package org.apache.torque.generator.control;
   
   /*
    * 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.
   */
  
  import org.apache.torque.generator.processor.string.StringProcessor;
  
  /**
   * Replaces placeholder tokens like ${option:optionName} in a string by the
   * resolved values. The escape character is the backslash (\).
   *
   * $Id: TokenReplacer.java 1331190 2012-04-27 02:41:35Z tfischer $
   */
  public class TokenReplacer implements StringProcessor
  {
      /** First character of a Token start. */
      public static final char TOKEN_START_1 = '$';
  
      /** Second character of a Token start. */
      public static final char TOKEN_START_2 = '{';
  
      /** The character ending a token. */
      public static final char TOKEN_END = '}';
  
      /** The escape character. */
      public static final char ESCAPE = '\\';
  
      /** The prefix for an option token. */
      public static final String OPTION_PREFIX = "option";
  
      /** The separator between prefix and key. */
      public static final char PREFIX_SEPARATOR = ':';
  
      /**
       * The controller state for resolving options.
       */
      private ControllerState controllerState;
  
      public TokenReplacer(ControllerState controllerState)
      {
          if (controllerState == null)
          {
              throw new NullPointerException("controllerState must not be null");
          }
          this.controllerState = controllerState;
      }
  
      /**
       * Resolves all Tokens ${option:optionName} and replaces them with the
       * appropriate value.
       *
       * @param toProcess the String to remove tokens from, or null.
       */
      public String process(String toProcess)
      {
          if (toProcess == null)
          {
              return null;
          }
          StringBuilder result = new StringBuilder();
          StringBuilder tokenName = new StringBuilder();
          boolean escape = false;
          boolean inTokenStart = false;
          boolean inToken = false;
          for (char currentChar : toProcess.toCharArray())
          {
              if (currentChar == ESCAPE && !escape)
              {
                  escape = true;
                  if (inTokenStart)
                  {
                      result.append(TOKEN_START_1);
                      inTokenStart = false; // $\ is not token start
                  }
                  continue;
              }
              if (escape)
              {
                  if (inToken)
                  {
                      tokenName.append(currentChar);
                  }
                  else
                 {
                     result.append(currentChar);
                 }
                 escape = false;
                 continue;
             }
             escape = false;
             if (currentChar == TOKEN_START_1 && !inTokenStart && !inToken)
             {
                 inTokenStart = true;
                 continue;
             }
             if (inTokenStart)
             {
                 if (currentChar == TOKEN_START_2)
                 {
                     inTokenStart = false;
                     inToken = true;
                     continue;
                 }
                 else
                 {
                     result.append(TOKEN_START_1); // did not copy that before
                     result.append(currentChar);
                     inTokenStart = false;
                     continue;
                 }
             }
             if (currentChar == TOKEN_END && inToken)
             {
                 result.append(resolveToken(tokenName.toString()));
                 tokenName = new StringBuilder();
                 inToken = false;
                 continue;
             }
             if (inToken)
             {
                 tokenName.append(currentChar);
             }
             else
             {
                 result.append(currentChar);
             }
         }
         if (escape)
         {
             throw new IllegalArgumentException("Single escape character "
                     + ESCAPE
                     + " encountered at end of String "
                     + toProcess);
         }
         if (inTokenStart)
         {
             result.append(TOKEN_START_1);
         }
         if (inToken)
         {
             throw new IllegalArgumentException("Token end "
                     + TOKEN_END
                     + " missing at end of String "
                     + toProcess);
         }
         return result.toString();
     }
 
     private String resolveToken(String tokenName)
     {
         if (!tokenName.startsWith(OPTION_PREFIX + PREFIX_SEPARATOR))
         {
             throw new IllegalArgumentException("Token name must start with"
                     + OPTION_PREFIX + PREFIX_SEPARATOR);
         }
         String optionName = tokenName.substring(
                 (OPTION_PREFIX + PREFIX_SEPARATOR).length());
         Object optionValue = controllerState.getOption(optionName);
         if (optionValue == null)
         {
             return "";
         }
         return optionValue.toString();
     }
 }