Merge branch 'release/3.2.0'

.github/ISSUE_TEMPLATE.md → .github/ISSUE_TEMPLATE/Bug_report.md

-**Bug Report**
-
-- What is the issue you have?
-
-- Please describe the steps to reproduce the issue. Can you provide a small but working code example?
-
-- What is the expected behavior?
-
-- And what is the actual behavior instead?
-
-- Which compiler and operating system are you using? Is it a [supported compiler](https://github.com/nlohmann/json#supported-compilers)?
-
-- Did you use a released version of the library or the version from the `develop` branch?
-
-- If you experience a compilation error: can you [compile and run the unit tests](https://github.com/nlohmann/json#execute-unit-tests)?
-
-
-**Feature Request**
-
-- Describe the feature in as much detail as possible.
-
-- Include sample usage where appropriate.
+---
+name: Bug report
+about: Create a report to help us improve
+
+---
+
+- What is the issue you have?
+
+- Please describe the steps to reproduce the issue. Can you provide a small but working code example?
+
+- What is the expected behavior?
+
+- And what is the actual behavior instead?
+
+- Which compiler and operating system are you using? Is it a [supported compiler](https://github.com/nlohmann/json#supported-compilers)?
+
+- Did you use a released version of the library or the version from the `develop` branch?
+
+- If you experience a compilation error: can you [compile and run the unit tests](https://github.com/nlohmann/json#execute-unit-tests)?

.github/ISSUE_TEMPLATE/Feature_request.md

+---
+name: Feature request
+about: Suggest an idea for this project
+
+---
+
+- Describe the feature in as much detail as possible.
+
+- Include sample usage where appropriate.

.travis.yml

@@ -155,6 +155,12 @@ matrix:
   - os: osx
     osx_image: xcode9.2
 
+  - os: osx
+    osx_image: xcode9.3
+
+  - os: osx
+    osx_image: xcode9.4
+
   # Linux / GCC
 
   - os: linux
@@ -189,15 +195,23 @@ matrix:
         sources: ['ubuntu-toolchain-r-test']
         packages: ['g++-7', 'ninja-build']
 
+  - os: linux
+    compiler: gcc
+    env: COMPILER=g++-8
+    addons:
+      apt:
+        sources: ['ubuntu-toolchain-r-test']
+        packages: ['g++-8', 'ninja-build']
+
   - os: linux
     compiler: gcc
     env:
-      - COMPILER=g++-7
+      - COMPILER=g++-8
       - CXXFLAGS=-std=c++17
     addons:
       apt:
         sources: ['ubuntu-toolchain-r-test']
-        packages: ['g++-7', 'ninja-build']
+        packages: ['g++-8', 'ninja-build']
 
   # Linux / Clang
 
@@ -257,15 +271,23 @@ matrix:
         sources: ['ubuntu-toolchain-r-test', 'llvm-toolchain-trusty-5.0']
         packages: ['g++-6', 'clang-5.0', 'ninja-build']
 
+  - os: linux
+    compiler: clang
+    env: COMPILER=clang++-6.0
+    addons:
+      apt:
+        sources: ['ubuntu-toolchain-r-test', 'llvm-toolchain-trusty-6.0']
+        packages: ['g++-6', 'clang-6.0', 'ninja-build']
+
   - os: linux
     compiler: clang
     env:
-      - COMPILER=clang++-5.0
+      - COMPILER=clang++-6.0
       - CXXFLAGS=-std=c++1z
     addons:
       apt:
-        sources: ['ubuntu-toolchain-r-test', 'llvm-toolchain-trusty-5.0']
-        packages: ['g++-6', 'clang-5.0', 'ninja-build']
+        sources: ['ubuntu-toolchain-r-test', 'llvm-toolchain-trusty-6.0']
+        packages: ['g++-6', 'clang-6.0', 'ninja-build']
 
 ################
 # build script #
@@ -277,6 +299,7 @@ script:
      if [[ (-x $(which brew)) ]]; then
        brew update
        brew install cmake ninja
+       brew upgrade cmake
        cmake --version
      fi
 

CMakeLists.txt

-cmake_minimum_required(VERSION 3.0.0)
+cmake_minimum_required(VERSION 3.8)
 
 ##
 ## PROJECT
 ## name and version
 ##
-project(nlohmann_json VERSION 3.1.2 LANGUAGES CXX)
+project(nlohmann_json VERSION 3.2.0 LANGUAGES CXX)
 
 ##
 ## INCLUDE
@@ -22,13 +22,15 @@ option(JSON_MultipleHeaders "Use non-amalgamated version of the library." OFF)
 ## CONFIGURATION
 ##
 set(NLOHMANN_JSON_TARGET_NAME               ${PROJECT_NAME})
-set(NLOHMANN_JSON_CONFIG_INSTALL_DIR        "lib/cmake/${PROJECT_NAME}")
+set(NLOHMANN_JSON_CONFIG_INSTALL_DIR        "lib/cmake/${PROJECT_NAME}"
+  CACHE INTERNAL "")
 set(NLOHMANN_JSON_INCLUDE_INSTALL_DIR       "include")
 set(NLOHMANN_JSON_TARGETS_EXPORT_NAME       "${PROJECT_NAME}Targets")
 set(NLOHMANN_JSON_CMAKE_CONFIG_TEMPLATE     "cmake/config.cmake.in")
-set(NLOHMANN_JSON_CMAKE_CONFIG_DIR          "${CMAKE_CURRENT_BINARY_DIR}/cmake_config")
+set(NLOHMANN_JSON_CMAKE_CONFIG_DIR          "${CMAKE_CURRENT_BINARY_DIR}")
 set(NLOHMANN_JSON_CMAKE_VERSION_CONFIG_FILE "${NLOHMANN_JSON_CMAKE_CONFIG_DIR}/${PROJECT_NAME}ConfigVersion.cmake")
 set(NLOHMANN_JSON_CMAKE_PROJECT_CONFIG_FILE "${NLOHMANN_JSON_CMAKE_CONFIG_DIR}/${PROJECT_NAME}Config.cmake")
+set(NLOHMANN_JSON_CMAKE_PROJECT_TARGETS_FILE "${NLOHMANN_JSON_CMAKE_CONFIG_DIR}/${PROJECT_NAME}Targets.cmake")
 
 if (JSON_MultipleHeaders)
     set(NLOHMANN_JSON_INCLUDE_BUILD_DIR "${PROJECT_SOURCE_DIR}/include/")
@@ -43,6 +45,8 @@ endif()
 ## create target and add include path
 ##
 add_library(${NLOHMANN_JSON_TARGET_NAME} INTERFACE)
+add_library(${PROJECT_NAME}::${NLOHMANN_JSON_TARGET_NAME} ALIAS ${NLOHMANN_JSON_TARGET_NAME})
+target_compile_features(${NLOHMANN_JSON_TARGET_NAME} INTERFACE cxx_std_11)
 
 target_include_directories(
     ${NLOHMANN_JSON_TARGET_NAME}
@@ -51,8 +55,8 @@ target_include_directories(
     $<INSTALL_INTERFACE:include>
 )
 
