Weaseljson

An rfc8259-compliant streaming json parser

Features

• SAX-style api
• No memory allocations during parsing
• O(1) stack memory usage
• Streaming api - no need to buffer the entire document in memory. Parsing is resumed when more data is available
• Strings are unescaped in place before they're presented. No unicode normalization is performed
• Robust to crashes with untrusted input

Rfc8259 conformance notes

• There are no limits on number precision. Numbers are only validated syntactically and are presented as is
• Only utf-8 is accepted
• Invalid utf-8 is rejected
• Byte order markers are rejected
• Invalid escaped utf16 surrogate pairs are rejected
• Documents that are too deeply nested are rejected to control memory usage
• Duplicate keys are presented

Caveats

• Users should be prepared to discard work done during SAX callbacks if the document is ultimately rejected