content: /*
   * StringArrayTransform.java May 2007
   *
   * Copyright (C) 2007, Niall Gallagher <niallg@users.sf.net>
   *
   * 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 com.aliyun.odps.simpleframework.xml.transform;
  
  import java.util.regex.Pattern;
  
  /**
   * The <code>StringArrayTransform</code>  is used to transform string
   * arrays to and from string representations, which will be inserted
   * in the generated XML document as the value place holder. The
   * value must be readable and writable in the same format. Fields
   * and methods annotated with the XML attribute annotation will use
   * this to persist and retrieve the value to and from the XML source.
   * <pre>
   * 
   *    &#64;Attribute
   *    private String[] array;
   *    
   * </pre>
   * As well as the XML attribute values using transforms, fields and
   * methods annotated with the XML element annotation will use this.
   * Aside from the obvious difference, the element annotation has an
   * advantage over the attribute annotation in that it can maintain
   * any references using the <code>CycleStrategy</code> object. 
   * 
   * @author Niall Gallagher
   */
  class StringArrayTransform implements Transform<String[]> {
  
     /**
      * Represents the pattern used to split the string values.
      */
     private final Pattern pattern;        
  
     /**
      * This is the token used to split the string into an array.
      */
     private final String token;        
  
     /**
      * Constructor for the <code>StringArrayTransform</code> object.
      * This will create a transform that will split an array using a
      * comma as the delimeter. In order to perform the split in a
      * reasonably performant manner the pattern used is compiled.
      */
     public StringArrayTransform() {
        this(",");           
     }        
    
     /**
      * Constructor for the <code>StringArrayTransform</code> object.
      * This will create a transform that will split an array using a
      * specified regular expression pattern. To keep the performance
      * of the transform reasonable the pattern used is compiled.
      * 
      * @param token the pattern used to split the string values
      */
     public StringArrayTransform(String token) {
        this.pattern = Pattern.compile(token);           
        this.token = token;           
     }
     
     /**
      * This method is used to convert the string value given to an
      * appropriate representation. This is used when an object is
      * being deserialized from the XML document and the value for
      * the string representation is required.
      * 
      * @param value this is the string representation of the value
      * 
      * @return this returns an appropriate instanced to be used
      */
     public String[] read(String value) {
        return read(value, token);           
     }
     
     /**
      * This method is used to convert the string value given to an
      * appropriate representation. This is used when an object is
      * being deserialized from the XML document and the value for
      * the string representation is required.
      * 
      * @param value this is the string representation of the value
      * @param token this is the token used to split the string
      * 
      * @return this returns an appropriate instanced to be used
      */
     private String[] read(String value, String token) {
        String[] list = pattern.split(value);
  
        for(int i = 0; i < list.length; i++) {
           String text = list[i];
  
           if(text != null) {              
              list[i] = text.trim();
           }
        }
        return list;
     }
     
     /**
      * This method is used to convert the provided value into an XML
      * usable format. This is used in the serialization process when
      * there is a need to convert a field value in to a string so 
      * that that value can be written as a valid XML entity.
      * 
      * @param list this is the value to be converted to a string
      * 
      * @return this is the string representation of the given value
      */
     public String write(String[] list) {
        return write(list, token);
     }
     
     /**
      * This method is used to convert the provided value into an XML
      * usable format. This is used in the serialization process when
      * there is a need to convert a field value in to a string so 
      * that that value can be written as a valid XML entity.
      * 
      * @param list this is the value to be converted to a string
      * @param token this is the token used to join the strings
      * 
      * @return this is the string representation of the given value
      */
     private String write(String[] list, String token) {                 
        StringBuilder text = new StringBuilder();           
  
        for(int i = 0; i < list.length; i++) {
           String item = list[i];
  
           if(item != null) { 
              if(text.length() > 0) {
                 text.append(token);
                 text.append(' ');
              }
              text.append(item);
           }
        }   
        return text.toString();
     }
  }
  