-## add debug view defintion file for msvc (natvis) [cmake <= 3.2.2 does not support export of source files]
-if (MSVC AND CMAKE_VERSION VERSION_GREATER "3.2.2")
+## add debug view definition file for msvc (natvis)
+if (MSVC)
     set(NLOHMANN_ADD_NATVIS TRUE)
     set(NLOHMANN_NATVIS_FILE "nlohmann_json.natvis")
     target_sources(
@@ -62,7 +66,7 @@ if (MSVC AND CMAKE_VERSION VERSION_GREATER "3.2.2")
             $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/${NLOHMANN_NATVIS_FILE}>  
     )
 endif()
-           
+
 ##
 ## TESTS
 ## create and configure the unit test target
@@ -102,6 +106,11 @@ if (NLOHMANN_ADD_NATVIS)
         DESTINATION .
 )
 endif()
+export(
+    TARGETS ${NLOHMANN_JSON_TARGET_NAME}
+    NAMESPACE ${PROJECT_NAME}::
+    FILE ${NLOHMANN_JSON_CMAKE_PROJECT_TARGETS_FILE}
+)
 install(
     TARGETS ${NLOHMANN_JSON_TARGET_NAME}
     EXPORT ${NLOHMANN_JSON_TARGETS_EXPORT_NAME}
@@ -109,5 +118,6 @@ install(
 )
 install(
     EXPORT ${NLOHMANN_JSON_TARGETS_EXPORT_NAME}
+    NAMESPACE ${PROJECT_NAME}::
     DESTINATION ${NLOHMANN_JSON_CONFIG_INSTALL_DIR}
 )

Makefile

@@ -9,6 +9,7 @@ SRCS = include/nlohmann/json.hpp \
        include/nlohmann/detail/exceptions.hpp \
        include/nlohmann/detail/input/binary_reader.hpp \
        include/nlohmann/detail/input/input_adapters.hpp \
+       include/nlohmann/detail/input/json_sax.hpp \
        include/nlohmann/detail/input/lexer.hpp \
        include/nlohmann/detail/input/parser.hpp \
        include/nlohmann/detail/iterators/internal_iterator.hpp \
@@ -20,7 +21,10 @@ SRCS = include/nlohmann/json.hpp \
        include/nlohmann/detail/json_ref.hpp \
        include/nlohmann/detail/macro_scope.hpp \
        include/nlohmann/detail/macro_unscope.hpp \
-       include/nlohmann/detail/meta.hpp \
+       include/nlohmann/detail/meta/cpp_future.hpp \
+       include/nlohmann/detail/meta/detected.hpp \
+       include/nlohmann/detail/meta/type_traits.hpp \
+       include/nlohmann/detail/meta/void_t.hpp \
        include/nlohmann/detail/output/binary_writer.hpp \
        include/nlohmann/detail/output/output_adapters.hpp \
        include/nlohmann/detail/output/serializer.hpp \
@@ -82,9 +86,9 @@ clean:
 
 coverage:
 	mkdir build_coverage
-	cd build_coverage ; CXX=g++-5 cmake .. -GNinja -DJSON_Coverage=ON -DJSON_MultipleHeaders=ON
+	cd build_coverage ; CXX=g++-7 cmake .. -GNinja -DJSON_Coverage=ON -DJSON_MultipleHeaders=ON
 	cd build_coverage ; ninja
-	cd build_coverage ; ctest -j10
+	cd build_coverage ; ctest -E '.*_default' -j10
 	cd build_coverage ; ninja lcov_html
 	open build_coverage/test/html/index.html
 

appveyor.yml

 version: '{build}'
 
-os: 
-  - Visual Studio 2015
-  - Visual Studio 2017
-
 environment:
   matrix:
-  - additional_flags: ""
-  - additional_flags: "/permissive- /std:c++latest /utf-8"
+    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
+      COMPILER: mingw
+      platform: x86
+      FLAGS: ""
+      GENERATOR: Ninja
+
+    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
+      platform: x86
+      FLAGS: ""
+      GENERATOR: Visual Studio 14 2015
+
+    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
+      platform: x86
+      FLAGS: ""
+      GENERATOR: Visual Studio 15 2017
+
+    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
+      platform: x86
+      FLAGS: "/permissive- /std:c++latest /utf-8"
+      GENERATOR: Visual Studio 15 2017
+
+    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
+      platform: x64
+      FLAGS: ""
+      GENERATOR: Visual Studio 14 2015
+
+    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
+      platform: x64
+      FLAGS: ""
+      GENERATOR: Visual Studio 15 2017
+
+    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
+      platform: x64
+      FLAGS: "/permissive- /std:c++latest /utf-8"
+      GENERATOR: Visual Studio 15 2017
+
+init:
+  - cmake --version
+  - msbuild /version
 
-matrix:
-  exclude:
-    - additional_flags: "/permissive- /std:c++latest /utf-8"
-      os: Visual Studio 2015
-  
-init: []
+install:
+  - if "%COMPILER%"=="mingw" appveyor DownloadFile https://github.com/ninja-build/ninja/releases/download/v1.6.0/ninja-win.zip -FileName ninja.zip
+  - if "%COMPILER%"=="mingw" 7z x ninja.zip -oC:\projects\deps\ninja > nul
+  - if "%COMPILER%"=="mingw" set PATH=C:\projects\deps\ninja;%PATH%
+  - if "%COMPILER%"=="mingw" set PATH=C:\mingw-w64\x86_64-7.3.0-posix-seh-rt_v5-rev0\mingw64\bin;%PATH%
+  - if "%COMPILER%"=="mingw" g++ --version
 
-install: []
+before_build:
+  - cmake . -G "%GENERATOR%" -DCMAKE_CXX_FLAGS="%FLAGS%" -DCMAKE_IGNORE_PATH="C:/Program Files/Git/usr/bin"
 
 build_script:
-  - IF "%APPVEYOR_BUILD_WORKER_IMAGE%" == "Visual Studio 2015" ( SET GEN="Visual Studio 14 2015") ELSE (SET GEN="Visual Studio 15 2017")
-  - cmake . -G%GEN% -DCMAKE_CXX_FLAGS="%additional_flags%"
   - cmake --build . --config Release
 
 test_script:

benchmarks/CMakeLists.txt

-cmake_minimum_required(VERSION 3.0)
+cmake_minimum_required(VERSION 3.8)
 project(JSON_Benchmarks LANGUAGES CXX)
 
 # set compiler flags
 if((CMAKE_CXX_COMPILER_ID MATCHES GNU) OR (CMAKE_CXX_COMPILER_ID MATCHES Clang))
-   set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11 -flto -DNDEBUG -O3")
+   set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -flto -DNDEBUG -O3")
 endif()
 
 # configure Google Benchmarks
@@ -23,4 +23,5 @@ file(COPY ${CMAKE_SOURCE_DIR}/../test/data/regression/floats.json
 
 # benchmark binary
 add_executable(json_benchmarks src/benchmarks.cpp)
+target_compile_features(json_benchmarks PRIVATE cxx_std_11)
 target_link_libraries(json_benchmarks benchmark ${CMAKE_THREAD_LIBS_INIT})

cmake/config.cmake.in

 @PACKAGE_INIT@
-include("${CMAKE_CURRENT_LIST_DIR}/@NLOHMANN_JSON_TARGETS_EXPORT_NAME@.cmake")
+if(NOT TARGET @PROJECT_NAME@::@NLOHMANN_JSON_TARGET_NAME@)
+    include("${CMAKE_CURRENT_LIST_DIR}/@NLOHMANN_JSON_TARGETS_EXPORT_NAME@.cmake")
+endif()
 check_required_components("@PROJECT_NAME@")

doc/Doxyfile

@@ -5,7 +5,7 @@
 #---------------------------------------------------------------------------
 DOXYFILE_ENCODING      = UTF-8
 PROJECT_NAME           = "JSON for Modern C++"
-PROJECT_NUMBER         = 3.1.2
+PROJECT_NUMBER         = 3.2.0
 PROJECT_BRIEF          =
 PROJECT_LOGO           =
 OUTPUT_DIRECTORY       = .

