| // Copyright 2011 Google Inc. All Rights Reserved. |
| // |
| // 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. |
| |
| #ifndef NINJA_STRINGPIECE_H_ |
| #define NINJA_STRINGPIECE_H_ |
| |
| #include <string.h> |
| |
| #include <algorithm> |
| #include <string> |
| |
| #include "hash_map.h" |
| |
| using namespace std; |
| |
| /// StringPiece represents a slice of a string whose memory is managed |
| /// externally. It is useful for reducing the number of std::strings |
| /// we need to allocate. |
| /// |
| /// This class is something like std::string_view from C++17. |
| struct StringPiece { |
| typedef const char* const_iterator; |
| typedef const char& const_reference; |
| |
| constexpr StringPiece() : str_(nullptr), len_(0) {} |
| |
| /// The constructors intentionally allow for implicit conversions. |
| StringPiece(const string& str) : str_(str.data()), len_(str.size()) {} |
| StringPiece(const char* str) : str_(str), len_(strlen(str)) {} |
| |
| constexpr StringPiece(const char* str, size_t len) : str_(str), len_(len) {} |
| |
| /// Convert the slice into a full-fledged std::string, copying the |
| /// data into a new string. |
| string AsString() const { |
| return len_ ? string(str_, len_) : string(); |
| } |
| |
| constexpr const_iterator begin() const { return str_; } |
| constexpr const_iterator end() const { return str_ + len_; } |
| constexpr const char* data() const { return str_; } |
| constexpr const_reference operator[](size_t pos) const { return str_[pos]; } |
| constexpr size_t size() const { return len_; } |
| constexpr bool empty() const { return len_ == 0; } |
| constexpr const_reference front() const { return str_[0]; } |
| constexpr const_reference back() const { return str_[len_ - 1]; } |
| |
| void remove_prefix(size_t n) { str_ += n; len_ -= n; } |
| void remove_suffix(size_t n) { len_ -= n; } |
| |
| StringPiece substr(size_t pos=0, size_t count=std::string::npos) const { |
| return StringPiece(str_ + pos, std::min(count, len_ - pos)); |
| } |
| |
| int compare(StringPiece other) const { |
| size_t min_len = std::min(len_, other.len_); |
| if (min_len != 0) { // strncmp(NULL, NULL, 0) has undefined behavior. |
| if (int cmp = strncmp(str_, other.str_, min_len)) { |
| return cmp; |
| } |
| } |
| return (len_ == other.len_) ? 0 : ((len_ < other.len_) ? -1 : 1); |
| } |
| |
| const char* str_; |
| size_t len_; |
| }; |
| |
| inline bool operator==(StringPiece x, StringPiece y) { |
| if (x.size() != y.size()) |
| return false; |
| if (x.size() == 0) // memcmp(NULL, NULL, 0) has undefined behavior. |
| return true; |
| return !memcmp(x.data(), y.data(), x.size()); |
| } |
| |
| inline bool operator!=(StringPiece x, StringPiece y) { |
| return !(x == y); |
| } |
| |
| inline bool operator<(StringPiece x, StringPiece y) { return x.compare(y) < 0; } |
| inline bool operator>(StringPiece x, StringPiece y) { return x.compare(y) > 0; } |
| inline bool operator<=(StringPiece x, StringPiece y) { return x.compare(y) <= 0; } |
| inline bool operator>=(StringPiece x, StringPiece y) { return x.compare(y) >= 0; } |
| |
| inline uint32_t HashStr(const StringPiece& str) { |
| if (str.empty()) { |
| // Returning 0 for an empty string allows HashedStrView to be zero-initialized. |
| return 0; |
| } |
| return MurmurHash2(str.data(), str.size()); |
| } |
| |
| namespace std { |
| template<> struct hash<StringPiece> { |
| size_t operator()(StringPiece key) const { |
| return HashStr(key); |
| } |
| }; |
| } |
| |
| #endif // NINJA_STRINGPIECE_H_ |