org.checkerframework.dataflow.cfg.block.BlockImpl Maven / Gradle / Ivy

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package org.checkerframework.dataflow.cfg.block;

import org.checkerframework.checker.initialization.qual.UnknownInitialization;
import org.plumelib.util.ArraySet;

import java.util.Set;
import java.util.concurrent.atomic.AtomicLong;

/** Base class of the {@link Block} implementation hierarchy. */
public abstract class BlockImpl implements Block {

    /** The type of this basic block. */
    protected final BlockType type;

    /** The set of predecessors. */
    protected final Set predecessors;

    /** The unique ID for the next-created object. */
    private static final AtomicLong nextUid = new AtomicLong(0);

    /** The unique ID of this object. */
    private final transient long uid = nextUid.getAndIncrement();

    @Override
    public long getUid(@UnknownInitialization BlockImpl this) {
        return uid;
    }

    /**
     * Create a new BlockImpl.
     *
     * @param type the type of this basic block
     */
    protected BlockImpl(BlockType type) {
        this.type = type;
        // Most blocks have few predecessors.
        this.predecessors = new ArraySet<>(2);
    }

    @Override
    public BlockType getType() {
        return type;
    }

    @Override
    public Set getPredecessors() {
        // Not "Collections.unmodifiableSet(predecessors)" which has nondeterministic iteration
        // order.
        return new ArraySet<>(predecessors);
    }

    public void addPredecessor(BlockImpl pred) {
        predecessors.add(pred);
    }

    public void removePredecessor(BlockImpl pred) {
        predecessors.remove(pred);
    }
}