Added arrayview

CMakeLists.txt

@@ -1,4 +1,5 @@
 set(headers
+    src/arrayview.h
     src/cleanuphelper.h
     src/color_utils.h
     src/cppbitmask.h

cpputils_src.pri

@@ -1,4 +1,5 @@
 HEADERS += \
+    $$PWD/src/arrayview.h \
     $$PWD/src/cleanuphelper.h \
     $$PWD/src/color_utils.h \
     $$PWD/src/cppbitmask.h \

src/arrayview.h

@@ -0,0 +1,126 @@
+#pragma once
+
+// system includes
+#include <cstddef>
+#include <iterator>
+
+namespace cpputils {
+
+//! TODO: replace this with std::span once we switch to C++20
+
+template<typename _Tp>
+struct ArrayView
+{
+    typedef _Tp 	    			      value_type;
+    typedef value_type*			      pointer;
+    typedef const value_type*                       const_pointer;
+    typedef value_type&                   	      reference;
+    typedef const value_type&             	      const_reference;
+    typedef value_type*          		      iterator;
+    typedef const value_type*			      const_iterator;
+    typedef std::size_t                    	      size_type;
+    typedef std::ptrdiff_t                   	      difference_type;
+    typedef std::reverse_iterator<iterator>	      reverse_iterator;
+    typedef std::reverse_iterator<const_iterator>   const_reverse_iterator;
+
+    constexpr ArrayView(pointer begin, pointer end) noexcept :
+        m_begin{begin}, m_end{end}
+    {}
+
+    // Iterators.
+    constexpr iterator begin() noexcept
+    { return iterator(data()); }
+
+    constexpr const_iterator begin() const noexcept
+    { return const_iterator(data()); }
+
+    constexpr iterator end() noexcept
+    { return iterator(data() + size()); }
+
+    constexpr const_iterator end() const noexcept
+    { return const_iterator(data() + size()); }
+
+    constexpr reverse_iterator rbegin() noexcept
+    { return reverse_iterator(end()); }
+
+    constexpr const_reverse_iterator rbegin() const noexcept
+    { return const_reverse_iterator(end()); }
+
+    constexpr reverse_iterator rend() noexcept
+    { return reverse_iterator(begin()); }
+
+    constexpr const_reverse_iterator rend() const noexcept
+    { return const_reverse_iterator(begin()); }
+
+    constexpr const_iterator cbegin() const noexcept
+    { return const_iterator(data()); }
+
+    constexpr const_iterator cend() const noexcept
+    { return const_iterator(data() + size()); }
+
+    constexpr const_reverse_iterator crbegin() const noexcept
+    { return const_reverse_iterator(end()); }
+
+    constexpr const_reverse_iterator crend() const noexcept
+    { return const_reverse_iterator(begin()); }
+
+    // Capacity.
+    constexpr size_type size() const noexcept { return std::distance(m_begin, m_end); }
+
+    constexpr size_type max_size() const noexcept { return size(); }
+
+    constexpr bool empty() const noexcept { return size() == 0; }
+
+    // Element access.
+    constexpr reference operator[](size_type __n) noexcept
+    { return m_begin[__n]; }
+
+    constexpr const_reference operator[](size_type __n) const noexcept
+    { return m_begin[__n]; }
+
+    constexpr reference at(size_type __n)
+    {
+        if (__n >= size())
+          std::__throw_out_of_range_fmt(__N("array_view::at: __n (which is %zu) "
+                            ">= size() (which is %zu)"),
+                        __n, size());
+        return m_begin[__n];
+    }
+
+    constexpr const_reference
+    at(size_type __n) const
+    {
+        // Result of conditional expression must be an lvalue so use
+        // boolean ? lvalue : (throw-expr, lvalue)
+        return __n < size() ? m_begin[__n]
+          : (std::__throw_out_of_range_fmt(__N("array_view::at: __n (which is %zu) "
+                               ">= size() (which is %zu)"),
+                           __n, size()),
+             m_begin[0]);
+    }
+
+    constexpr reference front() noexcept
+    { return *begin(); }
+
+    constexpr const_reference front() const noexcept
+    { return m_begin[0]; }
+
+    constexpr reference back() noexcept
+    { return size() ? *(end() - 1) : *end(); }
+
+    constexpr const_reference back() const noexcept
+    {
+        return size() ? m_begin[size() - 1] : m_begin[0];
+    }
+
+    constexpr pointer data() noexcept
+    { return m_begin; }
+
+    constexpr const_pointer data() const noexcept
+    { return m_begin; }
+
+private:
+    pointer m_begin, m_end;
+};
+
+} // namespace cpputils