/* Copyright (c) 2005 Ricebridge. All Rights Reserved.
 *
 * This file is available under the terms and conditions of the
 * Ricebridge "Open Source API" policy; Ricebridge grants use of this
 * copyrighted work under the terms of a BSD-style license only. See
 * http://www.opensource.org/licenses/bsd-license.php for more
 * information.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 
 *  - Redistributions of source code must retain the above copyright
 *  notice, this list of conditions and the following disclaimer.
 *
 *  - Redistributions 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 the Ricebridge nor the names of its
 *  contributors may be used to endorse or promote products derived
 *  from this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.  
 */


package com.ricebridge.xmlman.in.func;

import java.util.List;

import com.ricebridge.xmlman.tp.Context;
import com.ricebridge.xmlman.tp.Function;
import com.ricebridge.xmlman.tp.FunctionCallException;
import com.ricebridge.xmlman.tp.Navigator;

import com.ricebridge.xmlman.tp.function.StringFunction;

/** Defines XPath function to trim whitespace from strings.
 *    <p>Function signature: <code><i>string</i> trim(<i>object</i>)</code></p>
 *    <p>An implicit call to string() is made on the argument object. This function
 *  simply performs a Java {@link String#trim()}. Under the default settings
 *  it would normally be used like so: <code>rb:trim(' foo ')</code>, returning <code>'foo'</code>.</p>
 *    <p>The <b><a href="TrimFunction.java.html">Source Code</a></b> of this Java class 
 *    is available under a <a href="http://www.opensource.org/licenses/bsd-license.php">BSD-style license</a>.</p>
 */
public class TrimFunction implements Function {
    
  private static StringFunction sStringFunction = null;

  
  /** Call the function. 
   *  @param pContext XPath execution context
   *  @param pArgs    Function arguments
   */
  public Object call( Context pContext, List pArgs ) throws FunctionCallException {
    int size = pArgs.size();

    if( 1 == size ) {
      return evaluate( pArgs.get(0), pContext.getNavigator() );
    }

    throw new FunctionCallException( "trim() requires one string argument." );
  }
    

  /** Evaluate the function. 
   *  @param pObject    object representing string to trim
   *  @param pNavigator Source document navigator
   */
  public static String evaluate( Object pObject, Navigator pNavigator ) {
    String value = "";
    if( null != pObject ) {
      if( pObject instanceof String) {
        value = String.valueOf( pObject );
      }
      else {
        if( null == sStringFunction ) {
          sStringFunction = new StringFunction();
        }

        value = String.valueOf( sStringFunction.evaluate( pObject, pNavigator ) );
      }
    }
    return value.trim();
  }

}