Add json_document and json_view: node index, parser, and document

.github/labeler.yml

@@ -56,6 +56,23 @@ labels:
 - label: "aspect: binary formats"
   title: "(?i)(bson|cbor|msgpack|messagepack|ubjson|bjdata|bon8|binary format)"
 
+- label: "aspect: json_view"
+  files:
+    - "include/nlohmann/json_view\\.hpp"
+    - "include/nlohmann/detail/view/.*"
+    - "single_include/nlohmann/json_view\\.hpp"
+    - "tests/src/unit-json_view.*"
+    - "tests/src/fuzzer-parse_json_view\\.cpp"
+    - "tools/amalgamate/config_json_view\\.json"
+    - "docs/mkdocs/docs/features/json_view\\.md"
+    - "docs/mkdocs/docs/api/basic_json_(document|view)/.*"
+    - "docs/mkdocs/docs/api/(ordered_)?json_(document|view)\\.md"
+    - "docs/mkdocs/docs/examples/(basic_json_(document|view)__|(ordered_)?json_(document|view)).*"
+    - "tests/benchmarks/src/benchmarks_view\\.cpp"
+
+- label: "aspect: json_view"
+  title: "(?i)(json_view|json_document|zero-copy)"
+
 - label: "python"
   files:
     - "\\.py$"

.github/workflows/check_amalgamation.yml

@@ -116,12 +116,15 @@ jobs:
 
           python3 $TOOL_DIR/amalgamate.py -c $TOOL_DIR/config_json.json -s .
           python3 $TOOL_DIR/amalgamate.py -c $TOOL_DIR/config_json_fwd.json -s .
+          # the configuration of json_view.hpp comes with the pull request until
+          # it is on develop; the tool itself is still develop's
+          python3 $TOOL_DIR/amalgamate.py -c $MAIN_DIR/tools/amalgamate/config_json_view.json -s .
 
           # the header list of the Bazel "json" target must match the files in include/
           cmake -P cmake/scripts/gen_bazel_build_file.cmake
 
           ${{ github.workspace }}/venv/bin/astyle --project=tools/astyle/.astylerc --suffix=none --quiet \
-            $INCLUDE_DIR/json.hpp $INCLUDE_DIR/json_fwd.hpp
+            $INCLUDE_DIR/json.hpp $INCLUDE_DIR/json_fwd.hpp $INCLUDE_DIR/json_view.hpp
 
           # fail loudly if a directory is renamed or removed: find would only warn
           # about the missing path and silently drop its files from the check

BUILD.bazel

@@ -20,6 +20,7 @@ cc_library(
     hdrs = [
         "include/nlohmann/adl_serializer.hpp",
         "include/nlohmann/byte_container_with_subtype.hpp",
+        "include/nlohmann/detail/abi_config.hpp",
         "include/nlohmann/detail/abi_macros.hpp",
         "include/nlohmann/detail/bit_ops.hpp",
         "include/nlohmann/detail/conversions/from_json.hpp",
@@ -66,9 +67,21 @@ cc_library(
         "include/nlohmann/detail/string_escape.hpp",
         "include/nlohmann/detail/string_utils.hpp",
         "include/nlohmann/detail/value_t.hpp",
+        "include/nlohmann/detail/view/builder.hpp",
+        "include/nlohmann/detail/view/document_data.hpp",
+        "include/nlohmann/detail/view/errors.hpp",
+        "include/nlohmann/detail/view/input.hpp",
+        "include/nlohmann/detail/view/macro_scope.hpp",
+        "include/nlohmann/detail/view/macro_unscope.hpp",
+        "include/nlohmann/detail/view/materialize.hpp",
+        "include/nlohmann/detail/view/node.hpp",
+        "include/nlohmann/detail/view/number.hpp",
+        "include/nlohmann/detail/view/scan.hpp",
+        "include/nlohmann/detail/view/string_ref.hpp",
         "include/nlohmann/json.hpp",
         "include/nlohmann/json_fwd.hpp",
         "include/nlohmann/json_literals.hpp",
+        "include/nlohmann/json_view.hpp",
         "include/nlohmann/ordered_map.hpp",
         "include/nlohmann/thirdparty/hedley/hedley.hpp",
         "include/nlohmann/thirdparty/hedley/hedley_undef.hpp",
@@ -83,6 +96,7 @@ cc_library(
         "single_include/nlohmann/json.hpp",
         "single_include/nlohmann/json_fwd.hpp",
         "single_include/nlohmann/json_literals.hpp",
+        "single_include/nlohmann/json_view.hpp",
     ],
     includes = ["single_include"],
     visibility = ["//visibility:public"],

