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

Class DefaultDBCoalesceFunctionSymbol

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.DefaultDBCoalesceFunctionSymbol

All Implemented Interfaces:

DBFunctionSymbol, DBFunctionSymbolSerializer, FunctionSymbol, Predicate

public class DefaultDBCoalesceFunctionSymbol
extends AbstractArgDependentTypedDBFunctionSymbol

Nested Class Summary

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

FunctionSymbol.FunctionalTermNullability

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	DefaultDBCoalesceFunctionSymbol(String nameInDialect, int arity, 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) 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.
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, simplifyAsGuaranteedToBeNonNull, 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, simplifyAsGuaranteedToBeNonNull

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

getArity, getName

Constructor Detail

DefaultDBCoalesceFunctionSymbol

protected DefaultDBCoalesceFunctionSymbol(String nameInDialect,
                                          int arity,
                                          DBTermType rootDBTermType,
                                          DBFunctionSymbolSerializer serializer)

Method Detail

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

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.

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)

Description copied from interface: FunctionSymbol

1. When a functional term simplifies itself in a BOTTOM-UP manner: Returns true if is guaranteed to "simplify itself" as a Constant when receiving Constants as arguments (outside the optimization phase) . 2. When a functional term simplifies itself in a TOP-DOWN manner (e.g. IF-THEN-ELSE functional terms): The permission for post-processing may depend on the ability of sub-functional terms to be post-processed or safely evaluated by the DB engine. (Recall that top-down evaluation allows some arguments not to be evaluated when their pre-conditions are not met. This is particularly valuable for preventing fatal errors).

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