org.chronos.chronosphere.api.query

Interface QueryStepBuilder<S,E>

All Known Subinterfaces:

EObjectQueryStepBuilder<S>, NumericCastableQueryStepBuilder<S,E>, NumericQueryStepBuilder<S,E>, QueryStepBuilderInternal<S,E>, UntypedQueryStepBuilder<S,E>

All Known Implementing Classes:

AbstractQueryStepBuilder, EObjectQueryAllReferencingEObjectsQueryStep, EObjectQueryAndStepBuilder, EObjectQueryAsEObjectStepBuilder, EObjectQueryClosureStepBuilder, EObjectQueryDistinctStepBuilder, EObjectQueryEAllContentsStepBuilder, EObjectQueryEContainerStepBuilder, EObjectQueryEContentsStepBuilder, EObjectQueryEGetInverseByNameStepBuilder, EObjectQueryEGetInverseByReferenceStepBuilder, EObjectQueryEGetReferenceStepBuilder, EObjectQueryExceptObjectsStepBuilder, EObjectQueryHasFeatureValueStepBuilder, EObjectQueryIdentityStepBuilder, EObjectQueryInstanceOfEClassNameStepBuilder, EObjectQueryInstanceOfEClassStepBuilder, EObjectQueryLimitStepBuilder, EObjectQueryNonNullStepBuilder, EObjectQueryNotStepBuilder, EObjectQueryOrStepBuilder, EObjectQueryStepBuilderImpl, NumericQueryAsByteStepBuilder, NumericQueryAsDoubleStepBuilder, NumericQueryAsFloatStepBuilder, NumericQueryAsIntegerStepBuilder, NumericQueryAsLongStepBuilder, NumericQueryAsShortStepBuilder, NumericQueryCeilStepBuilder, NumericQueryFloorStepBuilder, NumericQueryRoundStepBuilder, NumericQueryRoundToIntStepBuilder, NumericQueryStepBuilderImpl, ObjectQueryAndStepBuilder, ObjectQueryAsBooleanStepBuilder, ObjectQueryAsCharacterStepBuilder, ObjectQueryBackStepBuilder, ObjectQueryDistinctStepBuilder, ObjectQueryEGetAttributeStepBuilder, ObjectQueryEGetByNameStepBuilder, ObjectQueryEObjectBackStepBuilder, ObjectQueryEObjectReifyStepBuilder, ObjectQueryEObjectUnionStepBuilder, ObjectQueryExceptNamedStepBuilder, ObjectQueryExceptSetStepBuilder, ObjectQueryFilterStepBuilder, ObjectQueryFlatMapStepBuilder, ObjectQueryLimitStepBuilder, ObjectQueryMapStepBuilder, ObjectQueryNamedStepBuilder, ObjectQueryNotStepBuilder, ObjectQueryOrderByStepBuilder, ObjectQueryOrStepBuilder, ObjectQueryStepBuilderImpl, ObjectQueryTerminalConverterStepBuilder, ObjectQueryUnionStepBuilder

public interface QueryStepBuilder<S,E>

Method Summary

Modifier and Type	Method and Description
QueryStepBuilder<S,E>	and(QueryStepBuilder<E,?>... subqueries)
UntypedQueryStepBuilder<S,java.lang.Object>	back(java.lang.String stepName) Exits the current traversal state and goes back to a named step, or a named set.
long	count() Counts the number of elements in the current result, and returns that count.
QueryStepBuilder<S,E>	distinct() Eliminates all duplicated values from the current result.
QueryStepBuilder<S,E>	except(java.util.Set<?> elementsToExclude) Removes all elements in the given set from the stream.
QueryStepBuilder<S,E>	except(java.lang.String stepName) Removes all elements from the given named step from this step.
QueryStepBuilder<S,E>	filter(java.util.function.Predicate<E> predicate) Applies the given filter predicate to all elements in the current result.
<T> UntypedQueryStepBuilder<S,T>	flatMap(java.util.function.Function<E,java.util.Iterator<T>> function) Uses the given function to map each element to an iterator of output elements.
QueryStepBuilder<S,E>	limit(long limit) Limits the number of elements in the result set to the given number.
<T> UntypedQueryStepBuilder<S,T>	map(java.util.function.Function<E,T> function) Uses the given function to map each element from the current result set to a new element.
QueryStepBuilder<S,E>	named(java.lang.String stepName) Assigns the given name to this QueryStepBuilder.
QueryStepBuilder<S,E>	not(QueryStepBuilder<E,?> subquery)
QueryStepBuilder<S,E>	notNull() Filters out and discards all null values from the current result set.
QueryStepBuilder<S,E>	or(QueryStepBuilder<E,?>... subqueries)
QueryStepBuilder<S,E>	orderBy(java.util.Comparator<E> comparator) Sorts the current result set by applying the given comparator.
java.util.Iterator<E>	toIterator() Creates an iterator over the elements in this query and returns it.
java.util.List<E>	toList() Calculates the result of this query and returns it as a List.
java.util.Set<E>	toSet() Calculates the result set of this query and returns it.
java.util.stream.Stream<E>	toStream() Converts this query into a Stream.
UntypedQueryStepBuilder<S,java.lang.Object>	union(QueryStepBuilder<E,?>... subqueries)

Method Detail

filter

QueryStepBuilder<S,E> filter(java.util.function.Predicate<E> predicate)

Applies the given filter predicate to all elements in the current result.