doc/examples/README.cpp

 #include <iostream>
+#include <iomanip>
 #include <nlohmann/json.hpp>
 
 using json = nlohmann::json;

doc/examples/README.link

-<a target="_blank" href="https://wandbox.org/permlink/TarF5pPn9NtHQjhf"><b>online</b></a>
\ No newline at end of file
+<a target="_blank" href="https://wandbox.org/permlink/VexEaSCbbvOOXsPt"><b>online</b></a>
\ No newline at end of file

doc/examples/diff.cpp

 #include <iostream>
+#include <iomanip>
 #include <nlohmann/json.hpp>
 
 using json = nlohmann::json;

doc/examples/diff.link

-<a target="_blank" href="https://wandbox.org/permlink/tfI8DuCuZs3VB9VF"><b>online</b></a>
\ No newline at end of file
+<a target="_blank" href="https://wandbox.org/permlink/3OPLSVPyweUyEHaX"><b>online</b></a>
\ No newline at end of file

doc/examples/flatten.cpp

 #include <iostream>
+#include <iomanip>
 #include <nlohmann/json.hpp>
 
 using json = nlohmann::json;

doc/examples/flatten.link

-<a target="_blank" href="https://wandbox.org/permlink/E1HQedkl1zo48WW5"><b>online</b></a>
\ No newline at end of file
+<a target="_blank" href="https://wandbox.org/permlink/4bn447WQbTERfBaL"><b>online</b></a>
\ No newline at end of file

doc/examples/from_cbor.cpp

 #include <iostream>
+#include <iomanip>
 #include <nlohmann/json.hpp>
 
 using json = nlohmann::json;

doc/examples/from_cbor.link

-<a target="_blank" href="https://wandbox.org/permlink/mya8dUDcDDVoUlBZ"><b>online</b></a>
\ No newline at end of file
+<a target="_blank" href="https://wandbox.org/permlink/AHKW5EMQN4YQ68TY"><b>online</b></a>
\ No newline at end of file

doc/examples/from_msgpack.cpp

 #include <iostream>
+#include <iomanip>
 #include <nlohmann/json.hpp>
 
 using json = nlohmann::json;

doc/examples/from_msgpack.link

-<a target="_blank" href="https://wandbox.org/permlink/sMmEKxW5MGOgLC7z"><b>online</b></a>
\ No newline at end of file
+<a target="_blank" href="https://wandbox.org/permlink/J0KoQF8sOpdMg4kN"><b>online</b></a>
\ No newline at end of file

doc/examples/from_ubjson.cpp

 #include <iostream>
+#include <iomanip>
 #include <nlohmann/json.hpp>
 
 using json = nlohmann::json;

doc/examples/from_ubjson.link

-<a target="_blank" href="https://wandbox.org/permlink/qq29jfETq7nZRrh5"><b>online</b></a>
\ No newline at end of file
+<a target="_blank" href="https://wandbox.org/permlink/uuQK0DAjhbSd96K6"><b>online</b></a>
\ No newline at end of file

doc/examples/meta.cpp

 #include <iostream>
+#include <iomanip>
 #include <nlohmann/json.hpp>
 
 using json = nlohmann::json;

doc/examples/meta.link

-<a target="_blank" href="https://wandbox.org/permlink/0zdmfNQCe4TMw0iI"><b>online</b></a>
\ No newline at end of file
+<a target="_blank" href="https://wandbox.org/permlink/eFzRNyod3g4aVkvl"><b>online</b></a>
\ No newline at end of file

doc/examples/meta.output

@@ -2,7 +2,7 @@
     "compiler": {
         "c++": "201103",
         "family": "clang",
-        "version": "9.0.0 (clang-900.0.39.2)"
+        "version": "9.1.0 (clang-902.0.39.2)"
     },
     "copyright": "(C) 2013-2017 Niels Lohmann",
     "name": "JSON for Modern C++",
@@ -10,8 +10,8 @@
     "url": "https://github.com/nlohmann/json",
     "version": {
         "major": 3,
-        "minor": 1,
-        "patch": 2,
-        "string": "3.1.2"
+        "minor": 2,
+        "patch": 0,
+        "string": "3.2.0"
     }
 }

doc/examples/operator__greater.cpp

@@ -17,8 +17,8 @@ int main()
 
     // output values and comparisons
     std::cout << std::boolalpha;
-    std::cout << array_1 << " == " << array_2 << " " << (array_1 > array_2) << '\n';
-    std::cout << object_1 << " == " << object_2 << " " << (object_1 > object_2) << '\n';
-    std::cout << number_1 << " == " << number_2 << " " << (number_1 > number_2) << '\n';
-    std::cout << string_1 << " == " << string_2 << " " << (string_1 > string_2) << '\n';
+    std::cout << array_1 << " > " << array_2 << " " << (array_1 > array_2) << '\n';
+    std::cout << object_1 << " > " << object_2 << " " << (object_1 > object_2) << '\n';
+    std::cout << number_1 << " > " << number_2 << " " << (number_1 > number_2) << '\n';
+    std::cout << string_1 << " > " << string_2 << " " << (string_1 > string_2) << '\n';
 }

doc/examples/operator__greater.link

-<a target="_blank" href="https://wandbox.org/permlink/yiz7oCHVpFHSALB1"><b>online</b></a>
\ No newline at end of file
+<a target="_blank" href="https://wandbox.org/permlink/ntF7DMzC85gbQKHu"><b>online</b></a>
\ No newline at end of file

doc/examples/operator__greater.output

-[1,2,3] == [1,2,4] false
-{"A":"a","B":"b"} == {"A":"a","B":"b"} false
-17 == 17.0000000000001 false
-"foo" == "bar" true
+[1,2,3] > [1,2,4] false
+{"A":"a","B":"b"} > {"A":"a","B":"b"} false
+17 > 17.0000000000001 false
+"foo" > "bar" true

doc/examples/operator_deserialize.cpp

 #include <iostream>
+#include <iomanip>
+#include <sstream>
 #include <nlohmann/json.hpp>
 
 using json = nlohmann::json;

doc/examples/operator_deserialize.link

-<a target="_blank" href="https://wandbox.org/permlink/YrUqrUFMD7JHwSQR"><b>online</b></a>
\ No newline at end of file
+<a target="_blank" href="https://wandbox.org/permlink/IvgowYGaX0SgOFIG"><b>online</b></a>
\ No newline at end of file

doc/examples/operator_serialize.cpp

 #include <iostream>
+#include <iomanip>
 #include <nlohmann/json.hpp>
 
 using json = nlohmann::json;

doc/examples/operator_serialize.link

-<a target="_blank" href="https://wandbox.org/permlink/wXcm4ObnoaXw7CRt"><b>online</b></a>
\ No newline at end of file
+<a target="_blank" href="https://wandbox.org/permlink/ckGZIBookDffV00n"><b>online</b></a>
\ No newline at end of file

doc/examples/operatorarray__key_type.cpp

 #include <iostream>
+#include <iomanip>
 #include <nlohmann/json.hpp>
 
 using json = nlohmann::json;

doc/examples/operatorarray__key_type.link

-<a target="_blank" href="https://wandbox.org/permlink/vxt8d8qvYorXS2yq"><b>online</b></a>
\ No newline at end of file
+<a target="_blank" href="https://wandbox.org/permlink/oKnfnFrLHG8H1OAl"><b>online</b></a>
\ No newline at end of file

doc/examples/parse__array__parser_callback_t.cpp

 #include <iostream>
+#include <iomanip>
 #include <nlohmann/json.hpp>
 
 using json = nlohmann::json;

doc/examples/parse__array__parser_callback_t.link

-<a target="_blank" href="https://wandbox.org/permlink/TSNxHmegVwLW2pXf"><b>online</b></a>
\ No newline at end of file
+<a target="_blank" href="https://wandbox.org/permlink/i3BBhl7Ub5y9b0yp"><b>online</b></a>
\ No newline at end of file

doc/examples/parse__contiguouscontainer__parser_callback_t.cpp

 #include <iostream>
+#include <iomanip>
 #include <nlohmann/json.hpp>
 
 using json = nlohmann::json;

