COPrimitiveCollection update issues

[ericwa]

Quentin says: (from 793a447#commitcomment-15704526 )

The current way of updating COPrimitiveCollection content has some logic holes, so this needs to be rewritten. I'll take a look at this soon.

For example, we probably want to pass an argument 'isDeserialization' to -setValue:forVariableStorageKey: so we can choose correctly between making a copy or updating the current collection content.

At deserialization time in -setValue:forVariableStorageKey:, we want to:

• avoid copying a COPrimitiveCollection argument (just created by the deserialization code)
• keep tombstones from the COPrimitiveCollection argument

If we have an existing collection, tombstones and live content must be replaced/overwritten by the ones from the collection passed in argument.

For a property update in -setValue:forVariableStorageKey:, when we replace a collection with another one, we want to:

• copy the collection in argument or insert its content into our existing collection (to avoid any accidental sharing)
• ignore tombstones (e.g. when we receive a COPrimitiveCollection in argument by doing an update like innerObject1.contents = innerObject2.contents)

This last point means that for COPrimitiveCollection, we cannot copy it but we must use -[COMutableSet setSet], -[COMutableArray setArray:]. Both methods will correctly ignore the tombstones. For any other collections, we could make a copy, but using -[NSMutableSet setSet] and -[NSMutableArray setArray:] works just fine and happens to make the code simpler.