create o3tl::array_view

A very basic implementation of the proposed std::array_view, similar to
clang's llvm::ArrayRef.

Mostly cribbed from the string_view implementation :-)

Use it for the SfxDispatcher::setSlotFilter function

Change-Id: Ife7e4971741b41827e145787899872c9b2bea82b
Reviewed-on: https://gerrit.libreoffice.org/38817
Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>

1 files changed, 169 insertions, 0 deletions

diff --git a/include/o3tl/array_view.hxx b/include/o3tl/array_view.hxx
new file mode 100644
index 000000000000..9da86866680e
--- /dev/null
+++ b/include/o3tl/array_view.hxx
@@ -0,0 +1,169 @@
+/* -*- 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_ARRAY_VIEW_HXX
+#define INCLUDED_O3TL_ARRAY_VIEW_HXX
+
+#include <sal/config.h>
+
+#include <algorithm>
+#include <cstddef>
+#include <ios>
+#include <iterator>
+#include <ostream>
+#include <stdexcept>
+#include <string>
+#include <type_traits>
+#include <utility>
+
+#include <config_global.h>
+#include <rtl/string.hxx>
+#include <rtl/ustring.hxx>
+#include <sal/types.h>
+
+// A barebones approximation of C++17(?) <array_view>, haven't bothered with more than single-dimensional arrays
+
+#if HAVE_CXX14_CONSTEXPR
+#define CONSTEXPR constexpr
+#else
+#define CONSTEXPR
+#endif
+
+namespace o3tl {
+
+#if defined _MSC_VER
+#pragma warning(push, 1)
+#pragma warning(disable: 4814) // in C++14 'constexpr' will not imply 'const'
+#endif
+
+template<typename T>
+class array_view {
+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 = const_iterator;
+    using const_reverse_iterator = std::reverse_iterator<const_iterator>;
+    using reverse_iterator = const_reverse_iterator;
+    using size_type = std::size_t;
+    using difference_type = std::ptrdiff_t;
+
+    static constexpr size_type npos = size_type(-1);
+
+    constexpr array_view() noexcept : data_(nullptr), size_(0) {}
+
+    template<size_type N>
+    CONSTEXPR array_view (T const (&a)[N]) noexcept : data_(a), size_(N) {}
+
+    CONSTEXPR array_view (T const *a, size_type len) noexcept
+        : data_(a), size_(len)
+    {
+#if HAVE_CXX14_CONSTEXPR
+        // not terribly sure about this, might need to relax it
+        assert((a == nullptr && len == 0) || (a != nullptr && len > 0));
+#endif
+    }
+
+    constexpr bool            empty() const noexcept { return size_ == 0; }
+
+    constexpr const_iterator begin() const noexcept { return data_; }
+    constexpr const_iterator end() const noexcept { return begin() + size(); }
+
+    constexpr const_iterator cbegin() const noexcept { return begin(); }
+    constexpr const_iterator cend() const noexcept { return end(); }
+
+    constexpr const_reverse_iterator rbegin() const noexcept
+    { return const_reverse_iterator(end()); }
+    constexpr const_reverse_iterator rend() const noexcept
+    { return const_reverse_iterator(begin()); }
+
+    constexpr const_reverse_iterator crbegin() const noexcept
+    { return rbegin(); }
+    constexpr const_reverse_iterator crend() const noexcept { return rend(); }
+
+    constexpr size_type size() const noexcept { return size_; }
+    constexpr size_type length() const noexcept { return size(); }
+
+#if !defined __clang__ || HAVE_CXX14_CONSTEXPR
+    constexpr
+#endif
+    size_type max_size() const noexcept {
+#if defined __clang__ // avoid constexpr issues with other, older compilers
+        (void) this; // loplugin:staticmethods
+#endif
+        return npos - 1;
+    }
+
+    constexpr const_reference operator [](size_type pos) const {
+#if HAVE_CXX14_CONSTEXPR
+        assert(pos < size());
+#endif
+        return data_[pos];
+    }
+
+    CONSTEXPR
+    const_reference at(size_type pos) const {
+        if (pos >= size()) {
+            throw std::out_of_range("o3tl::array_view::at");
+        }
+        return operator [](pos);
+    }
+
+    constexpr const_reference front() const {
+#if HAVE_CXX14_CONSTEXPR
+        assert(!empty());
+#endif
+        return operator [](0);
+    }
+
+    constexpr const_reference back() const {
+#if HAVE_CXX14_CONSTEXPR
+        assert(!empty());
+#endif
+        return operator [](size() - 1);
+    }
+
+    constexpr const_pointer data() const noexcept { return data_; }
+
+    CONSTEXPR void swap(array_view & s) noexcept {
+        std::swap(data_, s.data_);
+        std::swap(size_, s.size_);
+    }
+
+private:
+    const_pointer data_;
+    size_type     size_;
+};
+
+
+#if defined _MSC_VER
+#pragma warning(pop)
+#endif
+
+} // namespace o3tl
+
+namespace std {
+
+template<typename T>
+struct hash<o3tl::array_view<T>> {
+    std::size_t operator()(o3tl::array_view<T> s)
+    { return hash<T[]>()(s.data(), s.size()); }
+};
+
+} // namespace std
+
+
+#undef CONSTEXPR
+
+#endif
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */