/*
 *
 * Copyright (C) 1997, 1998 Yuuji ICHISUGI
 *
 * Permission to use, copy, modify and redistribution this software in
 * whole and in part, for evaluation or research purposes and without fee
 * is hereby granted provided this copyright notice.
 * See CopyrightAndLicensing.txt for licensing condition.
 */


/*
 BUGS:

1. "&" can only be used for int variable.
2. The followings do not work as was expected.

	if (foo(&x)) System.out.println(x);

	mmm(&x, x++);

*/

#epp "Symbol"
#epp "SystemMixin"
#epp "AutoSplitFiles"
#epp "BackQuote"


package CallByReference;
import epp.*;



SystemMixin CallByReference {
  class Epp {

    extend Tree unaryExpressionTop() {
      if (lookahead() == :"&") {
	matchAny();
	return new Tree(:preAnd , unaryExpression()) ;
      } else {
	return original() ;
      }
    }

    extend void initMacroTable() {
      original();
      defineMacro(:preAnd, new PreAndMacro());
    }
  }
}

class PreAndMacro extends Macro {

  public Tree call(Tree tree){
    checkArgsLength(tree, 1);
    if (tree.args()[0].tag() != :id){
      throw error("CallByReference: User Error: "+
		  "& is only applicable to variables.");
    }
    
    Tree tmp = new Identifier(genTemp("_T"));
    Tree var = tree.args()[0];
    
    ((TreeVec)Dynamic.get(:beforeCurrentBlockStatement))
      .add(macroExpandTree
	   (
	    `(decl (modifiers)
	      (arrayOf (id int))	// Assumed to be int !
	      (vardecls
	       (varInit ,tmp
		(arrayInitializer ,var))))
	    ));
    
    ((TreeVec)Dynamic.get(:afterCurrentBlockStatement))
      .add(macroExpandTree
	   (
	    `(expressionStatement
	      (= ,var
	       (array ,tmp (literalTree int "0"))))
	    ));
    
    return tmp;
  }
}