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// Copyright The OpenTelemetry Authors
// SPDX-License-Identifier: Apache-2.0
#pragma once
#ifdef HAVE_CPP_STDLIB
# include "opentelemetry/std/string_view.h"
#else
# include <algorithm>
# include <cstddef>
# include <cstring>
# include <ostream>
# include <stdexcept>
# include <string>
# include "opentelemetry/version.h"
OPENTELEMETRY_BEGIN_NAMESPACE
namespace nostd
{
using Traits = std::char_traits<char>;
/**
* Back port of std::string_view to work with pre-cpp-17 compilers.
*
* Note: This provides a subset of the methods available on std::string_view but
* tries to be as compatible as possible with the std::string_view interface.
*/
class string_view
{
public:
typedef std::size_t size_type;
static constexpr size_type npos = static_cast<size_type>(-1);
string_view() noexcept : length_(0), data_(nullptr) {}
string_view(const char *str) noexcept : length_(std::strlen(str)), data_(str) {}
string_view(const std::basic_string<char> &str) noexcept
: length_(str.length()), data_(str.c_str())
{}
string_view(const char *str, size_type len) noexcept : length_(len), data_(str) {}
explicit operator std::string() const { return {data_, length_}; }
const char *data() const noexcept { return data_; }
bool empty() const noexcept { return length_ == 0; }
size_type length() const noexcept { return length_; }
size_type size() const noexcept { return length_; }
const char *begin() const noexcept { return data(); }
const char *end() const noexcept { return data() + length(); }
const char &operator[](size_type i) { return *(data() + i); }
string_view substr(size_type pos, size_type n = npos) const
{
if (pos > length_)
{
# if __EXCEPTIONS
throw std::out_of_range{"opentelemetry::nostd::string_view"};
# else
std::terminate();
# endif
}
n = (std::min)(n, length_ - pos);
return string_view(data_ + pos, n);
}
int compare(string_view v) const noexcept
{
size_type len = (std::min)(size(), v.size());
int result = Traits::compare(data(), v.data(), len);
if (result == 0)
result = size() == v.size() ? 0 : (size() < v.size() ? -1 : 1);
return result;
};
int compare(size_type pos1, size_type count1, string_view v) const
{
return substr(pos1, count1).compare(v);
};
int compare(size_type pos1,
size_type count1,
string_view v,
size_type pos2,
size_type count2) const
{
return substr(pos1, count1).compare(v.substr(pos2, count2));
};
int compare(const char *s) const { return compare(string_view(s)); };
int compare(size_type pos1, size_type count1, const char *s) const
{
return substr(pos1, count1).compare(string_view(s));
};
int compare(size_type pos1, size_type count1, const char *s, size_type count2) const
{
return substr(pos1, count1).compare(string_view(s, count2));
};
size_type find(char ch, size_type pos = 0) const noexcept
{
size_type res = npos;
if (pos < length())
{
auto found = Traits::find(data() + pos, length() - pos, ch);
if (found)
{
res = found - data();
}
}
return res;
}
bool operator<(const string_view v) const noexcept { return compare(v) < 0; }
bool operator>(const string_view v) const noexcept { return compare(v) > 0; }
private:
// Note: uses the same binary layout as libstdc++'s std::string_view
// See
// https://github.com/gcc-mirror/gcc/blob/e0c554e4da7310df83bb1dcc7b8e6c4c9c5a2a4f/libstdc%2B%2B-v3/include/std/string_view#L466-L467
size_type length_;
const char *data_;
};
inline bool operator==(string_view lhs, string_view rhs) noexcept
{
return lhs.length() == rhs.length() &&
# if _MSC_VER == 1900
// Avoid SCL error in Visual Studio 2015
(std::memcmp(lhs.data(), rhs.data(), lhs.length()) == 0);
# else
std::equal(lhs.data(), lhs.data() + lhs.length(), rhs.data());
# endif
}
inline bool operator==(string_view lhs, const std::string &rhs) noexcept
{
return lhs == string_view(rhs);
}
inline bool operator==(const std::string &lhs, string_view rhs) noexcept
{
return string_view(lhs) == rhs;
}
inline bool operator==(string_view lhs, const char *rhs) noexcept
{
return lhs == string_view(rhs);
}
inline bool operator==(const char *lhs, string_view rhs) noexcept
{
return string_view(lhs) == rhs;
}
inline bool operator!=(string_view lhs, string_view rhs) noexcept
{
return !(lhs == rhs);
}
inline bool operator!=(string_view lhs, const std::string &rhs) noexcept
{
return !(lhs == rhs);
}
inline bool operator!=(const std::string &lhs, string_view rhs) noexcept
{
return !(lhs == rhs);
}
inline bool operator!=(string_view lhs, const char *rhs) noexcept
{
return !(lhs == rhs);
}
inline bool operator!=(const char *lhs, string_view rhs) noexcept
{
return !(lhs == rhs);
}
inline std::ostream &operator<<(std::ostream &os, string_view s)
{
return os.write(s.data(), static_cast<std::streamsize>(s.length()));
}
} // namespace nostd
OPENTELEMETRY_END_NAMESPACE
namespace std
{
template <>
struct hash<OPENTELEMETRY_NAMESPACE::nostd::string_view>
{
std::size_t operator()(const OPENTELEMETRY_NAMESPACE::nostd::string_view &k) const
{
// TODO: for C++17 that has native support for std::basic_string_view it would
// be more performance-efficient to provide a zero-copy hash.
auto s = std::string(k.data(), k.size());
return std::hash<std::string>{}(s);
}
};
} // namespace std
#endif
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