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TMessagesProj/jni/voip/webrtc/absl/strings/charset.h

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+// Copyright 2022 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.
+//
+// -----------------------------------------------------------------------------
+// File: charset.h
+// -----------------------------------------------------------------------------
+//
+// This file contains absl::CharSet, a fast, bit-vector set of 8-bit unsigned
+// characters.
+//
+// Instances can be initialized as constexpr constants. For example:
+//
+//   constexpr absl::CharSet kJustX = absl::CharSet::Char('x');
+//   constexpr absl::CharSet kMySymbols = absl::CharSet("$@!");
+//   constexpr absl::CharSet kLetters = absl::CharSet::Range('a', 'z');
+//
+// Multiple instances can be combined that still forms a constexpr expression.
+// For example:
+//
+//   constexpr absl::CharSet kLettersAndNumbers =
+//       absl::CharSet::Range('a', 'z') | absl::CharSet::Range('0', '9');
+//
+// Several pre-defined character classes are available that mirror the methods
+// from <cctype>. For example:
+//
+//   constexpr absl::CharSet kLettersAndWhitespace =
+//       absl::CharSet::AsciiAlphabet() | absl::CharSet::AsciiWhitespace();
+//
+// To check membership, use the .contains method, e.g.
+//
+//   absl::CharSet hex_letters("abcdef");
+//   hex_letters.contains('a');  // true
+//   hex_letters.contains('g');  // false
+
+#ifndef ABSL_STRINGS_CHARSET_H_
+#define ABSL_STRINGS_CHARSET_H_
+
+#include <cstdint>
+
+#include "absl/base/config.h"
+#include "absl/strings/string_view.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+
+class CharSet {
+ public:
+  constexpr CharSet() : m_() {}
+
+  // Initializes with a given string_view.
+  constexpr explicit CharSet(absl::string_view str) : m_() {
+    for (char c : str) {
+      SetChar(static_cast<unsigned char>(c));
+    }
+  }
+
+  constexpr bool contains(char c) const {
+    return ((m_[static_cast<unsigned char>(c) / 64] >>
+             (static_cast<unsigned char>(c) % 64)) &
+            0x1) == 0x1;
+  }
+
+  constexpr bool empty() const {
+    for (uint64_t c : m_) {
+      if (c != 0) return false;
+    }
+    return true;
+  }
+
+  // Containing only a single specified char.
+  static constexpr CharSet Char(char x) {
+    return CharSet(CharMaskForWord(x, 0), CharMaskForWord(x, 1),
+                   CharMaskForWord(x, 2), CharMaskForWord(x, 3));
+  }
+
+  // Containing all the chars in the closed interval [lo,hi].
+  static constexpr CharSet Range(char lo, char hi) {
+    return CharSet(RangeForWord(lo, hi, 0), RangeForWord(lo, hi, 1),
+                   RangeForWord(lo, hi, 2), RangeForWord(lo, hi, 3));
+  }
+
+  friend constexpr CharSet operator&(const CharSet& a, const CharSet& b) {
+    return CharSet(a.m_[0] & b.m_[0], a.m_[1] & b.m_[1], a.m_[2] & b.m_[2],
+                   a.m_[3] & b.m_[3]);
+  }
+
+  friend constexpr CharSet operator|(const CharSet& a, const CharSet& b) {
+    return CharSet(a.m_[0] | b.m_[0], a.m_[1] | b.m_[1], a.m_[2] | b.m_[2],
+                   a.m_[3] | b.m_[3]);
+  }
+
+  friend constexpr CharSet operator~(const CharSet& a) {
+    return CharSet(~a.m_[0], ~a.m_[1], ~a.m_[2], ~a.m_[3]);
+  }
+
+  // Mirrors the char-classifying predicates in <cctype>.
+  static constexpr CharSet AsciiUppercase() { return CharSet::Range('A', 'Z'); }
+  static constexpr CharSet AsciiLowercase() { return CharSet::Range('a', 'z'); }
+  static constexpr CharSet AsciiDigits() { return CharSet::Range('0', '9'); }
+  static constexpr CharSet AsciiAlphabet() {
+    return AsciiLowercase() | AsciiUppercase();
+  }
+  static constexpr CharSet AsciiAlphanumerics() {
+    return AsciiDigits() | AsciiAlphabet();
+  }
+  static constexpr CharSet AsciiHexDigits() {
+    return AsciiDigits() | CharSet::Range('A', 'F') | CharSet::Range('a', 'f');
+  }
+  static constexpr CharSet AsciiPrintable() {
+    return CharSet::Range(0x20, 0x7e);
+  }
+  static constexpr CharSet AsciiWhitespace() { return CharSet("\t\n\v\f\r "); }
+  static constexpr CharSet AsciiPunctuation() {
+    return AsciiPrintable() & ~AsciiWhitespace() & ~AsciiAlphanumerics();
+  }
+
+ private:
+  constexpr CharSet(uint64_t b0, uint64_t b1, uint64_t b2, uint64_t b3)
+      : m_{b0, b1, b2, b3} {}
+
+  static constexpr uint64_t RangeForWord(char lo, char hi, uint64_t word) {
+    return OpenRangeFromZeroForWord(static_cast<unsigned char>(hi) + 1, word) &
+           ~OpenRangeFromZeroForWord(static_cast<unsigned char>(lo), word);
+  }
+
+  // All the chars in the specified word of the range [0, upper).
+  static constexpr uint64_t OpenRangeFromZeroForWord(uint64_t upper,
+                                                     uint64_t word) {
+    return (upper <= 64 * word) ? 0
+           : (upper >= 64 * (word + 1))
+               ? ~static_cast<uint64_t>(0)
+               : (~static_cast<uint64_t>(0) >> (64 - upper % 64));
+  }
+
+  static constexpr uint64_t CharMaskForWord(char x, uint64_t word) {
+    return (static_cast<unsigned char>(x) / 64 == word)
+               ? (static_cast<uint64_t>(1)
+                  << (static_cast<unsigned char>(x) % 64))
+               : 0;
+  }
+
+  constexpr void SetChar(unsigned char c) {
+    m_[c / 64] |= static_cast<uint64_t>(1) << (c % 64);
+  }
+
+  uint64_t m_[4];
+};
+
+ABSL_NAMESPACE_END
+}  // namespace absl
+
+#endif  // ABSL_STRINGS_CHARSET_H_