Line data    Source code

       1             : // Copyright (C) 2012 The Android Open Source Project
       2             : //
       3             : // Licensed under the Apache License, Version 2.0 (the "License");
       4             : // you may not use this file except in compliance with the License.
       5             : // You may obtain a copy of the License at
       6             : //
       7             : // http://www.apache.org/licenses/LICENSE-2.0
       8             : //
       9             : // Unless required by applicable law or agreed to in writing, software
      10             : // distributed under the License is distributed on an "AS IS" BASIS,
      11             : // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
      12             : // See the License for the specific language governing permissions and
      13             : // limitations under the License.
      14             : 
      15             : package com.google.gerrit.server.ioutil;
      16             : 
      17           0 : public class StringUtil {
      18             :   /**
      19             :    * An array of the string representations that should be used in place of the non-printable
      20             :    * characters in the beginning of the ASCII table when escaping a string. The index of each
      21             :    * element in the array corresponds to its ASCII value, i.e. the string representation of ASCII 0
      22             :    * is found in the first element of this array.
      23             :    */
      24           1 :   private static final String[] NON_PRINTABLE_CHARS = {
      25             :     "\\x00", "\\x01", "\\x02", "\\x03", "\\x04", "\\x05", "\\x06", "\\a",
      26             :     "\\b", "\\t", "\\n", "\\v", "\\f", "\\r", "\\x0e", "\\x0f",
      27             :     "\\x10", "\\x11", "\\x12", "\\x13", "\\x14", "\\x15", "\\x16", "\\x17",
      28             :     "\\x18", "\\x19", "\\x1a", "\\x1b", "\\x1c", "\\x1d", "\\x1e", "\\x1f",
      29             :   };
      30             : 
      31             :   /**
      32             :    * Escapes the input string so that all non-printable characters (0x00-0x1f) are represented as a
      33             :    * hex escape (\x00, \x01, ...) or as a C-style escape sequence (\a, \b, \t, \n, \v, \f, or \r).
      34             :    * Backslashes in the input string are doubled (\\).
      35             :    */
      36             :   public static String escapeString(String str) {
      37             :     // Allocate a buffer big enough to cover the case with a string needed
      38             :     // very excessive escaping without having to reallocate the buffer.
      39           1 :     final StringBuilder result = new StringBuilder(3 * str.length());
      40             : 
      41           1 :     for (int i = 0; i < str.length(); i++) {
      42           1 :       char c = str.charAt(i);
      43           1 :       if (c < NON_PRINTABLE_CHARS.length) {
      44           1 :         result.append(NON_PRINTABLE_CHARS[c]);
      45           1 :       } else if (c == '\\') {
      46           1 :         result.append("\\\\");
      47             :       } else {
      48           1 :         result.append(c);
      49             :       }
      50             :     }
      51           1 :     return result.toString();
      52             :   }
      53             : }