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>
This patch reimplements the iterator extensions.
As we iterate (in StoreIdIterator) over Result<StoreId> now anyways, we
don't need the extensions for Result iterators anymore.
This patch rewrites the extensions to be more simple in every way and
generic over the error type in the iterator.
All the errors have to do is implement From<StoreError>, which is what
they do when linking the generated error types with error_chain to the
libimagstore error types.
This patch rewrites the Store::entries() function to not be collecting
the iterator.
It therefore introduces a new, internal, iterator type which creates the
StoreId objects from the pathes the PathIterator yields internally.
With this patch, the Store iterator interface changes, as the iterators
now yield `Result<StoreId, StoreError>` instead of `StoreId`.
This is necessary, as the internal conversion errors shouldn't be
hidden.
Of course, the iterator types (like the StoreGetIterator and so on)
should hold a Result<StoreId> internally as well, and also yield
appropritely. This was changed in this commit, too.
This patch adds API functions in the StoreIdIteratorWithStore iterator
type to transform it into a iterator which _does_ something (as in the
`libimagstore::iter` API).
It mimics the API which is offered by `libimagstore::iter`.
