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// 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 <cstring>
#include <string>
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] = {
0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, // 0x00
0x40, 0x68, 0x48, 0x48, 0x48, 0x48, 0x40, 0x40,
0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, // 0x10
0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40,
0x28, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10, // 0x20
0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10,
0x84, 0x84, 0x84, 0x84, 0x84, 0x84, 0x84, 0x84, // 0x30
0x84, 0x84, 0x10, 0x10, 0x10, 0x10, 0x10, 0x10,
0x10, 0x85, 0x85, 0x85, 0x85, 0x85, 0x85, 0x05, // 0x40
0x05, 0x05, 0x05, 0x05, 0x05, 0x05, 0x05, 0x05,
0x05, 0x05, 0x05, 0x05, 0x05, 0x05, 0x05, 0x05, // 0x50
0x05, 0x05, 0x05, 0x10, 0x10, 0x10, 0x10, 0x10,
0x10, 0x85, 0x85, 0x85, 0x85, 0x85, 0x85, 0x05, // 0x60
0x05, 0x05, 0x05, 0x05, 0x05, 0x05, 0x05, 0x05,
0x05, 0x05, 0x05, 0x05, 0x05, 0x05, 0x05, 0x05, // 0x70
0x05, 0x05, 0x05, 0x10, 0x10, 0x10, 0x10, 0x40,
};
// 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] = {
'\x00', '\x01', '\x02', '\x03', '\x04', '\x05', '\x06', '\x07',
'\x08', '\x09', '\x0a', '\x0b', '\x0c', '\x0d', '\x0e', '\x0f',
'\x10', '\x11', '\x12', '\x13', '\x14', '\x15', '\x16', '\x17',
'\x18', '\x19', '\x1a', '\x1b', '\x1c', '\x1d', '\x1e', '\x1f',
'\x20', '\x21', '\x22', '\x23', '\x24', '\x25', '\x26', '\x27',
'\x28', '\x29', '\x2a', '\x2b', '\x2c', '\x2d', '\x2e', '\x2f',
'\x30', '\x31', '\x32', '\x33', '\x34', '\x35', '\x36', '\x37',
'\x38', '\x39', '\x3a', '\x3b', '\x3c', '\x3d', '\x3e', '\x3f',
'\x40', 'a', 'b', 'c', 'd', 'e', 'f', 'g',
'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o',
'p', 'q', 'r', 's', 't', 'u', 'v', 'w',
'x', 'y', 'z', '\x5b', '\x5c', '\x5d', '\x5e', '\x5f',
'\x60', '\x61', '\x62', '\x63', '\x64', '\x65', '\x66', '\x67',
'\x68', '\x69', '\x6a', '\x6b', '\x6c', '\x6d', '\x6e', '\x6f',
'\x70', '\x71', '\x72', '\x73', '\x74', '\x75', '\x76', '\x77',
'\x78', '\x79', '\x7a', '\x7b', '\x7c', '\x7d', '\x7e', '\x7f',
'\x80', '\x81', '\x82', '\x83', '\x84', '\x85', '\x86', '\x87',
'\x88', '\x89', '\x8a', '\x8b', '\x8c', '\x8d', '\x8e', '\x8f',
'\x90', '\x91', '\x92', '\x93', '\x94', '\x95', '\x96', '\x97',
'\x98', '\x99', '\x9a', '\x9b', '\x9c', '\x9d', '\x9e', '\x9f',
'\xa0', '\xa1', '\xa2', '\xa3', '\xa4', '\xa5', '\xa6', '\xa7',
'\xa8', '\xa9', '\xaa', '\xab', '\xac', '\xad', '\xae', '\xaf',
'\xb0', '\xb1', '\xb2', '\xb3', '\xb4', '\xb5', '\xb6', '\xb7',
'\xb8', '\xb9', '\xba', '\xbb', '\xbc', '\xbd', '\xbe', '\xbf',
'\xc0', '\xc1', '\xc2', '\xc3', '\xc4', '\xc5', '\xc6', '\xc7',
