Crate json_syntax

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This library provides a strict JSON parser as defined by RFC 8259 and ECMA-404. Parsing values generates a CodeMap that keeps track of the position of each JSON value fragment in the parsed document.


  • Strict implementation of RFC 8259 and ECMA-404.
  • No stack overflow, your memory is the limit.
  • Numbers are stored in lexical form thanks to the json-number crate, their precision is not limited.
  • Duplicate values are preserved. A JSON object is just a list of entries, in the order of definition.
  • Strings are stored on the stack whenever possible, thanks to the smallstr crate.
  • The parser is configurable to accept documents that do not strictly adhere to the standard.
  • Highly configurable printing methods.
  • Macro to build any value statically.
  • JSON Canonicalization Scheme implementation (RFC 8785) enabled with the canonicalization feature.
  • serde support (by enabling the serde feature).
  • Conversion from/to serde_json::Value (by enabling the serde_json feature).
  • Thoroughly tested.


use std::fs;
use json_syntax::{Value, Parse, Print};

let filename = "tests/inputs/y_structure_500_nested_arrays.json";
let input = fs::read_to_string(filename).unwrap();
let mut value = Value::parse_str(&input).expect("parse error").0;
println!("value: {}", value.pretty_print());




  • Constructs a json_syntax::Value from a JSON literal.






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