net.sourceforge.czt.animation.eval.flatpred

Class FlatUnion

java.lang.Object

net.sourceforge.czt.animation.eval.flatpred.FlatPred

net.sourceforge.czt.animation.eval.flatpred.FlatEvalSet

net.sourceforge.czt.animation.eval.flatpred.FlatUnion

public class FlatUnion
extends FlatEvalSet

FlatUnion(a, b, r) implements a \cup b = s. It creates an EvalSet for s, that hides the two subsets a and b and can be used to do membership tests or to enumerate all members (with duplicates removed).

Author:

leo and marku

Field Summary

Fields

Modifier and Type	Field and Description
protected Bounds	bounds_ The most recent variable bounds information.

Fields inherited from class net.sourceforge.czt.animation.eval.flatpred.FlatPred

args_, evalMode_, freeVars_, INDENT, LOG, printer_, solutionsReturned_

Constructor Summary

Constructors

Constructor and Description
FlatUnion(net.sourceforge.czt.z.ast.ZName a, net.sourceforge.czt.z.ast.ZName b, net.sourceforge.czt.z.ast.ZName s) Creates a new instance of FlatUnion

Method Summary

Modifier and Type	Method and Description
<R> R	accept(net.sourceforge.czt.util.Visitor<R> visitor) Calls visitor.visitPred (preferably) or visitor.visitTerm.
Mode	chooseMode(Envir env) Choose the mode that this predicate could use in this environment.
double	estSize(Envir env) Estimate the size of the set in a given environment.
double	estSubsetSize(Envir env, net.sourceforge.czt.z.ast.ZName elem) Estimate the size of {x:this | x=elem} in a given environment.
BigInteger	getLower() The lower bound on numeric elements, if any, else null.
BigInteger	getUpper() The upper bound on numeric elements, if any, else null.
boolean	inferBounds(Bounds bnds) Numeric bounds information can flow both ways.
boolean	nextEvaluation() Generates the next solution that satisfies this predicate.
String	toString() Iterate through all members of this set that might equal element (which must be fully evaluated).

Methods inherited from class net.sourceforge.czt.animation.eval.flatpred.FlatPred

freeVars, getArgs, getEnvir, getLastArg, getMode, indent, modeAllDefined, modeCollection, modeFunction, modeOneOutput, printArg, printBinOp, printLastArg, printName, printQuant, setMode, startEvaluation

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

bounds_

protected Bounds bounds_

The most recent variable bounds information.

Constructor Detail

FlatUnion

public FlatUnion(net.sourceforge.czt.z.ast.ZName a,
                 net.sourceforge.czt.z.ast.ZName b,
                 net.sourceforge.czt.z.ast.ZName s)

Creates a new instance of FlatUnion

Method Detail

inferBounds

public boolean inferBounds(Bounds bnds)

Numeric bounds information can flow both ways. Any bounds on s are propagated to a and b. Any bounds on a and b are combined via min/max and then propagated to s.

Overrides:

inferBounds in class FlatPred

Parameters:

bnds - The database of lower and upper bounds for integer variables.

Returns:

true iff the bnds database has been changed.

The default implementation infers nothing and returns false.

chooseMode

public Mode chooseMode(Envir env)

Description copied from class: FlatPred

Choose the mode that this predicate could use in this environment. The result is null if no evaluation is possible. Otherwise, the resulting Mode object contains an updated environment (with any output variables added), plus various estimates about how expensive this predicate will be to execute.

Specified by:

chooseMode in class FlatPred

Returns:

The Mode object, with statistics and an updated environment.

nextEvaluation

public boolean nextEvaluation()

Description copied from class: FlatPred

Generates the next solution that satisfies this predicate. This must only be called after startEvaluation().

Specified by:

nextEvaluation in class FlatPred

Returns:

true iff another solution has been found.

getLower

public BigInteger getLower()

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

getUpper

public BigInteger getUpper()

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

estSize

public double estSize(Envir env)

Estimate the size of the set in a given environment.

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.

toString

public String toString()

Iterate through all members of this set that might equal element (which must be fully evaluated). The result will contain no duplicates. However, both subsets will be built before the iterator returns, so this might be expensive on space.

Overrides:

toString in class FlatPred

Returns:

an Iterator object. TODO: delete this??? public Iterator subsetIterator(ZName element) { assert bounds_ != null; // inferBounds should have been called. assert solutionsReturned_ > 0; // nextEvaluation() must have succeeded. Set subset = new HashSet(); // generate all subset members from BOTH sets. // Any duplicates will be removed, thanks to the HashSet. Iterator elems = leftSet_.subsetIterator(element); while (elems.hasNext()) subset.add(elems.next()); elems = rightSet_.subsetIterator(element); while (elems.hasNext()) subset.add(elems.next()); return subset.iterator(); }

accept

public <R> R accept(net.sourceforge.czt.util.Visitor<R> visitor)

Description copied from class: FlatPred

Calls visitor.visitPred (preferably) or visitor.visitTerm. Subclasses that correspond to particular kinds of Pred should override this to call more specific visitXXX methods (and should call super to handle the remaining cases).

Overrides:

accept in class FlatPred