Package org.apache.lucene.search

Class AutomatonQuery

  • All Implemented Interfaces:
    Accountable
    Direct Known Subclasses:
    PrefixQuery, RegexpQuery, TermRangeQuery, WildcardQuery
    public class AutomatonQuery
extends MultiTermQuery
implements Accountable
    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.

    • Field Detail

      • automaton

        protected final Automaton automaton
        the automaton to match index terms against

      • term

        protected final Term term
        term containing the field, and possibly some pattern structure

      • automatonIsBinary

        protected final boolean automatonIsBinary

    • Constructor Detail

      • 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.

      • AutomatonQuery

        public AutomatonQuery​(Term term,
                      Automaton automaton,
                      int determinizeWorkLimit)
        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.
        determinizeWorkLimit - maximum effort to spend determinizing the automaton. If the automaton would need more than this much effort, TooComplexToDeterminizeException is thrown. Higher numbers require more space but can process more complex automata.

      • AutomatonQuery

        public AutomatonQuery​(Term term,
                      Automaton automaton,
                      int determinizeWorkLimit,
                      boolean isBinary)
        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.
        determinizeWorkLimit - maximum effort to spend determinizing the automaton. If the automaton will need more than this much effort, TooComplexToDeterminizeException is thrown. Higher numbers require more space but can process more complex automata.
        isBinary - if true, this automaton is already binary and will not go through the UTF32ToUTF8 conversion

      • AutomatonQuery

        public AutomatonQuery​(Term term,
                      Automaton automaton,
                      int determinizeWorkLimit,
                      boolean isBinary,
                      MultiTermQuery.RewriteMethod rewriteMethod)
        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.
        isBinary - if true, this automaton is already binary and will not go through the UTF32ToUTF8 conversion
        rewriteMethod - the rewriteMethod to use to build the final query from the automaton

    • Method Detail

      • equals

        public boolean equals​(Object obj)
        Description copied from class: Query
        Override and implement query instance equivalence properly in a subclass. This is required so that QueryCache works properly.

        Typically a query will be equal to another only if it's an instance of the same class and its document-filtering properties are identical that other instance. Utility methods are provided for certain repetitive code.

        Overrides:
        equals in class MultiTermQuery
        See Also:
        Query.sameClassAs(Object), Query.classHash()

      • 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

      • visit

        public void visit​(QueryVisitor visitor)
        Description copied from class: Query
        Recurse through the query tree, visiting any child queries
        Specified by:
        visit in class Query
        Parameters:
        visitor - a QueryVisitor to be called by each query in the tree

      • getAutomaton

        public Automaton getAutomaton()
        Returns the automaton used to create this query

      • isAutomatonBinary

        public boolean isAutomatonBinary()
        Is this a binary (byte) oriented automaton. See the constructor.

      • ramBytesUsed

        public long ramBytesUsed()
        Description copied from interface: Accountable
        Return the memory usage of this object in bytes. Negative values are illegal.
        Specified by:
        ramBytesUsed in interface Accountable