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      1 /*
      2  * Copyright (C) 2008 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.android.common;
     18 
     19 import android.text.InputFilter;
     20 import android.text.Spanned;
     21 import android.text.SpannableStringBuilder;
     22 
     23 /**
     24  * Implements special address cleanup rules:
     25  * The first space key entry following an "@" symbol that is followed by any combination
     26  * of letters and symbols, including one+ dots and zero commas, should insert an extra
     27  * comma (followed by the space).
     28  *
     29  * @hide
     30  */
     31 public class Rfc822InputFilter implements InputFilter {
     32 
     33     public CharSequence filter(CharSequence source, int start, int end, Spanned dest,
     34         int dstart, int dend) {
     35 
     36         // quick check - did they enter a single space?
     37         if (end-start != 1 || source.charAt(start) != ' ') {
     38             return null;
     39         }
     40 
     41         // determine if the characters before the new space fit the pattern
     42         // follow backwards and see if we find a comma, dot, or @
     43         int scanBack = dstart;
     44         boolean dotFound = false;
     45         while (scanBack > 0) {
     46             char c = dest.charAt(--scanBack);
     47             switch (c) {
     48                 case '.':
     49                     dotFound = true;    // one or more dots are req'd
     50                     break;
     51                 case ',':
     52                     return null;
     53                 case '@':
     54                     if (!dotFound) {
     55                         return null;
     56                     }
     57                     // we have found a comma-insert case.  now just do it
     58                     // in the least expensive way we can.
     59                     if (source instanceof Spanned) {
     60                         SpannableStringBuilder sb = new SpannableStringBuilder(",");
     61                         sb.append(source);
     62                         return sb;
     63                     } else {
     64                         return ", ";
     65                     }
     66                 default:
     67                     // just keep going
     68             }
     69         }
     70 
     71         // no termination cases were found, so don't edit the input
     72         return null;
     73     }
     74 }
     75