Makefile

@@ -26,6 +26,7 @@ AMALGAMATED_FILE=single_include/nlohmann/json.hpp
 AMALGAMATED_FWD_FILE=single_include/nlohmann/json_fwd.hpp
 # json_literals.hpp only includes <nlohmann/json.hpp>, so it is copied verbatim
 AMALGAMATED_LITERALS_FILE=single_include/nlohmann/json_literals.hpp
+AMALGAMATED_VIEW_FILE=single_include/nlohmann/json_view.hpp
 
 # the header with the argument-counting macros generated by tools/macro_builder
 MACRO_SCOPE_HPP=include/nlohmann/detail/macro_scope.hpp
@@ -37,7 +38,7 @@ MACRO_SCOPE_HPP=include/nlohmann/detail/macro_scope.hpp
 
 # main target
 all:
-	@echo "amalgamate - amalgamate files single_include/nlohmann/json{,_fwd,_literals}.hpp from the include/nlohmann sources"
+	@echo "amalgamate - amalgamate files single_include/nlohmann/json{,_fwd,_literals,_view}.hpp from the include/nlohmann sources"
 	@echo "BUILD.bazel - regenerate the Bazel BUILD file from the include/nlohmann sources"
 	@echo "ChangeLog.md - generate ChangeLog file"
 	@echo "check-amalgamation - check whether sources have been amalgamated and BUILD.bazel is up to date"
@@ -96,10 +97,10 @@ install_astyle:
 
 # call the Artistic Style pretty printer on all source files
 pretty: install_astyle
-	$(ASTYLE) --project=tools/astyle/.astylerc $(SRCS) $(TESTS_SRCS) $(AMALGAMATED_FILE) $(AMALGAMATED_FWD_FILE) $(AMALGAMATED_LITERALS_FILE) docs/mkdocs/docs/examples/*.cpp docs/mkdocs/docs/examples/*.hpp
+	$(ASTYLE) --project=tools/astyle/.astylerc $(SRCS) $(TESTS_SRCS) $(AMALGAMATED_FILE) $(AMALGAMATED_FWD_FILE) $(AMALGAMATED_LITERALS_FILE) $(AMALGAMATED_VIEW_FILE) docs/mkdocs/docs/examples/*.cpp docs/mkdocs/docs/examples/*.hpp
 
 # create single header files and pretty print
-amalgamate: $(AMALGAMATED_FILE) $(AMALGAMATED_FWD_FILE) $(AMALGAMATED_LITERALS_FILE)
+amalgamate: $(AMALGAMATED_FILE) $(AMALGAMATED_FWD_FILE) $(AMALGAMATED_LITERALS_FILE) $(AMALGAMATED_VIEW_FILE)
 	$(MAKE) pretty
 
 # call the amalgamation tool for json.hpp
@@ -114,6 +115,10 @@ $(AMALGAMATED_FWD_FILE): $(SRCS)
 $(AMALGAMATED_LITERALS_FILE): include/nlohmann/json_literals.hpp
 	cp include/nlohmann/json_literals.hpp $(AMALGAMATED_LITERALS_FILE)
 
+# call the amalgamation tool for json_view.hpp (keeps including json.hpp)
+$(AMALGAMATED_VIEW_FILE): $(SRCS)
+	tools/amalgamate/amalgamate.py -c tools/amalgamate/config_json_view.json -s . --verbose=yes
+
 NATVIS_VENV=tools/generate_natvis/venv
 
