Package org.apache.lucene.index

Interface IndexSorter.ComparableValues

Enclosing interface:

IndexSorter

public static interface IndexSorter.ComparableValues

Caches the sort value of the current document of every segment being merged, and compares them.

This is the merge-sort counterpart of IndexSorter.DocComparator. Most sorts reduce a document to a single sortable long and should implement IndexSorter.getComparableProviders(List) instead; the fromComparableProviders(org.apache.lucene.index.IndexSorter.ComparableProvider[]) adapter exposes them through this interface with no change in behaviour. Sorts whose value cannot be represented as a long (for example raw bytes) implement IndexSorter.getComparableValues(List) directly.

Method Summary

Modifier and Type	Method	Description
int	compare(int readerIndexA, int readerIndexB)	Compares the values previously read by setTopValue(int, int) for the two segments.
static IndexSorter.ComparableValues	fromComparableProviders(IndexSorter.ComparableProvider[] providers)	Adapts an array of IndexSorter.ComparableProvider (one per segment) to IndexSorter.ComparableValues
void	setTopValue(int readerIndex, int docID)	Reads the value of the current document of the given segment so that it can later be compared by compare(int, int).

Method Details

setTopValue

void setTopValue(int readerIndex,
 int docID)
          throws IOException

Reads the value of the current document of the given segment so that it can later be compared by compare(int, int).

The merge sort visits the documents of each segment in increasing docID order, so docID is non-decreasing for a given readerIndex between consecutive calls.

Parameters:

readerIndex - the index of the segment in the list passed to IndexSorter.getComparableValues(List)

docID - the document whose value should be read

Throws:

IOException

compare

int compare(int readerIndexA,
 int readerIndexB)

Compares the values previously read by setTopValue(int, int) for the two segments. The returned value follows the same contract as Comparator.compare(Object, Object), without applying the reverse flag (the caller is responsible for that).

fromComparableProviders

static IndexSorter.ComparableValues fromComparableProviders(IndexSorter.ComparableProvider[] providers)

Adapts an array of IndexSorter.ComparableProvider (one per segment) to IndexSorter.ComparableValues