Class FunctionalDependencyHelper
- java.lang.Object
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- org.eclipse.viatra.query.runtime.matchers.planning.helpers.FunctionalDependencyHelper
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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)
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Method Summary
All Methods Static Methods Concrete Methods Modifier and Type Method 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 intargetAttributes
that are implied by a given source dependency set.
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Method Detail
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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.
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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
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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 intargetAttributes
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 attributestargetAttributes
- the set of attributes we are interested in- Since:
- 1.5
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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
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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
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