 # regenerate nlohmann_json.natvis from the ABI tags and version in include/nlohmann/detail/abi_macros.hpp
@@ -147,18 +152,18 @@ check_build_options:
 check-amalgamation:
 	@status=0; \
 	banner() { printf '===================================================================\n  %s\n===================================================================\n' "$$1"; }; \
-	for FILE in $(AMALGAMATED_FILE) $(AMALGAMATED_FWD_FILE) $(AMALGAMATED_LITERALS_FILE) BUILD.bazel nlohmann_json.natvis; do \
+	for FILE in $(AMALGAMATED_FILE) $(AMALGAMATED_FWD_FILE) $(AMALGAMATED_LITERALS_FILE) $(AMALGAMATED_VIEW_FILE) BUILD.bazel nlohmann_json.natvis; do \
 	    mv "$$FILE" "$$FILE~" || exit 1; \
 	done; \
 	$(MAKE) amalgamate || status=1; \
 	$(MAKE) BUILD.bazel || status=1; \
 	$(MAKE) natvis || status=1; \
-	for FILE in $(AMALGAMATED_FILE) $(AMALGAMATED_FWD_FILE) $(AMALGAMATED_LITERALS_FILE); do \
+	for FILE in $(AMALGAMATED_FILE) $(AMALGAMATED_FWD_FILE) $(AMALGAMATED_LITERALS_FILE) $(AMALGAMATED_VIEW_FILE); do \
 	    diff "$$FILE" "$$FILE~" || { banner "$$FILE is out of date! Amalgamation required! Please read the contribution guidelines in file .github/CONTRIBUTING.md."; status=1; }; \
 	done; \
 	diff BUILD.bazel BUILD.bazel~ || { banner "BUILD.bazel is out of date! Please run 'make BUILD.bazel'."; status=1; }; \
 	diff nlohmann_json.natvis nlohmann_json.natvis~ || { banner "nlohmann_json.natvis is out of date! Please run 'make natvis'."; status=1; }; \
-	for FILE in $(AMALGAMATED_FILE) $(AMALGAMATED_FWD_FILE) $(AMALGAMATED_LITERALS_FILE) BUILD.bazel nlohmann_json.natvis; do \
+	for FILE in $(AMALGAMATED_FILE) $(AMALGAMATED_FWD_FILE) $(AMALGAMATED_LITERALS_FILE) $(AMALGAMATED_VIEW_FILE) BUILD.bazel nlohmann_json.natvis; do \
 	    mv "$$FILE~" "$$FILE"; \
 	done; \
 	$(MAKE) macro_builder_check || status=1; \
@@ -199,7 +204,7 @@ json.tar.xz:
 # We use `-X` to make the resulting ZIP file reproducible, see
 # <https://content.pivotal.io/blog/barriers-to-deterministic-reproducible-zip-files>.
 include.zip: BUILD.bazel
-	zip -9 --recurse-paths -X include.zip $(SRCS) $(AMALGAMATED_FILE) $(AMALGAMATED_FWD_FILE) $(AMALGAMATED_LITERALS_FILE) BUILD.bazel MODULE.bazel meson.build meson_options.txt LICENSE.MIT
+	zip -9 --recurse-paths -X include.zip $(SRCS) $(AMALGAMATED_FILE) $(AMALGAMATED_FWD_FILE) $(AMALGAMATED_LITERALS_FILE) $(AMALGAMATED_VIEW_FILE) BUILD.bazel MODULE.bazel meson.build meson_options.txt LICENSE.MIT
 
 # Create the files for a release and add signatures and hashes.
 release: include.zip json.tar.xz
@@ -209,11 +214,13 @@ release: include.zip json.tar.xz
 	gpg --armor --detach-sig $(AMALGAMATED_FILE)
 	gpg --armor --detach-sig $(AMALGAMATED_FWD_FILE)
 	gpg --armor --detach-sig $(AMALGAMATED_LITERALS_FILE)
+	gpg --armor --detach-sig $(AMALGAMATED_VIEW_FILE)
 	gpg --armor --detach-sig json.tar.xz
 	cp $(AMALGAMATED_FILE) release_files
 	cp $(AMALGAMATED_FWD_FILE) release_files
 	cp $(AMALGAMATED_LITERALS_FILE) release_files
-	mv $(AMALGAMATED_FILE).asc $(AMALGAMATED_FWD_FILE).asc $(AMALGAMATED_LITERALS_FILE).asc json.tar.xz json.tar.xz.asc include.zip include.zip.asc release_files
+	cp $(AMALGAMATED_VIEW_FILE) release_files
+	mv $(AMALGAMATED_FILE).asc $(AMALGAMATED_FWD_FILE).asc $(AMALGAMATED_LITERALS_FILE).asc $(AMALGAMATED_VIEW_FILE).asc json.tar.xz json.tar.xz.asc include.zip include.zip.asc release_files
 	cd release_files ; shasum -a 256 $$(find . -type f -not -name '*.asc' | sed 's|^\./||' | sort) > hashes.txt
 
