Comments on: ANTLR: when a token is not a token http://blog.excastle.com/2006/04/28/antlr-when-a-token-is-not-a-token/ Life, .NET, and Cats Tue, 31 Aug 2010 13:47:10 +0000 http://wordpress.org/?v=2.9.2 hourly 1 By: Nguyen Minh Hai http://blog.excastle.com/2006/04/28/antlr-when-a-token-is-not-a-token/comment-page-1/#comment-33174 Nguyen Minh Hai Sat, 18 Oct 2008 22:14:48 +0000 http://blog.excastle.com/2006/04/28/antlr-when-a-token-is-not-a-token/#comment-33174 Hi. I'm using ANTLR 3.0. I have two grammars: (1) grammar Expr; stat : expr SEMI; expr : multExpr (PLUS multExpr | MINUS multExpr)*; multExpr: atom (MUL multExpr | DIV multExpr)*; atom : INT | '(' expr ')'; INT : '0'..'9'+ ; PLUS : '+'; MINUS : '-'; MUL : '*'; DIV : '/'; SEMI : ';'; (2) grammar Expr; stat : expr SEMI; expr : multExpr ((PLUS multExpr | MINUS multExpr)+ | ); multExpr: atom ((MUL multExpr | DIV multExpr)+ | ); atom : INT | '(' expr ')'; INT : '0'..'9'+ ; PLUS : '+'; MINUS : '-'; MUL : '*'; DIV : '/'; SEMI : ';'; As far as I know, (2) works well, but (1) gets stuck if MINUS or DIV is the very first operator, for example, "1-2+3", "1/2+3", etc. and I can not figure out what the reason is. I hope you can help me. Thanks in advance :D. Hi. I’m using ANTLR 3.0. I have two grammars:

(1)
grammar Expr;

stat : expr SEMI;
expr : multExpr (PLUS multExpr | MINUS multExpr)*;
multExpr: atom (MUL multExpr | DIV multExpr)*;
atom : INT | ‘(‘ expr ‘)’;

INT : ‘0′..’9′+ ;
PLUS : ‘+’;
MINUS : ‘-’;
MUL : ‘*’;
DIV : ‘/’;
SEMI : ‘;’;

(2)
grammar Expr;

stat : expr SEMI;
expr : multExpr ((PLUS multExpr | MINUS multExpr)+ | );
multExpr: atom ((MUL multExpr | DIV multExpr)+ | );
atom : INT | ‘(‘ expr ‘)’;

INT : ‘0′..’9′+ ;
PLUS : ‘+’;
MINUS : ‘-’;
MUL : ‘*’;
DIV : ‘/’;
SEMI : ‘;’;

As far as I know, (2) works well, but (1) gets stuck if MINUS or DIV is the very first operator, for example, “1-2+3″, “1/2+3″, etc. and I can not figure out what the reason is. I hope you can help me. Thanks in advance :D .

]]> By: Joe White's Blog http://blog.excastle.com/2006/04/28/antlr-when-a-token-is-not-a-token/comment-page-1/#comment-5571 Joe White's Blog Mon, 08 May 2006 01:26:00 +0000 http://blog.excastle.com/2006/04/28/antlr-when-a-token-is-not-a-token/#comment-5571 <strong>What to do when ANTLR moves your variables out of scope</strong> What to do when ANTLR moves your variables out of scope

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