it.unibz.inf.ontop.model.term.functionsymbol.db.impl

Class NullIfDBFunctionSymbolImpl

java.lang.Object

it.unibz.inf.ontop.model.term.impl.PredicateImpl

it.unibz.inf.ontop.model.term.functionsymbol.impl.FunctionSymbolImpl

it.unibz.inf.ontop.model.term.functionsymbol.db.impl.AbstractArgDependentTypedDBFunctionSymbol

it.unibz.inf.ontop.model.term.functionsymbol.db.impl.NullIfDBFunctionSymbolImpl

All Implemented Interfaces:

DBFunctionSymbol, DBFunctionSymbolSerializer, FunctionSymbol, Predicate

public class NullIfDBFunctionSymbolImpl
extends AbstractArgDependentTypedDBFunctionSymbol

Nested Class Summary

Nested classes/interfaces inherited from interface it.unibz.inf.ontop.model.term.functionsymbol.FunctionSymbol

FunctionSymbol.FunctionalTermNullability

Field Summary

Fields

Modifier and Type	Field and Description
protected static String	NULLIF_STR

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	NullIfDBFunctionSymbolImpl(DBTermType rootDBTermType)
protected	NullIfDBFunctionSymbolImpl(String name, DBTermType rootDBTermType, DBFunctionSymbolSerializer serializer)

Method Summary

Modifier and Type	Method and Description
protected ImmutableTerm	buildTermAfterEvaluation(com.google.common.collect.ImmutableList<ImmutableTerm> newTerms, TermFactory termFactory, VariableNullability variableNullability) By default, just build a new functional term.
boolean	canBePostProcessed(com.google.common.collect.ImmutableList<? extends ImmutableTerm> arguments) Currently cannot be post-processed as we are not sure which kind of equality is considered by the DB engine TODO: experiment
protected Map.Entry<ImmutableTerm,Stream<ImmutableTerm>>	decomposeNullIfHierarchy(com.google.common.collect.ImmutableList<? extends ImmutableTerm> terms) Decomposes hierarchies like NULLIF(NULLIF(x,1),0) into pairs like (x, [0,1])
IncrementalEvaluation	evaluateIsNotNull(com.google.common.collect.ImmutableList<? extends ImmutableTerm> terms, TermFactory termFactory, VariableNullability variableNullability) Default implementation, can be overridden
protected Stream<? extends ImmutableTerm>	extractPossibleValues(com.google.common.collect.ImmutableList<? extends ImmutableTerm> terms)
String	getNativeDBString(com.google.common.collect.ImmutableList<? extends ImmutableTerm> terms, Function<ImmutableTerm,String> termConverter, TermFactory termFactory) Returns a String in the native query language.
boolean	isAlwaysInjectiveInTheAbsenceOfNonInjectiveFunctionalTerms() When the function symbol is, in the absence of non-injective functional sub-terms, sometimes but not always injective, please override isInjective(...)
boolean	isPreferringToBePostProcessedOverBeingBlocked() If it is better to be post-processed than being blocked behind an UNION.
protected boolean	mayReturnNullWithoutNullArguments() Returns false when a functional term with this symbol: 1.
FunctionalTermSimplification	simplifyAsGuaranteedToBeNonNull(com.google.common.collect.ImmutableList<? extends ImmutableTerm> terms, TermFactory termFactory) If guaranteed to be non-null, only considers the first term.
protected boolean	tolerateNulls() Returns true if is not guaranteed to return NULL when one argument is NULL.

Methods inherited from class it.unibz.inf.ontop.model.term.functionsymbol.db.impl.AbstractArgDependentTypedDBFunctionSymbol

inferType

Methods inherited from class it.unibz.inf.ontop.model.term.functionsymbol.impl.FunctionSymbolImpl

analyzeInjectivity, canBeSafelyDecomposedIntoConjunction, decomposeInjectiveTopFunctionalTerm, enableIfElseNullLifting, evaluateNullability, evaluateStrictEq, evaluateStrictEqWithFunctionalTerm, evaluateStrictEqWithNonNullConstant, getExpectedBaseType, getExpectedBaseTypes, isAggregation, isDeterministic, isInjective, isNullable, proposeProvenanceVariables, simplify, transformIntoRegularArguments, tryToLiftMagicNumbers

Methods inherited from class it.unibz.inf.ontop.model.term.impl.PredicateImpl

equals, getArity, getName, hashCode, toString

Methods inherited from class java.lang.Object

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

Methods inherited from interface it.unibz.inf.ontop.model.term.functionsymbol.FunctionSymbol

analyzeInjectivity, evaluateNullability, evaluateStrictEq, getExpectedBaseType, isAggregation, isDeterministic, isNullable, proposeProvenanceVariables, simplify

