1 /* 2 * Copyright (C) 2017 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #ifndef LIBTEXTCLASSIFIER_UTIL_STRINGS_STRINGPIECE_H_ 18 #define LIBTEXTCLASSIFIER_UTIL_STRINGS_STRINGPIECE_H_ 19 20 #include <stddef.h> 21 22 #include <string> 23 24 namespace libtextclassifier2 { 25 26 // Read-only "view" of a piece of data. Does not own the underlying data. 27 class StringPiece { 28 public: 29 StringPiece() : StringPiece(nullptr, 0) {} 30 31 StringPiece(const char *str) // NOLINT(runtime/explicit) 32 : start_(str), size_(strlen(str)) {} 33 34 StringPiece(const char *start, size_t size) 35 : start_(start), size_(size) {} 36 37 // Intentionally no "explicit" keyword: in function calls, we want strings to 38 // be converted to StringPiece implicitly. 39 StringPiece(const std::string &s) // NOLINT(runtime/explicit) 40 : StringPiece(s.data(), s.size()) {} 41 42 StringPiece(const std::string &s, int offset, int len) 43 : StringPiece(s.data() + offset, len) {} 44 45 char operator[](size_t i) const { return start_[i]; } 46 47 // Returns start address of underlying data. 48 const char *data() const { return start_; } 49 50 // Returns number of bytes of underlying data. 51 size_t size() const { return size_; } 52 size_t length() const { return size_; } 53 54 bool empty() const { return size_ == 0; } 55 56 // Returns a std::string containing a copy of the underlying data. 57 std::string ToString() const { 58 return std::string(data(), size()); 59 } 60 61 private: 62 const char *start_; // Not owned. 63 size_t size_; 64 }; 65 66 } // namespace libtextclassifier2 67 68 #endif // LIBTEXTCLASSIFIER_UTIL_STRINGS_STRINGPIECE_H_ 69