 

README.md

@@ -1202,6 +1202,14 @@ binary.set_subtype(0x10);
 auto msgpack = json::to_msgpack(j); // 0xD5 (fixext2), 0x10, 0xCA, 0xFE
 ```
 
+### Zero-copy views
+
+Header `<nlohmann/json_view.hpp>` adds `json_document`/`json_view`, a read-only, non-owning way to look at a parsed
+JSON text: parsing builds a flat index (16 bytes per value) instead of a tree, strings and numbers stay in the source
+text, and `materialize()` builds a `json` value for a subtree only when you actually need one. See
+[Zero-copy JSON views](https://json.nlohmann.me/features/json_view/) for the details, including which inputs are
+borrowed and which are copied.
+
 ## Customers
 
 The library is used in multiple projects, applications, operating systems, etc. The list below is not exhaustive, but the result of an internet search. If you know further customers of the library, please let me know, see [contact](#contact).
@@ -1401,6 +1409,7 @@ THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR I
 - The class contains a copy of [Hedley](https://nemequ.github.io/hedley/) from Evan Nemerson which is licensed as [CC0-1.0](https://creativecommons.org/publicdomain/zero/1.0/).
 - The class contains parts of [Google Abseil](https://github.com/abseil/abseil-cpp) which is licensed under the [Apache 2.0 License](https://opensource.org/licenses/Apache-2.0).
 - The class contains an adapted version of the Eisel-Lemire algorithm, its table of powers of five, and its digit comparison for long numbers from [fast_float](https://github.com/fastfloat/fast_float) by Daniel Lemire and contributors, which is available under the [MIT License](https://opensource.org/licenses/MIT) (used here), the Apache 2.0 License, and the Boost Software License. Copyright &copy; 2021 The fast_float authors
+- The view's parser (`<nlohmann/json_view.hpp>`) contains techniques and code adapted from [yyjson](https://github.com/ibireme/yyjson) by YaoYuan, which is licensed under the [MIT License](https://opensource.org/licenses/MIT) (see above): table-driven decoding of `\u` escapes and fixed-offset unrolled checks.
 
 <img align="right" src="https://git.fsfe.org/reuse/reuse-ci/raw/branch/master/reuse-horizontal.png" alt="REUSE Software">
 

cmake/ci.cmake

@@ -407,10 +407,11 @@ list(FILTER INDENT_FILES EXCLUDE REGEX "/tests/thirdparty/|/tests/abi/include/nl
 set(include_dir ${PROJECT_SOURCE_DIR}/single_include/nlohmann)
 set(tool_dir ${PROJECT_SOURCE_DIR}/tools/amalgamate)
 add_custom_target(ci_test_amalgamation
-    COMMAND rm -fr ${include_dir}/json.hpp~ ${include_dir}/json_fwd.hpp~ ${include_dir}/json_literals.hpp~
+    COMMAND rm -fr ${include_dir}/json.hpp~ ${include_dir}/json_fwd.hpp~ ${include_dir}/json_literals.hpp~ ${include_dir}/json_view.hpp~
     COMMAND cp ${include_dir}/json.hpp ${include_dir}/json.hpp~
     COMMAND cp ${include_dir}/json_fwd.hpp ${include_dir}/json_fwd.hpp~
     COMMAND cp ${include_dir}/json_literals.hpp ${include_dir}/json_literals.hpp~
+    COMMAND cp ${include_dir}/json_view.hpp ${include_dir}/json_view.hpp~
     COMMAND cp ${PROJECT_SOURCE_DIR}/BUILD.bazel ${PROJECT_SOURCE_DIR}/BUILD.bazel~
 
     COMMAND ${Python3_EXECUTABLE} -mvenv venv_astyle
@@ -420,18 +421,20 @@ add_custom_target(ci_test_amalgamation
     COMMAND ${Python3_EXECUTABLE} ${tool_dir}/amalgamate.py -c ${tool_dir}/config_json.json -s .
     COMMAND ${Python3_EXECUTABLE} ${tool_dir}/amalgamate.py -c ${tool_dir}/config_json_fwd.json -s .
     COMMAND cp ${PROJECT_SOURCE_DIR}/include/nlohmann/json_literals.hpp ${include_dir}/json_literals.hpp
-    COMMAND venv_astyle/bin/astyle --project=tools/astyle/.astylerc --suffix=none ${include_dir}/json.hpp ${include_dir}/json_fwd.hpp ${include_dir}/json_literals.hpp
