com.yahoo.prelude.query

Class QueryCanonicalizer

java.lang.Object

com.yahoo.prelude.query.QueryCanonicalizer

public class QueryCanonicalizer
extends Object

Query normalizer and sanity checker.

Author:

bratseth

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	QueryCanonicalizer.CanonicalizationResult

Field Summary

Fields

Modifier and Type	Field and Description
static String	queryCanonicalization The name of the operation performed by this, for use in search chain ordering

Constructor Summary

Constructors

Constructor and Description
QueryCanonicalizer()

Method Summary

Modifier and Type	Method and Description
static String	canonicalize(Query query) Validates this query and carries out possible operations on this query which simplifies it without changing its semantics.
static String	canonicalize(QueryTree query) Canonicalize this query
private static QueryCanonicalizer.CanonicalizationResult	canonicalizeThis(Item item, ListIterator<Item> parentIterator)
private static boolean	collapseFalse(CompositeItem composite, ListIterator<Item> parentIterator) Handle FALSE items in the immediate children of this
private static void	collapseLevels(CompositeItem composite)
private static void	collapseLevels(CompositeItem composite, ListIterator<Item> i) Collapse the next item of this iterator into the given parent, if appropriate
private static boolean	containsFalse(CompositeItem composite)
private static void	makeDuplicatesCheap(Item item, Set<TermItem> rankTerms)
private static void	makeDuplicatesCheap(RankItem rankItem) If a term is present as both a rank term (i.e not the first child) and in the match condition (first child), then turn off any rank calculation for the term during matching, as it will be made available anyway for matches by the same term in the rank part.
private static void	moveChildren(CompositeItem from, ListIterator<Item> toIterator)
private static QueryCanonicalizer.CanonicalizationResult	recursivelyCanonicalize(Item item, ListIterator<Item> parentIterator) Canonicalize this query
private static void	removeDuplicates(EquivItem composite)
private static void	removeFalseIn(ListIterator<Item> iterator)

Methods inherited from class java.lang.Object

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

Field Detail

queryCanonicalization

public static final String queryCanonicalization

The name of the operation performed by this, for use in search chain ordering

See Also:

Constant Field Values

Constructor Detail

QueryCanonicalizer

public QueryCanonicalizer()

Method Detail

canonicalize

public static String canonicalize(Query query)

Validates this query and carries out possible operations on this query which simplifies it without changing its semantics.

Returns:

null if the query is valid, an error message if it is invalid

canonicalize

public static String canonicalize(QueryTree query)

Canonicalize this query

Returns:

null if the query is valid, an error message if it is invalid

recursivelyCanonicalize

private static QueryCanonicalizer.CanonicalizationResult recursivelyCanonicalize(Item item,
                                                                                 ListIterator<Item> parentIterator)

Canonicalize this query

Parameters:

item - the item to canonicalize

parentIterator - iterator for the parent of this item, never null

Returns:

true if the given query is valid, false otherwise

canonicalizeThis

private static QueryCanonicalizer.CanonicalizationResult canonicalizeThis(Item item,
                                                                          ListIterator<Item> parentIterator)

collapseLevels

private static void collapseLevels(CompositeItem composite)

collapseLevels

private static void collapseLevels(CompositeItem composite,
                                   ListIterator<Item> i)

Collapse the next item of this iterator into the given parent, if appropriate

moveChildren

private static void moveChildren(CompositeItem from,
                                 ListIterator<Item> toIterator)

collapseFalse

private static boolean collapseFalse(CompositeItem composite,
                                     ListIterator<Item> parentIterator)

Handle FALSE items in the immediate children of this

Returns:

true if this composite was replaced by FALSE

containsFalse

private static boolean containsFalse(CompositeItem composite)

removeFalseIn

private static void removeFalseIn(ListIterator<Item> iterator)

removeDuplicates

private static void removeDuplicates(EquivItem composite)

makeDuplicatesCheap

private static void makeDuplicatesCheap(RankItem rankItem)

If a term is present as both a rank term (i.e not the first child) and in the match condition (first child), then turn off any rank calculation for the term during matching, as it will be made available anyway for matches by the same term in the rank part.

Parameters:

rankItem - an item which will be simplified in place

makeDuplicatesCheap

private static void makeDuplicatesCheap(Item item,
                                        Set<TermItem> rankTerms)