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package org.checkerframework.checker.index;

import javax.lang.model.element.AnnotationMirror;
import org.checkerframework.dataflow.analysis.TransferInput;
import org.checkerframework.dataflow.analysis.TransferResult;
import org.checkerframework.dataflow.cfg.node.GreaterThanNode;
import org.checkerframework.dataflow.cfg.node.GreaterThanOrEqualNode;
import org.checkerframework.dataflow.cfg.node.LessThanNode;
import org.checkerframework.dataflow.cfg.node.LessThanOrEqualNode;
import org.checkerframework.dataflow.cfg.node.Node;
import org.checkerframework.framework.flow.CFAnalysis;
import org.checkerframework.framework.flow.CFStore;
import org.checkerframework.framework.flow.CFTransfer;
import org.checkerframework.framework.flow.CFValue;

/**
 * This class provides methods shared by the Index Checker's internal checkers in their transfer
 * functions. In particular, it provides a common framework for visiting comparison operators.
 */
@SuppressWarnings("ArgumentSelectionDefectChecker") // TODO: apply suggested error-prone fixes
public abstract class IndexAbstractTransfer extends CFTransfer {

    protected IndexAbstractTransfer(CFAnalysis analysis) {
        super(analysis);
    }

    @Override
    public TransferResult visitGreaterThan(
            GreaterThanNode node, TransferInput in) {
        TransferResult result = super.visitGreaterThan(node, in);

        IndexRefinementInfo rfi = new IndexRefinementInfo(result, analysis, node);
        if (rfi.leftAnno == null || rfi.rightAnno == null) {
            return result;
        }
        // Refine the then branch.
        refineGT(rfi.left, rfi.leftAnno, rfi.right, rfi.rightAnno, rfi.thenStore, in);

        // Refine the else branch, which is the inverse of the then branch.
        refineGTE(rfi.right, rfi.rightAnno, rfi.left, rfi.leftAnno, rfi.elseStore, in);

        return rfi.newResult;
    }

    @Override
    public TransferResult visitGreaterThanOrEqual(
            GreaterThanOrEqualNode node, TransferInput in) {
        TransferResult result = super.visitGreaterThanOrEqual(node, in);

        IndexRefinementInfo rfi = new IndexRefinementInfo(result, analysis, node);
        if (rfi.leftAnno == null || rfi.rightAnno == null) {
            return result;
        }

        // Refine the then branch.
        refineGTE(rfi.left, rfi.leftAnno, rfi.right, rfi.rightAnno, rfi.thenStore, in);

        // Refine the else branch.
        refineGT(rfi.right, rfi.rightAnno, rfi.left, rfi.leftAnno, rfi.elseStore, in);

        return rfi.newResult;
    }

    @Override
    public TransferResult visitLessThanOrEqual(
            LessThanOrEqualNode node, TransferInput in) {
        TransferResult result = super.visitLessThanOrEqual(node, in);

        IndexRefinementInfo rfi = new IndexRefinementInfo(result, analysis, node);
        if (rfi.leftAnno == null || rfi.rightAnno == null) {
            return result;
        }

        // Refine the then branch. A <= is just a flipped >=.
        refineGTE(rfi.right, rfi.rightAnno, rfi.left, rfi.leftAnno, rfi.thenStore, in);

        // Refine the else branch.
        refineGT(rfi.left, rfi.leftAnno, rfi.right, rfi.rightAnno, rfi.elseStore, in);
        return rfi.newResult;
    }

    @Override
    public TransferResult visitLessThan(
            LessThanNode node, TransferInput in) {
        TransferResult result = super.visitLessThan(node, in);

        IndexRefinementInfo rfi = new IndexRefinementInfo(result, analysis, node);
        if (rfi.leftAnno == null || rfi.rightAnno == null) {
            return result;
        }

        // Refine the then branch. A < is just a flipped >.
        refineGT(rfi.right, rfi.rightAnno, rfi.left, rfi.leftAnno, rfi.thenStore, in);

        // Refine the else branch.
        refineGTE(rfi.left, rfi.leftAnno, rfi.right, rfi.rightAnno, rfi.elseStore, in);
        return rfi.newResult;
    }

    protected abstract void refineGT(
            Node left,
            AnnotationMirror leftAnno,
            Node right,
            AnnotationMirror rightAnno,
            CFStore store,
            TransferInput in);

    protected abstract void refineGTE(
            Node left,
            AnnotationMirror leftAnno,
            Node right,
            AnnotationMirror rightAnno,
            CFStore store,
            TransferInput in);
}