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esphome/esphome/core/string_ref.h
J. Nick Koston c636984e3a deferred
2026-02-21 21:53:57 -06:00

247 lines
9.5 KiB
C++

#pragma once
#include <cstdint>
#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
#ifdef USE_ESP8266
#include <pgmspace.h>
#endif // USE_ESP8266
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 size_type length() 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(); }
/// Compare (compatible with std::string::compare)
int compare(const StringRef &other) const {
int result = std::memcmp(base_, other.base_, std::min(len_, other.len_));
if (result != 0)
return result;
if (len_ < other.len_)
return -1;
if (len_ > other.len_)
return 1;
return 0;
}
int compare(const char *s) const { return compare(StringRef(s)); }
int compare(const std::string &s) const { return compare(StringRef(s)); }
/// Find first occurrence of substring, returns std::string::npos if not found.
/// Note: Requires the underlying string to be null-terminated.
size_type find(const char *s, size_type pos = 0) const {
if (pos >= len_)
return std::string::npos;
const char *result = std::strstr(base_ + pos, s);
// Verify entire match is within bounds (strstr searches to null terminator)
if (result && result + std::strlen(s) <= base_ + len_)
return static_cast<size_type>(result - base_);
return std::string::npos;
}
size_type find(char c, size_type pos = 0) const {
if (pos >= len_)
return std::string::npos;
const void *result = std::memchr(base_ + pos, static_cast<unsigned char>(c), len_ - pos);
return result ? static_cast<size_type>(static_cast<const char *>(result) - base_) : std::string::npos;
}
/// Return substring as std::string
std::string substr(size_type pos = 0, size_type count = std::string::npos) const {
if (pos >= len_)
return std::string();
size_type actual_count = (count == std::string::npos || pos + count > len_) ? len_ - pos : count;
return std::string(base_ + pos, actual_count);
}
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); }
#ifdef USE_ESP8266
inline bool operator==(const StringRef &lhs, const __FlashStringHelper *rhs) {
PGM_P p = reinterpret_cast<PGM_P>(rhs);
size_t rhs_len = strlen_P(p);
if (lhs.size() != rhs_len) {
return false;
}
return memcmp_P(lhs.c_str(), p, rhs_len) == 0;
}
inline bool operator==(const __FlashStringHelper *lhs, const StringRef &rhs) { return rhs == lhs; }
inline bool operator!=(const StringRef &lhs, const __FlashStringHelper *rhs) { return !(lhs == rhs); }
inline bool operator!=(const __FlashStringHelper *lhs, const StringRef &rhs) { return !(rhs == lhs); }
#endif // USE_ESP8266
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;
}
inline std::string operator+(const StringRef &lhs, const std::string &rhs) {
auto str = lhs.str();
str.append(rhs);
return str;
}
inline std::string operator+(const std::string &lhs, const StringRef &rhs) {
std::string str(lhs);
str.append(rhs.c_str(), rhs.size());
return str;
}
// String conversion functions for ADL compatibility (allows stoi(x) where x is StringRef)
// Must be in esphome namespace for ADL to find them. Uses strtol/strtod directly to avoid heap allocation.
namespace internal {
// NOLINTBEGIN(google-runtime-int)
template<typename R, typename F> inline R parse_number(const StringRef &str, size_t *pos, F conv) {
char *end;
R result = conv(str.c_str(), &end);
// Set pos to 0 on conversion failure (when no characters consumed), otherwise index after number
if (pos)
*pos = (end == str.c_str()) ? 0 : static_cast<size_t>(end - str.c_str());
return result;
}
template<typename R, typename F> inline R parse_number(const StringRef &str, size_t *pos, int base, F conv) {
char *end;
R result = conv(str.c_str(), &end, base);
// Set pos to 0 on conversion failure (when no characters consumed), otherwise index after number
if (pos)
*pos = (end == str.c_str()) ? 0 : static_cast<size_t>(end - str.c_str());
return result;
}
// NOLINTEND(google-runtime-int)
} // namespace internal
// NOLINTBEGIN(readability-identifier-naming,google-runtime-int)
inline int stoi(const StringRef &str, size_t *pos = nullptr, int base = 10) {
return static_cast<int>(internal::parse_number<long>(str, pos, base, std::strtol));
}
inline long stol(const StringRef &str, size_t *pos = nullptr, int base = 10) {
return internal::parse_number<long>(str, pos, base, std::strtol);
}
inline float stof(const StringRef &str, size_t *pos = nullptr) {
return internal::parse_number<float>(str, pos, std::strtof);
}
inline double stod(const StringRef &str, size_t *pos = nullptr) {
return internal::parse_number<double>(str, pos, std::strtod);
}
// NOLINTEND(readability-identifier-naming,google-runtime-int)
#ifdef USE_JSON
// NOLINTNEXTLINE(readability-identifier-naming)
inline void convertToJson(const StringRef &src, JsonVariant dst) { dst.set(src.c_str()); }
#endif // USE_JSON
} // namespace esphome