Package org.eclipse.xtext.serializer.analysis

Class GrammarConstraintProvider.Constraint

java.lang.Object

org.eclipse.xtext.serializer.analysis.GrammarConstraintProvider.Constraint

All Implemented Interfaces:

java.lang.Comparable<IGrammarConstraintProvider.IConstraint>, IGrammarConstraintProvider.IConstraint

Enclosing class:

GrammarConstraintProvider

protected static class GrammarConstraintProvider.Constraint
extends java.lang.Object
implements IGrammarConstraintProvider.IConstraint

Constructor Summary

Constructors

Constructor	Description
Constraint(Grammar grammar, org.eclipse.emf.ecore.EClass type, org.eclipse.xtext.util.formallang.Nfa<ISemanticSequencerNfaProvider.ISemState> nfa)

Method Summary

Modifier and Type	Method	Description
int	compareTo(IGrammarConstraintProvider.IConstraint o)
protected int[]	computeLowerBounds()
protected int[]	computeUpperBounds()	Computing the upper bounds is equivalent to the longest path problem.
boolean	equals(java.lang.Object obj)
IGrammarConstraintProvider.IConstraintElement	getBody()
java.util.List<ISerializationContext>	getContexts()
IGrammarConstraintProvider.IFeatureInfo[]	getFeatures()
protected java.lang.String	getIdentity()
java.lang.String	getName()
org.eclipse.xtext.util.formallang.Nfa<ISemanticSequencerNfaProvider.ISemState>	getNfa()
java.lang.String	getSimpleName()
org.eclipse.emf.ecore.EClass	getType()
int	hashCode()
protected void	setName(java.lang.String name)
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

Constraint

public Constraint(Grammar grammar,
                  org.eclipse.emf.ecore.EClass type,
                  org.eclipse.xtext.util.formallang.Nfa<ISemanticSequencerNfaProvider.ISemState> nfa)

Method Detail

computeLowerBounds

protected int[] computeLowerBounds()

computeUpperBounds

protected int[] computeUpperBounds()

Computing the upper bounds is equivalent to the longest path problem. While this is NP-hard if constrained to simple paths, it becomes easily solvable in our case since we include infinite paths. All features that are assigned inside a cycle have infinity as upper bound. For the remaining features we can handle each cycle as if it was a single node because it is not relevant where we enter the cycle and where we exit it (traversing the cycle has zero weight). The resulting simplified graph is acyclic, and in such graphs the longest path can be computed in linear time with a simple recursive algorithm.

compareTo

public int compareTo(IGrammarConstraintProvider.IConstraint o)

Specified by:

compareTo in interface java.lang.Comparable<IGrammarConstraintProvider.IConstraint>

equals

public boolean equals(java.lang.Object obj)

Overrides:

equals in class java.lang.Object

getBody

public IGrammarConstraintProvider.IConstraintElement getBody()

Specified by:

getBody in interface IGrammarConstraintProvider.IConstraint

Returns:

the root of the tree of IGrammarConstraintProvider.IConstraintElement that defines this constraint.

getContexts

public java.util.List<ISerializationContext> getContexts()

Specified by:

getContexts in interface IGrammarConstraintProvider.IConstraint

getFeatures

public IGrammarConstraintProvider.IFeatureInfo[] getFeatures()

Specified by:

getFeatures in interface IGrammarConstraintProvider.IConstraint

Returns:

a list of IGrammarConstraintProvider.IFeatureInfo for all EStructuralFeatures from the EClass returned by IGrammarConstraintProvider.IConstraint.getType() that have an assignment if this constraint. If there is no assignment for an EStructuralFeature in this constraint, the array's item is null.

getIdentity

protected java.lang.String getIdentity()

getName

public java.lang.String getName()

Specified by:

getName in interface IGrammarConstraintProvider.IConstraint

Returns:

a name that is unique for a grammar and that aims to be human-readable.

getNfa

public org.eclipse.xtext.util.formallang.Nfa<ISemanticSequencerNfaProvider.ISemState> getNfa()

Specified by:

getNfa in interface IGrammarConstraintProvider.IConstraint

getSimpleName

public java.lang.String getSimpleName()

Specified by:

getSimpleName in interface IGrammarConstraintProvider.IConstraint

getType

public org.eclipse.emf.ecore.EClass getType()

Specified by:

getType in interface IGrammarConstraintProvider.IConstraint

Returns:

This constraint only applies to EObjects of this type.

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object

setName

protected void setName(java.lang.String name)

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object