edu.rice.cs.plt.iter
Class PermutationIterable<T>

java.lang.Object
  edu.rice.cs.plt.iter.AbstractIterable<java.lang.Iterable<T>>
      edu.rice.cs.plt.iter.PermutationIterable<T>

Type Parameters:

T - The element type of the permuted lists; note that the iterator returns Iterable<T>s, not Ts.

All Implemented Interfaces:

OptimizedLastIterable<java.lang.Iterable<T>>, SizedIterable<java.lang.Iterable<T>>, Composite, java.io.Serializable, java.lang.Iterable<java.lang.Iterable<T>>

public class PermutationIterable<T>
extends AbstractIterable<java.lang.Iterable<T>>
implements SizedIterable<java.lang.Iterable<T>>, OptimizedLastIterable<java.lang.Iterable<T>>, Composite, java.io.Serializable

An enumeration of all permutations of the given list. The size of the enumeration, where the original list has size n, is n! (and is thus guaranteed to be >= 1). The order of the results is "lexicographical" where each element of the original list is taken to lexicographically precede all of its successors. (Thus, the original list is the first to be returned, and a reversed list is the last.) Of course, due to the factorial complexity of enumerating all permutations, this class is probably not suitable for applications in which n is unbounded (or just intractably large).

See Also:

Serialized Form

Constructor Summary

PermutationIterable(java.lang.Iterable<? extends T> original)

Method Summary

int	compositeHeight() Get the maximum path length from this node to a leaf.
int	compositeSize() Get the number of nodes in the tree rooted at this node.
boolean	hasFixedSize() true if this iterable is known to have a fixed size.
boolean	isEmpty() Whether the iterable does not contain any elements.
boolean	isInfinite() true if the iterable is known to have infinite size.
boolean	isStatic() true if this iterable is unchanging.
PermutationIterator<T>	iterator()
java.lang.Iterable<T>	last() Get the last element of the list.
static <T> PermutationIterable<T>	make(java.lang.Iterable<? extends T> original) Call the constructor (allows T to be inferred)
static <T> SnapshotIterable<java.lang.Iterable<T>>	makeSnapshot(java.lang.Iterable<? extends T> original) Create a PermutationIterable and wrap it in a SnapshotIterable, forcing immediate evaluation of the permutations.
int	size() Compute the number of elements in the iterable.
int	size(int bound) Compute the number of elements in the iterable, up to the given bound.

Methods inherited from class edu.rice.cs.plt.iter.AbstractIterable

equals, hashCode, toString

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

PermutationIterable

public PermutationIterable(java.lang.Iterable<? extends T> original)

Method Detail

iterator

public PermutationIterator<T> iterator()

Specified by:

iterator in interface java.lang.Iterable<java.lang.Iterable<T>>

compositeHeight

public int compositeHeight()

Description copied from interface: Composite

Get the maximum path length from this node to a leaf.

Specified by:

compositeHeight in interface Composite

compositeSize

public int compositeSize()

Description copied from interface: Composite

Get the number of nodes in the tree rooted at this node. Always 1 or greater.

Specified by:

compositeSize in interface Composite

isEmpty

public boolean isEmpty()

Description copied from interface: SizedIterable

Whether the iterable does not contain any elements.

Specified by:

isEmpty in interface SizedIterable<java.lang.Iterable<T>>

size

public int size()

Description copied from interface: SizedIterable

Compute the number of elements in the iterable. If the size is infinite or too large to be represented as an int, Integer.MAX_VALUE should be returned. Otherwise, next() may be safely invoked on the iterator exactly this number of times.

Specified by:

size in interface SizedIterable<java.lang.Iterable<T>>

size

public int size(int bound)

Description copied from interface: SizedIterable

Compute the number of elements in the iterable, up to the given bound. If the size is infinite or greater than bound, bound is returned.

Specified by:

size in interface SizedIterable<java.lang.Iterable<T>>

Parameters:

bound - Maximum result. Assumed to be nonnegative.

isInfinite

public boolean isInfinite()

Description copied from interface: SizedIterable

true if the iterable is known to have infinite size. If true, an iterator over the iterable in its current state will never return false from hasNext().

Specified by:

isInfinite in interface SizedIterable<java.lang.Iterable<T>>

hasFixedSize

public boolean hasFixedSize()

Description copied from interface: SizedIterable

true if this iterable is known to have a fixed size. This is the case if the iterable is immutable, or if changes can only replace values, not remove or add them. An infinite iterable may be fixed if it is guaranteed to never become finite.

Specified by:

hasFixedSize in interface SizedIterable<java.lang.Iterable<T>>

isStatic

public boolean isStatic()

Description copied from interface: SizedIterable

true if this iterable is unchanging. This implies that hasFixedSize() is true, and that iterator() will always return the same (either == or equal() and immutable) elements in the same order. ("Immutable" here means that equals() invocations are consistent over time -- if two objects are equal, they will never become inequal, and vice versa.)

Specified by:

isStatic in interface SizedIterable<java.lang.Iterable<T>>

last

public java.lang.Iterable<T> last()

Description copied from interface: OptimizedLastIterable

Get the last element of the list. Assumed to execute more quickly than a traversal over all elements.

Specified by:

last in interface OptimizedLastIterable<java.lang.Iterable<T>>

make

public static <T> PermutationIterable<T> make(java.lang.Iterable<? extends T> original)

Call the constructor (allows T to be inferred)

makeSnapshot

public static <T> SnapshotIterable<java.lang.Iterable<T>> makeSnapshot(java.lang.Iterable<? extends T> original)

Create a PermutationIterable and wrap it in a SnapshotIterable, forcing immediate evaluation of the permutations.