/*
 * 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 org.apache.taglibs.standard.lang.jstl;

import java.util.Map;

/**
 * <p>Represents an expression String consisting of a mixture of
 * Strings and Expressions.
 *
 * @author Nathan Abramson - Art Technology Group
 * @author Shawn Bayern
 */

public class ExpressionString {
    //-------------------------------------
    // Properties
    //-------------------------------------
    // property elements

    Object[] mElements;

    public Object[] getElements() {
        return mElements;
    }

    public void setElements(Object[] pElements) {
        mElements = pElements;
    }

    //-------------------------------------

    /**
     * Constructor
     */
    public ExpressionString(Object[] pElements) {
        mElements = pElements;
    }

    //-------------------------------------

    /**
     * Evaluates the expression string by evaluating each element,
     * converting it to a String (using toString, or "" for null values)
     * and concatenating the results into a single String.
     */
    public String evaluate(Object pContext,
                           VariableResolver pResolver,
                           Map functions,
                           String defaultPrefix,
                           Logger pLogger)
            throws ELException {
        StringBuffer buf = new StringBuffer();
        for (int i = 0; i < mElements.length; i++) {
            Object elem = mElements[i];
            if (elem instanceof String) {
                buf.append((String) elem);
            } else if (elem instanceof Expression) {
                Object val =
                        ((Expression) elem).evaluate(pContext,
                                pResolver,
                                functions,
                                defaultPrefix,
                                pLogger);
                if (val != null) {
                    buf.append(val.toString());
                }
            }
        }
        return buf.toString();
    }

    //-------------------------------------

    /**
     * Returns the expression in the expression language syntax
     */
    public String getExpressionString() {
        StringBuffer buf = new StringBuffer();
        for (int i = 0; i < mElements.length; i++) {
            Object elem = mElements[i];
            if (elem instanceof String) {
                buf.append((String) elem);
            } else if (elem instanceof Expression) {
                buf.append("${");
                buf.append(((Expression) elem).getExpressionString());
                buf.append("}");
            }
        }
        return buf.toString();
    }

    //-------------------------------------
}
