THUAI6/CAPI/cpp/grpc/include/absl/strings/internal/char_map.h

// 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
{
    ABSL_NAMESPACE_BEGIN
    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-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
    ABSL_NAMESPACE_END
}  // namespace absl

#endif  // ABSL_STRINGS_INTERNAL_CHAR_MAP_H_