THUAI6/CAPI/cpp/grpc/include/re2/stringpiece.h

// Copyright 2001-2010 The RE2 Authors.  All Rights Reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

#ifndef RE2_STRINGPIECE_H_
#define RE2_STRINGPIECE_H_

// A string-like object that points to a sized piece of memory.
//
// Functions or methods may use const StringPiece& parameters to accept either
// a "const char*" or a "string" value that will be implicitly converted to
// a StringPiece.  The implicit conversion means that it is often appropriate
// to include this .h file in other files rather than forward-declaring
// StringPiece as would be appropriate for most other Google classes.
//
// Systematic usage of StringPiece is encouraged as it will reduce unnecessary
// conversions from "const char*" to "string" and back again.
//
//
// Arghh!  I wish C++ literals were "string".

// Doing this simplifies the logic below.
#ifndef __has_include
#define __has_include(x) 0
#endif

#include <stddef.h>
#include <string.h>
#include <algorithm>
#include <iosfwd>
#include <iterator>
#include <string>
#if __has_include(<string_view>) && __cplusplus >= 201703L
#include <string_view>
#endif

namespace re2
{

    class StringPiece
    {
    public:
        typedef std::char_traits<char> traits_type;
        typedef char value_type;
        typedef char* pointer;
        typedef const char* const_pointer;
        typedef char& reference;
        typedef const char& const_reference;
        typedef const char* const_iterator;
        typedef const_iterator iterator;
        typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
        typedef const_reverse_iterator reverse_iterator;
        typedef size_t size_type;
        typedef ptrdiff_t difference_type;
        static const size_type npos = static_cast<size_type>(-1);

        // We provide non-explicit singleton constructors so users can pass
        // in a "const char*" or a "string" wherever a "StringPiece" is
        // expected.
        StringPiece() :
            data_(NULL),
            size_(0)
        {
        }
#if __has_include(<string_view>) && __cplusplus >= 201703L
        StringPiece(const std::string_view& str) :
            data_(str.data()),
            size_(str.size())
        {
        }
#endif
        StringPiece(const std::string& str) :
            data_(str.data()),
            size_(str.size())
        {
        }
        StringPiece(const char* str) :
            data_(str),
            size_(str == NULL ? 0 : strlen(str))
        {
        }
        StringPiece(const char* str, size_type len) :
            data_(str),
            size_(len)
        {
        }

        const_iterator begin() const
        {
            return data_;
        }
        const_iterator end() const
        {
            return data_ + size_;
        }
        const_reverse_iterator rbegin() const
        {
            return const_reverse_iterator(data_ + size_);
        }
        const_reverse_iterator rend() const
        {
            return const_reverse_iterator(data_);
        }

        size_type size() const
        {
            return size_;
        }
        size_type length() const
        {
            return size_;
        }
        bool empty() const
        {
            return size_ == 0;
        }

        const_reference operator[](size_type i) const
        {
            return data_[i];
        }
        const_pointer data() const
        {
            return data_;
        }

        void remove_prefix(size_type n)
        {
            data_ += n;
            size_ -= n;
        }

        void remove_suffix(size_type n)
        {
            size_ -= n;
        }

        void set(const char* str)
        {
            data_ = str;
            size_ = str == NULL ? 0 : strlen(str);
        }

        void set(const char* str, size_type len)
        {
            data_ = str;
            size_ = len;
        }

        // Converts to `std::basic_string`.
        template<typename A>
        explicit operator std::basic_string<char, traits_type, A>() const
        {
            if (!data_)
                return {};
            return std::basic_string<char, traits_type, A>(data_, size_);
        }

        std::string as_string() const
        {
            return std::string(data_, size_);
        }

        // We also define ToString() here, since many other string-like
        // interfaces name the routine that converts to a C++ string
        // "ToString", and it's confusing to have the method that does that
        // for a StringPiece be called "as_string()".  We also leave the
        // "as_string()" method defined here for existing code.
        std::string ToString() const
        {
            return std::string(data_, size_);
        }

        void CopyToString(std::string* target) const
        {
            target->assign(data_, size_);
        }

        void AppendToString(std::string* target) const
        {
            target->append(data_, size_);
        }

        size_type copy(char* buf, size_type n, size_type pos = 0) const;
        StringPiece substr(size_type pos = 0, size_type n = npos) const;

        int compare(const StringPiece& x) const
        {
            size_type min_size = std::min(size(), x.size());
            if (min_size > 0)
            {
                int r = memcmp(data(), x.data(), min_size);
                if (r < 0)
                    return -1;
                if (r > 0)
                    return 1;
            }
            if (size() < x.size())
                return -1;
            if (size() > x.size())
                return 1;
            return 0;
        }

        // Does "this" start with "x"?
        bool starts_with(const StringPiece& x) const
        {
            return x.empty() ||
                   (size() >= x.size() && memcmp(data(), x.data(), x.size()) == 0);
        }

        // Does "this" end with "x"?
        bool ends_with(const StringPiece& x) const
        {
            return x.empty() ||
                   (size() >= x.size() &&
                    memcmp(data() + (size() - x.size()), x.data(), x.size()) == 0);
        }

        bool contains(const StringPiece& s) const
        {
            return find(s) != npos;
        }

        size_type find(const StringPiece& s, size_type pos = 0) const;
        size_type find(char c, size_type pos = 0) const;
        size_type rfind(const StringPiece& s, size_type pos = npos) const;
        size_type rfind(char c, size_type pos = npos) const;

    private:
        const_pointer data_;
        size_type size_;
    };

    inline bool operator==(const StringPiece& x, const StringPiece& y)
    {
        StringPiece::size_type len = x.size();
        if (len != y.size())
            return false;
        return x.data() == y.data() || len == 0 ||
               memcmp(x.data(), y.data(), len) == 0;
    }

    inline bool operator!=(const StringPiece& x, const StringPiece& y)
    {
        return !(x == y);
    }

    inline bool operator<(const StringPiece& x, const StringPiece& y)
    {
        StringPiece::size_type min_size = std::min(x.size(), y.size());
        int r = min_size == 0 ? 0 : memcmp(x.data(), y.data(), min_size);
        return (r < 0) || (r == 0 && x.size() < y.size());
    }

    inline bool operator>(const StringPiece& x, const StringPiece& y)
    {
        return y < x;
    }

    inline bool operator<=(const StringPiece& x, const StringPiece& y)
    {
        return !(x > y);
    }

    inline bool operator>=(const StringPiece& x, const StringPiece& y)
    {
        return !(x < y);
    }

    // Allow StringPiece to be logged.
    std::ostream& operator<<(std::ostream& o, const StringPiece& p);

}  // namespace re2

#endif  // RE2_STRINGPIECE_H_