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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to you under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
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package com.hazelcast.shaded.org.apache.calcite.runtime;

import com.hazelcast.shaded.org.apache.calcite.rel.core.Match;
import com.hazelcast.shaded.org.apache.calcite.util.ImmutableBitSet;

import com.hazelcast.shaded.com.google.common.collect.ImmutableList;

import com.hazelcast.shaded.org.checkerframework.checker.nullness.qual.Nullable;

import java.util.Objects;

/** A nondeterministic finite-state automaton (NFA).
 *
 * 

It is used to implement the {@link Match} * relational expression (for the {@code MATCH_RECOGNIZE} clause in SQL). * * @see Pattern * @see AutomatonBuilder * @see DeterministicAutomaton */ public class Automaton { final State startState; final State endState; private final ImmutableList transitions; private final ImmutableList epsilonTransitions; final ImmutableList symbolNames; /** Use an {@link AutomatonBuilder}. */ Automaton(State startState, State endState, ImmutableList transitions, ImmutableList epsilonTransitions, ImmutableList symbolNames) { this.startState = Objects.requireNonNull(startState, "startState"); this.endState = Objects.requireNonNull(endState, "endState"); this.transitions = Objects.requireNonNull(transitions, "transitions"); this.epsilonTransitions = epsilonTransitions; this.symbolNames = Objects.requireNonNull(symbolNames, "symbolNames"); } /** Returns the set of states, represented as a bit set, that the graph is * in when starting from {@code state} and receiving {@code symbol}. * * @param fromState Initial state * @param symbol Symbol received * @param bitSet Set of successor states (output) */ void successors(int fromState, int symbol, ImmutableBitSet.Builder bitSet) { for (SymbolTransition transition : transitions) { if (transition.fromState.id == fromState && transition.symbol == symbol) { epsilonSuccessors(transition.toState.id, bitSet); } } } void epsilonSuccessors(int state, ImmutableBitSet.Builder bitSet) { bitSet.set(state); for (EpsilonTransition transition : epsilonTransitions) { if (transition.fromState.id == state) { if (!bitSet.get(transition.toState.id)) { epsilonSuccessors(transition.toState.id, bitSet); } } } } public ImmutableList getTransitions() { return this.transitions; } public ImmutableList getEpsilonTransitions() { return this.epsilonTransitions; } /** Node in the finite-state automaton. A state has a number of * transitions to other states, each labeled with the symbol that * causes that transition. */ static class State { final int id; State(int id) { this.id = id; } @Override public boolean equals(@Nullable Object o) { return o == this || o instanceof State && ((State) o).id == id; } @Override public int hashCode() { return Objects.hash(id); } @Override public String toString() { return "State{" + "id=" + id + '}'; } } /** Transition from one state to another in the finite-state automaton. */ abstract static class Transition { final State fromState; final State toState; Transition(State fromState, State toState) { this.fromState = Objects.requireNonNull(fromState, "fromState"); this.toState = Objects.requireNonNull(toState, "toState"); } } /** A transition caused by reading a symbol. */ static class SymbolTransition extends Transition { final int symbol; SymbolTransition(State fromState, State toState, int symbol) { super(fromState, toState); this.symbol = symbol; } @Override public String toString() { return symbol + ":" + fromState.id + "->" + toState.id; } } /** A transition that may happen without reading a symbol. */ static class EpsilonTransition extends Transition { EpsilonTransition(State fromState, State toState) { super(fromState, toState); } @Override public String toString() { return "epsilon:" + fromState.id + "->" + toState.id; } } }





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