Tag constants

• JSONNull: null tag.
• JSONInt: signed-integer tag for Int64 values.
• JSONReal: real-number tag for Real64 values.
• JSONCond: boolean tag for Cond values.
• JSONString: string tag for String values.
• JSONArray: array tag for JSON Array values.
• JSONObject: object tag for String JSON HashTable values.

JSON

JSON stores one tagged value over Int64, Real64, Cond, String, JSON Array, and String JSON HashTable.

Methods

• getTag (-- tag): returns the current JSON tag.
• setTag (tag --): switches the active JSON tag.
• getInt, getReal, getCond, getString, getArray, and getObject: typed accessors that require the matching current tag.

Conversion helpers

• intAsJSON, realAsJSON, condAsJSON, stringAsJSON, arrayAsJSON, and objectAsJSON: construct one JSON from the corresponding typed value.

Object values store one String JSON HashTable, and array values store one JSON Array.

JSONParserResult

• success: TRUE when lexical processing and node parsing succeed and FALSE on invalid UTF-8 input or JSON failure.
• finished: TRUE when the whole source is consumed after one successful node parse and FALSE when trailing non-space input remains.
• errorInfo.message: parser failure description when success is FALSE.
• errorInfo.position: parser position at failure, or the first unparsed position when finished is FALSE.
• json: parsed JSON value when success is TRUE. When finished is FALSE, it still contains the first parsed node.
• On invalid UTF-8 input, only errorInfo.position.offset is meaningful; line and column are not derived.

Parser model

• parseJSONNode: lower-level parser entry that parses one JSON node from one already split UTF-8 source and one current parser position into supplied JSON and JSONParserResult objects.
• catJSONNodeWithPadding: lower-level serializer helper that appends formatted JSON to one existing String with one requested indentation level.
• Numbers without fractional or exponent part are parsed as JSONInt; numbers with fractional or exponent part are parsed as JSONReal.
• Leading zeros after the first digit are rejected, and signed-integer overflow beyond the Int64 range makes parsing fail.
• Object keys must be unique. Duplicate keys make parsing fail.
• String escapes include \", \\, \/, \b, \f, \t, \n, \r, and \uXXXX.
• \uXXXX escapes are interpreted one 16-bit code value at a time. Surrogate-pair combination is unsupported.
• Known source text can be parsed during compilation, and compile-time code can inspect the resulting tree.

parseStringToJSON (source -- result)

Parses one accepted UTF-8 source into JSONParserResult.

• Accepted source forms are StringView, Text, and String.
• The source is normalized through String.makeStringView before UTF-8 splitting begins.
• The result fields are described in JSONParserResult.

saveJSONToString (json -- string)

Serializes one JSON value to a formatted String.

• Arrays are written in item order.
• Object member order in serialized output is not specified.
• Objects and arrays use two-space indentation.
• Booleans and null are written as true, false, and null.
• The serializer supports only code points below 0x10000.

Examples

Successful object parse

"Json" use
"control" use

{} () {} [
  result: "{\"x\":1}" parseStringToJSON;
  @result.@success TRUE same printStack _:;
  @result.@finished TRUE same printStack _:;
  @[email protected] JSONObject same printStack _:;
  @[email protected] 1 same printStack _:;
] "main" exportFunction

Expected Output During Compilation

TRUE
TRUE
TRUE
TRUE

Trailing input and duplicate key

"Json" use
"control" use

{} () {} [
  trailing: "{} x" parseStringToJSON;
  @trailing.@success TRUE same printStack _:;
  @trailing.@finished FALSE same printStack _:;
  @trailing.@errorInfo.@position.@offset 3 same printStack _:;

  duplicate: "{\"x\":1,\"x\":2}" parseStringToJSON;
  @duplicate.@success FALSE same printStack _:;
] "main" exportFunction

Expected Output During Compilation

TRUE
TRUE
TRUE
TRUE

Parse and serialize array

"Json" use
"String" use
"control" use

{} Int32 {} [
  result: "[1,true]" parseStringToJSON;
  result.success ~ [
    1
  ] [
    result.json saveJSONToString print
    0
  ] if
] "main" exportFunction

Expected Output

[
  1,
  true
]

See also

• HashTable: Hash-based map and set module.
• String: UTF-8 string views, owned strings, formatting helpers, and text conversion utilities.
• Xml: XML document, parser, and serialization helpers.