Class Tree<A>

java.lang.Object
fj.data.Tree<A>
All Implemented Interfaces:
Iterable<A>
public final class Tree<A> extends Object implements Iterable<A>
Provides a lazy, immutable, non-empty, multi-way tree (a rose tree).

  • Field Details

    • root

      private final A root

    • subForest

      private final P1<Stream<Tree<A>>> subForest

  • Constructor Details

  • Method Details

    • iterator

      public Iterator<A> iterator()
      Returns an iterator for this tree. This method exists to permit the use in a for-each loop.
      Specified by:
      iterator in interface Iterable<A>
      Returns:
      A iterator for this tree.

    • leaf

      public static <A> Tree<A> leaf(A root)
      Creates a nullary tree.
      Parameters:
      root - The root element of the tree.
      Returns:
      A nullary tree with the root element in it.

    • node

      public static <A> Tree<A> node(A root, P1<Stream<Tree<A>>> forest)
      Creates a new tree given a root and a (potentially infinite) subforest.
      Parameters:
      root - The root element of the tree.
      forest - A stream of the tree's subtrees.
      Returns:
      A newly sprouted tree.

    • node

      public static <A> Tree<A> node(A root, Stream<Tree<A>> forest)
      Creates a new tree given a root and a (potentially infinite) subforest.
      Parameters:
      root - The root element of the tree.
      forest - A stream of the tree's subtrees.
      Returns:
      A newly sprouted tree.

    • node

      public static <A> Tree<A> node(A root, List<Tree<A>> forest)
      Creates a new n-ary given a root and a subforest of length n.
      Parameters:
      root - The root element of the tree.
      forest - A list of the tree's subtrees.
      Returns:
      A newly sprouted tree.

    • node

      public static <A> F<A, F<P1<Stream<Tree<A>>>, Tree<A>>> node()
      First-class constructor of trees.
      Returns:
      A function that constructs an n-ary tree given a root and a subforest or length n.

    • root

      public A root()
      Returns the root element of the tree.
      Returns:
      The root element of the tree.

    • subForest

      public P1<Stream<Tree<A>>> subForest()
      Returns a stream of the tree's subtrees.
      Returns:
      A stream of the tree's subtrees.

    • root_

      public static <A> F<Tree<A>,A> root_()
      Provides a transformation from a tree to its root.
      Returns:
      A transformation from a tree to its root.

    • subForest_

      public static <A> F<Tree<A>, P1<Stream<Tree<A>>>> subForest_()
      Provides a transformation from a tree to its subforest.
      Returns:
      A transformation from a tree to its subforest.

    • flatten

      public Stream<A> flatten()
      Puts the elements of the tree into a Stream, in pre-order.
      Returns:
      The elements of the tree in pre-order.

    • flatten_

      public static <A> F<Tree<A>, Stream<A>> flatten_()
      flatten :: Tree a -> [a]
flatten t = squish t []
      where squish (Node x ts) xs = x:Prelude.foldr squish xs ts Puts the elements of the tree into a Stream, in pre-order.
      Returns:
      The elements of the tree in pre-order.

    • levels

      public Stream<Stream<A>> levels()
      Provides a stream of the elements of the tree at each level, in level order.
      Returns:
      The elements of the tree at each level.

    • fmap

      public <B> Tree<B> fmap(F<A,B> f)
      Maps the given function over this tree.
      Parameters:
      f - The function to map over this tree.
      Returns:
      The new Tree after the function has been applied to each element in this Tree.

    • fmap_

      public static <A,B> F<F<A,B>, F<Tree<A>,Tree<B>>> fmap_()
      Provides a transformation to lift any function so that it maps over Trees.
      Returns:
      A transformation to lift any function so that it maps over Trees.

    • foldMap

      public <B> B foldMap(F<A,B> f, Monoid<B> m)
      Folds this tree using the given monoid.
      Parameters:
      f - A transformation from this tree's elements, to the monoid.
      m - The monoid to fold this tree with.
      Returns:
      The result of folding the tree with the given monoid.

