net.sourceforge.czt.animation.eval.result

Class DefaultEvalSet

java.lang.Object

net.sourceforge.czt.base.impl.TermImpl

net.sourceforge.czt.z.impl.ExprImpl

net.sourceforge.czt.animation.eval.result.EvalResult

net.sourceforge.czt.animation.eval.result.EvalSet

net.sourceforge.czt.animation.eval.result.DefaultEvalSet

All Implemented Interfaces:

Iterable<net.sourceforge.czt.z.ast.Expr>, Collection<net.sourceforge.czt.z.ast.Expr>, Set<net.sourceforge.czt.z.ast.Expr>, net.sourceforge.czt.base.ast.Term, net.sourceforge.czt.z.ast.Expr

Direct Known Subclasses:

PowerSet, ProdSet, SetComp, UnionSet

public abstract class DefaultEvalSet
extends EvalSet

TODO: move the caching functionality of this class into several different iterator-wrappers, one that caches elements, another that converts an Iterator into a ListIterator, etc. This class could then be deleted. This class provides a lazy-evaluation mechanism that uses the memberList and memberSet data structures to record which members of the set have already been evaluated and to remove duplicates. The contains() and iterator() methods are implemented on top of this lazy evaluation mechanism.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	DefaultEvalSet.SubsetIterator<E> Filters the master iterator, returning only those elements that are members of the slave set.

Field Summary

Fields

Modifier and Type	Field and Description
protected List<net.sourceforge.czt.z.ast.Expr>	memberList_ The list of known members so far.

Fields inherited from class net.sourceforge.czt.animation.eval.result.EvalSet

INFINITE_SIZE, UNKNOWN_SIZE

Constructor Summary

Constructors

Constructor and Description
DefaultEvalSet()

Method Summary

Modifier and Type	Method and Description
boolean	contains(Object expr) Tests for membership of the set.
boolean	equals(Object s2) Tests for the equality of any two sets.
double	estSubsetSize(Envir env, net.sourceforge.czt.z.ast.ZName elem) Estimate the size of {x:this | x=elem} in a given environment.
protected void	evaluateFully() This ensures that the set is completely evaluated and stored in the memberSet_ data structure.
BigInteger	getLower() The lower bound on numeric elements, if any, else null.
BigInteger	getUpper() The upper bound on numeric elements, if any, else null.
int	hashCode() This hashCode implementation returns a constant! The semantics of EvalSet is that its value depends only upon its members, but we do not want to have to evaluate all the members before calculating the hashCode, and it is not very useful (or desirable) to evaluate just a few members.
boolean	isEmpty()
Iterator<net.sourceforge.czt.z.ast.Expr>	iterator() Enumerates the members of the set.
ListIterator<net.sourceforge.czt.z.ast.Expr>	listIterator() Iterate forwards/backwards through all members of the set.
BigInteger	maxSize() The maximum size of the set in the default environment.
protected abstract net.sourceforge.czt.z.ast.Expr	nextMember() Returns the next expression in the set.
protected void	resetResult() This resets any cached results.
int	size() Returns the exact size (cardinality) of the set.
Iterator<net.sourceforge.czt.z.ast.Expr>	sortedIterator() Iterate through all members of the set in sorted order.
Iterator<net.sourceforge.czt.z.ast.Expr>	subsetIterator(EvalSet otherSet) Iterate through the intersection of this set and the 'other' set.
Object[]	toArray() Returns an array containing all of the elements in this set.
<T> T[]	toArray(T[] a) Returns an array containing all of the elements in this set.

Methods inherited from class net.sourceforge.czt.animation.eval.result.EvalSet

accept, add, addAll, clear, containsAll, estSize, getAnn, getAnns, matchIterator, remove, removeAll, retainAll, toString

Methods inherited from class net.sourceforge.czt.animation.eval.result.EvalResult

create, getChildren

Methods inherited from class net.sourceforge.czt.base.impl.TermImpl

annsSize, getFactory, hasAnn, hasAnn, removeAnn, removeAnn

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Set

spliterator

Methods inherited from interface java.util.Collection

parallelStream, removeIf, stream

Methods inherited from interface java.lang.Iterable

forEach

Methods inherited from interface net.sourceforge.czt.base.ast.Term

annsSize, hasAnn, hasAnn, removeAnn, removeAnn

Field Detail

memberList_

protected List<net.sourceforge.czt.z.ast.Expr> memberList_

The list of known members so far. This is guaranteed to contain no duplicates. It will be filled up lazily as the members of the set are requested.

Constructor Detail

DefaultEvalSet

public DefaultEvalSet()

Method Detail

getLower

public BigInteger getLower()

The lower bound on numeric elements, if any, else null.

FlatEvalSet provides a default implementation that always returns null.

Overrides:

getLower in class EvalSet

getUpper

public BigInteger getUpper()

The upper bound on numeric elements, if any, else null.

EvalSet provides a default implementation that always returns null.

Overrides:

getUpper in class EvalSet

maxSize

public BigInteger maxSize()

The maximum size of the set in the default environment.

