[antlr-interest] Tree walker grammer help.

[Jim Idle]

On Mon, 2008-09-22 at 00:43 -0700, jack zhang wrote:

Oh yeah, you will have to put your multiple words under an imaginary so
that WORD WORD WORD AND WORD WORD WORD are not clashing.

use (w+=WORD)   -> ^(WORDLIST $w+)  in your parser and

expr
: .....

| ^(WORDLIST WORD+)


In your tree grammar

JIm

> Sorry that I made a mistake in the previous post. So please ignore the
> previous one.
> 
> I want to achieve following: (convert the input logic query to a
> standard format)
> (1) a AND b  ==> (a and b)
> (2) a OR b   ==> (a or b)
> (3) a OR b AND c ==> (a or (b and c))
> (4) a b c ==> a b c (No change, since there is no logic involved)
> (5) a b AND c ==> a (b and c)
> 
> By using the Antworks tool I know that the lexer and parser grammar
> works just fine. 
> (It generate the correct AST tree). 
> But the strange thing is that my tree walker grammar doesn't work. 
> 
> If I use the TreeWalker version 1(see attached code),  test case 4 and
> 5 are not working.
> 
> (4) a b c ==> a
> (5) a b AND c ==> a
> 
> If I use the TreeWalker version 2(see attached code), test case 1,2,3
> and 5 are not working.
> 
> (1) a AND b ==> (a b and)
> (2) a OR b ==> (a b or)
> (3) a OR b AND c ==> ( a or ( b c and ))
> (5) a b AND c ==> a
> 
> 
> Also TreeWalker version 2 report warning:
> 
> -Decision can match input such as "WORD" using multiple alternatives:
> 1, 2
> As a result, alternative(s) 2 were disabled for that input-
> 
> 
> I know something is wrong with the matching of multiple WORD, But I
> just cannot figure out.
> The only difference with version 1 and verson 2 is the WORD rule.
> 
> Where am I wrong?
> Thx !
> 
> ----------------------Lexer and Parser ---------------------
> grammar Query;
> 
> //=== Parser Option ===//
> options {
>   output = AST;
>   k=*;
> }
> 
> 
> 
> 
> //=== Lexer ===//
> 
> LEFT_PAREN: '(';
> NOT: 'NOT';
> AND: 'AND';
> OR: 'OR';
> WORD: ('a'..'z' | 'A'..'Z' | '.' | ',' | '0'..'9')+ | '"'.+'"';
> RIGHT_PAREN: ')';
> WHITESPACE: (' ' | '\t' | '\r' | '\n') { $channel = HIDDEN; } ;
> 
> 
> 
> //=== Parser ===//
> expr: orexpression*;
> 
> orexpression
>     :   andexpression (OR^ andexpression)*
>     ;
> 
> andexpression
>     : notexpression (AND^ notexpression)*
>     ;
> 
> notexpression
>     : (NOT^)? atom
>     ;
> 
> atom
>     : WORD
>     | LEFT_PAREN! expr RIGHT_PAREN!
>     ;
> 
> ----------------------Tree Walker Version 1 ---------------------
> tree grammar QueryTree;
> 
> options { 
>   output = AST;
>   ASTLabelType = CommonTree;
>   tokenVocab=Query;
> }
> 
> 
> 
> expr returns [String value=""]
>     : ^(AND a=expr b=expr) {
>         $value = "(" + $a.value + " and " + $b.value + ")";
>     }
>     | ^(OR a=expr b=expr) {
>         $value = "(" + $a.value + " or " + $b.value+ ")";
>     }
>     | ^(NOT a=expr) {
>         $value = "(not " + $a.value +")";
>     }
>     |  ( WORD {  $value = $WORD.text;  }) ;
>     
>     
> ----------------------Tree Walker Version 2 ---------------------
> tree grammar QueryTree;
> 
> 
> options { 
>   output = AST;
>   ASTLabelType = CommonTree;
>   tokenVocab=Query;
> }
> 
> 
> 
> expr returns [String value=""]
>     : ^(AND a=expr b=expr) {
>         $value = "(" + $a.value + " and " + $b.value + ")";
>     }
>     | ^(OR a=expr b=expr) {
>         $value = "(" + $a.value + " or " + $b.value+ ")";
>     }
>     | ^(NOT a=expr) {
>         $value = "(not " + $a.value +")";
>     }
>     |  ( WORD {  $value +=  " " + $WORD.text;  })+  ;
>     
>     
> 
>     
> 
> 
> 
> 
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