com.yahoo.prelude.querytransform

Class RecallSearcher

java.lang.Object

com.yahoo.component.AbstractComponent

com.yahoo.component.chain.ChainedComponent

com.yahoo.processing.Processor

com.yahoo.search.Searcher

com.yahoo.prelude.querytransform.RecallSearcher

All Implemented Interfaces:

com.yahoo.component.Component, Comparable<com.yahoo.component.Component>

public class RecallSearcher
extends Searcher

This searcher parses the content of the "recall" query property as a filter expression alongside a placeholder query string. The node corresponding to the placeholder query is then swapped with the current query tree. This allows us to parse "recall" using the same rules as "filter" without modifying the parser. If the "recall" property is unset, this searcher does nothing.

Author:

Simon Thoresen

Field Summary

Fields

Modifier and Type	Field and Description
private static com.yahoo.processing.request.CompoundName	recallName

Fields inherited from class com.yahoo.component.AbstractComponent

isDeconstructable

Constructor Summary

Constructors

Constructor and Description
RecallSearcher()

Method Summary

Modifier and Type	Method and Description
private static WordItem	findOrigWordItem(Item root, String value) Returns the first word item contained in the given item tree that is an instance of WordItem with the given word value.
private static boolean	hasRankItem(Item root) Returns true if the given item tree contains at least one instance of RankItem.
Result	search(Query query, Execution execution) Override this to implement your searcher.
private static void	updateFilterTerms(Item root) Marks all filter terms in the given query tree as unranked.

Methods inherited from class com.yahoo.search.Searcher

ensureFilled, fill, getLogger, process, toString

Methods inherited from class com.yahoo.component.chain.ChainedComponent

getAnnotatedDependencies, getDefaultAnnotatedDependencies, getDependencies, initDependencies

Methods inherited from class com.yahoo.component.AbstractComponent

clone, compareTo, deconstruct, getClassName, getId, getIdString, hasInitializedId, initId, isDeconstructable, setIsDeconstructable

Methods inherited from class java.lang.Object

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

Field Detail

recallName

private static final com.yahoo.processing.request.CompoundName recallName

Constructor Detail

RecallSearcher

public RecallSearcher()

Method Detail

search

public Result search(Query query,
                     Execution execution)

Description copied from class: Searcher

Override this to implement your searcher.

Searcher implementation subclasses will, depending on their type of logic, do one of the following:

• Query processors: Access the query, then call execution.search and return the result
• Result processors: Call execution.search to get the result, access it and return
• Sources (which produces results): Create a result, add the desired hits and return it.
• Federators (which forwards the search to multiple subchains): Call search on the desired subchains in parallel and get the results. Combine the results to one and return it.
• Workflows: Call execution.search as many times as desired, using different queries. Eventually return a result.

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:

• Unexpected events: Throw any RuntimeException. This query will fail with the exception message, and the error will be logged
• Expected events: Create (new Result(Query, ErrorMessage) or add result.setErrorIfNoOtherErrors(ErrorMessage) an error message to the Result.
• Recoverable user errors: Add a FeedbackHit explaining the condition and how to correct it.

Specified by:

search in class Searcher

Parameters:

query - the query

Returns:

the result of making this query

hasRankItem

private static boolean hasRankItem(Item root)

Returns true if the given item tree contains at least one instance of RankItem.

Parameters:

root - The root of the tree to check.

Returns:

True if a rank item was found.

findOrigWordItem

private static WordItem findOrigWordItem(Item root,
                                         String value)

Returns the first word item contained in the given item tree that is an instance of WordItem with the given word value.

Parameters:

root - The root of the tree to check.

value - The word to look for.

Returns:

The first node found.

updateFilterTerms

private static void updateFilterTerms(Item root)

Marks all filter terms in the given query tree as unranked.

Parameters:

root - The root of the tree to update.