Armin Le Grand (Collabora)
9304f13db6
ItemType is useful and faster than RTTI. Until now it was implemented by a 16-bit member in the base class, plus (potentially) all constructors having to hand a value in at item construction type (of type SfxItemType) to get that member set correctly. This works, but there is no reliable way to guarantee coverage, and there have already been cases with missing SfxItemType - these fallback to '0' and thus all Items with ItemType() == 0 are assumed equal and might be static_cast'ed to the wrong classes. Note that I identified *35* Items that had no correct ItemType set/implemented actually. It also uses 16-bit per incarnated Item at runtime. I thought and realized now a more systematic approach to do that with a pure virtual function at the Item itself. That can also be secured by a clang compiler plugin in the future to keep it working. It uses one virtual function per derived class, no longer space in incarnated Items. Also the constructors will get more simple again. But the main aspect is security - we cannot afford Items potentially being held as equal if they are not. Unfortunately C++ does not offer something like a 'strict pure virtual function' that would force to be overloaded in every derivation, but the used methotology and adding a clang test is reasonably safe. Have now done the cleanup of previous method. Change-Id: I04768285f1e9b73d64b0bb87df401944b5d35678 Reviewed-on: https://gerrit.libreoffice.org/c/core/+/180017 Tested-by: Jenkins Reviewed-by: Armin Le Grand <Armin.Le.Grand@me.com>
Non-Graphical Helper Code (svtools light)
Contains non-graphical helper code for office applications.
Specifically this module does not depend on or use includes from module vcl. Originally all code in svtools that did not depend on vcl was split off into this svl ("svtools light") module.
In particular the SfxItemSet is a property-bag like container that
stores arbitrary sets of properties for everything from text run
formats, to Chart regression line properties.
There are lots of other useful helpers in here for various office
tasks; much of this code was originally moved from svx/sfx2.
Items, Pools and Sets
SfxPoolItem
A small reference counted piece of data. Many subclasses, each with a
unique integer to identify its type (WhichId). Can be compared for equality
(operator==), Clone()d, and converted to/from uno::Any (QueryValue/PutValue).
A pool item may have value semantics ("poolable"), meaning that
there will generally be only one instance that compares equal per item pool,
or not, in which case the item will be Clone()d quite a bit.
SfxItemPool
Usually there is one item pool per document, with a range of valid WhichIds
that is specific to the type of document.
The item pool owns all instances of SfxPoolItem or its subclasses that have
ever been added to an item set. It also contains a default item for
every WhichId, which will be (depending on parameters) returned from item
sets if the set does not contain an item at this WhichId.
SfxItemSet
The item set can be created with a user-supplied range of WhichIds; it
will accept SfxPoolItems with matching WhichIds and ignore attempts to
insert items with non-matching WhichIds.
Items that are successfully inserted into the set will be stored in the
set's SfxItemPool, and for poolable items only a single instance that
compares equal under the predicate operator== will be stored in the pool,
regardless of how many sets contain it, thus conserving memory.
There are members m_pWhichRanges for the valid ranges (as pairs of WhichIds),
m_nCount for the number of items contained, and m_pItems for the pointers to
the actual items.