binopexpr.java

java1.6众多例子参考

/*
 * Copyright 2001-2004 The Apache Software Foundation.
 *
 * Licensed 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: BinOpExpr.java,v 1.2.4.1 2005/09/01 11:42:27 pvedula Exp $
 */

package com.sun.org.apache.xalan.internal.xsltc.compiler;

import com.sun.org.apache.bcel.internal.generic.InstructionList;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.ClassGenerator;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.ErrorMsg;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.MethodGenerator;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.MethodType;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.Type;
import com.sun.org.apache.xalan.internal.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 + ')';
    }
}