From c2e754829628d1e9b7a16b3389cfdace76950fdf Mon Sep 17 00:00:00 2001 From: misterg Date: Tue, 19 Sep 2017 16:54:40 -0400 Subject: Initial Commit --- absl/strings/string_view.cc | 248 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 248 insertions(+) create mode 100644 absl/strings/string_view.cc (limited to 'absl/strings/string_view.cc') diff --git a/absl/strings/string_view.cc b/absl/strings/string_view.cc new file mode 100644 index 00000000..4d4ba6c1 --- /dev/null +++ b/absl/strings/string_view.cc @@ -0,0 +1,248 @@ +// 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 +// +// 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. + +#include "absl/strings/string_view.h" + +#ifndef ABSL_HAVE_STD_STRING_VIEW + +#include +#include +#include +#include +#include + +#include "absl/strings/internal/memutil.h" +#include "absl/strings/internal/resize_uninitialized.h" +#include "absl/strings/match.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(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(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(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 http://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 -- cgit v1.2.3