diff options
author | zxu <zxu@google.com> | 2018-01-25 13:03:07 -0500 |
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committer | GitHub <noreply@github.com> | 2018-01-25 13:03:07 -0500 |
commit | 5fdda3fa837f3138973d754f05aec7f541f806ce (patch) | |
tree | 6d440b3a7ac634c05890dade1e261aeb8ba03b31 /Firestore/core/src/firebase/firestore/util/string_util.cc | |
parent | 15a2926dcb986a84cf9969d7d20439d4ac2e46af (diff) |
normalize string_util (#708)
* refactoring string_util
* port string_util to iOS
Diffstat (limited to 'Firestore/core/src/firebase/firestore/util/string_util.cc')
-rw-r--r-- | Firestore/core/src/firebase/firestore/util/string_util.cc | 53 |
1 files changed, 53 insertions, 0 deletions
diff --git a/Firestore/core/src/firebase/firestore/util/string_util.cc b/Firestore/core/src/firebase/firestore/util/string_util.cc new file mode 100644 index 0000000..b7f1ed9 --- /dev/null +++ b/Firestore/core/src/firebase/firestore/util/string_util.cc @@ -0,0 +1,53 @@ +/* + * Copyright 2017 Google + * + * 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. + */ + +#include "Firestore/core/src/firebase/firestore/util/string_util.h" + +namespace firebase { +namespace firestore { +namespace util { + +std::string PrefixSuccessor(absl::string_view prefix) { + // We can increment the last character in the string and be done + // unless that character is 255 (0xff), in which case we have to erase the + // last character and increment the previous character, unless that + // is 255, etc. If the string is empty or consists entirely of + // 255's, we just return the empty string. + std::string limit(prefix); + while (!limit.empty()) { + size_t index = limit.length() - 1; + if (limit[index] == '\xff') { // char literal avoids signed/unsigned. + limit.erase(index); + } else { + limit[index]++; + break; + } + } + return limit; +} + +std::string ImmediateSuccessor(absl::string_view s) { + // Return the input string, with an additional NUL byte appended. + std::string out; + out.reserve(s.size() + 1); + out.append(s.data(), s.size()); + out.push_back('\0'); + return out; +} + +} // namespace util +} // namespace firestore +} // namespace firebase |