| // Copyright 2017 The Abseil Authors. |
| // |
| // 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 |
| // |
| // https://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. |
| |
| #include "absl/strings/string_view.h" |
| |
| #ifndef ABSL_HAVE_STD_STRING_VIEW |
| |
| #include <algorithm> |
| #include <climits> |
| #include <cstring> |
| #include <ostream> |
| |
| #include "absl/strings/internal/memutil.h" |
| |
| namespace absl { |
| |
| namespace { |
| void WritePadding(std::ostream& o, size_t pad) { |
| char fill_buf[32]; |
| memset(fill_buf, o.fill(), sizeof(fill_buf)); |
| while (pad) { |
| size_t n = std::min(pad, sizeof(fill_buf)); |
| o.write(fill_buf, n); |
| pad -= n; |
| } |
| } |
| |
| class LookupTable { |
| public: |
| // For each character in wanted, sets the index corresponding |
| // to the ASCII code of that character. This is used by |
| // the find_.*_of methods below to tell whether or not a character is in |
| // the lookup table in constant time. |
| explicit LookupTable(string_view wanted) { |
| for (char c : wanted) { |
| table_[Index(c)] = true; |
| } |
| } |
| bool operator[](char c) const { return table_[Index(c)]; } |
| |
| private: |
| static unsigned char Index(char c) { return static_cast<unsigned char>(c); } |
| bool table_[UCHAR_MAX + 1] = {}; |
| }; |
| |
| } // namespace |
| |
| std::ostream& operator<<(std::ostream& o, string_view piece) { |
| std::ostream::sentry sentry(o); |
| if (sentry) { |
| size_t lpad = 0; |
| size_t rpad = 0; |
| if (static_cast<size_t>(o.width()) > piece.size()) { |
| size_t pad = o.width() - piece.size(); |
| if ((o.flags() & o.adjustfield) == o.left) { |
| rpad = pad; |
| } else { |
| lpad = pad; |
| } |
| } |
| if (lpad) WritePadding(o, lpad); |
| o.write(piece.data(), piece.size()); |
| if (rpad) WritePadding(o, rpad); |
| o.width(0); |
| } |
| return o; |
| } |
| |
| string_view::size_type string_view::copy(char* buf, size_type n, |
| size_type pos) const { |
| size_type ulen = length_; |
| assert(pos <= ulen); |
| size_type rlen = std::min(ulen - pos, n); |
| if (rlen > 0) { |
| const char* start = ptr_ + pos; |
| std::copy(start, start + rlen, buf); |
| } |
| return rlen; |
| } |
| |
| string_view::size_type string_view::find(string_view s, size_type pos) const |
| noexcept { |
| if (empty() || pos > length_) { |
| if (empty() && pos == 0 && s.empty()) return 0; |
| return npos; |
| } |
| const char* result = |
| strings_internal::memmatch(ptr_ + pos, length_ - pos, s.ptr_, s.length_); |
| return result ? result - ptr_ : npos; |
| } |
| |
| string_view::size_type string_view::find(char c, size_type pos) const noexcept { |
| if (empty() || pos >= length_) { |
| return npos; |
| } |
| const char* result = |
| static_cast<const char*>(memchr(ptr_ + pos, c, length_ - pos)); |
| return result != nullptr ? result - ptr_ : npos; |
| } |
| |
| string_view::size_type string_view::rfind(string_view s, size_type pos) const |
| noexcept { |
| if (length_ < s.length_) return npos; |
| if (s.empty()) return std::min(length_, pos); |
| const char* last = ptr_ + std::min(length_ - s.length_, pos) + s.length_; |
| const char* result = std::find_end(ptr_, last, s.ptr_, s.ptr_ + s.length_); |
| return result != last ? result - ptr_ : npos; |
| } |
| |
| // Search range is [0..pos] inclusive. If pos == npos, search everything. |
| string_view::size_type string_view::rfind(char c, size_type pos) const |
| noexcept { |
| // Note: memrchr() is not available on Windows. |
