public class NGramSearcher extends Searcher
This declares it must be placed after Juniper searchers because it assumes Juniper token separators (which are returned on bolding) are not replaced by highlight tags when this is run (and "after" means "before" from the point of view of the result).
Constructor and Description |
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NGramSearcher(com.yahoo.language.Linguistics linguistics) |
Modifier and Type | Method and Description |
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protected CompositeItem |
createGramRoot(Query query)
Creates the root of the query subtree which will contain the grams to match,
called by
splitToGrams(com.yahoo.prelude.query.Item, java.lang.String, int, com.yahoo.search.Query) . |
void |
fill(Result result,
String summaryClass,
Execution execution)
Fill hit properties with data using the given summary class.
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protected com.yahoo.language.process.GramSplitter |
getGramSplitter()
Returns the (thread-safe) object to use to split the query text into grams.
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Result |
search(Query query,
Execution execution)
Override this to implement your searcher.
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protected Item |
splitToGrams(Item term,
String text,
int gramSize,
Query query)
Splits the given item into n-grams and adds them as a CompositeItem containing WordItems searching the
index of the input term.
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ensureFilled, getLogger, process, toString
getAnnotatedDependencies, getDefaultAnnotatedDependencies, getDependencies, initDependencies
public Result search(Query query, Execution execution)
Searcher
Searcher implementation subclasses will, depending on their type of logic, do one of the following:
Hits come in two kinds - concrete hits are actual content of the kind requested by the user, meta hits are hits which provides information about the collection of hits, on the query, the service and so on.
The query specifies a window into a larger result list that must be returned from the searcher through hits and offset; Searchers which returns list of hits in the top level in the result must return at least hits number of hits (or if impossible; all that are available), starting at the given offset. In addition, searchers are allowed to return any number of meta hits (although this number is expected to be low). For hits contained in nested hit groups, the concept of a window defined by hits and offset is not well defined and does not apply.
Error handling in searchers:
public void fill(Result result, String summaryClass, Execution execution)
Searcher
This needs to be overridden by federating searchers to contact search sources again by propagating the fill call down through the search chain, and by source searchers which talks to fill capable backends to request the data to be filled. Other searchers do not need to override this.
protected Item splitToGrams(Item term, String text, int gramSize, Query query)
term
- the term to split, must be an item which implement the IndexedItem and BlockItem "mixins"text
- the text of the item, just stringValue() if the item is a TermItemgramSize
- the gram size to split toquery
- the query in which this rewriting is doneprotected final com.yahoo.language.process.GramSplitter getGramSplitter()
protected CompositeItem createGramRoot(Query query)
splitToGrams(com.yahoo.prelude.query.Item, java.lang.String, int, com.yahoo.search.Query)
. This hook is provided to make it easy to create a subclass which
matches grams using a different composite item, e.g an OrItem.
This default implementation return new AndItem();
query
- the input query, to make it possible to return a different composite item type
depending on the query contentsplitToGrams(com.yahoo.prelude.query.Item, java.lang.String, int, com.yahoo.search.Query)
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