Interface CellExtractor
- All Superinterfaces:
IndexExtractor
- All Known Subinterfaces:
CountingBloomFilter
- All Known Implementing Classes:
ArrayCountingBloomFilter
- Functional Interface:
- This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.
Cell
is used to
refer to these counts and their associated index. This class is the equivalent of the index extractor except
that it produces cells.
Note that a CellExtractor must not return duplicate indices and must be ordered.
Implementations must guarantee that:
- The IndexExtractor implementation returns unique ordered indices.
- The cells are produced in IndexExtractor order.
- For every value produced by the IndexExtractor there will be only one matching cell produced by the CellExtractor.
- The CellExtractor will not generate cells with indices that are not output by the IndexExtractor.
- The IndexExtractor will not generate indices that have a zero count for the cell.
- Since:
- 4.5.0-M2
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Nested Class Summary
Nested ClassesModifier and TypeInterfaceDescriptionstatic interface
Represents an operation that accepts an<index, count>
pair. -
Method Summary
Modifier and TypeMethodDescriptionstatic CellExtractor
from
(IndexExtractor indexExtractor) Creates a CellExtractor from an IndexExtractor.boolean
processCells
(CellExtractor.CellPredicate consumer) Performs the given action for eachcell
where the cell count is non-zero.default boolean
processIndices
(IntPredicate predicate) The default implementation returns distinct and ordered indices for all cells with a non-zero count.default IndexExtractor
Creates an IndexExtractor comprising the unique indices for this extractor.Methods inherited from interface org.apache.commons.collections4.bloomfilter.IndexExtractor
asIndexArray
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Method Details
-
from
Creates a CellExtractor from an IndexExtractor.Note the following properties:
- Each index returned from the IndexExtractor is assumed to have a cell value of 1.
- The CellExtractor aggregates duplicate indices from the IndexExtractor.
A CellExtractor that outputs the mapping [(1,2),(2,3),(3,1)] can be created from many combinations of indices including:
[1, 1, 2, 2, 2, 3] [1, 3, 1, 2, 2, 2] [3, 2, 1, 2, 1, 2] ...
- Parameters:
indexExtractor
- An index indexExtractor.- Returns:
- A CellExtractor with the same indices as the IndexExtractor.
-
processCells
Performs the given action for eachcell
where the cell count is non-zero.Some Bloom filter implementations use a count rather than a bit flag. The term
Cell
is used to refer to these counts.Any exceptions thrown by the action are relayed to the caller. The consumer is applied to each cell. If the consumer returns
false
the execution is stopped,false
is returned, and no further pairs are processed.- Parameters:
consumer
- the action to be performed for each non-zero cell.- Returns:
true
if all cells return true from consumer,false
otherwise.- Throws:
NullPointerException
- if the specified consumer is null
-
processIndices
The default implementation returns distinct and ordered indices for all cells with a non-zero count.- Specified by:
processIndices
in interfaceIndexExtractor
- Parameters:
predicate
- the action to be performed for each non-zero bit index.- Returns:
true
if all indexes return true from consumer,false
otherwise.
-
uniqueIndices
Description copied from interface:IndexExtractor
Creates an IndexExtractor comprising the unique indices for this extractor.By default creates a new extractor with some overhead to remove duplicates. IndexExtractors that return unique indices by default should override this to return
this
.The default implementation will filter the indices from this instance and return them in ascending order.
- Specified by:
uniqueIndices
in interfaceIndexExtractor
- Returns:
- the IndexExtractor of unique values.
-