JSON parser in Self using the mango parser library

json.behavior.self

( |
  "_" parent* = traits oddball.

  object = (| eval = ( |dict = dictionary copy| 
                         members elements do: [|:v. :k|
                           dict at: v string eval Put: v value eval
                         ].
                         dict
                      ) 
           |).
  array = (| eval = ( elements elements copyMappedBy: [|:v. :k| v eval] ) |). 
  float = (| eval = ( source asFloat ) |).
  int = (| eval = ( source asInteger ) |).
  string = (| eval = ( source copyFrom: 1 UpTo: source size - 1 ) |).
  true = (| eval = true |).
  false = (| eval = false |).
  null = (| eval = nil |).
| )

json.grm

(*
  A basic JSON parser in Self using the mango parser system.

  Example run (Assumes files are in a json subdirectory):

    |grm. exp|
    grm: mango parsers stGrammerParser copy.
    grm parseFile: 'json/json.grm'.
    exp: grm output makeParser.

    exp parseString: '{\"a\":1,\"b\":2}'.
    exp output eval (* a dictionary with 'a' and 'b' *)
    exp parseString: '[1,2,3.45]'.
    exp output eval (* an array with 1,2,3.45 *)
*)

Name:     'json'
Behavior: 'json/json.behavior.self'

Syntax:  SLR(1)
Transformations: 'elimEpsilons', 'elimSingletons' ;

  <value>    ::| <number> {string} <array> <object> {true} {false} {null} ;
  <array>    ::= '[' <elements> ']' ;
  <elements> ::* <value> ',' ;
  <object>   ::= '{' <members> '}' ;
  <members>  ::* <pair> ',' ;
  <pair>     ::= {string} ':' <value> ;
  <number>   ::| {int} {float} ;

Lex:  SLR(1)
Transformations: 'elimEpsilons', 'elimSingletons', 'useCharClasses' ;

  {whitespace} ->  [ \t\n]+ ;
  {float}      ->  {int} '.' ({digits})? ([eE][+-]? {digits})?  ;
  {int}        ->  '-'? {digits} ;

  {digits}      =  [0-9]+ ;

  {string}     -> '"' [^"]* '"' ;
  {true}       -> 'true' ;
  {false}      -> 'false' ;
  {null}       -> 'null' ;