/*

 * Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.

 */

/*

 * 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.

 */

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

import com.sun.org.apache.bcel.internal.generic.ConstantPoolGen;

import com.sun.org.apache.bcel.internal.generic.PUSH;

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;

import java.util.List;

/**

 * @author Jacek Ambroziak

 * @author Santiago Pericas-Geertsen

 * @LastModified: Oct 2017

 */

final class ElementAvailableCall extends FunctionCall {

    public ElementAvailableCall(QName fname, List<Expression> arguments) {

        super(fname, arguments);

    }

    /**

     * Force the argument to this function to be a literal string.

     */

    public Type typeCheck(SymbolTable stable) throws TypeCheckError {

        if (argument() instanceof LiteralExpr) {

            return _type = Type.Boolean;

        }

        ErrorMsg err = new ErrorMsg(ErrorMsg.NEED_LITERAL_ERR,

                                    "element-available", this);

        throw new TypeCheckError(err);

    }

    /**

     * Returns an object representing the compile-time evaluation

     * of an expression. We are only using this for function-available

     * and element-available at this time.

     */

    public Object evaluateAtCompileTime() {

        return getResult() ? Boolean.TRUE : Boolean.FALSE;

    }

    /**

     * Returns the result that this function will return

     */

    public boolean getResult() {

        try {

            final LiteralExpr arg = (LiteralExpr) argument();

            final String qname = arg.getValue();

            final int index = qname.indexOf(':');

            final String localName = (index > 0) ?

                qname.substring(index + 1) : qname;

            return getParser().elementSupported(arg.getNamespace(),

                                                localName);

        }

        catch (ClassCastException e) {

            return false;

        }

    }

    /**

     * Calls to 'element-available' are resolved at compile time since

     * the namespaces declared in the stylsheet are not available at run

     * time. Consequently, arguments to this function must be literals.

     */

    public void translate(ClassGenerator classGen, MethodGenerator methodGen) {

        final ConstantPoolGen cpg = classGen.getConstantPool();

        final boolean result = getResult();

        methodGen.getInstructionList().append(new PUSH(cpg, result));

    }

}