/*
 * 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: StartsWithCall.java,v 1.7 2004/02/16 22:24:29 minchau Exp $
 */

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

import java.util.Vector;

import com.sun.org.apache.bcel.internal.generic.ConstantPoolGen;
import com.sun.org.apache.bcel.internal.generic.INVOKEVIRTUAL;
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.Type;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.TypeCheckError;

/**
 * @author Jacek Ambroziak
 * @author Santiago Pericas-Geertsen
 * @author Morten Jorgensen
 */
final class StartsWithCall extends FunctionCall {

    private Expression _base = null;
    private Expression _token = null;

    /**
     * Create a starts-with() call - two arguments, both strings
     */
    public StartsWithCall(QName fname, Vector arguments) {
	super(fname, arguments);
    }

    /**
     * Type check the two parameters for this function
     */
    public Type typeCheck(SymbolTable stable) throws TypeCheckError {

	// Check that the function was passed exactly two arguments
	if (argumentCount() != 2) {
	    ErrorMsg err = new ErrorMsg(ErrorMsg.ILLEGAL_ARG_ERR,
					getName(), this);
	    throw new TypeCheckError(err);
	}

	// The first argument must be a String, or cast to a String
	_base = argument(0);
	Type baseType = _base.typeCheck(stable);	
	if (baseType != Type.String)
	    _base = new CastExpr(_base, Type.String);

	// The second argument must also be a String, or cast to a String
	_token = argument(1);
	Type tokenType = _token.typeCheck(stable);	
	if (tokenType != Type.String)
	    _token = new CastExpr(_token, Type.String);

	return _type = Type.Boolean;
    }

    /**
     * Compile the expression - leave boolean expression on stack
     */
    public void translate(ClassGenerator classGen, MethodGenerator methodGen) {
	final ConstantPoolGen cpg = classGen.getConstantPool();
	final InstructionList il = methodGen.getInstructionList();
	_base.translate(classGen, methodGen);
	_token.translate(classGen, methodGen);
	il.append(new INVOKEVIRTUAL(cpg.addMethodref(STRING_CLASS,
						     "startsWith", 
						     "("+STRING_SIG+")Z")));
    }
}