1 files changed, 149 insertions, 0 deletions
diff --git a/include/svl/whichranges.hxx b/include/svl/whichranges.hxx
new file mode 100644
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+++ b/include/svl/whichranges.hxx
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+/* -*- 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/.
+ */
+#pragma once
+
+#include <sal/config.h>
+#include <sal/types.h>
+#include <svl/svldllapi.h>
+#include <array>
+#include <memory>
+#include <cassert>
+
+typedef std::pair<sal_uInt16, sal_uInt16> WhichPair;
+
+namespace svl
+{
+namespace detail
+{
+constexpr bool validRange(sal_uInt16 wid1, sal_uInt16 wid2) { return wid1 != 0 && wid1 <= wid2; }
+
+constexpr bool validGap(sal_uInt16 wid1, sal_uInt16 wid2) { return wid2 > wid1; }
+
+template <sal_uInt16 WID1, sal_uInt16 WID2> constexpr bool validRanges()
+{
+    return validRange(WID1, WID2);
+}
+
+template <sal_uInt16 WID1, sal_uInt16 WID2, sal_uInt16 WID3, sal_uInt16... WIDs>
+constexpr bool validRanges()
+{
+    return validRange(WID1, WID2) && validGap(WID2, WID3) && validRanges<WID3, WIDs...>();
+}
+
+// The calculations in rangeSize cannot overflow, assuming
+// std::size_t is no smaller than sal_uInt16:
+constexpr std::size_t rangeSize(sal_uInt16 wid1, sal_uInt16 wid2)
+{
+    assert(validRange(wid1, wid2));
+    return wid2 - wid1 + 1;
+}
+}
+
+template <sal_uInt16... WIDs> struct Items_t
+{
+    using Array = std::array<WhichPair, sizeof...(WIDs) / 2>;
+    template <sal_uInt16 WID1, sal_uInt16 WID2, sal_uInt16... Rest>
+    static constexpr void fill(typename Array::iterator it)
+    {
+        it->first = WID1;
+        it->second = WID2;
+        if constexpr (sizeof...(Rest) > 0)
+            fill<Rest...>(++it);
+    }
+    static constexpr Array make()
+    {
+        assert(svl::detail::validRanges<WIDs...>());
+        Array a{};
+        fill<WIDs...>(a.begin());
+        return a;
+    }
+    // This is passed to WhichRangesContainer so we can avoid needing to malloc()
+    // for compile-time data.
+    static constexpr Array value = make();
+};
+
+template <sal_uInt16... WIDs> inline static constexpr auto Items = Items_t<WIDs...>{};
+}
+
+#define INVALID_WHICHPAIR_OFFSET (sal_uInt16(0xffff))
+
+/**
+ * Most of the time, the which ranges we point at are a compile-time literal.
+ * So we take advantage of that, and avoid the cost of allocating our own array and copying into it.
+ */
+struct SVL_DLLPUBLIC WhichRangesContainer
+{
+    using const_iterator = WhichPair const*;
+
+    WhichPair const* m_pairs = nullptr;
+    sal_Int32 m_size = 0;
+    /** if true, we allocated and need to delete the pairs, if not, we are pointing
+      * at a global const literal */
+    bool m_bOwnRanges = false;
+
+    // variables for buffering the last used WhichPair to allow fast answers
+    // in getOffsetFromWhich
+    mutable sal_uInt16 m_aLastWhichPairOffset = INVALID_WHICHPAIR_OFFSET;
+    mutable sal_uInt16 m_aLastWhichPairFirst = 0;
+    mutable sal_uInt16 m_aLastWhichPairSecond = 0;
+
+    WhichRangesContainer() = default;
+
+    WhichRangesContainer(std::unique_ptr<WhichPair[]> wids, sal_Int32 nSize)
+        : m_pairs(wids.release())
+        , m_size(nSize)
+        , m_bOwnRanges(true)
+        , m_aLastWhichPairOffset(INVALID_WHICHPAIR_OFFSET)
+        , m_aLastWhichPairFirst(0)
+        , m_aLastWhichPairSecond(0)
+    {
+    }
+    template <sal_uInt16... WIDs>
+    WhichRangesContainer(svl::Items_t<WIDs...>)
+        : m_pairs(svl::Items_t<WIDs...>::value.data())
+        , m_size(svl::Items_t<WIDs...>::value.size())
+        , m_bOwnRanges(false)
+        , m_aLastWhichPairOffset(INVALID_WHICHPAIR_OFFSET)
+        , m_aLastWhichPairFirst(0)
+        , m_aLastWhichPairSecond(0)
+    {
+    }
+    WhichRangesContainer(const WhichPair* wids, sal_Int32 nSize);
+    WhichRangesContainer(sal_uInt16 nWhichStart, sal_uInt16 nWhichEnd);
+    WhichRangesContainer(WhichRangesContainer const& other) { operator=(other); }
+    WhichRangesContainer(WhichRangesContainer&& other);
+    ~WhichRangesContainer();
+
+    WhichRangesContainer& operator=(WhichRangesContainer&& other);
+    WhichRangesContainer& operator=(WhichRangesContainer const& other);
+
+    bool operator==(WhichRangesContainer const& other) const;
+    const_iterator begin() const noexcept { return m_pairs; }
+    const_iterator end() const noexcept { return begin() + size(); }
+    bool empty() const noexcept { return m_size == 0; }
+    sal_Int32 size() const noexcept { return m_size; }
+    WhichPair const& operator[](sal_Int32 idx) const noexcept
+    {
+        assert(idx >= 0 && idx < size() && "index out of range");
+        return m_pairs[idx];
+    }
+    void reset();
+
+    // calculate and return the offset inside the fixed SfxPoolItem
+    // array of SfxItemPool
+    sal_uInt16 getOffsetFromWhich(sal_uInt16 nWhich) const;
+
+    // extract the WhichID for given offset
+    sal_uInt16 getWhichFromOffset(sal_uInt16 nOffset) const;
+
+    // Adds a range to which ranges, keeping the ranges in valid state (sorted, non-overlapping)
+    SAL_WARN_UNUSED_RESULT WhichRangesContainer MergeRange(sal_uInt16 nFrom, sal_uInt16 nTo) const;
+};
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */