Add front methods to json_pointers (implements #4889) (#5152)

* Added front, pop_front, and push_front methods to json_pointers in order to facilitate root-to-leaf traversals of JSON object trees. (#4889) Signed-off-by: trdesilva <5818730+trdesilva@users.noreply.github.com> * undid VS autoformatting in irrelevant code Signed-off-by: trdesilva <5818730+trdesilva@users.noreply.github.com> * Ran make amalgamate, added navigation to json_pointer's new front methods in mkdocs, and fixed errors in documented complexity for those methods. Signed-off-by: trdesilva <5818730+trdesilva@users.noreply.github.com> * Fixed GCC 4.8 compile error caused by const iterators Signed-off-by: trdesilva <5818730+trdesilva@users.noreply.github.com> * Fixed another gcc-4.8 compile error Signed-off-by: trdesilva <5818730+trdesilva@users.noreply.github.com> * amalgamated Signed-off-by: trdesilva <5818730+trdesilva@users.noreply.github.com> --------- Signed-off-by: trdesilva <5818730+trdesilva@users.noreply.github.com>
2026-05-13 09:45:24 +00:00 · 2026-05-12 22:59:16 -07:00
parent 216c50365e
commit a0a4e7cc0b
14 changed files with 274 additions and 2 deletions
@@ -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()