doc/examples/parse__contiguouscontainer__parser_callback_t.link

-<a target="_blank" href="https://wandbox.org/permlink/l3zNo3YKC2X8yAw9"><b>online</b></a>
\ No newline at end of file
+<a target="_blank" href="https://wandbox.org/permlink/sGdJMOaJnFNJBtH7"><b>online</b></a>
\ No newline at end of file

doc/examples/parse__istream__parser_callback_t.cpp

 #include <iostream>
+#include <iomanip>
+#include <sstream>
 #include <nlohmann/json.hpp>
 
 using json = nlohmann::json;

doc/examples/parse__istream__parser_callback_t.link

-<a target="_blank" href="https://wandbox.org/permlink/Mf7A6JtvqT1Na7Pk"><b>online</b></a>
\ No newline at end of file
+<a target="_blank" href="https://wandbox.org/permlink/UZgRBIeqdZhm6M8F"><b>online</b></a>
\ No newline at end of file

doc/examples/parse__iteratortype__parser_callback_t.cpp

 #include <iostream>
+#include <iomanip>
 #include <nlohmann/json.hpp>
 
 using json = nlohmann::json;

doc/examples/parse__iteratortype__parser_callback_t.link

-<a target="_blank" href="https://wandbox.org/permlink/oa6BVkBXjG8DNkzX"><b>online</b></a>
\ No newline at end of file
+<a target="_blank" href="https://wandbox.org/permlink/VThe0hdMSUdNSOLK"><b>online</b></a>
\ No newline at end of file

doc/examples/parse__string__parser_callback_t.cpp

 #include <iostream>
+#include <iomanip>
 #include <nlohmann/json.hpp>
 
 using json = nlohmann::json;

doc/examples/parse__string__parser_callback_t.link

-<a target="_blank" href="https://wandbox.org/permlink/QXdl4yzts3qPeZ0U"><b>online</b></a>
\ No newline at end of file
+<a target="_blank" href="https://wandbox.org/permlink/QZgjsR0PiAw2Lqpk"><b>online</b></a>
\ No newline at end of file

doc/examples/patch.cpp

 #include <iostream>
+#include <iomanip>
 #include <nlohmann/json.hpp>
 
 using json = nlohmann::json;

doc/examples/patch.link

-<a target="_blank" href="https://wandbox.org/permlink/8ObNa6ejw4BXQ5qG"><b>online</b></a>
\ No newline at end of file
+<a target="_blank" href="https://wandbox.org/permlink/hFd1W46W2Hb81sHN"><b>online</b></a>
\ No newline at end of file

doc/examples/sax_parse.cpp

+#include <iostream>
+#include <iomanip>
+#include <sstream>
+#include <nlohmann/json.hpp>
+
+using json = nlohmann::json;
+
+// a simple event consumer that collects string representations of the passed
+// values; not inheriting from json::json_sax_t is not required, but can
+// help not to forget a required function
+class sax_event_consumer : public json::json_sax_t
+{
+  public:
+    std::vector<std::string> events;
+
+    bool null() override
+    {
+        events.push_back("value: null");
+        return true;
+    }
+
+    bool boolean(bool val) override
+    {
+        events.push_back("value: " + std::string(val ? "true" : "false"));
+        return true;
+    }
+
+    bool number_integer(number_integer_t val) override
+    {
+        events.push_back("value: " + std::to_string(val));
+        return true;
+    }
+
+    bool number_unsigned(number_unsigned_t val) override
+    {
+        events.push_back("value: " + std::to_string(val));
+        return true;
+    }
+
+    bool number_float(number_float_t val, const string_t& s) override
+    {
+        events.push_back("value: " + s);
+        return true;
+    }
+
+    bool string(string_t& val) override
+    {
+        events.push_back("value: " + val);
+        return true;
+    }
+
+    bool start_object(std::size_t elements) override
+    {
+        events.push_back("start: object");
+        return true;
+    }
+
+    bool end_object() override
+    {
+        events.push_back("end: object");
+        return true;
+    }
+
+    bool start_array(std::size_t elements) override
+    {
+        events.push_back("start: array");
+        return true;
+    }
+
+    bool end_array() override
+    {
+        events.push_back("end: array");
+        return true;
+    }
+
+    bool key(string_t& val) override
+    {
+        events.push_back("key: " + val);
+        return true;
+    }
+
+    bool parse_error(std::size_t position, const std::string& last_token, const json::exception& ex) override
+    {
+        events.push_back("error: " + std::string(ex.what()));
+        return false;
+    }
+};
+
+int main()
+{
+    // a JSON text
+    auto text = R"(
+    {
+        "Image": {
+            "Width":  800,
+            "Height": 600,
+            "Title":  "View from 15th Floor",
+            "Thumbnail": {
+                "Url":    "http://www.example.com/image/481989943",
+                "Height": 125,
+                "Width":  100
+            },
+            "Animated" : false,
+            "IDs": [116, 943, 234, 38793],
+            "Distance": 12.723374634
+        }
+    }
+    )";
+
+    // create a SAX event consumer object
+    sax_event_consumer sec;
+
+    // parse and serialize JSON
+    bool result = json::sax_parse(text, &sec);
+
+    // output the recorded events
+    for (auto& event : sec.events)
+    {
+        std::cout << "(" << event << ") ";
+    }
+
+    // output the result of sax_parse
+    std::cout << "\nresult: " << std::boolalpha << result << std::endl;
+}

doc/examples/sax_parse.link

+<a target="_blank" href="https://wandbox.org/permlink/fGkQLWbQn7enKkIG"><b>online</b></a>
\ No newline at end of file

doc/examples/sax_parse.output

+(start: object) (key: Image) (start: object) (key: Width) (value: 800) (key: Height) (value: 600) (key: Title) (value: View from 15th Floor) (key: Thumbnail) (start: object) (key: Url) (value: http://www.example.com/image/481989943) (key: Height) (value: 125) (key: Width) (value: 100) (end: object) (key: Animated) (value: false) (key: IDs) (start: array) (value: 116) (value: 943) (value: 234) (value: 38793) (end: array) (key: Distance) (value: 12.723374634) (end: object) (end: object) 
+result: true

doc/examples/to_cbor.cpp

 #include <iostream>
+#include <iomanip>
 #include <nlohmann/json.hpp>
 
 using json = nlohmann::json;

doc/examples/to_cbor.link

-<a target="_blank" href="https://wandbox.org/permlink/4bQSclXeqjVFYVL3"><b>online</b></a>
\ No newline at end of file
+<a target="_blank" href="https://wandbox.org/permlink/LRM37xarSuPJmv92"><b>online</b></a>
\ No newline at end of file

doc/examples/to_msgpack.cpp

 #include <iostream>
+#include <iomanip>
 #include <nlohmann/json.hpp>
 
 using json = nlohmann::json;

doc/examples/to_msgpack.link

-<a target="_blank" href="https://wandbox.org/permlink/WvT2Q0r9vlJYyMM8"><b>online</b></a>
\ No newline at end of file
+<a target="_blank" href="https://wandbox.org/permlink/CaRFhkrefL4miesE"><b>online</b></a>
\ No newline at end of file

doc/examples/to_ubjson.cpp

 #include <iostream>
+#include <iomanip>
 #include <nlohmann/json.hpp>
 
 using json = nlohmann::json;

doc/examples/to_ubjson.link

-<a target="_blank" href="https://wandbox.org/permlink/j3HE6cOkCmKbxxAt"><b>online</b></a>
\ No newline at end of file
+<a target="_blank" href="https://wandbox.org/permlink/2luqHy9iADx4UNm7"><b>online</b></a>
\ No newline at end of file

doc/examples/unflatten.cpp

 #include <iostream>
+#include <iomanip>
 #include <nlohmann/json.hpp>
 
 using json = nlohmann::json;

