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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.
//
// Character Map Class
//
// A fast, bit-vector map for 8-bit unsigned characters.
// This class is useful for non-character purposes as well.
#ifndef ABSL_STRINGS_INTERNAL_CHAR_MAP_H_
#define ABSL_STRINGS_INTERNAL_CHAR_MAP_H_
#include <cstddef>
#include <cstdint>
#include <cstring>
#include "absl/base/macros.h"
#include "absl/base/port.h"
namespace absl {
namespace strings_internal {
class Charmap {
public:
constexpr Charmap() : m_() {}
// Initializes with a given char*. Note that NUL is not treated as
// a terminator, but rather a char to be flicked.
Charmap(const char* str, int len) : m_() {
while (len--) SetChar(*str++);
}
// Initializes with a given char*. NUL is treated as a terminator
// and will not be in the charmap.
explicit Charmap(const char* str) : m_() {
while (*str) SetChar(*str++);
}
constexpr bool contains(unsigned char c) const {
return (m_[c / 64] >> (c % 64)) & 0x1;
}
// Returns true if and only if a character exists in both maps.
bool IntersectsWith(const Charmap& c) const {
for (size_t i = 0; i < ABSL_ARRAYSIZE(m_); ++i) {
if ((m_[i] & c.m_[i]) != 0) return true;
}
return false;
}
bool IsZero() const {
for (uint64_t c : m_) {
if (c != 0) return false;
}
return true;
}
// Containing only a single specified char.
static constexpr Charmap Char(char x) {
return Charmap(CharMaskForWord(x, 0), CharMaskForWord(x, 1),
CharMaskForWord(x, 2), CharMaskForWord(x, 3));
}
// Containing all the chars in the C-std::string 's'.
// Note that this is expensively recursive because of the C++11 constexpr
// formulation. Use only in constexpr initializers.
static constexpr Charmap FromString(const char* s) {
return *s == 0 ? Charmap() : (Char(*s) | FromString(s + 1));
}
// Containing all the chars in the closed interval [lo,hi].
static constexpr Charmap Range(char lo, char hi) {
return Charmap(RangeForWord(lo, hi, 0), RangeForWord(lo, hi, 1),
RangeForWord(lo, hi, 2), RangeForWord(lo, hi, 3));
}
friend constexpr Charmap operator&(const Charmap& a, const Charmap& b) {
return Charmap(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 Charmap operator|(const Charmap& a, const Charmap& b) {
return Charmap(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 Charmap operator~(const Charmap& a) {
return Charmap(~a.m_[0], ~a.m_[1], ~a.m_[2], ~a.m_[3]);
}
private:
constexpr Charmap(uint64_t b0, uint64_t b1, uint64_t b2, uint64_t b3)
: m_{b0, b1, b2, b3} {}
static constexpr uint64_t RangeForWord(unsigned char lo, unsigned char hi,
uint64_t word) {
return OpenRangeFromZeroForWord(hi + 1, word) &
~OpenRangeFromZeroForWord(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(unsigned char x, uint64_t word) {
return (x / 64 == word) ? (static_cast<uint64_t>(1) << (x % 64)) : 0;
}
private:
void SetChar(unsigned char c) {
m_[c / 64] |= static_cast<uint64_t>(1) << (c % 64);
}
uint64_t m_[4];
};
// Mirror the char-classifying predicates in <cctype>
constexpr Charmap UpperCharmap() { return Charmap::Range('A', 'Z'); }
constexpr Charmap LowerCharmap() { return Charmap::Range('a', 'z'); }
constexpr Charmap DigitCharmap() { return Charmap::Range('0', '9'); }
constexpr Charmap AlphaCharmap() { return LowerCharmap() | UpperCharmap(); }
constexpr Charmap AlnumCharmap() { return DigitCharmap() | AlphaCharmap(); }
constexpr Charmap XDigitCharmap() {
return DigitCharmap() | Charmap::Range('A', 'F') | Charmap::Range('a', 'f');
}
constexpr Charmap PrintCharmap() { return Charmap::Range(0x20, 0x7e); }
constexpr Charmap SpaceCharmap() { return Charmap::FromString("\t\n\v\f\r "); }
constexpr Charmap CntrlCharmap() {
return Charmap::Range(0, 0x7f) & ~PrintCharmap();
}
constexpr Charmap BlankCharmap() { return Charmap::FromString("\t "); }
constexpr Charmap GraphCharmap() { return PrintCharmap() & ~SpaceCharmap(); }
constexpr Charmap PunctCharmap() { return GraphCharmap() & ~AlnumCharmap(); }
} // namespace strings_internal
} // namespace absl
#endif // ABSL_STRINGS_INTERNAL_CHAR_MAP_H_
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