org.apache.lucene.search.postingshighlight

Class CustomPostingsHighlighter

java.lang.Object

org.apache.lucene.search.postingshighlight.XPostingsHighlighter

org.apache.lucene.search.postingshighlight.CustomPostingsHighlighter

public final class CustomPostingsHighlighter
extends XPostingsHighlighter

Subclass of the XPostingsHighlighter that works for a single field in a single document. It receives the field values as input and it performs discrete highlighting on each single value calling the highlightDoc method multiple times. It allows to pass in the query terms to avoid calling extract terms multiple times. The use that we make of the postings highlighter is not optimal. It would be much better to highlight multiple docs in a single call, as we actually lose its sequential IO. But that would require: 1) to make our fork more complex and harder to maintain to perform discrete highlighting (needed to return a different snippet per value when number_of_fragments=0 and the field has multiple values) 2) refactoring of the elasticsearch highlight api which currently works per hit

Field Summary

Fields inherited from class org.apache.lucene.search.postingshighlight.XPostingsHighlighter

DEFAULT_MAX_LENGTH

Constructor Summary

Constructors

Constructor and Description
CustomPostingsHighlighter(CustomPassageFormatter passageFormatter, List<Object> fieldValues, boolean mergeValues, int maxLength, int noMatchSize)

Method Summary

Modifier and Type	Method and Description
protected BreakIterator	getBreakIterator(String field) Returns the BreakIterator to use for dividing text into passages.
protected int	getContentLength(String field, int docId)
protected org.apache.lucene.search.postingshighlight.Passage[]	getEmptyHighlight(String fieldName, BreakIterator bi, int maxPassages) Called to summarize a document when no hits were found.
protected org.apache.lucene.search.postingshighlight.PassageFormatter	getFormatter(String field) Returns the PassageFormatter to use for formatting passages into highlighted snippets.
protected char	getMultiValuedSeparator(String field) Returns the logical separator between values for multi-valued fields.
protected int	getOffsetForCurrentValue(String field, int docId)
Snippet[]	highlightDoc(String field, org.apache.lucene.util.BytesRef[] terms, org.apache.lucene.search.IndexSearcher searcher, int docId, int maxPassages)
protected String	loadCurrentFieldValue()
protected String[][]	loadFieldValues(org.apache.lucene.search.IndexSearcher searcher, String[] fields, int[] docids, int maxLength) Loads the String values for each field X docID to be highlighted.
void	setBreakIterator(BreakIterator breakIterator)

Methods inherited from class org.apache.lucene.search.postingshighlight.XPostingsHighlighter

getScorer, highlight, highlight, highlightField, highlightFields, highlightFields, highlightFields, highlightFieldsAsObjects

Methods inherited from class java.lang.Object

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

Constructor Detail

CustomPostingsHighlighter

public CustomPostingsHighlighter(CustomPassageFormatter passageFormatter,
                                 List<Object> fieldValues,
                                 boolean mergeValues,
                                 int maxLength,
                                 int noMatchSize)

Method Detail

highlightDoc

public Snippet[] highlightDoc(String field,
                              org.apache.lucene.util.BytesRef[] terms,
                              org.apache.lucene.search.IndexSearcher searcher,
                              int docId,
                              int maxPassages)
                       throws IOException

Throws:

IOException

getContentLength

protected int getContentLength(String field,
                               int docId)

Overrides:

getContentLength in class XPostingsHighlighter

getOffsetForCurrentValue

protected int getOffsetForCurrentValue(String field,
                                       int docId)

Overrides:

getOffsetForCurrentValue in class XPostingsHighlighter

setBreakIterator

public void setBreakIterator(BreakIterator breakIterator)

getFormatter

protected org.apache.lucene.search.postingshighlight.PassageFormatter getFormatter(String field)

Description copied from class: XPostingsHighlighter

Returns the PassageFormatter to use for formatting passages into highlighted snippets. This returns a new PassageFormatter by default; subclasses can override to customize.

Overrides:

getFormatter in class XPostingsHighlighter

getBreakIterator

protected BreakIterator getBreakIterator(String field)

Description copied from class: XPostingsHighlighter

Returns the BreakIterator to use for dividing text into passages. This returns BreakIterator.getSentenceInstance(java.util.Locale) by default; subclasses can override to customize.

Overrides:

getBreakIterator in class XPostingsHighlighter

getMultiValuedSeparator

protected char getMultiValuedSeparator(String field)

Description copied from class: XPostingsHighlighter

Returns the logical separator between values for multi-valued fields. The default value is a space character, which means passages can span across values, but a subclass can override, for example with U+2029 PARAGRAPH SEPARATOR (PS) if each value holds a discrete passage for highlighting.

Overrides:

getMultiValuedSeparator in class XPostingsHighlighter

getEmptyHighlight

protected org.apache.lucene.search.postingshighlight.Passage[] getEmptyHighlight(String fieldName,
                                                                                 BreakIterator bi,
                                                                                 int maxPassages)

Description copied from class: XPostingsHighlighter

Called to summarize a document when no hits were found. By default this just returns the first maxPassages sentences; subclasses can override to customize.

Overrides:

getEmptyHighlight in class XPostingsHighlighter

loadFieldValues

protected String[][] loadFieldValues(org.apache.lucene.search.IndexSearcher searcher,
                                     String[] fields,
                                     int[] docids,
                                     int maxLength)
                              throws IOException

Description copied from class: XPostingsHighlighter

Loads the String values for each field X docID to be highlighted. By default this loads from stored fields, but a subclass can change the source. This method should allocate the String[fields.length][docids.length] and fill all values. The returned Strings must be identical to what was indexed.

Overrides:

loadFieldValues in class XPostingsHighlighter

Throws:

IOException

loadCurrentFieldValue

protected String loadCurrentFieldValue()