org.apache.lucene.util.automaton

## Class CompiledAutomaton

- java.lang.Object
- - org.apache.lucene.util.automaton.CompiledAutomaton

- All Implemented Interfaces:
    Accountable

      public class CompiledAutomaton
      extends Object
      implements Accountable

  Immutable class holding compiled details for a given Automaton. The Automaton is deterministic, must not have dead states but is not necessarily minimal.
  WARNING: This API is experimental and might change in incompatible ways in the next release.

- - ### Nested Class Summary

    Nested Classes
    Modifier and Type | Class and Description
    --- | ---
    `static class` | `CompiledAutomaton.AUTOMATON_TYPE` Automata are compiled into different internal forms for the most efficient execution depending upon the language they accept.

  - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `Automaton` | `automaton` Two dimensional array of transitions, indexed by state number for traversal.
    `BytesRef` | `commonSuffixRef` Shared common suffix accepted by the automaton.
    `Boolean` | `finite` Indicates if the automaton accepts a finite set of strings.
    `ByteRunAutomaton` | `runAutomaton` Matcher for quickly determining if a byte[] is accepted.
    `int` | `sinkState` Which state, if any, accepts all suffixes, else -1.
    `BytesRef` | `term` For `CompiledAutomaton.AUTOMATON_TYPE.SINGLE` this is the singleton term.
    `CompiledAutomaton.AUTOMATON_TYPE` | `type` If simplify is true this will be the "simplified" type; else, this is NORMAL

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `CompiledAutomaton(Automaton automaton)` Create this, passing simplify=true and finite=null, so that we try to simplify the automaton and determine if it is finite.
    `CompiledAutomaton(Automaton automaton, Boolean finite, boolean simplify)` Create this.
    `CompiledAutomaton(Automaton automaton, Boolean finite, boolean simplify, int maxDeterminizedStates, boolean isBinary)` Create this.

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `boolean` | `equals(Object obj)`
    `BytesRef` | `floor(BytesRef input, BytesRefBuilder output)` Finds largest term accepted by this Automaton, that's <= the provided input term.
    `TermsEnum` | `getTermsEnum(Terms terms)` Return a `TermsEnum` intersecting the provided `Terms` with the terms accepted by this automaton.
    `int` | `hashCode()`
    `long` | `ramBytesUsed()` Return the memory usage of this object in bytes.
    `void` | `visit(QueryVisitor visitor, Query parent, String field)` Report back to a QueryVisitor how this automaton matches terms

    - ### Methods inherited from class java.lang.Object

      `clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait`

    - ### Methods inherited from interface org.apache.lucene.util.Accountable

      `getChildResources`

- - ### Field Detail

    - #### type

          public final CompiledAutomaton.AUTOMATON_TYPE type

      If simplify is true this will be the "simplified" type; else, this is NORMAL

    - #### term

          public final BytesRef term

      For `CompiledAutomaton.AUTOMATON_TYPE.SINGLE` this is the singleton term.

    - #### runAutomaton

          public final ByteRunAutomaton runAutomaton

      Matcher for quickly determining if a byte[] is accepted. only valid for `CompiledAutomaton.AUTOMATON_TYPE.NORMAL`.

    - #### automaton

          public final Automaton automaton

      Two dimensional array of transitions, indexed by state number for traversal. The state numbering is consistent with `runAutomaton`. Only valid for `CompiledAutomaton.AUTOMATON_TYPE.NORMAL`.

    - #### commonSuffixRef

          public final BytesRef commonSuffixRef

      Shared common suffix accepted by the automaton. Only valid for `CompiledAutomaton.AUTOMATON_TYPE.NORMAL`, and only when the automaton accepts an infinite language. This will be null if the common prefix is length 0.

    - #### finite

          public final Boolean finite

      Indicates if the automaton accepts a finite set of strings. Null if this was not computed. Only valid for `CompiledAutomaton.AUTOMATON_TYPE.NORMAL`.

    - #### sinkState

          public final int sinkState

      Which state, if any, accepts all suffixes, else -1.

  - ### Constructor Detail

    - #### CompiledAutomaton

          public CompiledAutomaton(Automaton automaton)

      Create this, passing simplify=true and finite=null, so that we try to simplify the automaton and determine if it is finite.

    - #### CompiledAutomaton

          public CompiledAutomaton(Automaton automaton,
                                   Boolean finite,
                                   boolean simplify)

      Create this. If finite is null, we use `Operations.isFinite(org.apache.lucene.util.automaton.Automaton)` to determine whether it is finite. If simplify is true, we run possibly expensive operations to determine if the automaton is one the cases in `CompiledAutomaton.AUTOMATON_TYPE`.

    - #### CompiledAutomaton

          public CompiledAutomaton(Automaton automaton,
                                   Boolean finite,
                                   boolean simplify,
                                   int maxDeterminizedStates,
                                   boolean isBinary)

      Create this. If finite is null, we use `Operations.isFinite(org.apache.lucene.util.automaton.Automaton)` to determine whether it is finite. If simplify is true, we run possibly expensive operations to determine if the automaton is one the cases in `CompiledAutomaton.AUTOMATON_TYPE`. If simplify requires determinizing the automaton then only maxDeterminizedStates will be created. Any more than that will cause a TooComplexToDeterminizeException.

  - ### Method Detail

    - #### getTermsEnum

          public TermsEnum getTermsEnum(Terms terms)
                                 throws IOException

      Return a `TermsEnum` intersecting the provided `Terms` with the terms accepted by this automaton.
      Throws:
        `IOException`

    - #### visit

          public void visit(QueryVisitor visitor,
                            Query parent,
                            String field)

      Report back to a QueryVisitor how this automaton matches terms

    - #### floor

          public BytesRef floor(BytesRef input,
                                BytesRefBuilder output)

      Finds largest term accepted by this Automaton, that's <= the provided input term. The result is placed in output; it's fine for output and input to point to the same bytes. The returned result is either the provided output, or null if there is no floor term (ie, the provided input term is before the first term accepted by this Automaton).

    - #### hashCode

          public int hashCode()

      Overrides:
        `hashCode` in class `Object`

    - #### equals

          public boolean equals(Object obj)

      Overrides:
        `equals` in class `Object`

    - #### 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`

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