'\xc8', '\xc9', '\xca', '\xcb', '\xcc', '\xcd', '\xce', '\xcf',
'\xd0', '\xd1', '\xd2', '\xd3', '\xd4', '\xd5', '\xd6', '\xd7',
'\xd8', '\xd9', '\xda', '\xdb', '\xdc', '\xdd', '\xde', '\xdf',
'\xe0', '\xe1', '\xe2', '\xe3', '\xe4', '\xe5', '\xe6', '\xe7',
'\xe8', '\xe9', '\xea', '\xeb', '\xec', '\xed', '\xee', '\xef',
'\xf0', '\xf1', '\xf2', '\xf3', '\xf4', '\xf5', '\xf6', '\xf7',
'\xf8', '\xf9', '\xfa', '\xfb', '\xfc', '\xfd', '\xfe', '\xff',
};
// 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] = {
'\x00', '\x01', '\x02', '\x03', '\x04', '\x05', '\x06', '\x07',
'\x08', '\x09', '\x0a', '\x0b', '\x0c', '\x0d', '\x0e', '\x0f',
'\x10', '\x11', '\x12', '\x13', '\x14', '\x15', '\x16', '\x17',
'\x18', '\x19', '\x1a', '\x1b', '\x1c', '\x1d', '\x1e', '\x1f',
'\x20', '\x21', '\x22', '\x23', '\x24', '\x25', '\x26', '\x27',
'\x28', '\x29', '\x2a', '\x2b', '\x2c', '\x2d', '\x2e', '\x2f',
'\x30', '\x31', '\x32', '\x33', '\x34', '\x35', '\x36', '\x37',
'\x38', '\x39', '\x3a', '\x3b', '\x3c', '\x3d', '\x3e', '\x3f',
'\x40', '\x41', '\x42', '\x43', '\x44', '\x45', '\x46', '\x47',
'\x48', '\x49', '\x4a', '\x4b', '\x4c', '\x4d', '\x4e', '\x4f',
'\x50', '\x51', '\x52', '\x53', '\x54', '\x55', '\x56', '\x57',
'\x58', '\x59', '\x5a', '\x5b', '\x5c', '\x5d', '\x5e', '\x5f',
'\x60', 'A', 'B', 'C', 'D', 'E', 'F', 'G',
'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O',
'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W',
'X', 'Y', 'Z', '\x7b', '\x7c', '\x7d', '\x7e', '\x7f',
'\x80', '\x81', '\x82', '\x83', '\x84', '\x85', '\x86', '\x87',
'\x88', '\x89', '\x8a', '\x8b', '\x8c', '\x8d', '\x8e', '\x8f',
'\x90', '\x91', '\x92', '\x93', '\x94', '\x95', '\x96', '\x97',
'\x98', '\x99', '\x9a', '\x9b', '\x9c', '\x9d', '\x9e', '\x9f',
'\xa0', '\xa1', '\xa2', '\xa3', '\xa4', '\xa5', '\xa6', '\xa7',
'\xa8', '\xa9', '\xaa', '\xab', '\xac', '\xad', '\xae', '\xaf',
'\xb0', '\xb1', '\xb2', '\xb3', '\xb4', '\xb5', '\xb6', '\xb7',
'\xb8', '\xb9', '\xba', '\xbb', '\xbc', '\xbd', '\xbe', '\xbf',
'\xc0', '\xc1', '\xc2', '\xc3', '\xc4', '\xc5', '\xc6', '\xc7',
'\xc8', '\xc9', '\xca', '\xcb', '\xcc', '\xcd', '\xce', '\xcf',
'\xd0', '\xd1', '\xd2', '\xd3', '\xd4', '\xd5', '\xd6', '\xd7',
'\xd8', '\xd9', '\xda', '\xdb', '\xdc', '\xdd', '\xde', '\xdf',
'\xe0', '\xe1', '\xe2', '\xe3', '\xe4', '\xe5', '\xe6', '\xe7',
'\xe8', '\xe9', '\xea', '\xeb', '\xec', '\xed', '\xee', '\xef',
'\xf0', '\xf1', '\xf2', '\xf3', '\xf4', '\xf5', '\xf6', '\xf7',
'\xf8', '\xf9', '\xfa', '\xfb', '\xfc', '\xfd', '\xfe', '\xff',
};
// clang-format on
template <bool ToUpper>
constexpr void AsciiStrCaseFold(char* p, char* end) {
// The upper- and lowercase versions of ASCII characters differ by only 1 bit.
