1 // Copyright 1999-2005 The RE2 Authors. All Rights Reserved.
2 // Use of this source code is governed by a BSD-style
3 // license that can be found in the LICENSE file.
4
5 #include "util/strutil.h"
6
7 namespace re2 {
8
PrefixSuccessor(std::string * prefix)9 void PrefixSuccessor(std::string* prefix) {
10 // We can increment the last character in the string and be done
11 // unless that character is 255, in which case we have to erase the
12 // last character and increment the previous character, unless that
13 // is 255, etc. If the string is empty or consists entirely of
14 // 255's, we just return the empty string.
15 while (!prefix->empty()) {
16 char& c = prefix->back();
17 if (c == '\xff') { // char literal avoids signed/unsigned.
18 prefix->pop_back();
19 } else {
20 ++c;
21 break;
22 }
23 }
24 }
25
26 } // namespace re2
27