Methods inherited from interface it.unibz.inf.ontop.model.term.functionsymbol.Predicate

getArity, getName

Field Detail

NULLIF_STR

protected static final String NULLIF_STR

See Also:

Constant Field Values

Constructor Detail

NullIfDBFunctionSymbolImpl

protected NullIfDBFunctionSymbolImpl(String name,
                                     DBTermType rootDBTermType,
                                     DBFunctionSymbolSerializer serializer)

NullIfDBFunctionSymbolImpl

protected NullIfDBFunctionSymbolImpl(DBTermType rootDBTermType)

Method Detail

extractPossibleValues

protected Stream<? extends ImmutableTerm> extractPossibleValues(com.google.common.collect.ImmutableList<? extends ImmutableTerm> terms)

Specified by:

extractPossibleValues in class AbstractArgDependentTypedDBFunctionSymbol

isPreferringToBePostProcessedOverBeingBlocked

public boolean isPreferringToBePostProcessedOverBeingBlocked()

Description copied from interface: DBFunctionSymbol

If it is better to be post-processed than being blocked behind an UNION. Obviously, non post-processable function symbols must return false.

getNativeDBString

public String getNativeDBString(com.google.common.collect.ImmutableList<? extends ImmutableTerm> terms,
                                Function<ImmutableTerm,String> termConverter,
                                TermFactory termFactory)

Description copied from interface: DBFunctionSymbolSerializer

Returns a String in the native query language.

tolerateNulls

protected boolean tolerateNulls()

Description copied from class: FunctionSymbolImpl

Returns true if is not guaranteed to return NULL when one argument is NULL. Can be the case for some function symbols that are rejecting certain cases and therefore refuse to simplify themselves, e.g. RDF(NULL,IRI) is invalid and therefore cannot be simplified.

Specified by:

tolerateNulls in class FunctionSymbolImpl

mayReturnNullWithoutNullArguments

protected boolean mayReturnNullWithoutNullArguments()

Description copied from class: FunctionSymbolImpl

Returns false when a functional term with this symbol: 1. never produce NULLs 2. May produce NULLs but it is always due to a NULL argument

Specified by:

mayReturnNullWithoutNullArguments in class FunctionSymbolImpl

isAlwaysInjectiveInTheAbsenceOfNonInjectiveFunctionalTerms

public boolean isAlwaysInjectiveInTheAbsenceOfNonInjectiveFunctionalTerms()

Description copied from class: FunctionSymbolImpl

When the function symbol is, in the absence of non-injective functional sub-terms, sometimes but not always injective, please override isInjective(...)

Specified by:

isAlwaysInjectiveInTheAbsenceOfNonInjectiveFunctionalTerms in class FunctionSymbolImpl

canBePostProcessed

public boolean canBePostProcessed(com.google.common.collect.ImmutableList<? extends ImmutableTerm> arguments)

Currently cannot be post-processed as we are not sure which kind of equality is considered by the DB engine TODO: experiment

buildTermAfterEvaluation

protected ImmutableTerm buildTermAfterEvaluation(com.google.common.collect.ImmutableList<ImmutableTerm> newTerms,
                                                 TermFactory termFactory,
                                                 VariableNullability variableNullability)

Description copied from class: FunctionSymbolImpl

By default, just build a new functional term. NB: If the function symbol does not tolerate NULL values, no need to handle them here.

Overrides:

buildTermAfterEvaluation in class FunctionSymbolImpl

evaluateIsNotNull

public IncrementalEvaluation evaluateIsNotNull(com.google.common.collect.ImmutableList<? extends ImmutableTerm> terms,
                                               TermFactory termFactory,
                                               VariableNullability variableNullability)

Description copied from class: FunctionSymbolImpl

Default implementation, can be overridden

Specified by:

evaluateIsNotNull in interface FunctionSymbol

Overrides:

evaluateIsNotNull in class FunctionSymbolImpl

decomposeNullIfHierarchy

protected Map.Entry<ImmutableTerm,Stream<ImmutableTerm>> decomposeNullIfHierarchy(com.google.common.collect.ImmutableList<? extends ImmutableTerm> terms)

Decomposes hierarchies like NULLIF(NULLIF(x,1),0) into pairs like (x, [0,1])

simplifyAsGuaranteedToBeNonNull

public FunctionalTermSimplification simplifyAsGuaranteedToBeNonNull(com.google.common.collect.ImmutableList<? extends ImmutableTerm> terms,
                                                                    TermFactory termFactory)

If guaranteed to be non-null, only considers the first term.

Specified by:

simplifyAsGuaranteedToBeNonNull in interface FunctionSymbol

Overrides:

simplifyAsGuaranteedToBeNonNull in class FunctionSymbolImpl