doc/examples/unflatten.link

-<a target="_blank" href="https://wandbox.org/permlink/U45AGi5nsDtoDf3u"><b>online</b></a>
\ No newline at end of file
+<a target="_blank" href="https://wandbox.org/permlink/knK4jnD2hIVxQoyk"><b>online</b></a>
\ No newline at end of file

doc/examples/update.cpp

 #include <iostream>
+#include <iomanip>
 #include <nlohmann/json.hpp>
 
 using json = nlohmann::json;

doc/examples/update.link

-<a target="_blank" href="https://wandbox.org/permlink/TGvdYyJtstacZxWq"><b>online</b></a>
\ No newline at end of file
+<a target="_blank" href="https://wandbox.org/permlink/kjcoWACW7FMqKRBG"><b>online</b></a>
\ No newline at end of file

doc/examples/update__range.cpp

 #include <iostream>
+#include <iomanip>
 #include <nlohmann/json.hpp>
 
 using json = nlohmann::json;

doc/examples/update__range.link

-<a target="_blank" href="https://wandbox.org/permlink/BMlas6312rkE4cxz"><b>online</b></a>
\ No newline at end of file
+<a target="_blank" href="https://wandbox.org/permlink/0LBIsEa18IrerWwy"><b>online</b></a>
\ No newline at end of file

doc/index.md

@@ -39,9 +39,11 @@ These pages contain the API documentation of JSON for Modern C++, a C++11 header
     - @link nlohmann::basic_json::dump dump @endlink serialize to string
     - @link nlohmann::basic_json::operator<<(std::ostream&, const basic_json &) operator<< @endlink serialize to stream
   - deserialization / parsing
-    - @link nlohmann::basic_json::parse parse @endlink parse from string
+    - @link nlohmann::basic_json::parse parse @endlink parse from input (string, file, etc.) and return JSON value
+    - @link nlohmann::basic_json::sax_parse sax_parse @endlink parse from input (string, file, etc.) and generate SAX events
     - @link nlohmann::basic_json::operator>>(std::istream&, basic_json&) operator>> @endlink parse from stream
     - @link nlohmann::basic_json::accept accept @endlink check for syntax errors without parsing
+    - @link nlohmann::json_sax SAX interface @endlink define a user-defined SAX event consumer
   - [binary formats](binary_formats.md):
     - CBOR: @link nlohmann::basic_json::from_cbor from_cbor @endlink / @link nlohmann::basic_json::to_cbor to_cbor @endlink
     - MessagePack: @link nlohmann::basic_json::from_msgpack from_msgpack @endlink / @link nlohmann::basic_json::to_msgpack to_msgpack @endlink
@@ -304,4 +306,4 @@ Note that this table only lists those exceptions thrown due to the type. For ins
 @author [Niels Lohmann](http://nlohmann.me)
 @see https://github.com/nlohmann/json to download the source code
 
-@version 3.1.2
+@version 3.2.0

include/nlohmann/detail/conversions/from_json.hpp

@@ -5,21 +5,34 @@
 #include <ciso646> // and, not
 #include <forward_list> // forward_list
 #include <iterator> // inserter, front_inserter, end
+#include <map> // map
 #include <string> // string
 #include <tuple> // tuple, make_tuple
 #include <type_traits> // is_arithmetic, is_same, is_enum, underlying_type, is_convertible
+#include <unordered_map> // unordered_map
 #include <utility> // pair, declval
 #include <valarray> // valarray
 
 #include <nlohmann/detail/exceptions.hpp>
 #include <nlohmann/detail/macro_scope.hpp>
-#include <nlohmann/detail/meta.hpp>
+#include <nlohmann/detail/meta/cpp_future.hpp>
+#include <nlohmann/detail/meta/type_traits.hpp>
 #include <nlohmann/detail/value_t.hpp>
 
 namespace nlohmann
 {
 namespace detail
 {
+template<typename BasicJsonType>
+void from_json(const BasicJsonType& j, typename std::nullptr_t& n)
+{
+    if (JSON_UNLIKELY(not j.is_null()))
+    {
+        JSON_THROW(type_error::create(302, "type must be null, but is " + std::string(j.type_name())));
+    }
+    n = nullptr;
+}
+
 // overloads for basic_json template parameters
 template<typename BasicJsonType, typename ArithmeticType,
          enable_if_t<std::is_arithmetic<ArithmeticType>::value and
@@ -70,6 +83,23 @@ void from_json(const BasicJsonType& j, typename BasicJsonType::string_t& s)
     s = *j.template get_ptr<const typename BasicJsonType::string_t*>();
 }
 
+template <
+    typename BasicJsonType, typename CompatibleStringType,
+    enable_if_t <
+        is_compatible_string_type<BasicJsonType, CompatibleStringType>::value and
+        not std::is_same<typename BasicJsonType::string_t,
+                         CompatibleStringType>::value,
+        int > = 0 >
+void from_json(const BasicJsonType& j, CompatibleStringType& s)
+{
+    if (JSON_UNLIKELY(not j.is_string()))
+    {
+        JSON_THROW(type_error::create(302, "type must be string, but is " + std::string(j.type_name())));
+    }
+
+    s = *j.template get_ptr<const typename BasicJsonType::string_t*>();
+}
+
 template<typename BasicJsonType>
 void from_json(const BasicJsonType& j, typename BasicJsonType::number_float_t& val)
 {
@@ -277,6 +307,44 @@ void from_json(const BasicJsonType& j, std::tuple<Args...>& t)
     from_json_tuple_impl(j, t, index_sequence_for<Args...> {});
 }
 
+template <typename BasicJsonType, typename Key, typename Value, typename Compare, typename Allocator,
+          typename = enable_if_t<not std::is_constructible<
+                                     typename BasicJsonType::string_t, Key>::value>>
+void from_json(const BasicJsonType& j, std::map<Key, Value, Compare, Allocator>& m)
+{
+    if (JSON_UNLIKELY(not j.is_array()))
+    {
+        JSON_THROW(type_error::create(302, "type must be array, but is " + std::string(j.type_name())));
+    }
+    for (const auto& p : j)
+    {
+        if (JSON_UNLIKELY(not p.is_array()))
+        {
+            JSON_THROW(type_error::create(302, "type must be array, but is " + std::string(p.type_name())));
+        }
+        m.emplace(p.at(0).template get<Key>(), p.at(1).template get<Value>());
+    }
+}
+
+template <typename BasicJsonType, typename Key, typename Value, typename Hash, typename KeyEqual, typename Allocator,
+          typename = enable_if_t<not std::is_constructible<
+                                     typename BasicJsonType::string_t, Key>::value>>
+void from_json(const BasicJsonType& j, std::unordered_map<Key, Value, Hash, KeyEqual, Allocator>& m)
+{
+    if (JSON_UNLIKELY(not j.is_array()))
+    {
+        JSON_THROW(type_error::create(302, "type must be array, but is " + std::string(j.type_name())));
+    }
+    for (const auto& p : j)
+    {
+        if (JSON_UNLIKELY(not p.is_array()))
+        {
+            JSON_THROW(type_error::create(302, "type must be array, but is " + std::string(p.type_name())));
+        }
+        m.emplace(p.at(0).template get<Key>(), p.at(1).template get<Value>());
+    }
+}
+
 struct from_json_fn
 {
   private:

include/nlohmann/detail/conversions/to_chars.hpp

@@ -887,7 +887,7 @@ void grisu2(char* buf, int& len, int& decimal_exponent, FloatType value)
     // numbers, all float's can be recovered using strtod (and strtof). However, the resulting
     // decimal representations are not exactly "short".
     //
-    // The documentation for 'std::to_chars' (http://en.cppreference.com/w/cpp/utility/to_chars)
+    // The documentation for 'std::to_chars' (https://en.cppreference.com/w/cpp/utility/to_chars)
     // says "value is converted to a string as if by std::sprintf in the default ("C") locale"
     // and since sprintf promotes float's to double's, I think this is exactly what 'std::to_chars'
     // does.

