/*
 * Copyright (c) 1997-2018 Oracle and/or its affiliates. All rights reserved.
 * Copyright 2004 The Apache Software Foundation
 * Copyright (c) 2020 Payara Services Ltd.
 *
 * Licensed 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
 * @version $Change: 181177 $$DateTime: 2001/06/26 08:45:09 $$Author: kchung $
 **/

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
  {
        StringBuilder buf = new StringBuilder();
      for (Object elem : mElements) {
          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() {
        StringBuilder buf = new StringBuilder();
        for (Object elem : mElements) {
            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();
    }

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