nl_xlator.jj

java 编译器java复杂编译器,可以编译java文件的类库

/*
 * Copyright © 2002 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * California 95054, U.S.A. All rights reserved.  Sun Microsystems, Inc. has
 * intellectual property rights relating to technology embodied in the product
 * that is described in this document. In particular, and without limitation,
 * these intellectual property rights may include one or more of the U.S.
 * patents listed at http://www.sun.com/patents and one or more additional
 * patents or pending patent applications in the U.S. and in other countries.
 * U.S. Government Rights - Commercial software. Government users are subject
 * to the Sun Microsystems, Inc. standard license agreement and applicable
 * provisions of the FAR and its supplements.  Use is subject to license terms.
 * Sun,  Sun Microsystems,  the Sun logo and  Java are trademarks or registered
 * trademarks of Sun Microsystems, Inc. in the U.S. and other countries.  This
 * product is covered and controlled by U.S. Export Control laws and may be
 * subject to the export or import laws in other countries.  Nuclear, missile,
 * chemical biological weapons or nuclear maritime end uses or end users,
 * whether direct or indirect, are strictly prohibited.  Export or reexport
 * to countries subject to U.S. embargo or to entities identified on U.S.
 * export exclusion lists, including, but not limited to, the denied persons
 * and specially designated nationals lists is strictly prohibited.
 */


PARSER_BEGIN(NL_Xlator)

public class NL_Xlator {

  public static void main(String args[]) throws ParseException {
    NL_Xlator parser = new NL_Xlator(System.in);
    parser.ExpressionList();
  }

}

PARSER_END(NL_Xlator)

SKIP :
{
  " "
| "\t"
| "\n"
| "\r"
}

TOKEN :
{
  < ID: ["a"-"z","A"-"Z","_"] ( ["a"-"z","A"-"Z","_","0"-"9"] )* >
|
  < NUM: ( ["0"-"9"] )+ >
}

void ExpressionList() :
{
	String s;
}
{
	{
	  System.out.println("Please type in an expression followed by a \";\" or ^D to quit:");
	  System.out.println("");
	}
  ( s=Expression() ";"
	{
	  System.out.println(s);
	  System.out.println("");
	  System.out.println("Please type in another expression followed by a \";\" or ^D to quit:");
	  System.out.println("");
	}
  )*
  <EOF>
}

String Expression() :
{
	java.util.Vector termimage = new java.util.Vector();
	String s;
}
{
  s=Term()
	{
	  termimage.addElement(s);
	}
  ( "+" s=Term()
	{
	  termimage.addElement(s);
	}
  )*
	{
	  if (termimage.size() == 1) {
	    return (String)termimage.elementAt(0);
          } else {
            s = "the sum of " + (String)termimage.elementAt(0);
	    for (int i = 1; i < termimage.size()-1; i++) {
	      s += ", " + (String)termimage.elementAt(i);
	    }
	    if (termimage.size() > 2) {
	      s += ",";
	    }
	    s += " and " + (String)termimage.elementAt(termimage.size()-1);
            return s;
          }
	}
}

String Term() :
{
	java.util.Vector factorimage = new java.util.Vector();
	String s;
}
{
  s=Factor()
	{
	  factorimage.addElement(s);
	}
  ( "*" s=Factor()
	{
	  factorimage.addElement(s);
	}
  )*
	{
	  if (factorimage.size() == 1) {
	    return (String)factorimage.elementAt(0);
          } else {
            s = "the product of " + (String)factorimage.elementAt(0);
	    for (int i = 1; i < factorimage.size()-1; i++) {
	      s += ", " + (String)factorimage.elementAt(i);
	    }
	    if (factorimage.size() > 2) {
	      s += ",";
	    }
	    s += " and " + (String)factorimage.elementAt(factorimage.size()-1);
            return s;
          }
	}
}

String Factor() :
{
	Token t;
	String s;
}
{
  t=<ID>
	{
	  return t.image;
	}
|
  t=<NUM>
	{
	  return t.image;
	}
|
  "(" s=Expression() ")"
	{
	  return s;
	}
}