/*
 * @(#)StringFunction.java
 *
 * Copyright 2006 Sun Microsystems, Inc. All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *   1. Redistribution of source code must retain the above copyright notice,
 *      this list of conditions and the following disclaimer.
 * 
 *   2. Redistribution in binary form must reproduce the above copyright
 *      notice, this list of conditions and the following disclaimer in the
 *      documentation and/or other materials provided with the distribution.
 *
 * Neither the name of Sun Microsystems, Inc. or the names of contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 * 
 * This software is provided "AS IS," without a warranty of any kind. ALL
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING
 * ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
 * OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MICROSYSTEMS, INC. ("SUN")
 * AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE
 * AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
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package com.sun.xacml.cond;

import java.util.HashSet;
import java.util.List;
import java.util.Set;

import com.sun.xacml.EvaluationCtx;
import com.sun.xacml.attr.AttributeValue;
import com.sun.xacml.attr.StringAttribute;

/**
 * This class implements the string-concatenate function from XACML 2.0.
 * 
 * @since 2.0
 * @author Seth Proctor
 * 
 *         Adding generic type support by Christian Mueller (geotools)
 */
public class StringFunction extends FunctionBase {

    /**
     * Standard identifier for the string-concatenate function.
     */
    public static final String NAME_STRING_CONCATENATE = FUNCTION_NS_2 + "string-concatenate";

    // private identifiers for the supported functions
    private static final int ID_STRING_CONCATENATE = 0;

    /**
     * Creates a new <code>StringFunction</code> object.
     * 
     * @param functionName
     *            the standard XACML name of the function to be handled by this object, including
     *            the full namespace
     * 
     * @throws IllegalArgumentException
     *             if the function is unknown
     */
    public StringFunction(String functionName) {
        super(functionName, ID_STRING_CONCATENATE, StringAttribute.identifier, false, -1, 2,
                StringAttribute.identifier, false);
    }

    /**
     * Returns a <code>Set</code> containing all the function identifiers supported by this class.
     * 
     * @return a <code>Set</code> of <code>String</code>s
     */
    public static Set<String> getSupportedIdentifiers() {
        Set<String> set = new HashSet<String>();

        set.add(NAME_STRING_CONCATENATE);

        return set;
    }

    /**
     * Evaluate the function, using the specified parameters.
     * 
     * @param inputs
     *            a <code>List</code> of <code>Evaluatable</code> objects representing the arguments
     *            passed to the function
     * @param context
     *            an <code>EvaluationCtx</code> so that the <code>Evaluatable</code> objects can be
     *            evaluated
     * @return an <code>EvaluationResult</code> representing the function's result
     */
    public EvaluationResult evaluate(List<? extends Expression> inputs, EvaluationCtx context) {
        // Evaluate the arguments
        AttributeValue[] argValues = new AttributeValue[inputs.size()];
        EvaluationResult result = evalArgs(inputs, context, argValues);
        if (result != null)
            return result;

        switch (getFunctionId()) {
        case ID_STRING_CONCATENATE:
            String str = ((StringAttribute) argValues[0]).getValue();

            for (int i = 1; i < argValues.length; i++)
                str += ((StringAttribute) (argValues[i])).getValue();

            result = new EvaluationResult(new StringAttribute(str));

            break;
        }

        return result;
    }

}