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Xalan-Java is an XSLT processor for transforming XML documents into HTML, text, or other XML document types. It implements XSL Transformations (XSLT) Version 1.0 and XML Path Language (XPath) Version 1.0 and can be used from the command line, in an applet or a servlet, or as a module in other program.

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/*
 * 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: StartsWithCall.java 468650 2006-10-28 07:03:30Z minchau $
 */

package org.apache.xalan.xsltc.compiler;

import java.util.Vector;

import org.apache.bcel.generic.ConstantPoolGen;
import org.apache.bcel.generic.INVOKEVIRTUAL;
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.Type;
import org.apache.xalan.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")));
    }
}