chromium/third_party/abseil-cpp/absl/strings/ascii.cc

// 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/ascii.h"

#include <climits>
#include <cstddef>
#include <cstring>
#include <string>

#include "absl/base/attributes.h"
#include "absl/base/config.h"
#include "absl/base/nullability.h"
#include "absl/base/optimization.h"

namespace absl {
ABSL_NAMESPACE_BEGIN
namespace ascii_internal {

// # Table generated by this Python code (bit 0x02 is currently unused):
// TODO(mbar) Move Python code for generation of table to BUILD and link here.

// NOTE: The kAsciiPropertyBits table used within this code was generated by
// Python code of the following form. (Bit 0x02 is currently unused and
// available.)
//
// def Hex2(n):
//   return '0x' + hex(n/16)[2:] + hex(n%16)[2:]
// def IsPunct(ch):
//   return (ord(ch) >= 32 and ord(ch) < 127 and
//           not ch.isspace() and not ch.isalnum())
// def IsBlank(ch):
//   return ch in ' \t'
// def IsCntrl(ch):
//   return ord(ch) < 32 or ord(ch) == 127
// def IsXDigit(ch):
//   return ch.isdigit() or ch.lower() in 'abcdef'
// for i in range(128):
//   ch = chr(i)
//   mask = ((ch.isalpha() and 0x01 or 0) |
//           (ch.isalnum() and 0x04 or 0) |
//           (ch.isspace() and 0x08 or 0) |
//           (IsPunct(ch) and 0x10 or 0) |
//           (IsBlank(ch) and 0x20 or 0) |
//           (IsCntrl(ch) and 0x40 or 0) |
//           (IsXDigit(ch) and 0x80 or 0))
//   print Hex2(mask) + ',',
//   if i % 16 == 7:
//     print ' //', Hex2(i & 0x78)
//   elif i % 16 == 15:
//     print

// clang-format off
// Array of bitfields holding character information. Each bit value corresponds
// to a particular character feature. For readability, and because the value
// of these bits is tightly coupled to this implementation, the individual bits
// are not named. Note that bitfields for all characters above ASCII 127 are
// zero-initialized.
ABSL_DLL const unsigned char kPropertyBits[256] = …;

// Array of characters for the ascii_tolower() function. For values 'A'
// through 'Z', return the lower-case character; otherwise, return the
// identity of the passed character.
ABSL_DLL const char kToLower[256] = …;

// Array of characters for the ascii_toupper() function. For values 'a'
// through 'z', return the upper-case character; otherwise, return the
// identity of the passed character.
ABSL_DLL const char kToUpper[256] = …;
// clang-format on

// Returns whether `c` is in the a-z/A-Z range (w.r.t. `ToUpper`).
// Implemented by:
//  1. Pushing the a-z/A-Z range to [SCHAR_MIN, SCHAR_MIN + 26).
//  2. Comparing to SCHAR_MIN + 26.
template <bool ToUpper>
constexpr bool AsciiInAZRange(unsigned char c) { … }

// Force-inline so the compiler won't merge the short and long implementations.
template <bool ToUpper>
ABSL_ATTRIBUTE_ALWAYS_INLINE inline constexpr void AsciiStrCaseFoldImpl(
    absl::Nonnull<char*> dst, absl::Nonnull<const char*> src, size_t size) { … }

// The string size threshold for starting using the long string version.
constexpr size_t kCaseFoldThreshold = …;

// No-inline so the compiler won't merge the short and long implementations.
template <bool ToUpper>
ABSL_ATTRIBUTE_NOINLINE constexpr void AsciiStrCaseFoldLong(
    absl::Nonnull<char*> dst, absl::Nonnull<const char*> src, size_t size) { … }

// Splitting to short and long strings to allow vectorization decisions
// to be made separately in the long and short cases.
template <bool ToUpper>
constexpr void AsciiStrCaseFold(absl::Nonnull<char*> dst,
                                absl::Nonnull<const char*> src, size_t size) { … }

void AsciiStrToLower(absl::Nonnull<char*> dst, absl::Nonnull<const char*> src,
                     size_t n) { … }

void AsciiStrToUpper(absl::Nonnull<char*> dst, absl::Nonnull<const char*> src,
                     size_t n) { … }

static constexpr size_t ValidateAsciiCasefold() { … }

static_assert …;

}  // namespace ascii_internal

void AsciiStrToLower(absl::Nonnull<std::string*> s) { … }

void AsciiStrToUpper(absl::Nonnull<std::string*> s) { … }

void RemoveExtraAsciiWhitespace(absl::Nonnull<std::string*> str) { … }

ABSL_NAMESPACE_END
}  // namespace absl