The abstract representation of a Tree and useful abstract utilities to handle those.
- data Tree
- data Blob = Blob !(IO ByteString) !(Maybe Hash)
- data TreeItem
- data ItemType
- newtype Hash = Hash (Maybe Int64, ByteString)
- makeTree :: [(Name, TreeItem)] -> Tree
- makeTreeWithHash :: [(Name, TreeItem)] -> Hash -> Tree
- emptyTree :: Tree
- emptyBlob :: Blob
- expand :: Tree -> IO Tree
- expandPath :: Tree -> AnchoredPath -> IO Tree
- items :: Tree -> Map Name TreeItem
- list :: Tree -> [(AnchoredPath, TreeItem)]
- listImmediate :: Tree -> [(Name, TreeItem)]
- treeHash :: Tree -> Maybe Hash
- lookup :: Tree -> Name -> Maybe TreeItem
- find :: Tree -> AnchoredPath -> Maybe TreeItem
- findFile :: Tree -> AnchoredPath -> Maybe Blob
- findTree :: Tree -> AnchoredPath -> Maybe Tree
- itemHash :: TreeItem -> Maybe Hash
- itemType :: TreeItem -> ItemType
- zipCommonFiles :: (AnchoredPath -> Blob -> Blob -> a) -> Tree -> Tree -> [a]
- zipFiles :: (AnchoredPath -> Maybe Blob -> Maybe Blob -> a) -> Tree -> Tree -> [a]
- zipTrees :: (AnchoredPath -> Maybe TreeItem -> Maybe TreeItem -> a) -> Tree -> Tree -> [a]
- diffTrees :: Tree -> Tree -> IO (Tree, Tree)
- read :: Blob -> IO ByteString
- finish :: Tree -> Tree -> IO Tree
- filter :: (AnchoredPath -> TreeItem -> Bool) -> Tree -> Tree
- restrict :: Tree -> Tree -> Tree
- modifyTree :: Tree -> AnchoredPath -> Maybe TreeItem -> Tree
- updateTreePostorder :: (Tree -> Tree) -> Tree -> Tree
Abstraction of a filesystem tree. Please note that the Tree returned by the respective read operations will have TreeStub items in it. To obtain a Tree without such stubs, call expand on it, eg.:
tree <- readDarcsPristine "." >>= expand
When a Tree is expanded, it becomes final. All stubs are forced and the Tree can be traversed purely. Access to actual file contents stays in IO though.
A Tree may have a Hash associated with it. A pair of Tree's is identical whenever their hashes are (the reverse need not hold, since not all Trees come equipped with a hash).
Unfolding stubbed (lazy) Trees.
By default, Tree obtained by a read function is stubbed: it will
contain Stub items that need to be executed in order to access the
expand will produce an unstubbed Tree.
Unfold a stubbed Tree into a one with no stubs in it. You might want to filter the tree before expanding to save IO.
Unfold a path in a (stubbed) Tree, such that the leaf node of the path is reachable without crossing any stubs.
Tree access and lookup.
Get hash of a Tree. This is guaranteed to uniquely identify the Tree (including any blob content), as far as cryptographic hashes are concerned. Sha256 is recommended.
For every pair of corresponding blobs from the two supplied trees, evaluate the supplied function and accumulate the results in a list. Hint: to get IO actions through, just use sequence on the resulting list. NB. This won't expand any stubs.
For each file in each of the two supplied trees, evaluate the supplied function (supplying the corresponding file from the other tree, or Nothing) and accumulate the results in a list. Hint: to get IO actions through, just use sequence on the resulting list. NB. This won't expand any stubs.
Cautiously extracts differing subtrees from a pair of Trees. It will never
do any unneccessary expanding. Tree hashes are used to cut the comparison as
high up the Tree branches as possible. The result is a pair of trees that do
not share any identical subtrees. They are derived from the first and second
parameters respectively and they are always fully expanded. It might be
advantageous to feed the result into
Read a Blob into a Lazy ByteString. Might be backed by an mmap, use with care.
When implementing a Tree that has complex expanding semantics, the finish IO action lets you do arbitrary IO transform on the Tree after it is expanded but before it is given to the user by expand. (Used to implement Index updates, eg.)
Given a predicate of the form AnchoredPath -> TreeItem -> Bool, and a Tree, produce a Tree that only has items for which the predicate returned True. The tree might contain stubs. When expanded, these will be subject to filtering as well.
Given two Trees, a
guide and a
tree, produces a new Tree that is a
tree, but only has those items that are present in both
guide Tree may not contain any stubs.