org.checkerframework.dataflow.cfg.builder.LabelCell Maven / Gradle / Ivy

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package org.checkerframework.dataflow.cfg.builder;

import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
import org.checkerframework.javacutil.BugInCF;

/** Storage cell for a single Label, with tracking whether it was accessed. */
/*package-private*/ class LabelCell {
    /** The label. If it is null, then it will be lazily set if {@link #accessLabel} is called. */
    private @MonotonicNonNull Label label;

    /** True if the label has been accessed. */
    private boolean accessed;

    /** Create a LabelCell with no label; the label will be lazily created if needed. */
    protected LabelCell() {
        this.accessed = false;
    }

    /**
     * Create a LabelCell with the given label.
     *
     * @param label the label
     */
    protected LabelCell(Label label) {
        assert label != null;
        this.label = label;
        this.accessed = false;
    }

    public Label accessLabel() {
        if (label == null) {
            label = new Label();
        }
        accessed = true;
        return label;
    }

    public Label peekLabel() {
        if (label == null) {
            throw new BugInCF("called peekLabel prematurely");
        }
        return label;
    }

    public boolean wasAccessed() {
        return accessed;
    }
}