+    COMMAND ${Python3_EXECUTABLE} ${tool_dir}/amalgamate.py -c ${tool_dir}/config_json_view.json -s .
+    COMMAND venv_astyle/bin/astyle --project=tools/astyle/.astylerc --suffix=none ${include_dir}/json.hpp ${include_dir}/json_fwd.hpp ${include_dir}/json_literals.hpp ${include_dir}/json_view.hpp
     COMMAND ${CMAKE_COMMAND} -P ${PROJECT_SOURCE_DIR}/cmake/scripts/gen_bazel_build_file.cmake
 
     COMMAND diff ${include_dir}/json.hpp~ ${include_dir}/json.hpp
     COMMAND diff ${include_dir}/json_fwd.hpp~ ${include_dir}/json_fwd.hpp
     COMMAND diff ${include_dir}/json_literals.hpp~ ${include_dir}/json_literals.hpp
+    COMMAND diff ${include_dir}/json_view.hpp~ ${include_dir}/json_view.hpp
     COMMAND diff ${PROJECT_SOURCE_DIR}/BUILD.bazel~ ${PROJECT_SOURCE_DIR}/BUILD.bazel
 
     COMMAND venv_astyle/bin/astyle --project=tools/astyle/.astylerc --suffix=orig ${INDENT_FILES}
     COMMAND for FILE in `find . -name '*.orig'`\; do false \; done
 
-    COMMAND rm -f ${include_dir}/json.hpp~ ${include_dir}/json_fwd.hpp~ ${include_dir}/json_literals.hpp~ ${PROJECT_SOURCE_DIR}/BUILD.bazel~
+    COMMAND rm -f ${include_dir}/json.hpp~ ${include_dir}/json_fwd.hpp~ ${include_dir}/json_literals.hpp~ ${include_dir}/json_view.hpp~ ${PROJECT_SOURCE_DIR}/BUILD.bazel~
 
     WORKING_DIRECTORY ${PROJECT_SOURCE_DIR}
     COMMENT "Check amalgamation, formatting, and BUILD.bazel"

cmake/clang_sanitizer_ignorelist.txt

@@ -4,5 +4,11 @@
 # call converts -1 to size_t, which -fsanitize=integer reports as implicit-integer-sign-change. This is
 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119429, not a bug in this library. Only that check and only <format> are
 # excluded, so implicit sign changes in the library and the tests are still reported.
+#
+# libstdc++'s <string_view> compares two views of different lengths through `_S_compare(size_type __n1, size_type
+# __n2)`, which stores `__n1 - __n2` in a signed difference_type and clamps it to int. Any comparison with a shorter
+# view wraps that subtraction on purpose, and -fsanitize=integer reports it as implicit-integer-sign-change. json_view
+# compares keys as string views, so the same check is excluded for <string_view> as well.
 [implicit-integer-sign-change]
 src:*/include/c++/*/format
+src:*/include/c++/*/string_view

cmake/scripts/gen_bazel_build_file.cmake

@@ -50,6 +50,7 @@ cc_library(
         "single_include/nlohmann/json.hpp",
         "single_include/nlohmann/json_fwd.hpp",
         "single_include/nlohmann/json_literals.hpp",
+        "single_include/nlohmann/json_view.hpp",
     ],
     includes = ["single_include"],
     visibility = ["//visibility:public"],

docs/mkdocs/docs/api/basic_json/empty.md

@@ -64,6 +64,7 @@ itself is empty which is `#!cpp false` in the case of a string.
 
 - [size](size.md) returns the number of elements
 - [clear](clear.md) clears the content and resets the value to the default value
+- [basic_json_view::empty](../basic_json_view/empty.md) - the same check on a zero-copy view
 
 ## Version history
 

docs/mkdocs/docs/api/basic_json/is_array.md

@@ -40,6 +40,7 @@ Constant.
 - [is_structured](is_structured.md) checks whether the JSON value is structured (array or object)
 - [type](type.md) returns the type of the JSON value
 - [array_t](array_t.md) the type used to store JSON arrays
+- [basic_json_view::is_array](../basic_json_view/is_array.md) - the same check on a zero-copy view
 
 ## Version history
 

docs/mkdocs/docs/api/basic_json/is_binary.md

@@ -39,6 +39,7 @@ Constant.
 - [is_primitive](is_primitive.md) checks whether the JSON value is primitive
 - [binary_t](binary_t.md) the type used to store binary values
 - [get_binary](get_binary.md) returns a reference to the stored binary value
