rapidjson/doc/features.md

RapidJSON Features

General

• Cross-platform
• Compilers: Visual Studio, gcc, clang, etc.
• Architectures: x86, x64, ARM, etc.
• Operating systems: Windows, Mac OS X, Linux, iOS, Android, etc.
• Easy installation
• Header files only library. Just copy the headers to your project.
• Self-contained, minimal dependences
• No STL, BOOST, etc.
• Only included <cstdio>, <cstdlib>, <cstring>, <inttypes.h>, <new>, <stdint.h>. *
• Without C++ exception, RTTI
• High performance
• Use template and inline functions to reduce function call overheads.
• Optional SSE2/SSE4.1 support.

Standard compliance

• RapidJSON should be fully RFC4627/ECMA-404 compliance.
• Support unicode surrogate.
• Support null character ("\u0000")
• For example, ["Hello\u0000World"] can be parsed and handled gracefully. There is API for getting/setting lengths of string.

Unicode

• Support UTF-8, UTF-16, UTF-32 encodings, including little endian and big endian.
• These encodings are used in input/output streams and in-memory representation.
• Support automatic detection of encodings in input stream.
• Support transcoding between encodings internally.
• For example, you can read a UTF-8 file and let RapidJSON transcode the JSON strings into UTF-16 in the DOM.
• Support encoding validation internally.
• For example, you can read a UTF-8 file, and let RapidJSON check whether all JSON strings are valid UTF-8 byte sequence.
• Support custom character types.
• By default the character types are char for UTF8, wchar_t for UTF16, uint32_t for UTF32.
• Support custom encodings.

API styles

• SAX (Simple API for XML) style API
• Similar to SAX, RapidJSON provides a event sequential access parser API (GenericReader). It also provides a generator API (GenericWriter) which consumes the same set of events.
• DOM (Document Object Model) style API
• Similar to DOM for HTML/XML, RapidJSON can parse JSON into a DOM representation (GenericDocument), for easy manipulation, and finally stringify back to JSON if needed.
• The DOM style API (GenericDocument) is actually implemented with SAX style API (GenericReader). SAX is faster but sometimes DOM is easier. Users can pick their choices according to scenarios.

DOM (Document)

• Support insitu parsing.
• Parse JSON string values in-place at the source JSON, and then the DOM points to addresses of those strings.
• Faster than convention parsing: no allocation for strings, no copy (if string does not contain escapes), cache-friendly.
• Support 32-bit/64-bit signed/unsigned integer and double for JSON number type.
• RapidJSON checks range of numerical values for conversions.

SAX (Reader)

• Support comprehensive error code if parsing failed.
• Support localizable error message.

SAX (Writer)

• Support PrettyWriter for adding newlines and indentations.
• Support custom precision for floating point values.

Stream

• Support GenericStringBuffer for storing the output JSON as string.
• Support FileReadStream/FileWriteStream for input/output FILE object.
• Support custom streams.

Memory

• Minimize memory overheads for DOM.
• Each JSON value occupies exactly 16/20 bytes for most 32/64-bit machines (excluding text string).
• Support fast default allocator.
• A stack-based allocator (allocate sequentially, prohibit to free individual allocations, suitable for parsing).
• User can provide a pre-allocated buffer. (Possible to parse a number of JSONs without any CRT allocation)
• Support standard CRT(C-runtime) allocator.
• Support custom allocators.