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The Checker Framework enhances Java's type system to make it more powerful and useful. This lets software developers detect and prevent errors in their Java programs. The Checker Framework includes compiler plug-ins ("checkers") that find bugs or verify their absence. It also permits you to write your own compiler plug-ins.

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package org.checkerframework.dataflow.analysis;

import java.util.Map;
import javax.lang.model.type.TypeMirror;

/**
 * Implementation of a {@link TransferResult} with two non-exceptional store; one for the 'then'
 * edge and one for 'else'. The result of {@code getRegularStore} will be the least upper bound of
 * the two underlying stores.
 *
 * @author Stefan Heule
 * @param  the {@link Store} used to keep track of intermediate results
 */
public class ConditionalTransferResult, S extends Store>
        extends TransferResult {

    private final boolean storeChanged;

    /** The 'then' result store. */
    protected final S thenStore;

    /** The 'else' result store. */
    protected final S elseStore;

    /**
     * Create a {@code ConditionalTransferResult} with {@code thenStore} as the resulting store if
     * the corresponding {@link org.checkerframework.dataflow.cfg.node.Node} evaluates to {@code
     * true} and {@code elseStore} otherwise.
     *
     * For the meaning of storeChanged, see {@link
     * org.checkerframework.dataflow.analysis.TransferResult#storeChanged}.
     *
     * 
Exceptions: If the corresponding {@link
     * org.checkerframework.dataflow.cfg.node.Node} throws an exception, then it is assumed that no
     * special handling is necessary and the store before the corresponding {@link
     * org.checkerframework.dataflow.cfg.node.Node} will be passed along any exceptional edge.
     *
     * 
Aliasing: {@code thenStore} and {@code elseStore} are not allowed to be used
     * anywhere outside of this class (including use through aliases). Complete control over the
     * objects is transfered to this class.
     */
    public ConditionalTransferResult(A value, S thenStore, S elseStore, boolean storeChanged) {
        this(value, thenStore, elseStore, null, storeChanged);
    }

    public ConditionalTransferResult(A value, S thenStore, S elseStore) {
        this(value, thenStore, elseStore, false);
    }

    /**
     * Create a {@code ConditionalTransferResult} with {@code thenStore} as the resulting store if
     * the corresponding {@link org.checkerframework.dataflow.cfg.node.Node} evaluates to {@code
     * true} and {@code elseStore} otherwise.
     *
     * 
Exceptions: If the corresponding {@link
     * org.checkerframework.dataflow.cfg.node.Node} throws an exception, then the corresponding
     * store in {@code exceptionalStores} is used. If no exception is found in {@code
     * exceptionalStores}, then it is assumed that no special handling is necessary and the store
     * before the corresponding {@link org.checkerframework.dataflow.cfg.node.Node} will be passed
     * along any exceptional edge.
     *
     * Aliasing: {@code thenStore}, {@code elseStore}, and any store in {@code
     * exceptionalStores} are not allowed to be used anywhere outside of this class (including use
     * through aliases). Complete control over the objects is transfered to this class.
     */
    public ConditionalTransferResult(
            A value,
            S thenStore,
            S elseStore,
            Map exceptionalStores,
            boolean storeChanged) {
        super(value, exceptionalStores);
        this.thenStore = thenStore;
        this.elseStore = elseStore;
        this.storeChanged = storeChanged;
    }

    public ConditionalTransferResult(
            A value, S thenStore, S elseStore, Map exceptionalStores) {
        this(value, thenStore, elseStore, exceptionalStores, false);
    }

    @Override
    public S getRegularStore() {
        return thenStore.leastUpperBound(elseStore);
    }

    @Override
    public S getThenStore() {
        return thenStore;
    }

    @Override
    public S getElseStore() {
        return elseStore;
    }

    @Override
    public boolean containsTwoStores() {
        return true;
    }

    @Override
    public String toString() {
        StringBuilder result = new StringBuilder();
        result.append("RegularTransferResult(");
        result.append(System.getProperty("line.separator"));
        result.append("resultValue = " + resultValue);
        result.append(System.getProperty("line.separator"));
        result.append("thenStore = " + thenStore);
        result.append("elseStore = " + elseStore);
        result.append(System.getProperty("line.separator"));
        result.append(")");
        return result.toString();
    }

    /** @see org.checkerframework.dataflow.analysis.TransferResult#storeChanged() */
    @Override
    public boolean storeChanged() {
        return storeChanged;
    }
}