// JSON, straight from the ANTLR book. Try it on a .json file:
//   antlrlab examples/json/JSON.g4 examples/json/example.json
grammar JSON;

json  : value EOF ;

obj   : '{' pair (',' pair)* '}'
      | '{' '}'
      ;

pair  : STRING ':' value ;

arr   : '[' value (',' value)* ']'
      | '[' ']'
      ;

value : STRING | NUMBER | obj | arr | 'true' | 'false' | 'null' ;

STRING : '"' (ESC | SAFECODEPOINT)* '"' ;

fragment ESC           : '\\' (["\\/bfnrt] | UNICODE) ;
fragment UNICODE       : 'u' HEX HEX HEX HEX ;
fragment HEX           : [0-9a-fA-F] ;
fragment SAFECODEPOINT : ~["\\\u0000-\u001F] ;

NUMBER : '-'? INT ('.' [0-9]+)? EXP? ;

fragment INT : '0' | [1-9] [0-9]* ;
fragment EXP : [Ee] [+\-]? INT ;

WS : [ \t\n\r]+ -> skip ;