptrdiff_t len = (std::snprintf)(number_buffer.data(), number_buffer.size(), "%.*g", d, x);
 
         // negative value indicates an error
         JSON_ASSERT(len > 0);

include/nlohmann/json.hpp

@@ -741,10 +741,10 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
 #endif
     }
 
-    iterator set_parents(iterator it, typename iterator::difference_type count_set_parents)
+    iterator set_parents(iterator it, std::ptrdiff_t count_set_parents)
     {
 #if JSON_DIAGNOSTICS
-        for (typename iterator::difference_type i = 0; i < count_set_parents; ++i)
+        for (std::ptrdiff_t i = 0; i < count_set_parents; ++i)
         {
             (it + i)->m_parent = this;
         }

include/nlohmann/ordered_map.hpp

@@ -50,6 +50,25 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
         : Container{first, last, alloc} {}
     ordered_map(std::initializer_list<value_type> init, const Allocator& alloc = Allocator() )
         : Container{init, alloc} {}
+    ordered_map(const ordered_map&) = default;
+    ordered_map(ordered_map&&) noexcept(std::is_nothrow_move_constructible<Container>::value) = default;
+    ~ordered_map() = default;
+
+    ordered_map& operator=(const ordered_map& other)
+    {
+        if (this != &other)
+        {
+            ordered_map tmp(other);
+            Container::operator=(std::move(static_cast<Container&>(tmp)));
+        }
+        return *this;
+    }
+
+    ordered_map& operator=(ordered_map&& other) noexcept(std::is_nothrow_move_assignable<Container>::value)
+    {
+        Container::operator=(std::move(static_cast<Container&>(other)));
+        return *this;
+    }
 
     std::pair<iterator, bool> emplace(const key_type& key, T&& t)
     {

single_include/nlohmann/json.hpp

@@ -5306,14 +5306,10 @@ inline void from_json(const BasicJsonType& j, ConstructibleObjectType& obj)
 
     ConstructibleObjectType ret;
     const auto* inner_object = j.template get_ptr<const typename BasicJsonType::object_t*>();
-    using value_type = typename ConstructibleObjectType::value_type;
+    for (const auto& p : *inner_object)
-    std::transform(
-        inner_object->begin(), inner_object->end(),
-        std::inserter(ret, ret.begin()),
-        [](typename BasicJsonType::object_t::value_type const & p)
     {
-        return value_type(p.first, p.second.template get<typename ConstructibleObjectType::mapped_type>());
+        ret.emplace(p.first, p.second.template get<typename ConstructibleObjectType::mapped_type>());
-    });
+    }
     obj = std::move(ret);
 }
 
@@ -6027,10 +6023,7 @@ struct external_constructor<value_t::array>
         j.m_data.m_type = value_t::array;
         j.m_data.m_value = value_t::array;
         j.m_data.m_value.array->resize(arr.size());
-        if (arr.size() > 0)
-        {
         std::copy(std::begin(arr), std::end(arr), j.m_data.m_value.array->begin());
-        }
         j.set_parents();
         j.assert_invariant();
     }
@@ -13807,7 +13800,7 @@ This class implements a both iterators (iterator and const_iterator) for the
       been set (e.g., by a constructor or a copy assignment). If the iterator is
       default-constructed, it is *uninitialized* and most methods are undefined.
       **The library uses assertions to detect calls on uninitialized iterators.**
-@requirement The class satisfies the following concept requirements:
+@requirement REQ-JSON-01 The class satisfies the following concept requirements:
 -
 [BidirectionalIterator](https://en.cppreference.com/w/cpp/named_req/BidirectionalIterator):
   The iterator that can be moved can be moved in both directions (i.e.
@@ -14566,7 +14559,7 @@ namespace detail
 iterator (to create @ref reverse_iterator) and @ref const_iterator (to
 create @ref const_reverse_iterator).
 
-@requirement The class satisfies the following concept requirements:
+@requirement REQ-JSON-02 The class satisfies the following concept requirements:
 -
 [BidirectionalIterator](https://en.cppreference.com/w/cpp/named_req/BidirectionalIterator):
   The iterator that can be moved can be moved in both directions (i.e.
@@ -14872,6 +14865,44 @@ class json_pointer
         return res;
     }
 
