org.apache.lucene.search
Class AutomatonQuery
java.lang.Object
org.apache.lucene.search.Query
org.apache.lucene.search.MultiTermQuery
org.apache.lucene.search.AutomatonQuery
- All Implemented Interfaces:
- Cloneable
- Direct Known Subclasses:
- RegexpQuery, WildcardQuery
public class AutomatonQuery
- extends MultiTermQuery
A Query
that will match terms against a finite-state machine.
This query will match documents that contain terms accepted by a given
finite-state machine. The automaton can be constructed with the
org.apache.lucene.util.automaton
API. Alternatively, it can be
created from a regular expression with RegexpQuery
or from
the standard Lucene wildcard syntax with WildcardQuery
.
When the query is executed, it will create an equivalent DFA of the
finite-state machine, and will enumerate the term dictionary in an
intelligent way to reduce the number of comparisons. For example: the regular
expression of [dl]og?
will make approximately four comparisons:
do, dog, lo, and log.
- WARNING: This API is experimental and might change in incompatible ways in the next release.
automaton
protected final Automaton automaton
- the automaton to match index terms against
compiled
protected final CompiledAutomaton compiled
term
protected final Term term
- term containing the field, and possibly some pattern structure
AutomatonQuery
public AutomatonQuery(Term term,
Automaton automaton)
- Create a new AutomatonQuery from an
Automaton
.
- Parameters:
term
- Term containing field and possibly some pattern structure. The
term text is ignored.automaton
- Automaton to run, terms that are accepted are considered a
match.
getTermsEnum
protected TermsEnum getTermsEnum(Terms terms,
AttributeSource atts)
throws IOException
- Description copied from class:
MultiTermQuery
- Construct the enumeration to be used, expanding the
pattern term. This method should only be called if
the field exists (ie, implementations can assume the
field does exist). This method should not return null
(should instead return
TermsEnum.EMPTY
if no
terms match). The TermsEnum must already be
positioned to the first matching term.
The given AttributeSource
is passed by the MultiTermQuery.RewriteMethod
to
provide attributes, the rewrite method uses to inform about e.g. maximum competitive boosts.
This is currently only used by TopTermsRewrite
- Specified by:
getTermsEnum
in class MultiTermQuery
- Throws:
IOException
hashCode
public int hashCode()
- Overrides:
hashCode
in class MultiTermQuery
equals
public boolean equals(Object obj)
- Overrides:
equals
in class MultiTermQuery
toString
public String toString(String field)
- Description copied from class:
Query
- Prints a query to a string, with
field
assumed to be the
default field and omitted.
- Specified by:
toString
in class Query
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