// 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_USES_STD_STRING_VIEW #include <algorithm> #include <climits> #include <cstring> #include <ostream> #include "absl/strings/internal/memutil.h" namespace absl { ABSL_NAMESPACE_BEGIN 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::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; ABSL_NAMESPACE_END } // namespace absl #endif // ABSL_USES_STD_STRING_VIEW