EvalSet provides a default implementation that always returns null.

Overrides:

maxSize in class EvalSet

Returns:

Upper bound on the size of the set, or null if not known.

estSubsetSize

public double estSubsetSize(Envir env,
                            net.sourceforge.czt.z.ast.ZName elem)

Estimate the size of {x:this | x=elem} in a given environment. This allows the bounds of elem to be used to reduce the size of set.

EvalSet provides a default implementation that just calls estSize().

Overrides:

estSubsetSize in class EvalSet

size

public int size()

Returns the exact size (cardinality) of the set. This forces all the members to be evaluated if they were not already evaluated. This throws a RuntimeException if it is called when the set is fuzzy.

Returns:

Integer.MAX_VALUE if the set is infinite or too large.

iterator

public Iterator<net.sourceforge.czt.z.ast.Expr> iterator()

Enumerates the members of the set.

Specified by:

iterator in interface Iterable<net.sourceforge.czt.z.ast.Expr>

Specified by:

iterator in interface Collection<net.sourceforge.czt.z.ast.Expr>

Specified by:

iterator in interface Set<net.sourceforge.czt.z.ast.Expr>

Specified by:

iterator in class EvalSet

Returns:

an expression iterator.

sortedIterator

public Iterator<net.sourceforge.czt.z.ast.Expr> sortedIterator()

Description copied from class: EvalSet

Iterate through all members of the set in sorted order. It guarantees that there will be no duplicates. It will usually fully evaluate the set before the first element is returned. If you want lazy evaluation, you should use the normal iterator() method instead of this.

Specified by:

sortedIterator in class EvalSet

listIterator

public ListIterator<net.sourceforge.czt.z.ast.Expr> listIterator()

Description copied from class: EvalSet

Iterate forwards/backwards through all members of the set. It guarantees that there will be no duplicates.

Specified by:

listIterator in class EvalSet

Returns:

a ListIterator object.

subsetIterator

public Iterator<net.sourceforge.czt.z.ast.Expr> subsetIterator(EvalSet otherSet)

Description copied from class: EvalSet

Iterate through the intersection of this set and the 'other' set. This is intended purely to reduce the number of elements visited, so implementations are free to ignore otherSet if they wish. If otherSet==null, then it places no constraints on the iteration, and this method is equivalent to iterator(). The result will contain no duplicates.

EvalSet provides a default implementation that it iterates through the smaller of the two sets and checks membership in the other. TODO: add unit tests for this.

Overrides:

subsetIterator in class EvalSet

Returns:

an Iterator object.

contains

public boolean contains(Object expr)

Tests for membership of the set.

Parameters:

expr - The fully evaluated expression.

Returns:

true iff the given object is a member of the set.

isEmpty

public boolean isEmpty()

equals

public boolean equals(Object s2)

Tests for the equality of any two sets. Here, the equality is based upon both the sets having the same elements, not taking into consideration the duplication of elements. This is implemented using the ExprComparator class. TODO: Allow finite.equals(infinite) to be calculated as false, etc.

Specified by:

equals in interface Collection<net.sourceforge.czt.z.ast.Expr>

Specified by:

equals in interface Set<net.sourceforge.czt.z.ast.Expr>

Overrides:

equals in class EvalSet

hashCode

public int hashCode()

This hashCode implementation returns a constant! The semantics of EvalSet is that its value depends only upon its members, but we do not want to have to evaluate all the members before calculating the hashCode, and it is not very useful (or desirable) to evaluate just a few members. So try to avoid creating large hashsets of EvalSet objects!

Specified by:

hashCode in interface Collection<net.sourceforge.czt.z.ast.Expr>

Specified by:

hashCode in interface Set<net.sourceforge.czt.z.ast.Expr>

Overrides:

hashCode in class EvalSet

nextMember

protected abstract net.sourceforge.czt.z.ast.Expr nextMember()

Returns the next expression in the set. This is used during the first evaluation of the set. Once this returns null, the set is fully evaluated and its elements are all stored in memberSet_.

Returns:

The next Expr, or null if there are no more.

evaluateFully

protected void evaluateFully()

This ensures that the set is completely evaluated and stored in the memberSet_ data structure.

resetResult

protected void resetResult()

This resets any cached results. TODO: delete this, because the contents of a set should never change (though they may be enumerated).

toArray

public Object[] toArray()

Returns an array containing all of the elements in this set.

Specified by:

toArray in interface Collection<net.sourceforge.czt.z.ast.Expr>

Specified by:

toArray in interface Set<net.sourceforge.czt.z.ast.Expr>

Overrides:

toArray in class EvalSet

toArray

public <T> T[] toArray(T[] a)

Returns an array containing all of the elements in this set. The the runtime type of the returned array is that of the specified array.

Specified by:

toArray in interface Collection<net.sourceforge.czt.z.ast.Expr>

Specified by:

toArray in interface Set<net.sourceforge.czt.z.ast.Expr>

Overrides:

toArray in class EvalSet