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Maven 3 Plugin for processing JavaCC grammar files.
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/* Copyright (c) 2009, Paul Cager.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *     * Redistributions of source code must retain the above copyright notice,
 *       this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * This file contains a simple parser to evaulate simple boolean conditions,
 * such as
 *   !value1 || value2
 */

options {
  JAVA_UNICODE_ESCAPE = true;
  STATIC=false;
}

PARSER_BEGIN(ConditionParser)

package org.javacc.utils;

import java.io.StringReader;
import java.util.Map;

public class ConditionParser
{
    private Map options;
    
    public static void main(String... args) throws ParseException
    {
      test("F", false);
      test("T", true);
      test("F || T", true);
      test("T || F", true);
      test("T || will not be compiled )", true);
      test("F && T", false);
      test("T && T", true);
      test("unknown", false);
    }
    
    private static void test(String input, boolean expectedValue)  throws ParseException
    {
      ConditionParser cp = new ConditionParser(new StringReader(input));
      Map values = new java.util.HashMap();
      values.put("F", Boolean.FALSE);
      values.put("T", Boolean.TRUE);
      boolean value = cp.CompilationUnit(values);
      System.out.println(input + " = " + value);
      if (value != expectedValue)
        throw new RuntimeException();
    }
}

PARSER_END(ConditionParser)



/* WHITE SPACE */

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

}

/* COMMENTS */

MORE :
{
  "//" : IN_SINGLE_LINE_COMMENT
|
  <"/**" ~["/"]> { input_stream.backup(1); } : IN_FORMAL_COMMENT
|
  "/*" : IN_MULTI_LINE_COMMENT
}


SPECIAL_TOKEN :
{
   : DEFAULT
}


SPECIAL_TOKEN :
{
   : DEFAULT
}


SPECIAL_TOKEN :
{
   : DEFAULT
}


MORE :
{
  < ~[] >
}

TOKEN :
{
  < LPAREN: "(" >
| < RPAREN: ")" >
}

/* OPERATORS */

TOKEN :
{
  < BANG: "!" >
| < SC_OR: "||" >
| < SC_AND: "&&" >
}

boolean CompilationUnit(Map options):
{
	boolean value;
    this.options = options;
}
{
  value = ConditionalExpression()
  
  { return value; }
}

boolean ConditionalExpression():
{
	boolean value;
}
{
  value = ConditionalAndExpression() 
  	{ if (value) return true; }
  	
  ( "||" 
  	value = ConditionalAndExpression()
  	    { if (value) return true; }
  )*
  
  { return false; }
}

boolean ConditionalAndExpression():
{
	boolean value;
}
{
  value = UnaryExpressionNotPlusMinus()
  	{ if (!value) return false; }
  
  ( "&&"
    value = UnaryExpressionNotPlusMinus()
  	    { if (!value) return false; }
  )*
  
  { return true; }
}


boolean UnaryExpressionNotPlusMinus():
{
	boolean value;
}
{
  ( "~" | "!" ) value = UnaryExpressionNotPlusMinus() { return !value; }
  | value = UnaryExpression()    { return value; }
}

boolean UnaryExpression():
{
	boolean value;
}
{
  value = Literal()		{ return value; }
|
  "(" value = ConditionalExpression() ")" { return value; }
|
  value = Name()  { return value; } 
}

boolean Literal():
{
	boolean value;
}
{
  value = BooleanLiteral()     { return value; }
}

boolean BooleanLiteral() :
{}
{
       { return true; }
 |    { return false; }
}

boolean Name() :
{
  String name;
}
{
	
	
	{
	    name = getToken(0).image.trim();
	    
	    Object obj = options.get(name);
	    
	    if (obj instanceof Boolean)
	    {
	      return ((Boolean)obj).booleanValue();
	    }
	    else if (obj instanceof String)
	    {
	      String string = ((String)obj).trim();
	      return string.length() > 0 && !string.equalsIgnoreCase("false") && !string.equalsIgnoreCase("no");
	    }
	    
	    return false;
	}
}

/* IDENTIFIERS */

TOKEN :
{
  < TRUE: "true" >
|
  < FALSE: "false" >
|
  < IDENTIFIER:  ()* >
|
  < #LETTER:
      [  
         "$",
         "A"-"Z",
         "_",
         "a"-"z"
      ]
  >
|
  < #PART_LETTER:
      [
         "$",
         "0"-"9",
         "A"-"Z",
         "_",
         "a"-"z"
      ]
  >
}