content: /*
   * Copyright (C) 2008 The Android Open Source Project
   *
   * 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.android.common;
  
  import android.text.InputFilter;
  import android.text.Spanned;
  import android.text.SpannableStringBuilder;
  
  /**
   * Implements special address cleanup rules:
   * The first space key entry following an "@" symbol that is followed by any combination
   * of letters and symbols, including one+ dots and zero commas, should insert an extra
   * comma (followed by the space).
   *
   * @hide
   */
  public class Rfc822InputFilter implements InputFilter {
  
      public CharSequence filter(CharSequence source, int start, int end, Spanned dest,
          int dstart, int dend) {
  
          // quick check - did they enter a single space?
          if (end-start != 1 || source.charAt(start) != ' ') {
              return null;
          }
  
          // determine if the characters before the new space fit the pattern
          // follow backwards and see if we find a comma, dot, or @
          int scanBack = dstart;
          boolean dotFound = false;
          while (scanBack > 0) {
              char c = dest.charAt(--scanBack);
              switch (c) {
                  case '.':
                      dotFound = true;    // one or more dots are req'd
                      break;
                  case ',':
                      return null;
                  case '@':
                      if (!dotFound) {
                          return null;
                      }
                      // we have found a comma-insert case.  now just do it
                      // in the least expensive way we can.
                      if (source instanceof Spanned) {
                          SpannableStringBuilder sb = new SpannableStringBuilder(",");
                          sb.append(source);
                          return sb;
                      } else {
                          return ", ";
                      }
                  default:
                      // just keep going
              }
          }
  
          // no termination cases were found, so don't edit the input
          return null;
      }
  }
  