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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.
*/
// Useful string functions and so forth. This is a grab-bag file.
//
// These functions work fine for UTF-8 strings as long as you can
// consider them to be just byte strings. For example, due to the
// design of UTF-8 you do not need to worry about accidental matches,
// as long as all your inputs are valid UTF-8 (use \uHHHH, not \xHH or \oOOO).
#ifndef FIRESTORE_CORE_SRC_FIREBASE_FIRESTORE_UTIL_STRING_UTIL_H_
#define FIRESTORE_CORE_SRC_FIREBASE_FIRESTORE_UTIL_STRING_UTIL_H_
#include <string>
#include "absl/strings/string_view.h"
namespace firebase {
namespace firestore {
namespace util {
/**
* Returns the smallest lexicographically larger string of equal or smaller
* length. Returns an empty string if there is no such successor (if the input
* is empty or consists entirely of 0xff bytes).
* Useful for calculating the smallest lexicographically larger string
* that will not be prefixed by the input string.
*
* Examples:
* "a" -> "b", "aaa" -> "aab", "aa\xff" -> "ab", "\xff" -> "", "" -> ""
*/
std::string PrefixSuccessor(absl::string_view prefix);
/**
* Returns the immediate lexicographically-following string. This is useful to
* turn an inclusive range into something that can be used with Bigtable's
* SetLimitRow():
*
* // Inclusive range [min_element, max_element].
* string min_element = ...;
* string max_element = ...;
*
* // Equivalent range [range_start, range_end).
* string range_start = min_element;
* string range_end = ImmediateSuccessor(max_element);
*
* WARNING: Returns the input string with a '\0' appended; if you call c_str()
* on the result, it will compare equal to s.
*
* WARNING: Transforms "" -> "\0"; this doesn't account for Bigtable's special
* treatment of "" as infinity.
*/
std::string ImmediateSuccessor(absl::string_view s);
} // namespace util
} // namespace firestore
} // namespace firebase
#endif // FIRESTORE_CORE_SRC_FIREBASE_FIRESTORE_UTIL_STRING_UTIL_H_
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