[antlr-interest] Simple Grammar Question

[Gerald Rosenberg]

Your NAME rule is consuming all tokens.

The record rule fails to find a digit, recovers and finds a name, 
succeeds yet reports the exception.


At 07:08 PM 1/16/2009, John Gardener wrote:
>Hello;
>
>I am stuck with simple grammar; any help is much welcomed;
>
>I want to parse 2 term sentenses, such as:
><1: single digit > <2: name containing letters and digits > EOF
>
>Below comes:
>1) grammar
>2) test rig
>3) output
>
>PROBLEM:
>Second term (name) seems to greedily consume whole input;
>
>Please let me know what is the proper way to deal with this?
>
>1) GRAMMAR
>
>grammar Simple;
>
>options {
>     language = Java;
>}
>
>@parser::header {
>     package simple;
>     import static java.lang.System.out;
>}
>
>@lexer::header{
>   package simple;
>   import static java.lang.System.out;
>}
>
>// PARSER
>
>record :
>   digit name EOF
>   { out.println( "+record: " +  $text );  };
>
>digit : DIGIT
>   { out.println( "+digit: " +  $text );  };
>
>name : NAME
>   { out.println( "+name: " +  $text );  };
>
>
>// LEXER
>
>DIGIT : '0'..'9'
>   { out.println("+DIGIT: " + $text ); } ;
>
>LETTER : 'A'..'Z'
>   { out.println("+LETTER: " + $text ); } ;
>
>NAME : ( LETTER | DIGIT ) +
>   { out.println("+NAME: " + $text ); } ;
>
>
>2) TEST RIG
>
>package simple;
>
>import java.io.ByteArrayInputStream;
>
>import org.antlr.runtime.ANTLRInputStream;
>import org.antlr.runtime.CommonTokenStream;
>
>import static java.lang.System.out;
>
>public class SimpleTest {
>
>     public static void main(String[] args) throws Exception {
>
>         String record = "3B5A";
>
>         ByteArrayInputStream stream = new ByteArrayInputStream(record
>                 .getBytes());
>
>         ANTLRInputStream input = new ANTLRInputStream(stream);
>
>         SimpleLexer lexer = new SimpleLexer(input);
>
>         CommonTokenStream tokens = new CommonTokenStream(lexer);
>
>         SimpleParser parser = new SimpleParser(tokens);
>
>         parser.record();
>
>         out.println(record);
>
>     }
>
>}
>
>
>3) TEST OUTPUT
>
>+DIGIT: 3
>+LETTER: 3B
>+DIGIT: 3B5
>+LETTER: 3B5A
>+NAME: 3B5A
>line 1:0 missing DIGIT at '3B5A'
>+digit: null
>+name: 3B5A
>+record: 3B5A
>3B5A
>
>
>Thank you,
>
>John
>
>
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