Package org.apache.lucene.codecs.uniformsplit

Class IntersectBlockReader.AutomatonNextTermCalculator

java.lang.Object
org.apache.lucene.codecs.uniformsplit.IntersectBlockReader.AutomatonNextTermCalculator
Enclosing class:
IntersectBlockReader
protected class IntersectBlockReader.AutomatonNextTermCalculator extends Object
This is mostly a copy of AutomatonTermsEnum. Since it's an inner class, the outer class can call methods that ATE does not expose. It'd be nice if ATE's logic could be more extensible.

  • Field Details

    • visited

      protected short[] visited

    • curGen

      protected short curGen

    • seekBytesRef

      protected final BytesRefBuilder seekBytesRef

    • linear

      protected boolean linear

    • linearUpperBound

      protected final BytesRef linearUpperBound

    • transition

      protected final Transition transition

    • savedStates

      protected final IntsRefBuilder savedStates

  • Constructor Details

    • AutomatonNextTermCalculator

      protected AutomatonNextTermCalculator(CompiledAutomaton compiled)

  • Method Details

    • isLinearState

      protected boolean isLinearState(BytesRef term)
      True if the current state of the automata is best iterated linearly (without seeking).

    • nextSeekTerm

      protected BytesRef nextSeekTerm(BytesRef term)
      See Also:

    • setLinear

      protected void setLinear(int position)
      Sets the enum to operate in linear fashion, as we have found a looping transition at position: we set an upper bound and act like a TermRangeQuery for this portion of the term space.

    • nextString

      protected boolean nextString()
      Increments the byte buffer to the next String in binary order after s that will not put the machine into a reject state. If such a string does not exist, returns false.

      The correctness of this method depends upon the automaton being deterministic, and having no transitions to dead states.

      Returns:
      true if more possible solutions exist for the DFA

    • nextString

      protected boolean nextString(int state, int position)
      Returns the next String in lexicographic order that will not put the machine into a reject state.

      This method traverses the DFA from the given position in the String, starting at the given state.

      If this cannot satisfy the machine, returns false. This method will walk the minimal path, in lexicographic order, as long as possible.

      If this method returns false, then there might still be more solutions, it is necessary to backtrack to find out.

      Parameters:
      state - current non-reject state
      position - useful portion of the string
      Returns:
      true if more possible solutions exist for the DFA from this position

    • backtrack

      protected int backtrack(int position)
      Attempts to backtrack thru the string after encountering a dead end at some given position. Returns false if no more possible strings can match.
      Parameters:
      position - current position in the input String
      Returns:
      position >= 0 if more possible solutions exist for the DFA