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#pragma once
#include <cstddef>
#include <string>
#include <string_view>
class Utf8Iterator {
public:
using iterator_category = std::bidirectional_iterator_tag;
using value_type = char32_t;
using difference_type = std::string_view::difference_type;
using pointer = const char32_t*;
using reference = const char32_t&;
private:
std::string_view::iterator mIter;
mutable char32_t mCurrentCodePoint = 0;
mutable bool mDirty = true;
public:
Utf8Iterator(std::string_view::iterator it);
~Utf8Iterator() = default;
Utf8Iterator(const Utf8Iterator& that) = default;
Utf8Iterator& operator=(const Utf8Iterator& that) = default;
Utf8Iterator(Utf8Iterator&& that) = default;
Utf8Iterator& operator=(Utf8Iterator&& that) = default;
Utf8Iterator& operator++();
Utf8Iterator operator++(int);
Utf8Iterator& operator--();
Utf8Iterator operator--(int);
char32_t operator*() const;
std::string_view::iterator AsInternal() const;
friend bool operator==(const Utf8Iterator& lhs, const Utf8Iterator& rhs);
friend bool operator!=(const Utf8Iterator& lhs, const Utf8Iterator& rhs);
friend bool operator==(const Utf8Iterator& lhs, std::string_view::iterator rhs);
friend bool operator!=(const Utf8Iterator& lhs, std::string_view::iterator rhs);
private:
void UpdateCurrentValue() const;
};
class Utf8IterableString {
private:
std::string_view mStr;
public:
Utf8IterableString(std::string_view str);
Utf8Iterator begin() const;
Utf8Iterator end() const;
};
struct StringEqual {
using is_transparent = std::true_type;
bool operator()(std::string_view l, std::string_view r) const noexcept { return l == r; }
};
struct StringHash {
using is_transparent = std::true_type;
auto operator()(std::string_view str) const noexcept { return std::hash<std::string_view>{}(str); }
};
std::u32string ConvertUtf8To32(std::string_view str);
std::string ConvertUtf32To8(std::u32string_view str);
/// Slice the given UTF-8 string into the given range, in codepoints.
std::string_view StringRange(std::string_view str, size_t begin, size_t end);
/// Calculate the given UTF-8 string's number of codepoints.
size_t StringLength(std::string_view str);
struct CodepointInfo {
size_t index;
size_t byteOffset;
};
/// Find info about the last codepoint in the given UTF-8 string.
/// \param str A non-empty UTF-8 encoded string.
CodepointInfo StringLastCodepoint(std::string_view str);
/// Find info about the nth codepoint in the given UTF-8 string. If codepointIdx is larger than the length, info for the last codepoint will be returned.
/// \param str A non-empty UTF-8 encoded string.
CodepointInfo StringCodepoint(std::string_view str, size_t codepointIdx);
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