net.sourceforge.czt.animation.eval.flatpred

Class FlatSetComp

java.lang.Object

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

net.sourceforge.czt.animation.eval.flatpred.FlatSetComp

public class FlatSetComp
extends FlatPred

Author:

Mark Utting FlatSetComp(decls,pred,expr) implements {decls|pred@expr}

Field Summary

Fields

Modifier and Type	Field and Description
protected Bounds	bounds_ The most recent variable bounds information.
protected FlatPredList	predsAll_ This FlatPredList is used to evaluate ALL members of the set.
protected net.sourceforge.czt.z.ast.ZName	resultName_ The fresh ZName which will be bound to a member of the set.

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

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

Constructor Summary

Constructors

Constructor and Description
FlatSetComp(ZLive zlive, net.sourceforge.czt.z.ast.ZSchText stext, net.sourceforge.czt.z.ast.Expr result, net.sourceforge.czt.z.ast.ZName set) FlatSetComp(D,P,E,S) implements {D|P@E} = S.

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) Like other Flat*Set* objects, this acts as a function: the free variables of the set are the inputs and the resulting EvalSet object is the output.
boolean	inferBounds(Bounds bnds) This does local bounds inference.
boolean	nextEvaluation() Does the actual evaluation.
String	toString() A default implementation of toString.

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.

predsAll_

protected FlatPredList predsAll_

This FlatPredList is used to evaluate ALL members of the set.

resultName_

protected net.sourceforge.czt.z.ast.ZName resultName_

The fresh ZName which will be bound to a member of the set.

Constructor Detail

FlatSetComp

public FlatSetComp(ZLive zlive,
                   net.sourceforge.czt.z.ast.ZSchText stext,
                   net.sourceforge.czt.z.ast.Expr result,
                   net.sourceforge.czt.z.ast.ZName set)

FlatSetComp(D,P,E,S) implements {D|P@E} = S.

Parameters:

decls - A list of Decl objects (ConstDecl and VarDecl only).

pred - The predicate that filters the declarations.

result - The expression returned by the set.

set - The variable that the whole set will be equated to.

Method Detail

inferBounds

public boolean inferBounds(Bounds bnds)

This does local bounds inference. So bounds information flows into the set, but only information about the whole set flows out.

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)

Like other Flat*Set* objects, this acts as a function: the free variables of the set are the inputs and the resulting EvalSet object is the output. The number of solutions is always 1, since this just defines the whole set, rather than iterating through it.

Specified by:

chooseMode in class FlatPred

Returns:

The Mode object, with statistics and an updated environment.

nextEvaluation

public boolean nextEvaluation()

Does the actual evaluation. In fact, in output mode this is lazy -- it just assigns a SetComp object to the output variable, so that the members of the set can be evaluated (and cached) only when needed. This is the same as lazy evaluation in functional languages.

Specified by:

nextEvaluation in class FlatPred

Returns:

true iff another solution has been found.

toString

public String toString()

Description copied from class: FlatPred

A default implementation of toString. This returns "FlatXXX(args[0], args[1], ...)".

Overrides:

toString in class FlatPred

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