options { JAVA_UNICODE_ESCAPE = true; } PARSER_BEGIN(ConstraintParser) public class ConstraintParser {} PARSER_END(ConstraintParser) SKIP : /* WHITE SPACE */ { " " | "\t" | "\n" | "\r" | "\f" } SPECIAL_TOKEN : /* COMMENTS */ { | | } TOKEN : /* RESERVED WORDS AND LITERALS */ { < IN: "in" > | < SUB: "sub" > | < PRINT: "print" > } TOKEN : /* LITERALS */ { < INTEGER_LITERAL: ["1"-"9"] (["0"-"9"])* > } TOKEN : /* IDENTIFIERS */ { < IDENTIFIER: (|)* > | < #LETTER: [ "\u0024", "\u0041"-"\u005a", "\u005f", "\u0061"-"\u007a", "\u00c0"-"\u00d6", "\u00d8"-"\u00f6", "\u00f8"-"\u00ff", "\u0100"-"\u1fff", "\u3040"-"\u318f", "\u3300"-"\u337f", "\u3400"-"\u3d2d", "\u4e00"-"\u9fff", "\uf900"-"\ufaff" ] > | < #DIGIT: [ "\u0030"-"\u0039", "\u0660"-"\u0669", "\u06f0"-"\u06f9", "\u0966"-"\u096f", "\u09e6"-"\u09ef", "\u0a66"-"\u0a6f", "\u0ae6"-"\u0aef", "\u0b66"-"\u0b6f", "\u0be7"-"\u0bef", "\u0c66"-"\u0c6f", "\u0ce6"-"\u0cef", "\u0d66"-"\u0d6f", "\u0e50"-"\u0e59", "\u0ed0"-"\u0ed9", "\u1040"-"\u1049" ] > } TOKEN : /* SEPARATORS */ { < IMPLIES: "=>" > } /************************************** * THE CONSTRAINT GRAMMAR STARTS HERE * **************************************/ void Goal() : {} { ( Constraint() | Print() )* } void Constraint() : {} { PropConstraint() | LOOKAHEAD(4) CondConstraint() | LOOKAHEAD(4) StartConstraint() } void StartConstraint() : {} { Constant() "in" Variable() } void PropConstraint() : {} { Variable() "sub" Variable() } void CondConstraint() : {} { Constant() "in" Variable() "=>" Variable() "sub" Variable() } void Print() : {} { "print" Variable() } void Constant() : {} { } void Variable() : {} { }