Package com.apple.foundationdb.record.query.expressions

Class EmptyComparison

java.lang.Object

com.apple.foundationdb.record.query.expressions.BaseField

com.apple.foundationdb.record.query.expressions.EmptyComparison

All Implemented Interfaces:

PlanHashable, ComponentWithNoChildren, QueryComponent, QueryHashable

@API(MAINTAINED)
public class EmptyComparison
extends BaseField
implements ComponentWithNoChildren

A comparison to determine whether a repeated field is empty (has no occurrences).

Nested Class Summary

Nested classes/interfaces inherited from interface com.apple.foundationdb.record.PlanHashable

PlanHashable.PlanHashKind

Nested classes/interfaces inherited from interface com.apple.foundationdb.record.QueryHashable

QueryHashable.QueryHashKind

Constructor Summary

Constructors

Constructor	Description
EmptyComparison(String fieldName, boolean isEmpty)

Method Summary

Modifier and Type	Method	Description
protected int	basePlanHash(PlanHashable.PlanHashKind hashKind, ObjectPlanHash baseHash, Object... hashables)	Base implementation of PlanHashable.planHash(com.apple.foundationdb.record.PlanHashable.PlanHashKind).
protected int	baseQueryHash(QueryHashable.QueryHashKind hashKind, ObjectPlanHash baseHash, Object... hashables)	Base implementation of QueryHashable.queryHash(com.apple.foundationdb.record.QueryHashable.QueryHashKind).
boolean	equals(Object o)
<M extends Message> Boolean	evalMessage(FDBRecordStoreBase<M> store, EvaluationContext context, FDBRecord<M> record, Message message)	Return whether or not the given record matches this component.
GraphExpansion	expand(CorrelationIdentifier baseAlias, List<String> fieldNamePrefix)	Expand this query component into a data flow graph.
Field.OneOfThemEmptyMode	getEmptyMode()
protected List<Object>	getValues(MessageOrBuilder message)
int	hashCode()
boolean	isEmpty()
int	planHash(PlanHashable.PlanHashKind hashKind)	Return a hash similar to hashCode, but with the additional guarantee that is is stable across JVMs.
int	queryHash(QueryHashable.QueryHashKind hashKind)	Return a hash similar to hashCode, but with the additional guarantee that is is stable across JVMs.
String	toString()
void	validate(Descriptors.Descriptor descriptor)	Validate that the given descriptor is consistent with this component.
protected Descriptors.FieldDescriptor	validateRepeatedField(Descriptors.Descriptor descriptor)

Methods inherited from class com.apple.foundationdb.record.query.expressions.BaseField

findFieldDescriptor, getFieldName, getFieldValue, getName, requireMessageField, requirePrimitiveField, requireScalarField, validateFieldExistence

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.apple.foundationdb.record.PlanHashable

planHash

Methods inherited from interface com.apple.foundationdb.record.query.expressions.QueryComponent

eval, evalAsync, evalMessageAsync, expand, isAsync

Constructor Detail

EmptyComparison

public EmptyComparison(@Nonnull
                       String fieldName,
                       boolean isEmpty)

Method Detail

evalMessage

@Nullable
public <M extends Message> Boolean evalMessage(@Nonnull
                                               FDBRecordStoreBase<M> store,
                                               @Nonnull
                                               EvaluationContext context,
                                               @Nullable
                                               FDBRecord<M> record,
                                               @Nullable
                                               Message message)

Description copied from interface: QueryComponent

Return whether or not the given record matches this component. The message might be the Protobuf form of a record or a piece of that record. If the key expression is meaningful against a subrecord, it should evaluate against the message. Otherwise, it should evaluate against the record and ignore what part of that record is being considered. There should not be any reason to call this method outside of the implementation of another evalMessage. Under ordinary circumstances, if record is null, then message will be null. Otherwise, message will be record.getRecord() or some submessage of that, possibly null if the corresponding field is missing.

Specified by:

evalMessage in interface QueryComponent

Type Parameters:

M - the type of record

Parameters:

store - the record store from which the record came

context - context for bound expressions

record - the record

message - the Protobuf message to evaluate against

Returns:

true/false/null, true if the given record should be included in results, false if it should not, and null if this component cannot determine whether it should be included or not

See Also:

QueryComponent.eval(com.apple.foundationdb.record.provider.foundationdb.FDBRecordStoreBase<M>, com.apple.foundationdb.record.EvaluationContext, com.apple.foundationdb.record.provider.foundationdb.FDBRecord<M>)

validate

public void validate(@Nonnull
                     Descriptors.Descriptor descriptor)

Description copied from interface: QueryComponent

Validate that the given descriptor is consistent with this component. e.g. it has all the fields defined that this component wants to inspect.

Specified by:

validate in interface QueryComponent

Parameters:

descriptor - a record type descriptor, or a submessage descriptor

toString

public String toString()

Overrides:

toString in class Object

isEmpty

public boolean isEmpty()

expand

public GraphExpansion expand(@Nonnull
                             CorrelationIdentifier baseAlias,
                             @Nonnull
                             List<String> fieldNamePrefix)

Description copied from interface: QueryComponent

Expand this query component into a data flow graph. The returned graph represents an adequate representation of the component as composition of relational expressions and operators.

Specified by:

expand in interface QueryComponent

Parameters:

baseAlias - a an alias that refers to the data flow equivalent of an input to this component

fieldNamePrefix - a list of field names that accumulate a field nesting chain for non-repeated fields

Returns:

a new GraphExpansion representing the query graph equivalent of this query component

See Also:

TODO make this method private in Java 11

equals

public boolean equals(Object o)

hashCode

public int hashCode()

planHash

public int planHash(@Nonnull
                    PlanHashable.PlanHashKind hashKind)

Description copied from interface: PlanHashable

Return a hash similar to hashCode, but with the additional guarantee that is is stable across JVMs.

Specified by:

planHash in interface PlanHashable

Parameters:

hashKind - the "kind" of hash to calculate. Each kind of hash has a particular logic with regards to included and excluded items.

Returns:

a stable hash code

queryHash

public int queryHash(@Nonnull
                     QueryHashable.QueryHashKind hashKind)

Description copied from interface: QueryHashable

Return a hash similar to hashCode, but with the additional guarantee that is is stable across JVMs.

Specified by:

queryHash in interface QueryHashable

Parameters:

hashKind - the "kind" of hash to calculate. Each kind of hash has a particular logic with regards to included and excluded items.

Returns:

a stable hash code

getEmptyMode

@Nonnull
public Field.OneOfThemEmptyMode getEmptyMode()

getValues

@Nullable
protected List<Object> getValues(@Nonnull
                                 MessageOrBuilder message)

validateRepeatedField

@Nonnull
protected Descriptors.FieldDescriptor validateRepeatedField(@Nonnull
                                                            Descriptors.Descriptor descriptor)

basePlanHash

protected int basePlanHash(@Nonnull
                           PlanHashable.PlanHashKind hashKind,
                           ObjectPlanHash baseHash,
                           Object... hashables)

Base implementation of PlanHashable.planHash(com.apple.foundationdb.record.PlanHashable.PlanHashKind). This implementation makes each concrete subclass implement its own version of PlanHashable.planHash(com.apple.foundationdb.record.PlanHashable.PlanHashKind) so that they are guided to add their own class modifier (See ObjectPlanHash). This implementation is meant to give subclasses common functionality for their own implementation.

Overrides:

basePlanHash in class BaseField

Parameters:

hashKind - the plan hash kind to use

baseHash - the subclass' base hash (concrete identifier)

hashables - the rest of the subclass' hashable parameters (if any)

Returns:

the plan hash value calculated

baseQueryHash

protected int baseQueryHash(@Nonnull
                            QueryHashable.QueryHashKind hashKind,
                            ObjectPlanHash baseHash,
                            Object... hashables)

Base implementation of QueryHashable.queryHash(com.apple.foundationdb.record.QueryHashable.QueryHashKind). This implementation makes each concrete subclass implement its own version of QueryHashable.queryHash(com.apple.foundationdb.record.QueryHashable.QueryHashKind) so that they are guided to add their own class modifier (See ObjectPlanHash). This implementation is meant to give subclasses common functionality for their own implementation.

Overrides:

baseQueryHash in class BaseField

Parameters:

hashKind - the query hash kind to use

baseHash - the subclass' base hash (concrete identifier)

hashables - the rest of the subclass' hashable parameters (if any)

Returns:

the query hash value calculated