| Safe Haskell | Safe |
|---|---|
| Language | Haskell2010 |
Data.Generics.Fixplate.Zipper
Contents
Description
The Zipper is a data structure which maintains a location in a tree, and allows O(1) movement and local changes (to be more precise, in our case it is O(k) where k is the number of children of the node at question; typically this is a very small number).
- type Node f = Either (Mu f) (Path f)
- data Path f
- data Loc f = Loc {}
- root :: Mu f -> Loc f
- defocus :: Traversable f => Loc f -> Mu f
- locations :: Traversable f => Mu f -> Attr f (Loc f)
- locationsList :: Traversable f => Mu f -> [Loc f]
- locForget :: Functor f => Loc (Ann f a) -> Loc f
- extract :: Loc f -> Mu f
- replace :: Mu f -> Loc f -> Loc f
- modify :: (Mu f -> Mu f) -> Loc f -> Loc f
- moveDown :: Traversable f => Int -> Loc f -> Maybe (Loc f)
- moveDownL :: Traversable f => Loc f -> Maybe (Loc f)
- moveDownR :: Traversable f => Loc f -> Maybe (Loc f)
- moveUp :: Traversable f => Loc f -> Maybe (Loc f)
- moveRight :: Traversable f => Loc f -> Maybe (Loc f)
- moveLeft :: Traversable f => Loc f -> Maybe (Loc f)
- isTop :: Loc f -> Bool
- isBottom :: Traversable f => Loc f -> Bool
- isLeftmost :: Traversable f => Loc f -> Bool
- isRightmost :: Traversable f => Loc f -> Bool
- horizontalPos :: Foldable f => Loc f -> Int
- fullPathDown :: Foldable f => Loc f -> [Int]
- fullPathUp :: Foldable f => Loc f -> [Int]
- moveTop :: Traversable f => Loc f -> Loc f
- leftmost :: Traversable f => Loc f -> Loc f
- rightmost :: Traversable f => Loc f -> Loc f
- unsafeMoveDown :: Traversable f => Int -> Loc f -> Loc f
- unsafeMoveDownL :: Traversable f => Loc f -> Loc f
- unsafeMoveDownR :: Traversable f => Loc f -> Loc f
- unsafeMoveUp :: Traversable f => Loc f -> Loc f
- unsafeMoveLeft :: Traversable f => Loc f -> Loc f
- unsafeMoveRight :: Traversable f => Loc f -> Loc f
Types
The context or path type. The invariant we must respect is that there is exactly
one child with the Right constructor.
The zipper type itself, which encodes a locations in thre tree Mu f.
Converting to and from zippers
locations :: Traversable f => Mu f -> Attr f (Loc f) Source #
We attribute all nodes with a zipper focused at that location.
locationsList :: Traversable f => Mu f -> [Loc f] Source #
The list of all locations.
Manipulating the subtree at focus
Safe movements
moveDown :: Traversable f => Int -> Loc f -> Maybe (Loc f) Source #
Moves down to the child with the given index.
The leftmost children has index 0.
Testing for borders
isLeftmost :: Traversable f => Loc f -> Bool Source #
isRightmost :: Traversable f => Loc f -> Bool Source #
Location queries
horizontalPos :: Foldable f => Loc f -> Int Source #
Gives back the index of the given location among the children of its parent. Indexing starts from zero. In case of root node (no parent), we also return zero.
fullPathDown :: Foldable f => Loc f -> [Int] Source #
We return the full path from the root as a sequence of child indices. This means that
loc == foldl (flip unsafeMoveDown) (moveTop loc) (fullPathDown loc)
fullPathUp :: Foldable f => Loc f -> [Int] Source #
The following equations hold for fullPathUp and fullPathDown:
fullPathUp == reverse . fullPathDown loc == foldr unsafeMoveDown (moveTop loc) (fullPathUp loc)
Compound movements
leftmost :: Traversable f => Loc f -> Loc f Source #
Moves left until it can. It should be faster than repeated left steps.
rightmost :: Traversable f => Loc f -> Loc f Source #
Moves right until it can. It should be faster than repeated right steps.
Unsafe movements
unsafeMoveDown :: Traversable f => Int -> Loc f -> Loc f Source #
unsafeMoveDownL :: Traversable f => Loc f -> Loc f Source #
unsafeMoveDownR :: Traversable f => Loc f -> Loc f Source #
unsafeMoveUp :: Traversable f => Loc f -> Loc f Source #
unsafeMoveLeft :: Traversable f => Loc f -> Loc f Source #
unsafeMoveRight :: Traversable f => Loc f -> Loc f Source #