Iam trying to build the grammar fiel for parsing expressions like


((a=b AND b=c)OR(b=d OR x=y)).


Iam using the following grammar.

			

			class LangParser extends Parser;
			

			

			options {
			

			codeGenMakeSwitchThreshold = 3;
			

			codeGenBitsetTestThreshold = 4;
			

			buildAST=true;
			

			genHashLines = true;
			

			}
			

			

			block
			

			:  LPAREN^ (statement)* RPAREN!
			

			;
			

			

			statement
			

			: expr SEMI!
			

			| "if"^ LPAREN! expr RPAREN! statement
			

			( "else"! statement )?
			

			| "while"^ LPAREN! expr RPAREN! statement
			

			|! b:block { statement_AST = b_AST; }
			

			// do some manual tree returning
			

			;
			

			

			expr: assignExpr
			

			;
			

			

			assignExpr
			

			: aexpr (ASSIGN^ assignExpr)?
			

			;
			

			

			aexpr
			

			: mexpr (AND^ mexpr)*
			

			|       LPAREN^ (aexpr OR^ (mexpr))* RPAREN!
			

			;
			

			

			mexpr: atom ((OR^ | NOT^) atom)*
			

			

			;
			

			

			atom: ID
			

			| STRING
			

			;
			

			

			class LangWalker extends TreeParser;
			

			

			block
			

			: #( LPAREN( stat )+ )
			

			;
			

			

			stat: #("if" expr stat (stat)?)
			

			| #("while" expr stat)
			

			| expr
			

			| block
			

			;
			

			

			expr: #(ASSIGN expr expr)  {System.out.println("found assign");}
			

			| #(AND expr expr) {System.out.println("found AND");}
			

			| #(OR expr expr)  {System.out.println("found OR");}
			

			|       #(NOT expr expr)        {System.out.println("found NOT");}
			

			| a:ID   {System.out.println("found ID "+a.getText());}
			

			| b:STRING  {System.out.println("found String "+b.getText());}
			

			;
			

			

			class LangLexer extends Lexer;
			

			

			WS : (' '
			

			| ' '
			

			| '
			

			'
			

			| '
			

			')
			

			{ _ttype = Token.SKIP; }
			

			;
			

			

			LPAREN: '('
			

			;
			

			

			RPAREN: ')'
			

			;
			

			

			LCURLY: '{'
			

			;
			

			

			RCURLY: '}'
			

			;
			

			

			NOT:    '!'
			

			;
			

			

			OR: '|' ;
			

			

			AND: '&'
			

			;
			

			

			ASSIGN
			

			: '='
			

			;
			

			

			SEMI: ';'
			

			;
			

			

			COMMA
			

			: ','
			

			;
			

			

			protected
			

			ESC : '\\'
			

			( 'n'
			

			| 'r'
			

			| 't'
			

			| 'b'
			

			| 'f'
			

			| '"'
			

			| '\''
			

			| '\\'
			

			

			)
			

			;
			

			

			protected
			

			CHAR
			

			: ('0'..'9'|'a'..'z'|'='|'A'..'Z')
			

			;
			

			

			STRING: (CHAR)+
			

			;
			

			

			ID : ('a'..'z'|'A'..'Z'|'_') ('a'..'z'|'A'..'Z'|'_'|'0'..'9')*
			

			{
			

			String i = (String)literals.get(getText());
			

			

			}
			

			;