1 files changed, 84 insertions, 0 deletions
diff --git a/core/src/Utils/String.hpp b/core/src/Utils/String.hpp
new file mode 100644
index 0000000..f2829d7
--- /dev/null
+++ b/core/src/Utils/String.hpp
@@ -0,0 +1,84 @@
+#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);