Copyright 2008 - 2010 Tony Morris, Runar Bjarnason, Tom Adams, Brad Clow, Ricky Clarkson, Nick Partridge, Jason Zaugg

This software is released under an open source BSD licence.

fj.data
Class Tree<A>

java.lang.Object
  extended by fj.data.Tree<A>
All Implemented Interfaces:
java.lang.Iterable<A>

public final class Tree<A>
extends java.lang.Object
implements java.lang.Iterable<A>

Provides a lazy, immutable, non-empty, multi-way tree (a rose tree).


Method Summary
<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).
 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).
 java.lang.String draw(Show<A> s)
          Draws a 2-dimensional representation of a tree.
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.
 Stream<A> flatten()
          Puts the elements of the tree into a Stream, in pre-order.
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.
<B> Tree<B>
fmap(F<A,B> f)
          Maps the given function over this tree.
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.
<B> B
foldMap(F<A,B> f, Monoid<B> m)
          Folds this tree using the given monoid.
 java.util.Iterator<A> iterator()
          Returns an iterator for this tree.
static
<A> Tree<A>
leaf(A root)
          Creates a nullary tree.
 Stream<Stream<A>> levels()
          Provides a stream of the elements of the tree at each level, in level order.
static
<A> F<A,F<P1<Stream<Tree<A>>>,Tree<A>>>
node()
          First-class constructor of trees.
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.
static
<A> Tree<A>
node(A root, P1<Stream<Tree<A>>> forest)
          Creates a new tree given a root and a (potentially infinite) subforest.
static
<A> Tree<A>
node(A root, Stream<Tree<A>> forest)
          Creates a new tree given a root and a (potentially infinite) subforest.
static
<A> F<Tree<A>,A>
root_()
          Provides a transformation from a tree to its root.
 A root()
          Returns the root element of the tree.
static
<A> Show<Tree<A>>
show2D(Show<A> s)
          Provides a show instance that draws a 2-dimensional representation of a tree.
static
<A> F<Tree<A>,P1<Stream<Tree<A>>>>
subForest_()
          Provides a transformation from a tree to its subforest.
 P1<Stream<Tree<A>>> subForest()
          Returns a stream of the tree's subtrees.
 java.util.Collection<A> toCollection()
          Projects an immutable collection of this tree.
static
<A,B> F<B,Tree<A>>
unfoldTree(F<B,P2<A,P1<Stream<B>>>> f)
          Builds a tree from a seed value.
<B,C> Tree<C>
zipWith(Tree<B> bs, F<A,F<B,C>> f)
          Zips this tree with another, using the given function.
<B,C> Tree<C>
zipWith(Tree<B> bs, F2<A,B,C> f)
          Zips this tree with another, using the given function.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Method Detail

iterator

public java.util.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 java.lang.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 java.util.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.

draw

public java.lang.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.

Copyright 2008 - 2010 Tony Morris, Runar Bjarnason, Tom Adams, Brad Clow, Ricky Clarkson, Nick Partridge, Jason Zaugg

This software is released under an open source BSD licence.