1 // Copyright 2017 The Abseil Authors.
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
7 // https://www.apache.org/licenses/LICENSE-2.0
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
15 // Character Map Class
17 // A fast, bit-vector map for 8-bit unsigned characters.
18 // This class is useful for non-character purposes as well.
20 #ifndef ABSL_STRINGS_INTERNAL_CHAR_MAP_H_
21 #define ABSL_STRINGS_INTERNAL_CHAR_MAP_H_
27 #include "absl/base/macros.h"
28 #include "absl/base/port.h"
31 namespace strings_internal {
35 constexpr Charmap() : m_() {}
37 // Initializes with a given char*. Note that NUL is not treated as
38 // a terminator, but rather a char to be flicked.
39 Charmap(const char* str, int len) : m_() {
40 while (len--) SetChar(*str++);
43 // Initializes with a given char*. NUL is treated as a terminator
44 // and will not be in the charmap.
45 explicit Charmap(const char* str) : m_() {
46 while (*str) SetChar(*str++);
49 constexpr bool contains(unsigned char c) const {
50 return (m_[c / 64] >> (c % 64)) & 0x1;
53 // Returns true if and only if a character exists in both maps.
54 bool IntersectsWith(const Charmap& c) const {
55 for (size_t i = 0; i < ABSL_ARRAYSIZE(m_); ++i) {
56 if ((m_[i] & c.m_[i]) != 0) return true;
62 for (uint64_t c : m_) {
63 if (c != 0) return false;
68 // Containing only a single specified char.
69 static constexpr Charmap Char(char x) {
70 return Charmap(CharMaskForWord(x, 0), CharMaskForWord(x, 1),
71 CharMaskForWord(x, 2), CharMaskForWord(x, 3));
74 // Containing all the chars in the C-std::string 's'.
75 // Note that this is expensively recursive because of the C++11 constexpr
76 // formulation. Use only in constexpr initializers.
77 static constexpr Charmap FromString(const char* s) {
78 return *s == 0 ? Charmap() : (Char(*s) | FromString(s + 1));
81 // Containing all the chars in the closed interval [lo,hi].
82 static constexpr Charmap Range(char lo, char hi) {
83 return Charmap(RangeForWord(lo, hi, 0), RangeForWord(lo, hi, 1),
84 RangeForWord(lo, hi, 2), RangeForWord(lo, hi, 3));
87 friend constexpr Charmap operator&(const Charmap& a, const Charmap& b) {
88 return Charmap(a.m_[0] & b.m_[0], a.m_[1] & b.m_[1], a.m_[2] & b.m_[2],
92 friend constexpr Charmap operator|(const Charmap& a, const Charmap& b) {
93 return Charmap(a.m_[0] | b.m_[0], a.m_[1] | b.m_[1], a.m_[2] | b.m_[2],
97 friend constexpr Charmap operator~(const Charmap& a) {
98 return Charmap(~a.m_[0], ~a.m_[1], ~a.m_[2], ~a.m_[3]);
102 constexpr Charmap(uint64_t b0, uint64_t b1, uint64_t b2, uint64_t b3)
103 : m_{b0, b1, b2, b3} {}
105 static constexpr uint64_t RangeForWord(unsigned char lo, unsigned char hi,
107 return OpenRangeFromZeroForWord(hi + 1, word) &
108 ~OpenRangeFromZeroForWord(lo, word);
111 // All the chars in the specified word of the range [0, upper).
112 static constexpr uint64_t OpenRangeFromZeroForWord(uint64_t upper,
114 return (upper <= 64 * word)
116 : (upper >= 64 * (word + 1))
117 ? ~static_cast<uint64_t>(0)
118 : (~static_cast<uint64_t>(0) >> (64 - upper % 64));
121 static constexpr uint64_t CharMaskForWord(unsigned char x, uint64_t word) {
122 return (x / 64 == word) ? (static_cast<uint64_t>(1) << (x % 64)) : 0;
126 void SetChar(unsigned char c) {
127 m_[c / 64] |= static_cast<uint64_t>(1) << (c % 64);
133 // Mirror the char-classifying predicates in <cctype>
134 constexpr Charmap UpperCharmap() { return Charmap::Range('A', 'Z'); }
135 constexpr Charmap LowerCharmap() { return Charmap::Range('a', 'z'); }
136 constexpr Charmap DigitCharmap() { return Charmap::Range('0', '9'); }
137 constexpr Charmap AlphaCharmap() { return LowerCharmap() | UpperCharmap(); }
138 constexpr Charmap AlnumCharmap() { return DigitCharmap() | AlphaCharmap(); }
139 constexpr Charmap XDigitCharmap() {
140 return DigitCharmap() | Charmap::Range('A', 'F') | Charmap::Range('a', 'f');
142 constexpr Charmap PrintCharmap() { return Charmap::Range(0x20, 0x7e); }
143 constexpr Charmap SpaceCharmap() { return Charmap::FromString("\t\n\v\f\r "); }
144 constexpr Charmap CntrlCharmap() {
145 return Charmap::Range(0, 0x7f) & ~PrintCharmap();
147 constexpr Charmap BlankCharmap() { return Charmap::FromString("\t "); }
148 constexpr Charmap GraphCharmap() { return PrintCharmap() & ~SpaceCharmap(); }
149 constexpr Charmap PunctCharmap() { return GraphCharmap() & ~AlnumCharmap(); }
151 } // namespace strings_internal
154 #endif // ABSL_STRINGS_INTERNAL_CHAR_MAP_H_