include/nlohmann/detail/conversions/to_json.hpp

@@ -8,8 +8,10 @@
 #include <valarray> // valarray
 #include <vector> // vector
 
-#include <nlohmann/detail/meta.hpp>
+#include <nlohmann/detail/meta/cpp_future.hpp>
+#include <nlohmann/detail/meta/type_traits.hpp>
 #include <nlohmann/detail/value_t.hpp>
+#include <nlohmann/detail/iterators/iteration_proxy.hpp>
 
 namespace nlohmann
 {
@@ -51,6 +53,16 @@ struct external_constructor<value_t::string>
         j.m_value = std::move(s);
         j.assert_invariant();
     }
+
+    template<typename BasicJsonType, typename CompatibleStringType,
+             enable_if_t<not std::is_same<CompatibleStringType, typename BasicJsonType::string_t>::value,
+                         int> = 0>
+    static void construct(BasicJsonType& j, const CompatibleStringType& str)
+    {
+        j.m_type = value_t::string;
+        j.m_value.string = j.template create<typename BasicJsonType::string_t>(str);
+        j.assert_invariant();
+    }
 };
 
 template<>
@@ -247,7 +259,7 @@ void to_json(BasicJsonType& j, const CompatibleArrayType& arr)
 
 template<typename BasicJsonType, typename T,
          enable_if_t<std::is_convertible<T, BasicJsonType>::value, int> = 0>
-void to_json(BasicJsonType& j, std::valarray<T> arr)
+void to_json(BasicJsonType& j, const std::valarray<T>& arr)
 {
     external_constructor<value_t::array>::construct(j, std::move(arr));
 }
@@ -284,6 +296,14 @@ void to_json(BasicJsonType& j, const std::pair<Args...>& p)
     j = {p.first, p.second};
 }
 
+// for https://github.com/nlohmann/json/pull/1134
+template<typename BasicJsonType, typename T,
+         enable_if_t<std::is_same<T, typename iteration_proxy<typename BasicJsonType::iterator>::iteration_proxy_internal>::value, int> = 0>
+void to_json(BasicJsonType& j, T b) noexcept
+{
+    j = {{b.key(), b.value()}};
+}
+
 template<typename BasicJsonType, typename Tuple, std::size_t... Idx>
 void to_json_tuple_impl(BasicJsonType& j, const Tuple& t, index_sequence<Idx...>)
 {

include/nlohmann/detail/input/input_adapters.hpp

 #pragma once
 
-#include <algorithm> // min
-#include <array> // array
 #include <cassert> // assert
 #include <cstddef> // size_t
 #include <cstring> // strlen
-#include <ios> // streamsize, streamoff, streampos
 #include <istream> // istream
 #include <iterator> // begin, end, iterator_traits, random_access_iterator_tag, distance, next
 #include <memory> // shared_ptr, make_shared, addressof
@@ -20,6 +17,9 @@ namespace nlohmann
 {
 namespace detail
 {
+/// the supported input formats
+enum class input_format_t { json, cbor, msgpack, ubjson };
+
 ////////////////////
 // input adapters //
 ////////////////////
@@ -28,19 +28,17 @@ namespace detail
 @brief abstract input adapter interface
 
 Produces a stream of std::char_traits<char>::int_type characters from a
-std::istream, a buffer, or some other input type.  Accepts the return of exactly
-one non-EOF character for future input.  The int_type characters returned
-consist of all valid char values as positive values (typically unsigned char),
-plus an EOF value outside that range, specified by the value of the function
-std::char_traits<char>::eof().  This value is typically -1, but could be any
-arbitrary value which is not a valid char value.
+std::istream, a buffer, or some other input type. Accepts the return of
+exactly one non-EOF character for future input. The int_type characters
+returned consist of all valid char values as positive values (typically
+unsigned char), plus an EOF value outside that range, specified by the value
+of the function std::char_traits<char>::eof(). This value is typically -1, but
+could be any arbitrary value which is not a valid char value.
 */
 struct input_adapter_protocol
 {
     /// get a character [0,255] or std::char_traits<char>::eof().
     virtual std::char_traits<char>::int_type get_character() = 0;
-    /// restore the last non-eof() character to input
-    virtual void unget_character() = 0;
     virtual ~input_adapter_protocol() = default;
 };
 
@@ -68,34 +66,7 @@ class input_stream_adapter : public input_adapter_protocol
 
     explicit input_stream_adapter(std::istream& i)
         : is(i), sb(*i.rdbuf())
-    {
-        // skip byte order mark
-        std::char_traits<char>::int_type c;
-        if ((c = get_character()) == 0xEF)
-        {
-            if ((c = get_character()) == 0xBB)
-            {
-                if ((c = get_character()) == 0xBF)
-                {
-                    return; // Ignore BOM
-                }
-                else if (c != std::char_traits<char>::eof())
-                {
-                    is.unget();
-                }
-                is.putback('\xBB');
-            }
-            else if (c != std::char_traits<char>::eof())
-            {
-                is.unget();
-            }
-            is.putback('\xEF');
-        }
-        else if (c != std::char_traits<char>::eof())
-        {
-            is.unget(); // no byte order mark; process as usual
-        }
-    }
+    {}
 
     // delete because of pointer members
     input_stream_adapter(const input_stream_adapter&) = delete;
@@ -109,11 +80,6 @@ class input_stream_adapter : public input_adapter_protocol
         return sb.sbumpc();
     }
 
-    void unget_character() override
-    {
-        sb.sungetc();  // is.unget() avoided for performance
-    }
-
   private:
     /// the associated input stream
     std::istream& is;
@@ -125,14 +91,8 @@ class input_buffer_adapter : public input_adapter_protocol
 {
   public:
     input_buffer_adapter(const char* b, const std::size_t l)
-        : cursor(b), limit(b + l), start(b)
-    {
-        // skip byte order mark
-        if (l >= 3 and b[0] == '\xEF' and b[1] == '\xBB' and b[2] == '\xBF')
-        {
-            cursor += 3;
-        }
-    }
+        : cursor(b), limit(b + l)
+    {}
 
     // delete because of pointer members
     input_buffer_adapter(const input_buffer_adapter&) = delete;
@@ -148,21 +108,164 @@ class input_buffer_adapter : public input_adapter_protocol
         return std::char_traits<char>::eof();
     }
 
-    void unget_character() noexcept override
+  private:
+    /// pointer to the current character
+    const char* cursor;
+    /// pointer past the last character
+    const char* const limit;
+};
+
+template<typename WideStringType>
+class wide_string_input_adapter : public input_adapter_protocol
+{
+  public:
+    explicit wide_string_input_adapter(const WideStringType& w) : str(w) {}
+
+    std::char_traits<char>::int_type get_character() noexcept override
     {
-        if (JSON_LIKELY(cursor > start))
+        // check if buffer needs to be filled
+        if (utf8_bytes_index == utf8_bytes_filled)
         {
-            --cursor;
+            if (sizeof(typename WideStringType::value_type) == 2)
+            {
+                fill_buffer_utf16();
+            }
+            else
+            {
+                fill_buffer_utf32();
+            }
+
+            assert(utf8_bytes_filled > 0);
+            assert(utf8_bytes_index == 0);
         }
+
+        // use buffer
+        assert(utf8_bytes_filled > 0);
+        assert(utf8_bytes_index < utf8_bytes_filled);
+        return utf8_bytes[utf8_bytes_index++];
     }
 
