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/*
* 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
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