commit | 71f0fa7eb385c7d78c2100b676f4eca1d47b0fe0 | [log] [tgz] |
---|---|---|
author | ylavic <ylavic.dev@gmail.com> | Thu Apr 01 18:20:09 2021 +0200 |
committer | ylavic <ylavic.dev@gmail.com> | Wed Apr 07 18:22:46 2021 +0200 |
tree | 3d7cd6a00ef7bf1d068e58b7daadc2a185eb9f89 | |
parent | 7d801bbe45a0bebbc97d4485a8e1d75b99a0cae0 [diff] |
Set RAPIDJSON_USE_MEMBERSMAP to use a (std::multi)map for object members. When RAPIDJSON_USE_MEMBERSMAP is defined, an object Value will store its members in an (re)allocated array of Members like before, but also in an std::multimap<GenericValue::Data,SizeType> where the key and value reference the corresponding Member by its Data and index in the array, respectively, and in a relocatable manner. The layout of the members map/array is now: {multimap*}<>{capacity}<>{Member[capacity]}<>{multimap::iterator[capacity]} where <> stands for the RAPIDJSON_ALIGN-ment of each part, if needed. This layout needs to be reallocated when the current capacity is exhausted, which requires to take care of the multimap and its iterators explicitely. The multimap is allocated separately and only its pointer is saved in this layout, so it can easily be restored in its new position. As for the old/alive iterators, they must move to their new offset according to the new capacity. With this in place, it's immediate to get the multimap::iterator from a MemberIterator and vice versa, thus the same complexity applies for the operations with MemberIterator or MapIterator. For FindMember() and RemoveMember(), the complexity drops from O(n) to the multimap/rbtree's O(log n). For EraseMember() it drops from O(n-m) to O((log n)-m), m representing the move/copy of the trailing members. For AddMember() though, the complexity grows from O(1) to O(log n) due to the insertion in the multimap too. Consequently parsing will be slower, up to ~20% measured in perftests on my laptop (since it's mainly composed of insertions). But later work on the Document (usually the goal of parsing...) will be much faster; the new DocumentFind perftest included in this commit is 8 times faster with RAPIDJSON_USE_MEMBERSMAP (still on my laptop). Overall the tests are 4% slower (mainly composed of parsing), and notably 15% slower for schemas parsing/validation (which supposedly comes from the larger JSON files parsing, still). As a side note, when RAPIDJSON_USE_MEMBERSMAP is not defined, this commit does nothing (same results for perftest with regard to previous versions). Finally, the multimap is allocated and constructed using StdAllocator, so they will use the same Allocator than for any other Value allocation, and thus will benefit from the same performance/safety/security/whatever provided by the user given Allocator.
Tencent is pleased to support the open source community by making RapidJSON available.
Copyright (C) 2015 THL A29 Limited, a Tencent company, and Milo Yip.
Linux | Windows | Coveralls |
---|---|---|
RapidJSON is a JSON parser and generator for C++. It was inspired by RapidXml.
RapidJSON is small but complete. It supports both SAX and DOM style API. The SAX parser is only a half thousand lines of code.
RapidJSON is fast. Its performance can be comparable to strlen()
. It also optionally supports SSE2/SSE4.2 for acceleration.
RapidJSON is self-contained and header-only. It does not depend on external libraries such as BOOST. It even does not depend on STL.
RapidJSON is memory-friendly. Each JSON value occupies exactly 16 bytes for most 32/64-bit machines (excluding text string). By default it uses a fast memory allocator, and the parser allocates memory compactly during parsing.
RapidJSON is Unicode-friendly. It supports UTF-8, UTF-16, UTF-32 (LE & BE), and their detection, validation and transcoding internally. For example, you can read a UTF-8 file and let RapidJSON transcode the JSON strings into UTF-16 in the DOM. It also supports surrogates and “\u0000” (null character).
More features can be read here.
JSON(JavaScript Object Notation) is a light-weight data exchange format. RapidJSON should be in full compliance with RFC7159/ECMA-404, with optional support of relaxed syntax. More information about JSON can be obtained at
Value
from 24 bytes to 16 bytes in x86-64 architecture.For other changes please refer to change log.
RapidJSON is cross-platform. Some platform/compiler combinations which have been tested are shown as follows.
Users can build and run the unit tests on their platform/compiler.
RapidJSON is a header-only C++ library. Just copy the include/rapidjson
folder to system or project's include path.
Alternatively, if you are using the vcpkg dependency manager you can download and install rapidjson with CMake integration in a single command:
RapidJSON uses following software as its dependencies:
To generate user documentation and run tests please proceed with the steps below:
git submodule update --init
to get the files of thirdparty submodules (google test).build
in rapidjson source directory.build
directory and run cmake ..
command to configure your build. Windows users can do the same with cmake-gui application.make
from the build directory.On successful build you will find compiled test and example binaries in bin
directory. The generated documentation will be available in doc/html
directory of the build tree. To run tests after finished build please run make test
or ctest
from your build tree. You can get detailed output using ctest -V
command.
It is possible to install library system-wide by running make install
command from the build tree with administrative privileges. This will install all files according to system preferences. Once RapidJSON is installed, it is possible to use it from other CMake projects by adding find_package(RapidJSON)
line to your CMakeLists.txt.
This simple example parses a JSON string into a document (DOM), make a simple modification of the DOM, and finally stringify the DOM to a JSON string.
// rapidjson/example/simpledom/simpledom.cpp` #include "rapidjson/document.h" #include "rapidjson/writer.h" #include "rapidjson/stringbuffer.h" #include <iostream> using namespace rapidjson; int main() { // 1. Parse a JSON string into DOM. const char* json = "{\"project\":\"rapidjson\",\"stars\":10}"; Document d; d.Parse(json); // 2. Modify it by DOM. Value& s = d["stars"]; s.SetInt(s.GetInt() + 1); // 3. Stringify the DOM StringBuffer buffer; Writer<StringBuffer> writer(buffer); d.Accept(writer); // Output {"project":"rapidjson","stars":11} std::cout << buffer.GetString() << std::endl; return 0; }
Note that this example did not handle potential errors.
The following diagram shows the process.
More examples are available:
DOM API
SAX API
Reader
.PrettyWriter
.JsonxWriter
which stringify SAX events into JSONx (a kind of XML) format. The example is a command line tool which converts input JSON into JSONx format.Schema
Advanced
AsyncDocumentParser
which can parse JSON in parts, using C++11 thread.Document
.RapidJSON welcomes contributions. When contributing, please follow the code below.
Feel free to submit issues and enhancement requests.
Please help us by providing minimal reproducible examples, because source code is easier to let other people understand what happens. For crash problems on certain platforms, please bring stack dump content with the detail of the OS, compiler, etc.
Please try breakpoint debugging first, tell us what you found, see if we can start exploring based on more information been prepared.
In general, we follow the “fork-and-pull” Git workflow.
unittest
and preftest
, please add test case for each new feature or bug-fix if needed.NOTE: Be sure to merge the latest from “upstream” before making a pull request!
You can copy and paste the license summary from below.
Tencent is pleased to support the open source community by making RapidJSON available. Copyright (C) 2015 THL A29 Limited, a Tencent company, and Milo Yip. Licensed under the MIT License (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://opensource.org/licenses/MIT Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.