atomparser.jj

该原代码是实现机器学习中条件随机场模型的Java代码

options {

  STATIC = false;

}

PARSER_BEGIN(AtomParser)

package lcrf.logic.parser;

import lcrf.logic.*;
import java.util.Vector;

public class AtomParser {

}

PARSER_END(AtomParser)

SKIP:
{
 " "
}

TOKEN: 
{
  < VARIABLE : (["A"-"Z","_"])+ (["A"-"Z","a"-"z","0"-"9","_"])* >
| < CONSTANT : (["a"-"z"])+ (["A"-"Z","a"-"z","0"-"9","_"])* >
| < STRING   : ["'"] (~["'"])* ["'"] >
| < NUMBER   : (["0"-"9"])+ >
| < COMMA    : "," >
| < LPAREN   : "(" >
| < RPAREN   : ")" >  
}


Term Term() :
{
  Token t;
  Term subterm;
  Vector subterms = new Vector();
}
{

     t=<STRING>  { return new StringConstant(t.image.substring(1,t.image.length()-1)); }
   | t=<NUMBER> { return new NumberConstant(new Integer(t.image).intValue()); }
   | t=<VARIABLE> { return new Variable(t.image); }       
   | LOOKAHEAD(2)
     t=<CONSTANT>
      <LPAREN>
        subterm=Term() { subterms.add(subterm); }
        (
         <COMMA> subterm=Term() { subterms.add(subterm);}
         )*
      <RPAREN>  {return new Constant(t.image,subterms);}  
   | t=<CONSTANT> { return new Constant(t.image); }      
}