esphome/esphome/core/string_ref.h
2023-05-04 10:13:30 +12:00

135 lines
5.1 KiB
C++

#pragma once
#include <cstring>
#include <iterator>
#include <memory>
#include <string>
#include "esphome/core/defines.h"
#ifdef USE_JSON
#include "esphome/components/json/json_util.h"
#endif // USE_JSON
namespace esphome {
/**
* StringRef is a reference to a string owned by something else. So it behaves like simple string, but it does not own
* pointer. When it is default constructed, it has empty string. You can freely copy or move around this struct, but
* never free its pointer. str() function can be used to export the content as std::string. StringRef is adopted from
* <https://github.com/nghttp2/nghttp2/blob/29cbf8b83ff78faf405d1086b16adc09a8772eca/src/template.h#L376>
*/
class StringRef {
public:
using traits_type = std::char_traits<char>;
using value_type = traits_type::char_type;
using allocator_type = std::allocator<char>;
using size_type = std::allocator_traits<allocator_type>::size_type;
using difference_type = std::allocator_traits<allocator_type>::difference_type;
using const_reference = const value_type &;
using const_pointer = const value_type *;
using const_iterator = const_pointer;
using const_reverse_iterator = std::reverse_iterator<const_iterator>;
constexpr StringRef() : base_(""), len_(0) {}
explicit StringRef(const std::string &s) : base_(s.c_str()), len_(s.size()) {}
explicit StringRef(const char *s) : base_(s), len_(strlen(s)) {}
constexpr StringRef(const char *s, size_t n) : base_(s), len_(n) {}
template<typename CharT>
constexpr StringRef(const CharT *s, size_t n) : base_(reinterpret_cast<const char *>(s)), len_(n) {}
template<typename InputIt>
StringRef(InputIt first, InputIt last)
: base_(reinterpret_cast<const char *>(&*first)), len_(std::distance(first, last)) {}
template<typename InputIt>
StringRef(InputIt *first, InputIt *last)
: base_(reinterpret_cast<const char *>(first)), len_(std::distance(first, last)) {}
template<typename CharT, size_t N> constexpr static StringRef from_lit(const CharT (&s)[N]) {
return StringRef{s, N - 1};
}
static StringRef from_maybe_nullptr(const char *s) {
if (s == nullptr) {
return StringRef();
}
return StringRef(s);
}
constexpr const_iterator begin() const { return base_; };
constexpr const_iterator cbegin() const { return base_; };
constexpr const_iterator end() const { return base_ + len_; };
constexpr const_iterator cend() const { return base_ + len_; };
const_reverse_iterator rbegin() const { return const_reverse_iterator{base_ + len_}; }
const_reverse_iterator crbegin() const { return const_reverse_iterator{base_ + len_}; }
const_reverse_iterator rend() const { return const_reverse_iterator{base_}; }
const_reverse_iterator crend() const { return const_reverse_iterator{base_}; }
constexpr const char *c_str() const { return base_; }
constexpr size_type size() const { return len_; }
constexpr bool empty() const { return len_ == 0; }
constexpr const_reference operator[](size_type pos) const { return *(base_ + pos); }
std::string str() const { return std::string(base_, len_); }
const uint8_t *byte() const { return reinterpret_cast<const uint8_t *>(base_); }
operator std::string() const { return str(); }
private:
const char *base_;
size_type len_;
};
inline bool operator==(const StringRef &lhs, const StringRef &rhs) {
return lhs.size() == rhs.size() && std::equal(std::begin(lhs), std::end(lhs), std::begin(rhs));
}
inline bool operator==(const StringRef &lhs, const std::string &rhs) {
return lhs.size() == rhs.size() && std::equal(std::begin(lhs), std::end(lhs), std::begin(rhs));
}
inline bool operator==(const std::string &lhs, const StringRef &rhs) { return rhs == lhs; }
inline bool operator==(const StringRef &lhs, const char *rhs) {
return lhs.size() == strlen(rhs) && std::equal(std::begin(lhs), std::end(lhs), rhs);
}
inline bool operator==(const char *lhs, const StringRef &rhs) { return rhs == lhs; }
inline bool operator!=(const StringRef &lhs, const StringRef &rhs) { return !(lhs == rhs); }
inline bool operator!=(const StringRef &lhs, const std::string &rhs) { return !(lhs == rhs); }
inline bool operator!=(const std::string &lhs, const StringRef &rhs) { return !(rhs == lhs); }
inline bool operator!=(const StringRef &lhs, const char *rhs) { return !(lhs == rhs); }
inline bool operator!=(const char *lhs, const StringRef &rhs) { return !(rhs == lhs); }
inline bool operator<(const StringRef &lhs, const StringRef &rhs) {
return std::lexicographical_compare(std::begin(lhs), std::end(lhs), std::begin(rhs), std::end(rhs));
}
inline std::string &operator+=(std::string &lhs, const StringRef &rhs) {
lhs.append(rhs.c_str(), rhs.size());
return lhs;
}
inline std::string operator+(const char *lhs, const StringRef &rhs) {
auto str = std::string(lhs);
str.append(rhs.c_str(), rhs.size());
return str;
}
inline std::string operator+(const StringRef &lhs, const char *rhs) {
auto str = lhs.str();
str.append(rhs);
return str;
}
#ifdef USE_JSON
// NOLINTNEXTLINE(readability-identifier-naming)
void convertToJson(const StringRef &src, JsonVariant dst);
#endif // USE_JSON
} // namespace esphome