+- [basic_json_view::is_binary](../basic_json_view/is_binary.md) - the same check on a zero-copy view
 
 ## Version history
 

docs/mkdocs/docs/api/basic_json/is_boolean.md

@@ -38,6 +38,7 @@ Constant.
 
 - [boolean_t](boolean_t.md) the type used to store JSON booleans
 - [is_primitive](is_primitive.md) checks whether the JSON value is primitive
+- [basic_json_view::is_boolean](../basic_json_view/is_boolean.md) - the same check on a zero-copy view
 
 ## Version history
 

docs/mkdocs/docs/api/basic_json/is_discarded.md

@@ -85,6 +85,11 @@ with `allow_exceptions` set to `#!cpp false`: a parse error then yields a discar
     --8<-- "examples/is_discarded__parse.output"
     ```
 
+## See also
+
+- [basic_json_view::is_discarded](../basic_json_view/is_discarded.md) - the corresponding check on a zero-copy view,
+  which is `#!cpp true` if the view refers to no value
+
 ## Version history
 
 - Added in version 1.0.0.

docs/mkdocs/docs/api/basic_json/is_null.md

@@ -40,6 +40,7 @@ Constant.
 - [is_object](is_object.md) checks whether the JSON value is an object
 - [type](type.md) returns the type of the JSON value
 - [value_t](value_t.md) the enumeration of JSON types
+- [basic_json_view::is_null](../basic_json_view/is_null.md) - the same check on a zero-copy view
 
 ## Version history
 

docs/mkdocs/docs/api/basic_json/is_number.md

@@ -49,6 +49,7 @@ constexpr bool is_number() const noexcept
 - [is_number_integer()](is_number_integer.md) check if the value is an integer or unsigned integer number
 - [is_number_unsigned()](is_number_unsigned.md) check if the value is an unsigned integer number
 - [is_number_float()](is_number_float.md) check if the value is a floating-point number
+- [basic_json_view::is_number](../basic_json_view/is_number.md) - the same check on a zero-copy view
 
 ## Version history
 

docs/mkdocs/docs/api/basic_json/is_number_float.md

@@ -40,6 +40,7 @@ Constant.
 - [is_number()](is_number.md) check if the value is a number
 - [is_number_integer()](is_number_integer.md) check if the value is an integer or unsigned integer number
 - [is_number_unsigned()](is_number_unsigned.md) check if the value is an unsigned integer number
+- [basic_json_view::is_number_float](../basic_json_view/is_number_float.md) - the same check on a zero-copy view
 
 ## Version history
 

docs/mkdocs/docs/api/basic_json/is_number_integer.md

@@ -40,6 +40,7 @@ Constant.
 - [is_number()](is_number.md) check if the value is a number
 - [is_number_unsigned()](is_number_unsigned.md) check if the value is an unsigned integer number
 - [is_number_float()](is_number_float.md) check if the value is a floating-point number
+- [basic_json_view::is_number_integer](../basic_json_view/is_number_integer.md) - the same check on a zero-copy view
 
 ## Version history
 

docs/mkdocs/docs/api/basic_json/is_number_unsigned.md

@@ -43,6 +43,7 @@ Constant.
 - [is_number()](is_number.md) check if the value is a number
 - [is_number_integer()](is_number_integer.md) check if the value is an integer or unsigned integer number
 - [is_number_float()](is_number_float.md) check if the value is a floating-point number
+- [basic_json_view::is_number_unsigned](../basic_json_view/is_number_unsigned.md) - the same check on a zero-copy view
 
 ## Version history
 

docs/mkdocs/docs/api/basic_json/is_object.md

@@ -40,6 +40,7 @@ Constant.
 - [is_structured](is_structured.md) checks whether the JSON value is structured (array or object)
 - [type](type.md) returns the type of the JSON value
 - [object_t](object_t.md) the type used to store JSON objects
+- [basic_json_view::is_object](../basic_json_view/is_object.md) - the same check on a zero-copy view
 
 ## Version history