   private:
-    /// pointer to the current character
-    const char* cursor;
-    /// pointer past the last character
-    const char* limit;
-    /// pointer to the first character
-    const char* start;
+    void fill_buffer_utf16()
+    {
+        utf8_bytes_index = 0;
+
+        if (current_wchar == str.size())
+        {
+            utf8_bytes[0] = std::char_traits<char>::eof();
+            utf8_bytes_filled = 1;
+        }
+        else
+        {
+            // get the current character
+            const int wc = static_cast<int>(str[current_wchar++]);
+
+            // UTF-16 to UTF-8 encoding
+            if (wc < 0x80)
+            {
+                utf8_bytes[0] = wc;
+                utf8_bytes_filled = 1;
+            }
+            else if (wc <= 0x7FF)
+            {
+                utf8_bytes[0] = 0xC0 | ((wc >> 6));
+                utf8_bytes[1] = 0x80 | (wc & 0x3F);
+                utf8_bytes_filled = 2;
+            }
+            else if (0xD800 > wc or wc >= 0xE000)
+            {
+                utf8_bytes[0] = 0xE0 | ((wc >> 12));
+                utf8_bytes[1] = 0x80 | ((wc >> 6) & 0x3F);
+                utf8_bytes[2] = 0x80 | (wc & 0x3F);
+                utf8_bytes_filled = 3;
+            }
+            else
+            {
+                if (current_wchar < str.size())
+                {
+                    const int wc2 = static_cast<int>(str[current_wchar++]);
+                    const int charcode = 0x10000 + (((wc & 0x3FF) << 10) | (wc2 & 0x3FF));
+                    utf8_bytes[0] = 0xf0 | (charcode >> 18);
+                    utf8_bytes[1] = 0x80 | ((charcode >> 12) & 0x3F);
+                    utf8_bytes[2] = 0x80 | ((charcode >> 6) & 0x3F);
+                    utf8_bytes[3] = 0x80 | (charcode & 0x3F);
+                    utf8_bytes_filled = 4;
+                }
+                else
+                {
+                    // unknown character
+                    ++current_wchar;
+                    utf8_bytes[0] = wc;
+                    utf8_bytes_filled = 1;
+                }
+            }
+        }
+    }
+
+    void fill_buffer_utf32()
+    {
+        utf8_bytes_index = 0;
+
+        if (current_wchar == str.size())
+        {
+            utf8_bytes[0] = std::char_traits<char>::eof();
+            utf8_bytes_filled = 1;
+        }
+        else
+        {
+            // get the current character
+            const int wc = static_cast<int>(str[current_wchar++]);
+
+            // UTF-32 to UTF-8 encoding
+            if (wc < 0x80)
+            {
+                utf8_bytes[0] = wc;
+                utf8_bytes_filled = 1;
+            }
+            else if (wc <= 0x7FF)
+            {
+                utf8_bytes[0] = 0xC0 | ((wc >> 6) & 0x1F);
+                utf8_bytes[1] = 0x80 | (wc & 0x3F);
+                utf8_bytes_filled = 2;
+            }
+            else if (wc <= 0xFFFF)
+            {
+                utf8_bytes[0] = 0xE0 | ((wc >> 12) & 0x0F);
+                utf8_bytes[1] = 0x80 | ((wc >> 6) & 0x3F);
+                utf8_bytes[2] = 0x80 | (wc & 0x3F);
+                utf8_bytes_filled = 3;
+            }
+            else if (wc <= 0x10FFFF)
+            {
+                utf8_bytes[0] = 0xF0 | ((wc >> 18 ) & 0x07);
+                utf8_bytes[1] = 0x80 | ((wc >> 12) & 0x3F);
+                utf8_bytes[2] = 0x80 | ((wc >> 6) & 0x3F);
+                utf8_bytes[3] = 0x80 | (wc & 0x3F);
+                utf8_bytes_filled = 4;
+            }
+            else
+            {
+                // unknown character
+                utf8_bytes[0] = wc;
+                utf8_bytes_filled = 1;
+            }
+        }
+    }
+
+  private:
+    /// the wstring to process
+    const WideStringType& str;
+
+    /// index of the current wchar in str
+    std::size_t current_wchar = 0;
+
+    /// a buffer for UTF-8 bytes
+    std::array<std::char_traits<char>::int_type, 4> utf8_bytes = {{0, 0, 0, 0}};
+
+    /// index to the utf8_codes array for the next valid byte
+    std::size_t utf8_bytes_index = 0;
+    /// number of valid bytes in the utf8_codes array
+    std::size_t utf8_bytes_filled = 0;
 };
 
 class input_adapter
@@ -178,6 +281,15 @@ class input_adapter
     input_adapter(std::istream&& i)
         : ia(std::make_shared<input_stream_adapter>(i)) {}
 
+    input_adapter(const std::wstring& ws)
+        : ia(std::make_shared<wide_string_input_adapter<std::wstring>>(ws)) {}
+
+    input_adapter(const std::u16string& ws)
+        : ia(std::make_shared<wide_string_input_adapter<std::u16string>>(ws)) {}
+
+    input_adapter(const std::u32string& ws)
+        : ia(std::make_shared<wide_string_input_adapter<std::u32string>>(ws)) {}
+
     /// input adapter for buffer
     template<typename CharT,
              typename std::enable_if<

include/nlohmann/detail/input/lexer.hpp

@@ -3,10 +3,8 @@
 #include <clocale> // localeconv
 #include <cstddef> // size_t
 #include <cstdlib> // strtof, strtod, strtold, strtoll, strtoull
+#include <cstdio> // snprintf
 #include <initializer_list> // initializer_list
-#include <ios> // hex, uppercase
-#include <iomanip> // setw, setfill
-#include <sstream> // stringstream
 #include <string> // char_traits, string
 #include <vector> // vector
 
@@ -94,12 +92,14 @@ class lexer
                 return "end of input";
             case token_type::literal_or_value:
                 return "'[', '{', or a literal";
+            // LCOV_EXCL_START
             default: // catch non-enum values
-                return "unknown token"; // LCOV_EXCL_LINE
+                return "unknown token";
+                // LCOV_EXCL_STOP
         }
     }
 
-    explicit lexer(detail::input_adapter_t adapter)
+    explicit lexer(detail::input_adapter_t&& adapter)
         : ia(std::move(adapter)), decimal_point_char(get_decimal_point()) {}
 
     // delete because of pointer members
@@ -747,11 +747,13 @@ class lexer
                 goto scan_number_any1;
             }
 
+            // LCOV_EXCL_START
             default:
             {
                 // all other characters are rejected outside scan_number()
-                assert(false); // LCOV_EXCL_LINE
+                assert(false);
             }
+                // LCOV_EXCL_STOP
         }
 
 scan_number_minus:
@@ -1081,7 +1083,16 @@ scan_number_done:
     std::char_traits<char>::int_type get()
     {
         ++chars_read;
-        current = ia->get_character();
+        if (next_unget)
+        {
+            // just reset the next_unget variable and work with current
+            next_unget = false;
+        }
+        else
+        {
+            current = ia->get_character();
+        }
+
         if (JSON_LIKELY(current != std::char_traits<char>::eof()))
         {
             token_string.push_back(std::char_traits<char>::to_char_type(current));
@@ -1089,13 +1100,20 @@ scan_number_done:
         return current;
     }
 
-    /// unget current character (return it again on next get)
+    /*!
+    @brief unget current character (read it again on next get)
+
+    We implement unget by setting variable next_unget to true. The input is not
+    changed - we just simulate ungetting by modifying chars_read and
+    token_string. The next call to get() will behave as if the unget character
+    is read again.
+    */
     void unget()
     {
+        next_unget = true;
         --chars_read;
         if (JSON_LIKELY(current != std::char_traits<char>::eof()))
         {
-            ia->unget_character();
             assert(token_string.size() != 0);
             token_string.pop_back();
         }
@@ -1131,9 +1149,9 @@ scan_number_done:
     }
 
