jif.types
Class LabelConstraint

java.lang.Object
  jif.types.Constraint
      jif.types.LabelConstraint

public class LabelConstraint
extends Constraint

A LabelConstraint represents a constraint on labels, which may either be an inequality or equality constraint. LabelConstraints are generated during type checking. LabelConstraints in turn produce Equations which are what the Solver will use to find a satisfying assignment for Variables.

Nested Class Summary

Nested classes/interfaces inherited from class jif.types.Constraint

Constraint.Kind

Field Summary

static Constraint.Kind	EQUAL An equality kind of constraint.
static Constraint.Kind	LEQ An inequality kind of constraint.
protected NamedLabel	namedLHS Names for the LHS
protected NamedLabel	namedRHS Names for the RHS

Fields inherited from class jif.types.Constraint

env, kind, lhs, messages, pos, report, rhs

Constructor Summary

LabelConstraint(NamedLabel lhs, Constraint.Kind kind, NamedLabel rhs, LabelEnv env, polyglot.util.Position pos, ConstraintMessage msg, boolean report)

Method Summary

protected void	addLEQEqns(java.util.Collection eqns, Label left, Label right) Produce equations that require left to be less than or equal to right, and add them to eqns.
java.util.Map	definitions(VarMap bounds) Returns a Map of Strings to List[String]s which is the definitions/bounds of the NamedLabels, and the description of any components that appear in the NamedLabels.
java.util.Collection	getEquations() Produce a Collection of Equations for this constraint.
boolean	hasVariables()
Label	lhsLabel()
protected java.util.Map	namedDescrips() Return a map from Strings to Strings, which are the descriptions of names in the left and right hand sides.
protected java.util.Map	namedLabels() Return a map from Strings to Labels, which are the named elements of the left and right hand sides.
NamedLabel	namedLhs()
NamedLabel	namedRhs()
Label	rhsLabel()

Methods inherited from class jif.types.Constraint

detailMsg, env, isCanonical, kind, messages, msg, position, report, technicalMsg, toString

Methods inherited from class java.lang.Object

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

Field Detail

EQUAL

public static final Constraint.Kind EQUAL

An equality kind of constraint. That is, the constraint requires that lhs <= rhs and rhs <= lhs.

LEQ

public static final Constraint.Kind LEQ

An inequality kind of constraint. That is, the constraint requires that lhs <= rhs.

namedLHS

protected NamedLabel namedLHS

Names for the LHS

namedRHS

protected NamedLabel namedRHS

Names for the RHS

Constructor Detail

LabelConstraint

public LabelConstraint(NamedLabel lhs,
                       Constraint.Kind kind,
                       NamedLabel rhs,
                       LabelEnv env,
                       polyglot.util.Position pos,
                       ConstraintMessage msg,
                       boolean report)

Method Detail

lhsLabel

public Label lhsLabel()

rhsLabel

public Label rhsLabel()

namedLhs

public NamedLabel namedLhs()

namedRhs

public NamedLabel namedRhs()

namedLabels

protected java.util.Map namedLabels()

Return a map from Strings to Labels, which are the named elements of the left and right hand sides.

namedDescrips

protected java.util.Map namedDescrips()

Return a map from Strings to Strings, which are the descriptions of names in the left and right hand sides.

definitions

public java.util.Map definitions(VarMap bounds)

Returns a Map of Strings to List[String]s which is the definitions/bounds of the NamedLabels, and the description of any components that appear in the NamedLabels. This map is used for verbose output to the user, to help explain the meaning of this constraint.

getEquations

public java.util.Collection getEquations()

Produce a Collection of Equations for this constraint.

Specified by:

getEquations in class Constraint

addLEQEqns

protected void addLEQEqns(java.util.Collection eqns,
                          Label left,
                          Label right)

Produce equations that require left to be less than or equal to right, and add them to eqns.

hasVariables

public boolean hasVariables()

Specified by:

hasVariables in class Constraint