Assert on valid order of which ids in ranges on SfxItemSet creation

This allows to make sure we actually use sorted which ranges,
and then it's safe to call SfxItemSet::MergeRange when needed.

Also this change relaxes the previous requirement that ranges
must be separated by at least one; this allows to have adjacent
ranges, like in

    RES_FRMATR_BEGIN, RES_FRMATR_END-1,
    RES_GRFATR_BEGIN, RES_GRFATR_END-1,

where RES_FRMATR_END is equal to RES_GRFATR_BEGIN. Allowing this
makes possible to (1) self-document the ranges, so it's clear
which ranges are included; and (2) be safe in case when these
constants would change, so that the one merged range would not
unexpectedly contain everything inserted between RES_FRMATR_END
and RES_GRFATR_BEGIN.

Change-Id: Iaad0f099b85059b3aa318a347aa7fbd3f6d455c7
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/116909
Tested-by: Jenkins
Reviewed-by: Mike Kaganski <mike.kaganski@collabora.com>
(cherry picked from commit 8aaa28ed43978a9a4a20d62368410a57ec05c23f)
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/117114

1 files changed, 35 insertions, 4 deletions

diff --git a/include/svl/itemset.hxx b/include/svl/itemset.hxx
index 41a782d7966f..d4a9304a85dd 100644
--- a/include/svl/itemset.hxx
+++ b/include/svl/itemset.hxx
@@ -21,11 +21,13 @@
 
 #include <sal/config.h>
 
+#include <array>
 #include <cassert>
 #include <cstddef>
 #include <initializer_list>
 #include <type_traits>
 #include <memory>
+#include <utility>
 
 #include <svl/svldllapi.h>
 #include <svl/poolitem.hxx>
@@ -41,7 +43,7 @@ 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 && wid2 - wid1 > 1; }
+{ return wid2 > wid1; }
 
 template<sal_uInt16 WID1, sal_uInt16 WID2> constexpr bool validRanges()
 { return validRange(WID1, WID2); }
@@ -52,6 +54,19 @@ constexpr bool validRanges() {
         && validRanges<WID3, WIDs...>();
 }
 
+inline constexpr bool validRanges(const sal_uInt16* pRanges)
+{
+    for (auto p = pRanges; p && *p; p += 2)
+    {
+        if (!validRange(p[0], p[1]))
+            return false;
+        // ranges must be sorted
+        if (p[2] != 0 && !validGap(p[1], p[2]))
+            return false;
+    }
+    return true;
+}
+
 // The calculations in rangeSize and rangesSize cannot overflow, assuming
 // std::size_t is no smaller than sal_uInt16:
 
@@ -71,6 +86,24 @@ constexpr std::size_t rangesSize()
 
 template<sal_uInt16... WIDs> struct Items {};
 
+// This allows creating compile-time which id arrays using syntax like
+//
+//     constexpr auto aWids = svl::ItemsArray({ { widFrom1, widTo2 }, { widFrom2, widTo2 }, ... });
+//
+// so that e.g. clang-format would not try to rearrange the initializer sequence to break pairs.
+// Additionally, the array validity is checked in debug builds.
+template <size_t N> constexpr auto ItemsArray(const std::pair<sal_uInt16, sal_uInt16> (&wids)[N])
+{
+    std::array<sal_uInt16, N * 2 + 1> aArray{};
+    sal_uInt16* p = aArray.data();
+    for (const auto& [wid1, wid2] : wids)
+    {
+        *p++ = wid1;
+        *p++ = wid2;
+    }
+    assert(svl::detail::validRanges(aArray.data()));
+    return aArray;
+}
 }
 
 class SAL_WARN_UNUSED SVL_DLLPUBLIC SfxItemSet
@@ -88,7 +121,7 @@ friend class SfxItemPoolCache;
 friend class SfxAllItemSet;
 
 private:
-    SVL_DLLPRIVATE void                     InitRanges_Impl(const sal_uInt16 *nWhichPairTable);
+    SVL_DLLPRIVATE sal_uInt16 InitRanges_Impl(const sal_uInt16 *nWhichPairTable);
 
     SfxItemSet(
         SfxItemPool & pool, std::initializer_list<sal_uInt16> wids,
@@ -249,8 +282,6 @@ class SVL_DLLPUBLIC SfxAllItemSet: public SfxItemSet
 //  Handles all Ranges. Ranges are automatically modified by putting items.
 
 {
-    sal_uInt16                      nFree;
-
 public:
                                 SfxAllItemSet( SfxItemPool &rPool );
                                 SfxAllItemSet( const SfxItemSet & );