+    /// @brief remove first reference token
+    /// @sa https://json.nlohmann.me/api/json_pointer/pop_front/
+    void pop_front()
+    {
+        if (JSON_HEDLEY_UNLIKELY(empty()))
+        {
+            JSON_THROW(detail::out_of_range::create(405, "JSON pointer has no parent", nullptr));
+        }
+
+        reference_tokens.erase(reference_tokens.begin());
+    }
+
+    /// @brief return first reference token
+    /// @sa https://json.nlohmann.me/api/json_pointer/front/
+    const string_t& front() const
+    {
+        if (JSON_HEDLEY_UNLIKELY(empty()))
+        {
+            JSON_THROW(detail::out_of_range::create(405, "JSON pointer has no parent", nullptr));
+        }
+
+        return reference_tokens.front();
+    }
+
+    /// @brief append an unescaped token at the start of the reference pointer
+    /// @sa https://json.nlohmann.me/api/json_pointer/push_front/
+    void push_front(const string_t& token)
+    {
+        reference_tokens.insert(reference_tokens.begin(), token);
+    }
+
+    /// @brief append an unescaped token at the start of the reference pointer
+    /// @sa https://json.nlohmann.me/api/json_pointer/push_front/
+    void push_front(string_t&& token)
+    {
+        reference_tokens.insert(reference_tokens.begin(), std::move(token));
+    }
+
     /// @brief remove last reference token
     /// @sa https://json.nlohmann.me/api/json_pointer/pop_back/
     void pop_back()
@@ -19773,14 +19804,27 @@ class serializer
         o->write_characters(begin, static_cast<size_t>(end - begin));
     }
 
+    JSON_HEDLEY_NON_NULL(1)
+    static int snprintf_float(char* buf, std::size_t size, int d, double x)
+    {
+        // NOLINTNEXTLINE(cppcoreguidelines-pro-type-vararg,hicpp-vararg)
+        return (std::snprintf)(buf, size, "%.*g", d, x);
+    }
+
+    JSON_HEDLEY_NON_NULL(1)
+    static int snprintf_float(char* buf, std::size_t size, int d, long double x)
+    {
+        // NOLINTNEXTLINE(cppcoreguidelines-pro-type-vararg,hicpp-vararg)
+        return (std::snprintf)(buf, size, "%.*lg", d, x);
+    }
+
     void dump_float(number_float_t x, std::false_type /*is_ieee_single_or_double*/)
     {
         // get the number of digits for a float -> text -> float round-trip
         static constexpr auto d = std::numeric_limits<number_float_t>::max_digits10;
 
         // the actual conversion
-        // NOLINTNEXTLINE(cppcoreguidelines-pro-type-vararg,hicpp-vararg)
+        std::ptrdiff_t len = snprintf_float(number_buffer.data(), number_buffer.size(), d, x);
-        std::ptrdiff_t len = (std::snprintf)(number_buffer.data(), number_buffer.size(), "%.*g", d, x);
 
         // negative value indicates an error
         JSON_ASSERT(len > 0);
@@ -19994,6 +20038,25 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
         : Container{first, last, alloc} {}
     ordered_map(std::initializer_list<value_type> init, const Allocator& alloc = Allocator() )
         : Container{init, alloc} {}
+    ordered_map(const ordered_map&) = default;
+    ordered_map(ordered_map&&) noexcept(std::is_nothrow_move_constructible<Container>::value) = default;
+    ~ordered_map() = default;
+
+    ordered_map& operator=(const ordered_map& other)
+    {
+        if (this != &other)
+        {
+            ordered_map tmp(other);
+            Container::operator=(std::move(static_cast<Container&>(tmp)));
+        }
+        return *this;
+    }
+
+    ordered_map& operator=(ordered_map&& other) noexcept(std::is_nothrow_move_assignable<Container>::value)
+    {
+        Container::operator=(std::move(static_cast<Container&>(other)));
+        return *this;
+    }
 
     std::pair<iterator, bool> emplace(const key_type& key, T&& t)
     {
@@ -20982,10 +21045,10 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
 #endif
     }
 
-    iterator set_parents(iterator it, typename iterator::difference_type count_set_parents)
+    iterator set_parents(iterator it, std::ptrdiff_t count_set_parents)
     {
 #if JSON_DIAGNOSTICS
-        for (typename iterator::difference_type i = 0; i < count_set_parents; ++i)
+        for (std::ptrdiff_t i = 0; i < count_set_parents; ++i)
         {
             (it + i)->m_parent = this;
         }

tests/src/unit-json_pointer.cpp

@@ -564,6 +564,14 @@ TEST_CASE("JSON pointers")
         CHECK(!ptr.empty());
         CHECK(j[ptr] == j["answer"]["everything"]);
 
+        ptr.pop_front();
+        CHECK(ptr.front() == "everything");
+        ptr.pop_front();
+        CHECK(ptr.empty());
+        ptr.push_front("everything");
+        ptr.push_front(answer);
+        CHECK(j[ptr] == j["answer"]["everything"]);
+
         // check access via const pointer
         const auto cptr = ptr;
         CHECK(cptr.back() == "everything");
@@ -588,8 +596,17 @@ TEST_CASE("JSON pointers")
         CHECK(ptr.empty());
         CHECK(j[ptr] == j);
 
-        CHECK_THROWS_WITH(ptr.pop_back(),
+        CHECK_THROWS_WITH_AS(ptr.pop_back(),
-                          "[json.exception.out_of_range.405] JSON pointer has no parent");
+                             "[json.exception.out_of_range.405] JSON pointer has no parent", json::out_of_range&);
+
+        CHECK_THROWS_WITH_AS(ptr.back(),
+                             "[json.exception.out_of_range.405] JSON pointer has no parent", json::out_of_range&);
+
+        CHECK_THROWS_WITH_AS(ptr.pop_front(),
+                             "[json.exception.out_of_range.405] JSON pointer has no parent", json::out_of_range&);
+
+        CHECK_THROWS_WITH_AS(ptr.front(),
+                             "[json.exception.out_of_range.405] JSON pointer has no parent", json::out_of_range&);
     }
 
