Add Entries::into_storeid_iter()

This is a more complicated functionality (implementation-wise) of the
`Entries` iterator, which allows a callee to transform it into a
`StoreIdIterator`.

It uses the crate internal `PathIterator` type and a function to extract
the internals of that iterator which is then turned into an iterator
over `Result<StoreId>`, which can be used to build a `StoreIdIterator`.

The implementation is ugly, but we need to be able to transform a
`Entries` iterator into a `StoreIdIterator` in the
`libimagentryannotation`, and possibly in more cases where we want to be
agnostic over iterators.

Maybe there is a cleaner solution to this, hence the comment about
whether this should be removed.

Signed-off-by: Matthias Beyer <mail@beyermatthias.de>

lib/core/libimagstore/src/file_abstraction/iter.rs

@@ -71,6 +71,18 @@ impl<'a> PathIterator<'a> {
         self
     }
 
+    /// Turn iterator into its internals
+    ///
+    /// Used for `Entries::into_storeid_iter()`
+    ///
+    /// # TODO
+    ///
+    /// Revisit whether this can be done in a cleaner way. See commit message for why this is
+    /// needed.
+    pub(crate) fn into_inner(self) -> Box<Iterator<Item = Result<PathBuf>>> {
+        self.iter
+    }
+
 }
 
 impl<'a> Iterator for PathIterator<'a> {

lib/core/libimagstore/src/iter.rs

@@ -138,6 +138,7 @@ mod compile_test {
 }
 
 use storeid::StoreId;
+use storeid::StoreIdIterator;
 use self::delete::StoreDeleteIterator;
 use self::get::StoreGetIterator;
 use self::retrieve::StoreRetrieveIterator;
@@ -178,10 +179,18 @@ impl<'a> Entries<'a> {
         Entries(self.0.in_collection(c), self.1)
     }
 
-    // TODO: Remove or fix me
-    //pub fn without_store(self) -> StoreIdIterator {
-    //    StoreIdIterator::new(Box::new(self.0.map(|r| r.map(|id| id.without_base()))))
-    //}
+    /// Turn `Entries` iterator into generic `StoreIdIterator`
+    ///
+    /// # TODO
+    ///
+    /// Revisit whether this can be done in a cleaner way. See commit message for why this is
+    /// needed.
+    pub fn into_storeid_iter(self) -> StoreIdIterator {
+        let iter = self.0
+            .into_inner()
+            .map(|r| r.and_then(StoreId::new));
+        StoreIdIterator::new(Box::new(iter))
+    }
 
     /// Transform the iterator into a StoreDeleteIterator
     ///