| if (empty()) return npos; |
| for (size_type i = std::min(pos, length_ - 1);; --i) { |
| if (ptr_[i] == c) { |
| return i; |
| } |
| if (i == 0) break; |
| } |
| return npos; |
| } |
| |
| string_view::size_type string_view::find_first_of(string_view s, |
| size_type pos) const |
| noexcept { |
| if (empty() || s.empty()) { |
| return npos; |
| } |
| // Avoid the cost of LookupTable() for a single-character search. |
| if (s.length_ == 1) return find_first_of(s.ptr_[0], pos); |
| LookupTable tbl(s); |
| for (size_type i = pos; i < length_; ++i) { |
| if (tbl[ptr_[i]]) { |
| return i; |
| } |
| } |
| return npos; |
| } |
| |
| string_view::size_type string_view::find_first_not_of(string_view s, |
| size_type pos) const |
| noexcept { |
| if (empty()) return npos; |
| // Avoid the cost of LookupTable() for a single-character search. |
| if (s.length_ == 1) return find_first_not_of(s.ptr_[0], pos); |
| LookupTable tbl(s); |
| for (size_type i = pos; i < length_; ++i) { |
| if (!tbl[ptr_[i]]) { |
| return i; |
| } |
| } |
| return npos; |
| } |
| |
| string_view::size_type string_view::find_first_not_of(char c, |
| size_type pos) const |
| noexcept { |
| if (empty()) return npos; |
| for (; pos < length_; ++pos) { |
| if (ptr_[pos] != c) { |
| return pos; |
| } |
| } |
| return npos; |
| } |
| |
| string_view::size_type string_view::find_last_of(string_view s, |
| size_type pos) const noexcept { |
| if (empty() || s.empty()) return npos; |
| // Avoid the cost of LookupTable() for a single-character search. |
| if (s.length_ == 1) return find_last_of(s.ptr_[0], pos); |
| LookupTable tbl(s); |
| for (size_type i = std::min(pos, length_ - 1);; --i) { |
| if (tbl[ptr_[i]]) { |
| return i; |
| } |
| if (i == 0) break; |
| } |
| return npos; |
| } |
| |
| string_view::size_type string_view::find_last_not_of(string_view s, |
| size_type pos) const |
| noexcept { |
| if (empty()) return npos; |
| size_type i = std::min(pos, length_ - 1); |
| if (s.empty()) return i; |
| // Avoid the cost of LookupTable() for a single-character search. |
| if (s.length_ == 1) return find_last_not_of(s.ptr_[0], pos); |
| LookupTable tbl(s); |
| for (;; --i) { |
| if (!tbl[ptr_[i]]) { |
| return i; |
| } |
| if (i == 0) break; |
| } |
| return npos; |
| } |
| |
| string_view::size_type string_view::find_last_not_of(char c, |
| size_type pos) const |
| noexcept { |
| if (empty()) return npos; |
| size_type i = std::min(pos, length_ - 1); |
| for (;; --i) { |
| if (ptr_[i] != c) { |
| return i; |
| } |
| if (i == 0) break; |
| } |
| return npos; |
| } |
| |
| // MSVC has non-standard behavior that implicitly creates definitions for static |
| // const members. These implicit definitions conflict with explicit out-of-class |
| // member definitions that are required by the C++ standard, resulting in |
| // LNK1169 "multiply defined" errors at link time. __declspec(selectany) asks |
| // MSVC to choose only one definition for the symbol it decorates. See details |
| // at https://msdn.microsoft.com/en-us/library/34h23df8(v=vs.100).aspx |
| #ifdef _MSC_VER |
| #define ABSL_STRING_VIEW_SELECTANY __declspec(selectany) |
| #else |
| #define ABSL_STRING_VIEW_SELECTANY |
| #endif |
| |
| ABSL_STRING_VIEW_SELECTANY |
| constexpr string_view::size_type string_view::npos; |
| ABSL_STRING_VIEW_SELECTANY |
| constexpr string_view::size_type string_view::kMaxSize; |
| |
| } // namespace absl |
| |
| #endif // ABSL_HAVE_STD_STRING_VIEW |