code: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements. See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership. The ASF licenses this file
   * to you under the Apache License, Version 2.0 (the  "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  /*
   * $Id$
   */
  
  package org.apache.xalan.xsltc.compiler;
  
  import org.apache.bcel.generic.InstructionList;
  import org.apache.xalan.xsltc.compiler.util.ClassGenerator;
  import org.apache.xalan.xsltc.compiler.util.ErrorMsg;
  import org.apache.xalan.xsltc.compiler.util.MethodGenerator;
  import org.apache.xalan.xsltc.compiler.util.MethodType;
  import org.apache.xalan.xsltc.compiler.util.Type;
  import org.apache.xalan.xsltc.compiler.util.TypeCheckError;
  
  /**
   * @author Jacek Ambroziak
   * @author Santiago Pericas-Geertsen
   */
  final class BinOpExpr extends Expression {
      public static final int PLUS  = 0;
      public static final int MINUS = 1;
      public static final int TIMES = 2;
      public static final int DIV   = 3;
      public static final int MOD   = 4;
  	
      private static final String[] Ops = {
  	"+", "-", "*", "/", "%"
      };
  
      private int _op;
      private Expression _left, _right;
  	
      public BinOpExpr(int op, Expression left, Expression right) {
  	_op = op;
  	(_left = left).setParent(this);
  	(_right = right).setParent(this);
      }
  
      /**
       * Returns true if this expressions contains a call to position(). This is
       * needed for context changes in node steps containing multiple predicates.
       */
      public boolean hasPositionCall() {
  	if (_left.hasPositionCall()) return true;
  	if (_right.hasPositionCall()) return true;
  	return false;
      }
  
      /**
       * Returns true if this expressions contains a call to last()
       */
      public boolean hasLastCall() {
              return (_left.hasLastCall() || _right.hasLastCall());
      }
      
      public void setParser(Parser parser) {
  	super.setParser(parser);
  	_left.setParser(parser);
  	_right.setParser(parser);
      }
      
      public Type typeCheck(SymbolTable stable) throws TypeCheckError {
  	final Type tleft = _left.typeCheck(stable); 
  	final Type tright = _right.typeCheck(stable);
  	final MethodType ptype = lookupPrimop(stable, Ops[_op],
  					      new MethodType(Type.Void,
  							     tleft, tright)); 
  	if (ptype != null) {
  	    final Type arg1 = (Type) ptype.argsType().elementAt(0);
  	    if (!arg1.identicalTo(tleft)) {
  		_left = new CastExpr(_left, arg1);
  	    }
  	    final Type arg2 = (Type) ptype.argsType().elementAt(1);
  	    if (!arg2.identicalTo(tright)) {
  		_right = new CastExpr(_right, arg1);
  	    }
  	    return _type = ptype.resultType();
  	}
  	throw new TypeCheckError(this);
      }
  
      public void translate(ClassGenerator classGen, MethodGenerator methodGen) {
  	final InstructionList il = methodGen.getInstructionList();
  
  	_left.translate(classGen, methodGen);
  	_right.translate(classGen, methodGen);
  
  	switch (_op) {
  	case PLUS:
  	    il.append(_type.ADD());
  	    break;
  	case MINUS:
  	    il.append(_type.SUB());
  	    break;
  	case TIMES:
  	    il.append(_type.MUL());
  	    break;
  	case DIV:
  	    il.append(_type.DIV());
  	    break;
  	case MOD:
  	    il.append(_type.REM());
  	    break;
  	default:
  	    ErrorMsg msg = new ErrorMsg(ErrorMsg.ILLEGAL_BINARY_OP_ERR, this);
  	    getParser().reportError(Constants.ERROR, msg);
  	}
      }
  
      public String toString() {
  	return Ops[_op] + '(' + _left + ", " + _right + ')';
      }
  } 
  