com.apple.foundationdb.record.query.plan.temp.matchers

Class AnyChildWithRestMatcher<T extends PlannerExpression>

java.lang.Object

com.apple.foundationdb.record.query.plan.temp.matchers.AnyChildWithRestMatcher<T>

Type Parameters:

T - the type of the matcher for the selected child

All Implemented Interfaces:

ExpressionChildrenMatcher

@API(value=EXPERIMENTAL)
public class AnyChildWithRestMatcher<T extends PlannerExpression>
extends Object
implements ExpressionChildrenMatcher

An expression matcher that tries to match any child to the given ExpressionMatcher while providing a ReferenceMatcher binding to all other children. This can be quite useful when matching to a planner expression that might have an unbounded number of children when a planner rule wants to inspect exactly one of those children deeply. This matcher might produce several possible bindings because the ExpressionMatcher for the distinguished child might match several children.

Method Summary

Modifier and Type	Method and Description
static <T extends PlannerExpression> AnyChildWithRestMatcher<T>	anyMatchingWithRest(ExpressionMatcher<T> selectedChildMatcher, ReferenceMatcher<? super T> otherChildrenMatcher)
Stream<PlannerBindings>	matches(Iterator<? extends ExpressionRef<? extends PlannerExpression>> childIterator) Apply this matcher to the children provided by the given iterator and produce a stream of possible bindings.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

matches

@Nonnull
public Stream<PlannerBindings> matches(@Nonnull
                                                Iterator<? extends ExpressionRef<? extends PlannerExpression>> childIterator)

Description copied from interface: ExpressionChildrenMatcher

Apply this matcher to the children provided by the given iterator and produce a stream of possible bindings. If the match is not successful, produce an empty stream. Note that this method should not generally match to the children themselves; instead, it should delegate that work to one or more inner ExpressionMatchers.

Specified by:

matches in interface ExpressionChildrenMatcher

Parameters:

childIterator - an iterator of references to the children of a planner expression

Returns:

a stream of the possible bindings from applying this match to the children in the given iterator

anyMatchingWithRest

@Nonnull
public static <T extends PlannerExpression> AnyChildWithRestMatcher<T> anyMatchingWithRest(@Nonnull
                                                                                                    ExpressionMatcher<T> selectedChildMatcher,
                                                                                                    @Nonnull
                                                                                                    ReferenceMatcher<? super T> otherChildrenMatcher)