1 // Copyright (C) 2023 Google LLC 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 #ifndef ICING_UTIL_ENCODE_UTIL_H_ 16 #define ICING_UTIL_ENCODE_UTIL_H_ 17 18 #include <cstdint> 19 #include <string> 20 #include <string_view> 21 22 namespace icing { 23 namespace lib { 24 25 namespace encode_util { 26 27 // Converts an unsigned 64-bit integer to a C string that doesn't contain 0-byte 28 // since C string uses 0-byte as terminator. This increases the size of the 29 // encoded_str from 8-bytes to 10-bytes at worst. 30 // 31 // Note that it is compatible with unsigned 32-bit integers, i.e. casting an 32 // uint32_t to uint64_t with the same value and encoding it by this method will 33 // get the same string. 34 std::string EncodeIntToCString(uint64_t value); 35 36 // Converts a C string (encoded from EncodeIntToCString()) to an unsigned 64-bit 37 // integer. 38 uint64_t DecodeIntFromCString(std::string_view encoded_str); 39 40 // Converts the given string which may contains 0-byte to a C string. 41 // 42 // The output C string that does not contain 0-byte since C string uses 0-byte 43 // as terminator. 44 // This will increase the size of the encoded_str. 45 // new_length = ceil(old_length / 7.0 * 8.0) 46 // Eg1: This increases the size from 32-bytes of sha-256 hash to 37-bytes C 47 // string. 48 // Eg2: This increases the size from 1-byte string to 2-bytes C string. 49 // Eg3: This increases the size from 2-byte string to 3-bytes C string. 50 std::string EncodeStringToCString(const std::string& input); 51 52 } // namespace encode_util 53 54 } // namespace lib 55 } // namespace icing 56 57 #endif // ICING_UTIL_ENCODE_UTIL_H_ 58