The previous iterator was implemented to simply fetch _all_ pathes from
the filesystem, no matter what.
With this implementation, this changes. The iterator now has
functionality to optimize the iteration, if only a subdirectory of the
store is required, for example `$STORE/foo`.
This is done via functionality where the underlying iterator gets
altered.
First of all, the interface was changed to return a `Entries` object,
which itself only covers the libimagstore-internal `PathIterator` type.
This type was changed so that the backend implementation provides an
"PathIterBuilder`, which builds the actual iterator object for the
`PathIterator` type.
The intermediate `StoreIdConstructingIterator` was merged into
`PathIterator` for simplicity.
The `Entries` type got functionality similar to the
`StoreIdIteratorWithStore` type for easier transition to the new API.
This should probably be removed at a later point, though.
As the `walkdir::WalkDir` type is not as nice as it could be, iterators
for two collections in the store could be built like this (untested):
store
.entries()?
.in_collection("foo")
.chain(store.entries()?.in_collection("bar"))
Functionality to exclude subdirectories is not possible with the current
`walkdir::WalkDir` implementation and has to be done during iteration,
with filtering (as usual).
Signed-off-by: Matthias Beyer <mail@beyermatthias.de>
