1 // Copyright (C) 2019 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_LEGACY_CORE_ICING_STRING_UTIL_H_ 16 #define ICING_LEGACY_CORE_ICING_STRING_UTIL_H_ 17 18 #include <cstdarg> 19 #include <cstdint> 20 #include <string> 21 22 #include "icing/legacy/core/icing-compat.h" 23 24 namespace icing { 25 namespace lib { 26 27 class IcingStringUtil { 28 public: 29 // Returns true if the character is not the first byte of 30 // a multi-byte UTF8 character IsContinuationByte(char byte)31 static bool IsContinuationByte(char byte) { 32 return (static_cast<uint8_t>(byte) & 0xC0) == 0x80; 33 } 34 35 // Update a rolling crc32. This undoes the one's complement 36 // pre-conditioning and post-conditioning of zlib's 37 // crc32. Therefore, UpdateCrc32(0, str, len) != HashCrc32(str, 38 // len). 39 static uint32_t UpdateCrc32(uint32_t crc, const char *str, int len); 40 41 // Update a string's rolling crc for when its value at offset is 42 // xor'ed with the buffer [xored_str, xored_str + len). 43 // 44 // REQUIRES: orig_len >= offset + len. 45 static uint32_t UpdateAtPositionCrc32(uint32_t crc, int orig_len, int offset, 46 const char *xored_str, int len); 47 48 // Append vsnprintf to strp. If bufsize hint is > 0 it is 49 // used. Otherwise we compute the required bufsize (which is somewhat 50 // expensive). 51 static void SStringAppendV(std::string *strp, int bufsize, const char *fmt, 52 va_list arglist); 53 static void SStringAppendF(std::string *strp, int bufsize, const char *fmt, 54 ...) __attribute__((format(printf, 3, 4))); 55 static std::string StringPrintf(const char *fmt, ...) 56 __attribute__((format(printf, 1, 2))); 57 }; 58 59 } // namespace lib 60 } // namespace icing 61 62 #endif // ICING_LEGACY_CORE_ICING_STRING_UTIL_H_ 63