package com.icl.saxon.functions;
import com.icl.saxon.*;
import com.icl.saxon.om.Namespace;
import com.icl.saxon.expr.*;
import com.icl.saxon.style.*;

import java.util.*;


public class ElementAvailable extends Function {

    /**
    * Function name (for diagnostics)
    */

    public String getName() {
        return "element-available";
    };

    /**
    * Determine the data type of the expression
    * @return Value.BOOLEAN
    */

    public int getDataType() {
        return Value.BOOLEAN;
    }

    /**
    * Simplify and validate.
    * This is a pure function so it can be simplified in advance if the arguments are known
    */

    public Expression simplify() throws XPathException {
        checkArgumentCount(1, 1);
        argument[0] = argument[0].simplify();
        if (argument[0] instanceof Value) {
            return evaluate(null);
        }
        return this;
    }

    /**
    * Evaluate the function in a boolean context
    */

    public boolean evaluateAsBoolean(Context c) throws XPathException {
        String qname = argument[0].evaluateAsString(c);
        return getStaticContext().isElementAvailable(qname);
    }

    /**
    * Evaluate in a general context
    */

    public Value evaluate(Context c) throws XPathException {
        return new BooleanValue(evaluateAsBoolean(c));
    }

    /**
    * Determine the dependencies
    */

    public int getDependencies() {
        return argument[0].getDependencies();
    }

    /**
    * Reduce the dependencies
    */

    public Expression reduce(int dep, Context c) throws XPathException {
        ElementAvailable f = new ElementAvailable();
        f.addArgument(argument[0].reduce(dep, c));
        f.setStaticContext(getStaticContext());
        return f.simplify();
    }

    /**
    * Get the factory class for user extension elements
    */

    //private ExtensionElementFactory getFactory(String uri) throws XPathException {
    //    int lastSlash = uri.lastIndexOf('/');
    //    if (lastSlash<0 || lastSlash==uri.length()-1) {
    //        return null;
    //    }
    //    String factoryClass = uri.substring(lastSlash+1);
    //    ExtensionElementFactory factory;
	//
    //    try {
    //        return (ExtensionElementFactory)Loader.getInstance(factoryClass);
    //    } catch (Exception err) {
    //        return null;
    //    } 
    ///}

}



//
// The contents of this file are subject to the Mozilla Public License Version 1.0 (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.mozilla.org/MPL/ 
//
// Software distributed under the License is distributed on an "AS IS" basis,
// WITHOUT WARRANTY OF ANY KIND, either express or implied.
// See the License for the specific language governing rights and limitations under the License. 
//
// The Original Code is: all this file. 
//
// The Initial Developer of the Original Code is
// Michael Kay of International Computers Limited (mhkay@iclway.co.uk).
//
// Portions created by (your name) are Copyright (C) (your legal entity). All Rights Reserved. 
//
// Contributor(s): none. 
//