Adding upstream version 4:7.4.7.upstream/4%7.4.7upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 100 insertions, 0 deletions

diff --git a/include/o3tl/span.hxx b/include/o3tl/span.hxx
new file mode 100644
index 000000000..cfe4c1ffa
--- /dev/null
+++ b/include/o3tl/span.hxx
@@ -0,0 +1,100 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4; fill-column: 100 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+#ifndef INCLUDED_O3TL_SPAN_HXX
+#define INCLUDED_O3TL_SPAN_HXX
+
+#include <sal/config.h>
+
+#include <config_global.h>
+
+#if HAVE_CPP_SPAN
+
+#include <span>
+
+namespace o3tl { using std::span; }
+
+#else
+
+#include <cassert>
+#include <cstddef>
+#include <iterator>
+#include <type_traits>
+#include <vector>
+
+namespace o3tl {
+
+/** A barebones approximation of C++20 <span>.
+*/
+template<typename T>
+class span {
+public:
+    using value_type = T;
+    using pointer = value_type *;
+    using const_pointer = value_type const *;
+    using reference = value_type &;
+    using const_reference = value_type const &;
+    using const_iterator = const_pointer;
+    using iterator = pointer;
+    using const_reverse_iterator = std::reverse_iterator<const_iterator>;
+    using reverse_iterator = std::reverse_iterator<iterator>;
+    using size_type = std::size_t;
+    using difference_type = std::ptrdiff_t;
+
+    constexpr span() noexcept : data_(nullptr), size_(0) {}
+
+    template<std::size_t N>
+    constexpr span (T (&a)[N]) noexcept : data_(a), size_(N) {}
+
+    constexpr span (T *a, size_type len) noexcept
+        : data_(a), size_(len)
+    {
+        // not terribly sure about this, might need to strengthen it
+        assert(a != nullptr || len == 0);
+    }
+
+    template<typename T2>
+    constexpr span(const std::vector<T2>& vec)
+        : data_(vec.data()), size_(vec.size()) {}
+
+    /** for assigning from span<T> to span<const T> */
+    constexpr span (const span<typename std::remove_const<T>::type>& other) noexcept
+        : data_(other.data()), size_(other.size()) {}
+
+    constexpr bool empty() const noexcept { return size_ == 0; }
+
+    constexpr iterator begin() const noexcept { return data_; }
+    constexpr iterator end() const noexcept { return begin() + size(); }
+
+    reverse_iterator rbegin() const noexcept
+    { return reverse_iterator(end()); }
+    reverse_iterator rend() const noexcept
+    { return reverse_iterator(begin()); }
+
+    constexpr size_type size() const noexcept { return size_; }
+
+    constexpr reference operator [](size_type pos) const {
+        assert(pos < size());
+        return data_[pos];
+    }
+
+    constexpr pointer data() const noexcept { return data_; }
+
+private:
+    pointer    data_;
+    size_type size_;
+};
+
+} // namespace o3tl
+
+#endif
+
+#endif
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */