Class ExpressionRefDelegate<T extends RelationalExpression>
- java.lang.Object
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- com.apple.foundationdb.record.query.plan.temp.ExpressionRefDelegate<T>
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- Type Parameters:
T
- the type
- All Implemented Interfaces:
Bindable
,Correlated<ExpressionRef<T>>
,ExpressionRef<T>
- Direct Known Subclasses:
ExpressionRefTraversal.FullyTraversableExpressionRef
@API(EXPERIMENTAL) public class ExpressionRefDelegate<T extends RelationalExpression> extends Object implements ExpressionRef<T>
An expression reference that wraps another expression reference.
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Nested Class Summary
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Nested classes/interfaces inherited from interface com.apple.foundationdb.record.query.plan.temp.ExpressionRef
ExpressionRef.UngettableReferenceException
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Constructor Summary
Constructors Modifier Constructor Description protected
ExpressionRefDelegate(ExpressionRef<T> delegate)
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description <U> U
acceptPropertyVisitor(PlannerProperty<U> property)
Stream<PlannerBindings>
bindWithin(ExpressionMatcher<? extends Bindable> matcher)
Try to bind the given matcher to the members of this reference.boolean
containsAllInMemo(ExpressionRef<? extends RelationalExpression> otherRef, AliasMap equivalenceMap)
<U extends RelationalExpression>
ExpressionRef<U>flatMapNullable(Function<T,ExpressionRef<U>> nullableFunc)
T
get()
Return the expression contained in this reference.Set<CorrelationIdentifier>
getCorrelatedTo()
Returns the set ofCorrelationIdentifier
s this entity is correlated to.ExpressionRef<T>
getDelegate()
RelationalExpressionPointerSet<T>
getMembers()
ExpressionRef<T>
getNewRefWith(T expression)
boolean
insert(T newValue)
Insert a new expression into this reference.<U extends RelationalExpression>
ExpressionRef<U>map(Function<T,U> func)
ExpressionRef<T>
rebase(AliasMap translationMap)
Rebases this and all other objects this objects is composed of using a given translation map.boolean
semanticEquals(Object other, AliasMap equivalenceMap)
Determine equality with respect to an equivalence map betweenCorrelationIdentifier
s based on semantic equality: equality of the plan fragments implementing under the given correlation bindings.int
semanticHashCode()
Return a semantic hash code for this object.-
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
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Methods inherited from interface com.apple.foundationdb.record.query.plan.temp.ExpressionRef
bindTo
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Constructor Detail
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ExpressionRefDelegate
protected ExpressionRefDelegate(ExpressionRef<T> delegate)
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Method Detail
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getDelegate
@Nonnull public ExpressionRef<T> getDelegate()
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insert
public boolean insert(@Nonnull T newValue)
Description copied from interface:ExpressionRef
Insert a new expression into this reference.- Specified by:
insert
in interfaceExpressionRef<T extends RelationalExpression>
- Parameters:
newValue
- the value to be inserted- Returns:
true
if the value was not already part of the reference and was inserted,false
if the given value was already contained in the reference and was therefore not inserted.
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get
@Nonnull public T get()
Description copied from interface:ExpressionRef
Return the expression contained in this reference. If the reference does not support getting its expresssion (for example, because it holds more than one expression, or none at all), this should throw an exception.- Specified by:
get
in interfaceExpressionRef<T extends RelationalExpression>
- Returns:
- the expression contained in this reference
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acceptPropertyVisitor
@Nullable public <U> U acceptPropertyVisitor(@Nonnull PlannerProperty<U> property)
- Specified by:
acceptPropertyVisitor
in interfaceExpressionRef<T extends RelationalExpression>
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bindWithin
@Nonnull public Stream<PlannerBindings> bindWithin(@Nonnull ExpressionMatcher<? extends Bindable> matcher)
Description copied from interface:ExpressionRef
Try to bind the given matcher to the members of this reference. If this reference has more than one member, it should try to match to any of them and produce a stream of bindings covering all possible combinations. If possible, this should be done in a lazy fashion using theStream
API, so as to minimize unnecessary work.- Specified by:
bindWithin
in interfaceExpressionRef<T extends RelationalExpression>
- Parameters:
matcher
- an expression matcher to match the member(s) of this reference with- Returns:
- a stream of bindings if the match succeeded or an empty stream if it failed
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map
@Nonnull public <U extends RelationalExpression> ExpressionRef<U> map(@Nonnull Function<T,U> func)
- Specified by:
map
in interfaceExpressionRef<T extends RelationalExpression>
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flatMapNullable
@Nullable public <U extends RelationalExpression> ExpressionRef<U> flatMapNullable(@Nonnull Function<T,ExpressionRef<U>> nullableFunc)
- Specified by:
flatMapNullable
in interfaceExpressionRef<T extends RelationalExpression>
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getNewRefWith
@Nonnull public ExpressionRef<T> getNewRefWith(@Nonnull T expression)
- Specified by:
getNewRefWith
in interfaceExpressionRef<T extends RelationalExpression>
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containsAllInMemo
public boolean containsAllInMemo(@Nonnull ExpressionRef<? extends RelationalExpression> otherRef, @Nonnull AliasMap equivalenceMap)
- Specified by:
containsAllInMemo
in interfaceExpressionRef<T extends RelationalExpression>
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getMembers
public RelationalExpressionPointerSet<T> getMembers()
- Specified by:
getMembers
in interfaceExpressionRef<T extends RelationalExpression>
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getCorrelatedTo
@Nonnull public Set<CorrelationIdentifier> getCorrelatedTo()
Description copied from interface:Correlated
Returns the set ofCorrelationIdentifier
s this entity is correlated to. This means that without a process that binds these correlations to values, theRelationalExpression
(or others that implement this interface) cannot even in principle produce a meaningful result. As often times entities that implement this interface use composition and effectively describe trees or DAGs, this method should be the set union of theCorrelationIdentifier
s this object is correlated to as well as all children, constituent parts, etc.- Specified by:
getCorrelatedTo
in interfaceCorrelated<T extends RelationalExpression>
- Returns:
- the set of
CorrelationIdentifier
s this entity is correlated to
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rebase
@Nonnull public ExpressionRef<T> rebase(@Nonnull AliasMap translationMap)
Description copied from interface:Correlated
Rebases this and all other objects this objects is composed of using a given translation map.- Specified by:
rebase
in interfaceCorrelated<T extends RelationalExpression>
- Parameters:
translationMap
- a map defining a translation fromCorrelationIdentifier
sids
toCorrelationIdentifier
sids'
. After the rebase, every correlation to anid
containedids
that is contained or referred to directly or indirectly bythis
must have been transformed to use the mapped counterpart ofid
id'
inids'
. IDs not contained in the translation map must remain unmodified by the rebase operation.- Returns:
- a new entity that has been rebased
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semanticEquals
public boolean semanticEquals(@Nullable Object other, @Nonnull AliasMap equivalenceMap)
Description copied from interface:Correlated
Determine equality with respect to an equivalence map betweenCorrelationIdentifier
s based on semantic equality: equality of the plan fragments implementing under the given correlation bindings. The contract of this variant ofequals()
differs from its regular Java counterpart. A correlation is mostly just one part inside of composition of objects that expresses a more complicated (correlated) structure such as a filter. For instanceq1.x = 5
uses a correlation toq1
. That entity representing the filter is said to be correlated toq1
. Similarly,q1.x = 6
is a different filter and is not equal under any correlation mapping. In contrast, consider a predicate where everything except the correlation is the same, such asq2.x = 5
. Without a binding, these two filters are not the same. However, the filters may be a part of some other entity that can express correlations:SELECT * FROM T as q1 WHERE q1.x = 5
is equal toSELECT * FROM T as q2 WHERE q2.x = 5
. It does not matter thatq1
andq2
are named differently. It is important, however, that their semantic meaning is the same. In the example bothq1
andq2
refer to a record typeT
which presumably is the same record type. Therefore, these two query blocks are the same, even though they are labelled differently. In the context of this method, we can establish equality betweenq1.x = 5
andq2.x = 5
if we know thatq1
andq2
refer to the same underlying entity. The equivalence map passed in encodes that equality betweenCorrelationIdentifier
s. Note: This method has the same interaction withObject.hashCode()
as the regularequals()
method. As we can only ever establish true equality using equivalence maps,hashCode()
implementations in implementors of this interface must not be dependent on any correlation identifiers used in the structure of the entity. Doing so might violate the fundamental property of hash codes:e1.equals(e2, ...) => e1.hashCode() == e2.hashCode()
- Specified by:
semanticEquals
in interfaceCorrelated<T extends RelationalExpression>
- Parameters:
other
- the other object to establish equality withequivalenceMap
- a map ofCorrelationIdentifier
sids
toids'
. A correlation identifierid
used inthis
should be considered equal to another correlation identifierid'
used inother
if either they are the same byObject.equals(java.lang.Object)
of if there is a mapping fromid
toid'
.- Returns:
true
if both entities are considered equal using the equivalences passed in,false
otherwise
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semanticHashCode
public int semanticHashCode()
Description copied from interface:Correlated
Return a semantic hash code for this object. The hash code must obey the convention that for any two objectso1
ando2
and for everyAliasMap
aliasMap
:o1.semanticEquals(o1, aliasMap)
followso1.semanticHash() == o2.semanticHash()
Correlated.semanticEquals(java.lang.Object, com.apple.foundationdb.record.query.plan.temp.AliasMap)
returnstrue
for these two objects the plan fragments are considered to produce the same result under the given correlations bindings. The left sideo1.semanticEquals(o1, aliasMap)
depends on anAliasMap
whileo1.semanticHash() == o2.semanticHash()
does not. Hence, the hash that is computed is identical regardless of possible bindings.- Specified by:
semanticHashCode
in interfaceCorrelated<T extends RelationalExpression>
- Returns:
- the semantic hash code
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