105 lines
4.9 KiB
Markdown
105 lines
4.9 KiB
Markdown
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# Features
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## General
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* Cross-platform
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* Compilers: Visual Studio, gcc, clang, etc.
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* Architectures: x86, x64, ARM, etc.
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* Operating systems: Windows, Mac OS X, Linux, iOS, Android, etc.
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* Easy installation
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* Header files only library. Just copy the headers to your project.
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* Self-contained, minimal dependences
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* No STL, BOOST, etc.
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* Only included `<cstdio>`, `<cstdlib>`, `<cstring>`, `<inttypes.h>`, `<new>`, `<stdint.h>`.
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* Without C++ exception, RTTI
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* High performance
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* Use template and inline functions to reduce function call overheads.
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* Internal optimized Grisu2 and floating point parsing implementations.
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* Optional SSE2/SSE4.2 support.
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## Standard compliance
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* RapidJSON should be fully RFC4627/ECMA-404 compliance.
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* Support JSON Pointer (RFC6901).
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* Support JSON Schema Draft v4.
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* Support Unicode surrogate.
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* Support null character (`"\u0000"`)
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* For example, `["Hello\u0000World"]` can be parsed and handled gracefully. There is API for getting/setting lengths of string.
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* Support optional relaxed syntax.
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* Single line (`// ...`) and multiple line (`/* ... */`) comments (`kParseCommentsFlag`).
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* Trailing commas at the end of objects and arrays (`kParseTrailingCommasFlag`).
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* `NaN`, `Inf`, `Infinity`, `-Inf` and `-Infinity` as `double` values (`kParseNanAndInfFlag`)
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* [NPM compliant](http://github.com/miloyip/rapidjson/blob/master/doc/npm.md).
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## Unicode
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* Support UTF-8, UTF-16, UTF-32 encodings, including little endian and big endian.
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* These encodings are used in input/output streams and in-memory representation.
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* Support automatic detection of encodings in input stream.
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* Support transcoding between encodings internally.
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* For example, you can read a UTF-8 file and let RapidJSON transcode the JSON strings into UTF-16 in the DOM.
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* Support encoding validation internally.
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* For example, you can read a UTF-8 file, and let RapidJSON check whether all JSON strings are valid UTF-8 byte sequence.
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* Support custom character types.
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* By default the character types are `char` for UTF8, `wchar_t` for UTF16, `uint32_t` for UTF32.
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* Support custom encodings.
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## API styles
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* SAX (Simple API for XML) style API
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* Similar to [SAX](http://en.wikipedia.org/wiki/Simple_API_for_XML), RapidJSON provides a event sequential access parser API (`rapidjson::GenericReader`). It also provides a generator API (`rapidjson::Writer`) which consumes the same set of events.
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* DOM (Document Object Model) style API
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* Similar to [DOM](http://en.wikipedia.org/wiki/Document_Object_Model) for HTML/XML, RapidJSON can parse JSON into a DOM representation (`rapidjson::GenericDocument`), for easy manipulation, and finally stringify back to JSON if needed.
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* The DOM style API (`rapidjson::GenericDocument`) is actually implemented with SAX style API (`rapidjson::GenericReader`). SAX is faster but sometimes DOM is easier. Users can pick their choices according to scenarios.
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## Parsing
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* Recursive (default) and iterative parser
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* Recursive parser is faster but prone to stack overflow in extreme cases.
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* Iterative parser use custom stack to keep parsing state.
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* Support *in situ* parsing.
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* Parse JSON string values in-place at the source JSON, and then the DOM points to addresses of those strings.
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* Faster than convention parsing: no allocation for strings, no copy (if string does not contain escapes), cache-friendly.
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* Support 32-bit/64-bit signed/unsigned integer and `double` for JSON number type.
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* Support parsing multiple JSONs in input stream (`kParseStopWhenDoneFlag`).
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* Error Handling
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* Support comprehensive error code if parsing failed.
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* Support error message localization.
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## DOM (Document)
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* RapidJSON checks range of numerical values for conversions.
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* Optimization for string literal
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* Only store pointer instead of copying
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* Optimization for "short" strings
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* Store short string in `Value` internally without additional allocation.
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* For UTF-8 string: maximum 11 characters in 32-bit, 21 characters in 64-bit (13 characters in x86-64).
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* Optionally support `std::string` (define `RAPIDJSON_HAS_STDSTRING=1`)
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## Generation
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* Support `rapidjson::PrettyWriter` for adding newlines and indentations.
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## Stream
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* Support `rapidjson::GenericStringBuffer` for storing the output JSON as string.
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* Support `rapidjson::FileReadStream` and `rapidjson::FileWriteStream` for input/output `FILE` object.
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* Support custom streams.
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## Memory
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* Minimize memory overheads for DOM.
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* Each JSON value occupies exactly 16/20 bytes for most 32/64-bit machines (excluding text string).
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* Support fast default allocator.
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* A stack-based allocator (allocate sequentially, prohibit to free individual allocations, suitable for parsing).
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* User can provide a pre-allocated buffer. (Possible to parse a number of JSONs without any CRT allocation)
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* Support standard CRT(C-runtime) allocator.
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* Support custom allocators.
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## Miscellaneous
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* Some C++11 support (optional)
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* Rvalue reference
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* `noexcept` specifier
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* Range-based for loop
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