// When we need to flip the case, we can xor with this bit to achieve the
// desired result. Note that the choice of 'a' and 'A' here is arbitrary. We
// could have chosen 'z' and 'Z', or any other pair of characters as they all
// have the same single bit difference.
constexpr unsigned char kAsciiCaseBitFlip = 'a' ^ 'A';
constexpr char ch_a = ToUpper ? 'a' : 'A';
constexpr char ch_z = ToUpper ? 'z' : 'Z';
for (; p < end; ++p) {
unsigned char v = static_cast<unsigned char>(*p);
// We use & instead of && to ensure this always stays branchless
// We use static_cast<int> to suppress -Wbitwise-instead-of-logical
bool is_in_range = static_cast<bool>(static_cast<int>(ch_a <= v) &
static_cast<int>(v <= ch_z));
v ^= is_in_range ? kAsciiCaseBitFlip : 0;
*p = static_cast<char>(v);
}
}
static constexpr size_t ValidateAsciiCasefold() {
constexpr size_t num_chars = 1 + CHAR_MAX - CHAR_MIN;
size_t incorrect_index = 0;
char lowered[num_chars] = {};
char uppered[num_chars] = {};
for (unsigned int i = 0; i < num_chars; ++i) {
uppered[i] = lowered[i] = static_cast<char>(i);
}
AsciiStrCaseFold<false>(&lowered[0], &lowered[num_chars]);
AsciiStrCaseFold<true>(&uppered[0], &uppered[num_chars]);
for (size_t i = 0; i < num_chars; ++i) {
const char ch = static_cast<char>(i),
ch_upper = ('a' <= ch && ch <= 'z' ? 'A' + (ch - 'a') : ch),
ch_lower = ('A' <= ch && ch <= 'Z' ? 'a' + (ch - 'A') : ch);
if (uppered[i] != ch_upper || lowered[i] != ch_lower) {
incorrect_index = i > 0 ? i : num_chars;
break;
}
}
return incorrect_index;
}
static_assert(ValidateAsciiCasefold() == 0, "error in case conversion");
} // namespace ascii_internal
void AsciiStrToLower(std::string* s) {
char* p = &(*s)[0]; // Guaranteed to be valid for empty strings
return ascii_internal::AsciiStrCaseFold<false>(p, p + s->size());
}
void AsciiStrToUpper(std::string* s) {
char* p = &(*s)[0]; // Guaranteed to be valid for empty strings
return ascii_internal::AsciiStrCaseFold<true>(p, p + s->size());
}
void RemoveExtraAsciiWhitespace(std::string* str) {
auto stripped = StripAsciiWhitespace(*str);
if (stripped.empty()) {
str->clear();
return;
}
auto input_it = stripped.begin();
auto input_end = stripped.end();
auto output_it = &(*str)[0];
bool is_ws = false;
for (; input_it < input_end; ++input_it) {
if (is_ws) {
// Consecutive whitespace? Keep only the last.
is_ws = absl::ascii_isspace(static_cast<unsigned char>(*input_it));
if (is_ws) --output_it;
} else {
is_ws = absl::ascii_isspace(static_cast<unsigned char>(*input_it));
}
*output_it = *input_it;
++output_it;
}
str->erase(static_cast<size_t>(output_it - &(*str)[0]));
}
ABSL_NAMESPACE_END
} // namespace absl
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