org.eclipse.viatra.query.runtime.matchers.planning.helpers

Class FunctionalDependencyHelper

java.lang.Object

org.eclipse.viatra.query.runtime.matchers.planning.helpers.FunctionalDependencyHelper

public class FunctionalDependencyHelper
extends java.lang.Object

Helper utility class for functional dependency analysis. Throughout this class attribute sets are represented as generic sets and functional dependencies as maps from attribute set (generic sets) to attribute set (generic sets)

Constructor Summary

Constructors

Constructor and Description
FunctionalDependencyHelper()

Method Summary

Modifier and Type	Method and Description
static <A> java.util.Set<A>	closureOf(java.util.Collection<A> attributes, java.util.Map<java.util.Set<A>,java.util.Set<A>> dependencies) Get the closure of the specified attribute set relative to the specified functional dependencies.
static <A> void	includeDependencies(java.util.Map<java.util.Set<A>,java.util.Set<A>> accumulator, java.util.Map<java.util.Set<A>,java.util.Set<A>> additionalDependencies) Adds all given dependencies to a mutable accumulator.
static <A> void	includeDependency(java.util.Map<java.util.Set<A>,java.util.Set<A>> accumulator, java.util.Set<A> left, java.util.Set<A> right) Adds a given dependency to a mutable accumulator.
static <A> boolean	isTrivial(java.util.Set<A> left, java.util.Set<A> right)
static <A> java.util.Map<java.util.Set<A>,java.util.Set<A>>	projectDependencies(java.util.Map<java.util.Set<A>,java.util.Set<A>> originalDependencies, java.util.Set<A> targetAttributes) Returns the dependency set over attributes in targetAttributes that are implied by a given source dependency set.

Methods inherited from class java.lang.Object

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

Constructor Detail

FunctionalDependencyHelper

public FunctionalDependencyHelper()

Method Detail

closureOf

public static <A> java.util.Set<A> closureOf(java.util.Collection<A> attributes,
                                             java.util.Map<java.util.Set<A>,java.util.Set<A>> dependencies)

Get the closure of the specified attribute set relative to the specified functional dependencies.

Parameters:

attributes - The attributes to get the closure of.

dependencies - The functional dependencies of which the closure operation is relative to.

Returns:

The closure of the specified attribute set relative to the specified functional dependencies.

isTrivial

public static <A> boolean isTrivial(java.util.Set<A> left,
                                    java.util.Set<A> right)

Returns:

true if the dependency from the left set to the right set is trivial

Since:

1.5

projectDependencies

public static <A> java.util.Map<java.util.Set<A>,java.util.Set<A>> projectDependencies(java.util.Map<java.util.Set<A>,java.util.Set<A>> originalDependencies,
                                                                                       java.util.Set<A> targetAttributes)

Returns the dependency set over attributes in targetAttributes that are implied by a given source dependency set.

Note: exponential in the size of the target attribute set.

Note: minimality of the returned dependency set is currently not guaranteed.

Parameters:

originalDependencies - all dependencies that are known to hold on a wider set of attributes

targetAttributes - the set of attributes we are interested in

Since:

1.5

includeDependency

public static <A> void includeDependency(java.util.Map<java.util.Set<A>,java.util.Set<A>> accumulator,
                                         java.util.Set<A> left,
                                         java.util.Set<A> right)

Adds a given dependency to a mutable accumulator.

Since:

1.5

includeDependencies

public static <A> void includeDependencies(java.util.Map<java.util.Set<A>,java.util.Set<A>> accumulator,
                                           java.util.Map<java.util.Set<A>,java.util.Set<A>> additionalDependencies)

Adds all given dependencies to a mutable accumulator.

Since:

1.5