     SECTION("operators")

tests/src/unit-ordered_json.cpp

@@ -69,3 +69,15 @@ TEST_CASE("ordered_json")
     CHECK(oj1.size() == 4);
     CHECK(oj1.dump() == "{\"c\":1,\"b\":2,\"a\":3,\"d\":42}");
 }
+
+TEST_CASE("regression test for issue #3732 - iteration_proxy_value<iter_impl<ordered_json>>")
+{
+    // Naming the proxy type in a function-parameter position forces eager
+    // instantiation of basic_json<ordered_map>; previously this hit an
+    // incomplete-type error in set_parents().
+    auto fn = [](nlohmann::detail::iteration_proxy_value<nlohmann::detail::iter_impl<nlohmann::ordered_json>> const & val)
+    {
+        return val.value();
+    };
+    static_cast<void>(fn);
+}

tests/src/unit-regression2.cpp

@@ -1240,4 +1240,93 @@ TEST_CASE("regression test #5074 - single-element brace init with JSON_BRACE_INI
 }
 #endif
 
+struct Example_5122
+{
+    float b = 2;
+    nlohmann::ordered_map<std::string, std::string> c{}; // NOLINT(readability-redundant-member-init): needed for GCC -Weffc++
+    int a = 1;
+    NLOHMANN_DEFINE_TYPE_INTRUSIVE_WITH_DEFAULT(Example_5122, b, c, a)
+};
+
+TEST_CASE("regression test #5122 - from_json into types holding nlohmann::ordered_map")
+{
+    Example_5122 src;
+    src.c.emplace("first", "1");
+    src.c.emplace("second", "2");
+
+    ordered_json const j = src;
+    Example_5122 const dst = j.get<Example_5122>();
+
+    CHECK(dst.b == src.b);
+    CHECK(dst.a == src.a);
+    REQUIRE(dst.c.size() == src.c.size());
+    auto src_it = src.c.begin();
+    auto dst_it = dst.c.begin();
+    for (; src_it != src.c.end(); ++src_it, ++dst_it)
+    {
+        CHECK(dst_it->first == src_it->first);
+        CHECK(dst_it->second == src_it->second);
+    }
+}
+
+// -Wself-assign-overloaded was introduced in Clang 7. Gate the pragma on
+// __has_warning so older Clang versions do not error with "unknown warning
+// group". The __has_warning check has to stay inside the __clang__ branch
+// because GCC does not provide it and would tokenize-error on the argument.
+#if defined(__clang__) && defined(__has_warning)
+    #if __has_warning("-Wself-assign-overloaded")
+        DOCTEST_CLANG_SUPPRESS_WARNING_PUSH
+        DOCTEST_CLANG_SUPPRESS_WARNING("-Wself-assign-overloaded")
+    #endif
+#endif
+
+TEST_CASE("regression test #5122 - nlohmann::ordered_map copy-assignment is self-assignment safe")
+{
+    nlohmann::ordered_map<std::string, std::string> m;
+    m.emplace("first", "1");
+    m.emplace("second", "2");
+
+    // Insertion order is preserved by ordered_map, so we can check it directly.
+    m = m;
+
+    REQUIRE(m.size() == 2);
+    auto it = m.begin();
+    CHECK(it->first == "first");
+    CHECK(it->second == "1");
+    ++it;
+    CHECK(it->first == "second");
+    CHECK(it->second == "2");
+}
+
+#if defined(__clang__) && defined(__has_warning)
+    #if __has_warning("-Wself-assign-overloaded")
+        DOCTEST_CLANG_SUPPRESS_WARNING_POP
+    #endif
+#endif
+
+TEST_CASE("regression test #5122 - nlohmann::ordered_map move-assignment transfers contents")
+{
+    nlohmann::ordered_map<std::string, std::string> src;
+    src.emplace("first", "1");
+    src.emplace("second", "2");
+
+    nlohmann::ordered_map<std::string, std::string> dst;
+    dst.emplace("stale", "x");
+    dst = std::move(src);
+
+    REQUIRE(dst.size() == 2);
+    auto it = dst.begin();
+    CHECK(it->first == "first");
+    CHECK(it->second == "1");
+    ++it;
+    CHECK(it->first == "second");
+    CHECK(it->second == "2");
+
+    // Re-assigning into the moved-from object must leave it in a usable state.
+    src = nlohmann::ordered_map<std::string, std::string> {};
+    src.emplace("after-move", "3");
+    REQUIRE(src.size() == 1);
+    CHECK(src.begin()->first == "after-move");
+}
+
 DOCTEST_CLANG_SUPPRESS_WARNING_POP