     /// return current string value (implicitly resets the token; useful only once)
-    string_t&& move_string()
+    string_t& get_string()
     {
-        return std::move(token_buffer);
+        return token_buffer;
     }
 
     /////////////////////
@@ -1158,10 +1176,9 @@ scan_number_done:
             if ('\x00' <= c and c <= '\x1F')
             {
                 // escape control characters
-                std::stringstream ss;
-                ss << "<U+" << std::setw(4) << std::uppercase << std::setfill('0')
-                   << std::hex << static_cast<int>(c) << ">";
-                result += ss.str();
+                char cs[9];
+                snprintf(cs, 9, "<U+%.4X>", static_cast<unsigned char>(c));
+                result += cs;
             }
             else
             {
@@ -1183,8 +1200,43 @@ scan_number_done:
     // actual scanner
     /////////////////////
 
+    /*!
+    @brief skip the UTF-8 byte order mark
+    @return true iff there is no BOM or the correct BOM has been skipped
+    */
+    bool skip_bom()
+    {
+        if (get() == 0xEF)
+        {
+            if (get() == 0xBB and get() == 0xBF)
+            {
+                // we completely parsed the BOM
+                return true;
+            }
+            else
+            {
+                // after reading 0xEF, an unexpected character followed
+                return false;
+            }
+        }
+        else
+        {
+            // the first character is not the beginning of the BOM; unget it to
+            // process is later
+            unget();
+            return true;
+        }
+    }
+
     token_type scan()
     {
+        // initially, skip the BOM
+        if (chars_read == 0 and not skip_bom())
+        {
+            error_message = "invalid BOM; must be 0xEF 0xBB 0xBF if given";
+            return token_type::parse_error;
+        }
+
         // read next character and ignore whitespace
         do
         {
@@ -1254,6 +1306,9 @@ scan_number_done:
     /// the current character
     std::char_traits<char>::int_type current = std::char_traits<char>::eof();
 
+    /// whether the next get() call should just return current
+    bool next_unget = false;
+
     /// the number of characters read
     std::size_t chars_read = 0;
 

include/nlohmann/detail/iterators/iter_impl.hpp

@@ -8,7 +8,7 @@
 #include <nlohmann/detail/iterators/internal_iterator.hpp>
 #include <nlohmann/detail/iterators/primitive_iterator.hpp>
 #include <nlohmann/detail/macro_scope.hpp>
-#include <nlohmann/detail/meta.hpp>
+#include <nlohmann/detail/meta/cpp_future.hpp>
 #include <nlohmann/detail/value_t.hpp>
 
 namespace nlohmann
@@ -31,7 +31,7 @@ This class implements a both iterators (iterator and const_iterator) for the
 
 @requirement The class satisfies the following concept requirements:
 -
-[BidirectionalIterator](http://en.cppreference.com/w/cpp/concept/BidirectionalIterator):
+[BidirectionalIterator](https://en.cppreference.com/w/cpp/named_req/BidirectionalIterator):
   The iterator that can be moved can be moved in both directions (i.e.
   incremented and decremented).
 
@@ -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);
 

include/nlohmann/detail/iterators/iteration_proxy.hpp

@@ -2,6 +2,7 @@
 
 #include <cstddef> // size_t
 #include <string> // string, to_string
+#include <iterator> // input_iterator_tag
 
 #include <nlohmann/detail/value_t.hpp>
 
@@ -16,15 +17,31 @@ template<typename IteratorType> class iteration_proxy
     /// helper class for iteration
     class iteration_proxy_internal
     {
+      public:
+        using difference_type = std::ptrdiff_t;
+        using value_type = iteration_proxy_internal;
+        using pointer = iteration_proxy_internal*;
+        using reference = iteration_proxy_internal&;
+        using iterator_category = std::input_iterator_tag;
+
       private:
         /// the iterator
         IteratorType anchor;
         /// an index for arrays (used to create key names)
         std::size_t array_index = 0;
+        /// last stringified array index
+        mutable std::size_t array_index_last = 0;
+        /// a string representation of the array index
+        mutable 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) {}
 
+        iteration_proxy_internal(const iteration_proxy_internal&) = default;
+        iteration_proxy_internal& operator=(const iteration_proxy_internal&) = default;
+
         /// dereference operator (needed for range-based for)
         iteration_proxy_internal& operator*()
         {
@@ -40,6 +57,12 @@ template<typename IteratorType> class iteration_proxy
             return *this;
         }
 
+        /// equality operator (needed for InputIterator)
+        bool operator==(const iteration_proxy_internal& o) const noexcept
+        {
+            return anchor == o.anchor;
+        }
+
         /// inequality operator (needed for range-based for)
         bool operator!=(const iteration_proxy_internal& o) const noexcept
         {
@@ -47,7 +70,7 @@ 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 +78,14 @@ template<typename IteratorType> class iteration_proxy
             {
                 // use integer array index as key
                 case value_t::array:
-                    return std::to_string(array_index);
+                {
+                    if (array_index != array_index_last)
+                    {
+                        array_index_str = std::to_string(array_index);
+                        array_index_last = array_index;
+                    }
+                    return array_index_str;
+                }
 
                 // use key from the object
                 case value_t::object:
@@ -63,7 +93,7 @@ template<typename IteratorType> class iteration_proxy
 
                 // use an empty key for all primitive types
                 default:
-                    return "";
+                    return empty_str;
             }
         }
 

include/nlohmann/detail/iterators/json_reverse_iterator.hpp

@@ -21,10 +21,10 @@ create @ref const_reverse_iterator).
 
 @requirement The class satisfies the following concept requirements:
 -
-[BidirectionalIterator](http://en.cppreference.com/w/cpp/concept/BidirectionalIterator):
+[BidirectionalIterator](https://en.cppreference.com/w/cpp/named_req/BidirectionalIterator):
   The iterator that can be moved can be moved in both directions (i.e.
   incremented and decremented).
-- [OutputIterator](http://en.cppreference.com/w/cpp/concept/OutputIterator):
+- [OutputIterator](https://en.cppreference.com/w/cpp/named_req/OutputIterator):
   It is possible to write to the pointed-to element (only if @a Base is
   @ref iterator).
 
@@ -41,11 +41,11 @@ class json_reverse_iterator : public std::reverse_iterator<Base>
     using reference = typename Base::reference;
 
     /// create reverse iterator from iterator
-    json_reverse_iterator(const typename base_iterator::iterator_type& it) noexcept
+    explicit json_reverse_iterator(const typename base_iterator::iterator_type& it) noexcept
         : base_iterator(it) {}
 
     /// create reverse iterator from base class
-    json_reverse_iterator(const base_iterator& it) noexcept : base_iterator(it) {}
+    explicit json_reverse_iterator(const base_iterator& it) noexcept : base_iterator(it) {}
 
     /// post-increment (it++)
     json_reverse_iterator const operator++(int)

include/nlohmann/detail/iterators/primitive_iterator.hpp

@@ -87,7 +87,7 @@ class primitive_iterator_t
     primitive_iterator_t const operator++(int) noexcept
     {
         auto result = *this;
-        m_it++;
+        ++m_it;
         return result;
     }
 
@@ -100,7 +100,7 @@ class primitive_iterator_t
     primitive_iterator_t const operator--(int) noexcept
     {
         auto result = *this;
-        m_it--;
+        --m_it;
         return result;
     }
 

test/data/nst_json_testsuite2/test_parsing/i_number_double_huge_neg_exp.json

+[123.456e-789]
\ No newline at end of file

test/data/nst_json_testsuite2/test_parsing/i_number_huge_exp.json

+[0.4e00669999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999969999999006]
\ No newline at end of file