Parameters:

predicate - The predicate to apply. Must not be null. All elements for which the predicate function returns false will be filtered out and discarded.

Returns:

The query builder, for method chaining. Never null.

limit

QueryStepBuilder<S,E> limit(long limit)

Limits the number of elements in the result set to the given number.

Please note that the order of elements is in general arbitrary. Therefore, usually a limit(long) is preceded by a orderBy(Comparator).

Parameters:

limit - The limit to apply. Must not be negative.

Returns:

The query builder, for method chaining. Never null.

orderBy

QueryStepBuilder<S,E> orderBy(java.util.Comparator<E> comparator)

Sorts the current result set by applying the given comparator.

This method requires full resolution of all elements and is therefore non-lazy.

Parameters:

comparator - The comparator to use. Must not be null.

Returns:

The query builder, for method chaining. Never null.

distinct

QueryStepBuilder<S,E> distinct()

Eliminates all duplicated values from the current result.

This method is lazy, but requires to keep track of the "already encountered" elements in a set. Therefore, RAM consumption on this method may be high if it is applied on very large result sets.

Returns:

The distinct step builder, for method chaining. Never null.

map

<T> UntypedQueryStepBuilder<S,T> map(java.util.function.Function<E,T> function)

Uses the given function to map each element from the current result set to a new element.

Parameters:

function - The mapping function to apply. Must not be null. Should be idempotent and side-effect free.

Returns:

The query step builder, for method chaining. Never null.

flatMap

<T> UntypedQueryStepBuilder<S,T> flatMap(java.util.function.Function<E,java.util.Iterator<T>> function)

Uses the given function to map each element to an iterator of output elements. These output iterators will be concatenated and forwarded.

Parameters:

function - The map function to apply. Must not be null. Should be idempotent and side-effect free.

Returns:

The query step builder, for method chaining. Never null.

notNull

QueryStepBuilder<S,E> notNull()

Filters out and discards all null values from the current result set.

This is the same as:

 query.filter(element -> element != null)
 

Returns:

The query step builder, for method chaining. Never null.

See Also:

filter(Predicate)

named

QueryStepBuilder<S,E> named(java.lang.String stepName)

Assigns the given name to this QueryStepBuilder.

Note that only the step is named. When coming back to this step, the query result may be different than it was when it was first reached, depending on the traversal.

Parameters:

stepName - The name of the step. Must not be null. Must be unique within the query.

Returns:

The named step, for method chaining. Never null.

See Also:

back(String)

back

UntypedQueryStepBuilder<S,java.lang.Object> back(java.lang.String stepName)

Exits the current traversal state and goes back to a named step, or a named set.

Parameters:

stepName - The name of the step to go back to. Must not be null, must refer to a named step.

Returns:

The step after going back, for method chaining. Never null.

See Also:

named(String)

except

QueryStepBuilder<S,E> except(java.lang.String stepName)

Removes all elements from the given named step from this step.

Parameters:

stepName - The name of the step. Must not be null, must refer to a named step.

Returns:

The step after removing the elements in the given named step, for method chaining. Never null.

except

QueryStepBuilder<S,E> except(java.util.Set<?> elementsToExclude)

Removes all elements in the given set from the stream.

Parameters:

elementsToExclude - The elements to remove. Must not be null.

Returns:

The step after removing the elements in the given set, for method chaining. Never null.

union

UntypedQueryStepBuilder<S,java.lang.Object> union(QueryStepBuilder<E,?>... subqueries)

and

QueryStepBuilder<S,E> and(QueryStepBuilder<E,?>... subqueries)

or

QueryStepBuilder<S,E> or(QueryStepBuilder<E,?>... subqueries)

not

QueryStepBuilder<S,E> not(QueryStepBuilder<E,?> subquery)

toSet

java.util.Set<E> toSet()

Calculates the result set of this query and returns it.

Please note that iterating over the result set via toIterator() is in general faster and consumes less RAM than first converting the result into a set.

Returns:

The result set. Never null. May be empty.

toList

java.util.List<E> toList()

Calculates the result of this query and returns it as a List.

Please note that iterating over the result via toIterator() is in general faster and consumes less RAM than first converting the result into a list.

Returns:

The result list. Never null. May be empty.

toIterator

java.util.Iterator<E> toIterator()

Creates an iterator over the elements in this query and returns it.

Returns:

The iterator over the resulting elements. May be empty, but never null.

toStream

java.util.stream.Stream<E> toStream()

Converts this query into a Stream.

Returns:

The stream representation of this query.

count

long count()

Counts the number of elements in the current result, and returns that count.

Returns:

The count. Never negative, may be zero.