text: /*
   * 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.
   */
  
  #include "URLDecoder.h"
  #include <decaf/lang/Character.h>
  #include <decaf/lang/exceptions/IllegalArgumentException.h>
  
  using namespace std;
  using namespace decaf;
  using namespace decaf::lang;
  using namespace decaf::lang::exceptions;
  using namespace decaf::net;
  
  ////////////////////////////////////////////////////////////////////////////////
  URLDecoder::URLDecoder() {
  }
  
  ////////////////////////////////////////////////////////////////////////////////
  std::string URLDecoder::decode( const std::string& src ) {
  
      std::string decoded = "";
  
      for( size_t i = 0; i < src.length(); ) {
          char c = src.at(i);
  
          if (c == '+') {
              decoded += ' ';
          } else if (c == '%') {
  
              do {
  
                  if( i + 2 >= src.length() ) {
                      throw IllegalArgumentException(
                          __FILE__, __LINE__,
                          "Incomplete % sequence at: %d.", i );
                  }
  
                  int d1 = Character::digit( src.at(i + 1), 16 );
                  int d2 = Character::digit( src.at(i + 2), 16 );
  
                  if( d1 == -1 || d2 == -1 ) {
                      throw IllegalArgumentException(
                          __FILE__, __LINE__,
                          "Invalid % sequence (%s) at: %d.",
                          src.substr( i, 3 ).c_str(), i );
                  }
  
                  decoded += (char)( ( d1 << 4 ) + d2 );
                  i += 3;
              } while( i < src.length() && src.at(i) == '%' );
  
              continue;
          } else {
              decoded += c;
          }
  
          i++;
      }
  
      return decoded;
  }
  