Class AInterpreter

rhino/src/main/java/org/mozilla/javascript/AInterpreter.java:14–415

import java.util.Objects;

public abstract class AInterpreter<T extends ACallFrame<T, U>, U extends ACompilerData<?, U>>
        implements Evaluator {

    protected static final class ContinuationJump<
                    T extends ACallFrame<T, U>, U extends ACompilerData<?, U>>
            implements Serializable {
        private static final long serialVersionUID = 7687739156004308247L;

        T capturedFrame;
        T branchFrame;
        Object result;
        double resultDbl;

        ContinuationJump(NativeContinuation c, T current) {
            @SuppressWarnings("unchecked")
            var cf = (T) c.getImplementation();
            capturedFrame = cf;
            if (this.capturedFrame == null || current == null) {
                // Continuation and current execution does not share
                // any frames if there is nothing to capture or
                // if there is no currently executed frames
                this.branchFrame = null;
            } else {
                // Search for branch frame where parent frame chains starting
                // from captured and current meet.
                T chain1 = this.capturedFrame;
                T chain2 = current;

                // First work parents of chain1 or chain2 until the same
                // frame depth.
                int diff = chain1.frameIndex - chain2.frameIndex;
                if (diff != 0) {
                    if (diff < 0) {
                        // swap to make sure that
                        // chain1.frameIndex > chain2.frameIndex and diff > 0
                        chain1 = current;
                        chain2 = this.capturedFrame;
                        diff = -diff;
                    }
                    do {
                        chain1 = chain1.parentFrame;
                    } while (--diff != 0);
                    if (chain1.frameIndex != chain2.frameIndex) Kit.codeBug();
                }

                // Now walk parents in parallel until a shared frame is found
                // or until the root is reached.
                while (!Objects.equals(chain1, chain2) && chain1 != null) {
                    chain1 = chain1.parentFrame;
                    chain2 = chain2.parentFrame;
                }

                this.branchFrame = chain1;
                if (this.branchFrame != null && !this.branchFrame.frozen) Kit.codeBug();
            }
        }
    }