More implementation of the C standard library.

targets/_any/bastl/include/string_view

@@ -0,0 +1,82 @@
+
+#pragma once
+
+#if !defined(BAD_APPLE_OS_STRING_VIEW_INCLUDED)
+#define BAD_APPLE_OS_STRING_VIEW_INCLUDED
+
+#include <limits>
+#include <stdexcept>
+#include <string>
+
+namespace std
+{
+template<typename CharT, typename Traits = char_traits<CharT>>
+class basic_string_view
+{
+public:
+    using traits_type = Traits;
+    using value_type = CharT;
+    using pointer = CharT*;
+    using const_pointer = const CharT*;
+    using reference = CharT&;
+    using const_reference = const CharT&;
+    using iterator = const CharT*;
+    using const_iterator = const CharT*;
+    // TODO: reverse iterators
+    using size_type = size_t;
+    using difference_type = ptrdiff_t;
+private:
+    const_pointer _begin = nullptr;
+    const_pointer _end = nullptr;
+public:
+    constexpr basic_string_view() noexcept = default;
+    constexpr basic_string_view(const basic_string_view&) noexcept = default;
+    constexpr basic_string_view(const_pointer s, size_type count) noexcept : _begin(s), _end(s + count) {}
+    constexpr basic_string_view(const_pointer s) noexcept : _begin(s), _end(s)
+    {
+        while (*_end) { ++_end; }
+    }
+    template<typename It, typename End>
+    constexpr basic_string_view(It first, End last) noexcept : _begin(first), _end(last) {}
+    constexpr basic_string_view(nullptr_t) = delete;
+
+    constexpr basic_string_view& operator=(const basic_string_view&) noexcept = default;
+
+    [[nodiscard]] constexpr iterator begin() const noexcept { return _begin; }
+    [[nodiscard]] constexpr const_iterator cbegin() const noexcept { return _begin; }
+    [[nodiscard]] constexpr iterator end() const noexcept { return _end; }
+    [[nodiscard]] constexpr const_iterator cend() const noexcept { return _end; }
+    // TODO: reverse iterators
+
+    [[nodiscard]] constexpr const_reference operator[](size_type pos) const noexcept { return _begin[pos]; }
+    [[nodiscard]] constexpr const_reference at(size_type pos) const
+    {
+        if (pos >= size()) {
+            __ba_throw out_of_range();
+        }
+        return _begin[pos];
+    }
+    [[nodiscard]] constexpr const_reference front() const noexcept { return *_begin; }
+    [[nodiscard]] constexpr const_reference back() const noexcept { return _end[-1]; }
+    [[nodiscard]] constexpr const_pointer data() const noexcept { return _begin; }
+
+    [[nodiscard]] constexpr size_type size() const noexcept { return _end - _begin; }
+    [[nodiscard]] constexpr size_type length() const noexcept { return _end - _begin; }
+    [[nodiscard]] constexpr size_type max_size() const noexcept { return numeric_limits<size_type>::max(); }
+    [[nodiscard]] constexpr bool empty() const noexcept { return size() == 0; }
+
+    constexpr void remove_prefix(size_type n) noexcept { _begin += n; }
+    constexpr void remove_suffix(size_type n) noexcept { _end -= n; }
+
+    constexpr void swap(basic_string_view& v) noexcept
+    {
+        swap(_begin, v._begin);
+        swap(_end, v._end);
+    }
+};
+
+using string_view = basic_string_view<char>;
+using wstring_view = basic_string_view<wchar_t>;
+}
+
+#endif // !defined(BAD_APPLE_OS_STRING_VIEW_INCLUDED)