Package fj.data
Class Tree<A>
- java.lang.Object
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- fj.data.Tree<A>
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- 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).
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description static <A,B>
Tree<B>bottomUp(Tree<A> t, F<P2<A,Stream<B>>,B> f)
<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.private static <A> Stream<java.lang.String>
drawSubTrees(Show<A> s, Stream<Tree<A>> ts)
private Stream<java.lang.String>
drawTree(Show<A> s)
boolean
equals(java.lang.Object other)
Stream<A>
flatten()
Puts the elements of the tree into a Stream, in pre-order.static <A> F<Tree<A>,Stream<A>>
flatten_()
flatten :: Tree a -> [a] flatten t = squish t []
<B> Tree<B>
fmap(F<A,B> f)
Maps the given function over this tree.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> B
foldMap(F<A,B> f, Monoid<B> m)
Folds this tree using the given monoid.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.private static <A> F<Tree<A>,A>
getRoot()
int
hashCode()
boolean
isLeaf()
java.util.Iterator<A>
iterator()
Returns an iterator for this tree.static <A> Tree<A>
leaf(A root)
Creates a nullary tree.int
length()
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, Stream<Tree<A>> forest)
Creates a new tree given a root and a (potentially infinite) subforest.static <A> Tree<A>
node(A root, P1<Stream<Tree<A>>> forest)
Creates a new tree given a root and a (potentially infinite) subforest.A
root()
Returns the root element of the tree.static <A> F<Tree<A>,A>
root_()
Provides a transformation from a tree to its root.private static Stream<java.lang.String>
shift(java.lang.String f, java.lang.String o, Stream<java.lang.String> s)
static <A> Show<Tree<A>>
show2D(Show<A> s)
Provides a show instance that draws a 2-dimensional representation of a tree.P1<Stream<Tree<A>>>
subForest()
Returns a stream of the tree's subtrees.static <A> F<Tree<A>,P1<Stream<Tree<A>>>>
subForest_()
Provides a transformation from a tree to its subforest.java.util.Collection<A>
toCollection()
Projects an immutable collection of this tree.java.lang.String
toString()
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.
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Method Detail
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iterator
public java.util.Iterator<A> iterator()
Returns an iterator for this tree. This method exists to permit the use in afor
-each loop.- Specified by:
iterator
in interfacejava.lang.Iterable<A>
- Returns:
- A iterator for this tree.
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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.
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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.
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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.
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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.
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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.
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root
public A root()
Returns the root element of the tree.- Returns:
- The root element of the tree.
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subForest
public P1<Stream<Tree<A>>> subForest()
Returns a stream of the tree's subtrees.- Returns:
- A stream of the tree's subtrees.
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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.
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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.
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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.
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flatten_
public static <A> F<Tree<A>,Stream<A>> flatten_()
where squish (Node x ts) xs = x:Prelude.foldr squish xs ts Puts the elements of the tree into a Stream, in pre-order.flatten :: Tree a -> [a] flatten t = squish t []
- Returns:
- The elements of the tree in pre-order.
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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.
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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.
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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.
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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.
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toCollection
public java.util.Collection<A> toCollection()
Projects an immutable collection of this tree.- Returns:
- An immutable collection of this tree.
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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.
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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.
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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.
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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.
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drawSubTrees
private static <A> Stream<java.lang.String> drawSubTrees(Show<A> s, Stream<Tree<A>> ts)
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shift
private static Stream<java.lang.String> shift(java.lang.String f, java.lang.String o, Stream<java.lang.String> s)
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equals
public boolean equals(java.lang.Object other)
- Overrides:
equals
in classjava.lang.Object
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hashCode
public int hashCode()
- Overrides:
hashCode
in classjava.lang.Object
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toString
public java.lang.String toString()
- Overrides:
toString
in classjava.lang.Object
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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.
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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.
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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.
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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.
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bottomUp
public static <A,B> Tree<B> bottomUp(Tree<A> t, F<P2<A,Stream<B>>,B> f)
- 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
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isLeaf
public boolean isLeaf()
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length
public int length()
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