Abseil Common Libraries (C++) (grcp 依赖)
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219 lines
6.1 KiB
219 lines
6.1 KiB
// Copyright 2017 The Abseil Authors. |
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// |
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// Licensed under the Apache License, Version 2.0 (the "License"); |
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// you may not use this file except in compliance with the License. |
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// You may obtain a copy of the License at |
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// |
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// https://www.apache.org/licenses/LICENSE-2.0 |
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// |
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// Unless required by applicable law or agreed to in writing, software |
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// distributed under the License is distributed on an "AS IS" BASIS, |
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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// See the License for the specific language governing permissions and |
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// limitations under the License. |
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#include "absl/strings/string_view.h" |
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#ifndef ABSL_USES_STD_STRING_VIEW |
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#include <algorithm> |
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#include <climits> |
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#include <cstring> |
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#include <ostream> |
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#include "absl/strings/internal/memutil.h" |
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namespace absl { |
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ABSL_NAMESPACE_BEGIN |
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namespace { |
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void WritePadding(std::ostream& o, size_t pad) { |
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char fill_buf[32]; |
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memset(fill_buf, o.fill(), sizeof(fill_buf)); |
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while (pad) { |
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size_t n = std::min(pad, sizeof(fill_buf)); |
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o.write(fill_buf, n); |
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pad -= n; |
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} |
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} |
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class LookupTable { |
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public: |
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// For each character in wanted, sets the index corresponding |
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// to the ASCII code of that character. This is used by |
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// the find_.*_of methods below to tell whether or not a character is in |
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// the lookup table in constant time. |
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explicit LookupTable(string_view wanted) { |
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for (char c : wanted) { |
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table_[Index(c)] = true; |
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} |
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} |
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bool operator[](char c) const { return table_[Index(c)]; } |
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private: |
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static unsigned char Index(char c) { return static_cast<unsigned char>(c); } |
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bool table_[UCHAR_MAX + 1] = {}; |
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}; |
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} // namespace |
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std::ostream& operator<<(std::ostream& o, string_view piece) { |
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std::ostream::sentry sentry(o); |
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if (sentry) { |
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size_t lpad = 0; |
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size_t rpad = 0; |
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if (static_cast<size_t>(o.width()) > piece.size()) { |
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size_t pad = o.width() - piece.size(); |
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if ((o.flags() & o.adjustfield) == o.left) { |
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rpad = pad; |
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} else { |
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lpad = pad; |
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} |
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} |
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if (lpad) WritePadding(o, lpad); |
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o.write(piece.data(), piece.size()); |
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if (rpad) WritePadding(o, rpad); |
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o.width(0); |
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} |
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return o; |
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} |
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string_view::size_type string_view::find(string_view s, |
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size_type pos) const noexcept { |
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if (empty() || pos > length_) { |
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if (empty() && pos == 0 && s.empty()) return 0; |
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return npos; |
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} |
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const char* result = |
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strings_internal::memmatch(ptr_ + pos, length_ - pos, s.ptr_, s.length_); |
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return result ? result - ptr_ : npos; |
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} |
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string_view::size_type string_view::find(char c, size_type pos) const noexcept { |
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if (empty() || pos >= length_) { |
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return npos; |
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} |
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const char* result = |
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static_cast<const char*>(memchr(ptr_ + pos, c, length_ - pos)); |
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return result != nullptr ? result - ptr_ : npos; |
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} |
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string_view::size_type string_view::rfind(string_view s, |
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size_type pos) const noexcept { |
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if (length_ < s.length_) return npos; |
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if (s.empty()) return std::min(length_, pos); |
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const char* last = ptr_ + std::min(length_ - s.length_, pos) + s.length_; |
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const char* result = std::find_end(ptr_, last, s.ptr_, s.ptr_ + s.length_); |
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return result != last ? result - ptr_ : npos; |
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} |
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// Search range is [0..pos] inclusive. If pos == npos, search everything. |
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string_view::size_type string_view::rfind(char c, |
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size_type pos) const noexcept { |
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// Note: memrchr() is not available on Windows. |
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if (empty()) return npos; |
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for (size_type i = std::min(pos, length_ - 1);; --i) { |
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if (ptr_[i] == c) { |
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return i; |
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} |
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if (i == 0) break; |
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} |
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return npos; |
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} |
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string_view::size_type string_view::find_first_of( |
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string_view s, size_type pos) const noexcept { |
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if (empty() || s.empty()) { |
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return npos; |
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} |
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// Avoid the cost of LookupTable() for a single-character search. |
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if (s.length_ == 1) return find_first_of(s.ptr_[0], pos); |
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LookupTable tbl(s); |
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for (size_type i = pos; i < length_; ++i) { |
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if (tbl[ptr_[i]]) { |
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return i; |
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} |
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} |
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return npos; |
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} |
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string_view::size_type string_view::find_first_not_of( |
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string_view s, size_type pos) const noexcept { |
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if (empty()) return npos; |
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// Avoid the cost of LookupTable() for a single-character search. |
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if (s.length_ == 1) return find_first_not_of(s.ptr_[0], pos); |
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LookupTable tbl(s); |
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for (size_type i = pos; i < length_; ++i) { |
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if (!tbl[ptr_[i]]) { |
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return i; |
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} |
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} |
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return npos; |
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} |
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string_view::size_type string_view::find_first_not_of( |
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char c, size_type pos) const noexcept { |
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if (empty()) return npos; |
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for (; pos < length_; ++pos) { |
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if (ptr_[pos] != c) { |
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return pos; |
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} |
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} |
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return npos; |
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} |
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string_view::size_type string_view::find_last_of(string_view s, |
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size_type pos) const noexcept { |
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if (empty() || s.empty()) return npos; |
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// Avoid the cost of LookupTable() for a single-character search. |
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if (s.length_ == 1) return find_last_of(s.ptr_[0], pos); |
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LookupTable tbl(s); |
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for (size_type i = std::min(pos, length_ - 1);; --i) { |
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if (tbl[ptr_[i]]) { |
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return i; |
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} |
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if (i == 0) break; |
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} |
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return npos; |
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} |
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string_view::size_type string_view::find_last_not_of( |
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string_view s, size_type pos) const noexcept { |
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if (empty()) return npos; |
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size_type i = std::min(pos, length_ - 1); |
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if (s.empty()) return i; |
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// Avoid the cost of LookupTable() for a single-character search. |
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if (s.length_ == 1) return find_last_not_of(s.ptr_[0], pos); |
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LookupTable tbl(s); |
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for (;; --i) { |
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if (!tbl[ptr_[i]]) { |
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return i; |
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} |
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if (i == 0) break; |
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} |
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return npos; |
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} |
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string_view::size_type string_view::find_last_not_of( |
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char c, size_type pos) const noexcept { |
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if (empty()) return npos; |
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size_type i = std::min(pos, length_ - 1); |
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for (;; --i) { |
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if (ptr_[i] != c) { |
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return i; |
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} |
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if (i == 0) break; |
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} |
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return npos; |
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} |
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#ifdef ABSL_INTERNAL_NEED_REDUNDANT_CONSTEXPR_DECL |
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constexpr string_view::size_type string_view::npos; |
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constexpr string_view::size_type string_view::kMaxSize; |
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#endif |
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ABSL_NAMESPACE_END |
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} // namespace absl |
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#endif // ABSL_USES_STD_STRING_VIEW
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