    • toCollection

      public Collection<A> toCollection()
      Projects an immutable collection of this tree.
      Returns:
      An immutable collection of this tree.

    • foldMap_

      public static <A,B> F<Tree<A>,B> foldMap_(F<A,B> f, Monoid<B> m)
      Provides a function that folds a tree with the given monoid.
      Parameters:
      f - A transformation from a tree's elements to the monoid.
      m - A monoid to fold the tree with.
      Returns:
      A function that, given a tree, folds it with the given monoid.

    • unfoldTree

      public static <A,B> F<B,Tree<A>> unfoldTree(F<B, P2<A, P1<Stream<B>>>> f)
      Builds a tree from a seed value.
      Parameters:
      f - A function with which to build the tree.
      Returns:
      A function which, given a seed value, yields a tree.

    • cobind

      public <B> Tree<B> cobind(F<Tree<A>,B> f)
      Applies the given function to all subtrees of this tree, returning a tree of the results (comonad pattern).
      Parameters:
      f - A function to bind across all the subtrees of this tree.
      Returns:
      A new tree, with the results of applying the given function to each subtree of this tree. The result of applying the function to the entire tree is the root label, and the results of applying to the root's children are labels of the root's subforest, etc.

    • cojoin

      public Tree<Tree<A>> cojoin()
      Expands this tree into a tree of trees, with this tree as the root label, and subtrees as the labels of child nodes (comonad pattern).
      Returns:
      A tree of trees, with this tree as its root label, and subtrees of this tree as the labels of its child nodes.

    • drawSubTrees

      private static <A> Stream<String> drawSubTrees(Show<A> s, Stream<Tree<A>> ts)

    • shift

      private static Stream<String> shift(String f, String o, Stream<String> s)

    • drawTree

      private Stream<String> drawTree(Show<A> s)

    • equals

      public boolean equals(Object other)
      Overrides:
      equals in class Object

    • hashCode

      public int hashCode()
      Overrides:
      hashCode in class Object

    • toString

      public String toString()
      Overrides:
      toString in class Object

    • draw

      public String draw(Show<A> s)
      Draws a 2-dimensional representation of a tree.
      Parameters:
      s - A show instance for the elements of the tree.
      Returns:
      a String showing this tree in two dimensions.

    • show2D

      public static <A> Show<Tree<A>> show2D(Show<A> s)
      Provides a show instance that draws a 2-dimensional representation of a tree.
      Parameters:
      s - A show instance for the elements of the tree.
      Returns:
      a show instance that draws a 2-dimensional representation of a tree.

    • zipWith

      public <B,C> Tree<C> zipWith(Tree<B> bs, F2<A,B,C> f)
      Zips this tree with another, using the given function. The resulting tree is the structural intersection of the two trees.
      Parameters:
      bs - A tree to zip this tree with.
      f - A function with which to zip together the two trees.
      Returns:
      A new tree of the results of applying the given function over this tree and the given tree, position-wise.

    • zipWith

      public <B,C> Tree<C> zipWith(Tree<B> bs, F<A,F<B,C>> f)
      Zips this tree with another, using the given function. The resulting tree is the structural intersection of the two trees.
      Parameters:
      bs - A tree to zip this tree with.
      f - A function with which to zip together the two trees.
      Returns:
      A new tree of the results of applying the given function over this tree and the given tree, position-wise.

    • bottomUp

      public static <A,B> Tree<B> bottomUp(Tree<A> t, F<P2<A, Stream<B>>, B> f)
      Folds a Tree into a Tree by applying the function f from the bottom of the Tree to the top
      Parameters:
      t - A tree to fold from the bottom to the top.
      f - A function transforming the current node and a stream of already transformed nodes (its children) into a new node
      Returns:
      The folded tree

    • getRoot

      private static <A> F<Tree<A>,A> getRoot()
      Returns:
      a function getting the root of a Tree

    • isLeaf

      public boolean isLeaf()

    • length

      public int length()