package org.checkerframework.dataflow.analysis;
/*>>>
import org.checkerframework.checker.nullness.qual.Nullable;
*/
import org.checkerframework.dataflow.cfg.node.Node;
import org.checkerframework.dataflow.util.HashCodeUtils;
/**
* {@code TransferInput} is used as the input type of the individual transfer functions of a {@link
* TransferFunction}. It also contains a reference to the node for which the transfer function will
* be applied.
*
* <p>A {@code TransferInput} contains one or two stores. If two stores are present, one belongs to
* 'then', and the other to 'else'.
*
* @author Stefan Heule
* @param <S> the {@link Store} used to keep track of intermediate results
*/
public class TransferInput<A extends AbstractValue<A>, S extends Store<S>> {
/** The corresponding node. */
protected Node node;
/**
* The regular result store (or {@code null} if none is present). The following invariant is
* maintained:
*
* <pre>{@code
* store == null ⇔ thenStore != null && elseStore != null
* }</pre>
*/
protected final /*@Nullable*/ S store;
/**
* The 'then' result store (or {@code null} if none is present). The following invariant is
* maintained:
*
* <pre>{@code
* store == null ⇔ thenStore != null && elseStore != null
* }</pre>
*/
protected final /*@Nullable*/ S thenStore;
/**
* The 'else' result store (or {@code null} if none is present). The following invariant is
* maintained:
*
* <pre>{@code
* store == null ⇔ thenStore != null && elseStore != null
* }</pre>
*/
protected final /*@Nullable*/ S elseStore;
/** The corresponding analysis class to get intermediate flow results. */
protected final Analysis<A, S, ?> analysis;
/**
* Create a {@link TransferInput}, given a {@link TransferResult} and a node-value mapping.
*
* <p><em>Aliasing</em>: The stores returned by any methods of {@code to} will be stored
* internally and are not allowed to be used elsewhere. Full control of them is transfered to
* this object.
*
* <p>The node-value mapping {@code nodeValues} is provided by the analysis and is only read
* from within this {@link TransferInput}.
*/
public TransferInput(Node n, Analysis<A, S, ?> analysis, TransferResult<A, S> to) {
node = n;
this.analysis = analysis;
if (to.containsTwoStores()) {
thenStore = to.getThenStore();
elseStore = to.getElseStore();
store = null;
} else {
store = to.getRegularStore();
thenStore = elseStore = null;
}
}
/**
* Create a {@link TransferInput}, given a store and a node-value mapping.
*
* <p><em>Aliasing</em>: The store {@code s} will be stored internally and is not allowed to be
* used elsewhere. Full control over {@code s} is transfered to this object.
*
* <p>The node-value mapping {@code nodeValues} is provided by the analysis and is only read
* from within this {@link TransferInput}.
*/
public TransferInput(Node n, Analysis<A, S, ?> analysis, S s) {
node = n;
this.analysis = analysis;
store = s;
thenStore = elseStore = null;
}
/**
* Create a {@link TransferInput}, given two stores and a node-value mapping.
*
* <p><em>Aliasing</em>: The two stores {@code s1} and {@code s2} will be stored internally and
* are not allowed to be used elsewhere. Full control of them is transfered to this object.
*/
public TransferInput(Node n, Analysis<A, S, ?> analysis, S s1, S s2) {
node = n;
this.analysis = analysis;
thenStore = s1;
elseStore = s2;
store = null;
}
/** Copy constructor. */
protected TransferInput(TransferInput<A, S> from) {
this.node = from.node;
this.analysis = from.analysis;
if (from.store == null) {
thenStore = from.thenStore.copy();
elseStore = from.elseStore.copy();
store = null;
} else {
store = from.store.copy();
thenStore = elseStore = null;
}
}
/** @return the {@link Node} for this {@link TransferInput}. */
public Node getNode() {
return node;
}
/**
* @return the abstract value of {@link Node} {@code n}, which is required to be a 'sub-node'
* (that is, a direct or indirect child) of the node this transfer input is associated with.
* Furthermore, {@code n} cannot be a l-value node. Returns {@code null} if no value if
* available.
*/
public /*@Nullable*/ A getValueOfSubNode(Node n) {
return analysis.getValue(n);
}
/**
* @return the regular result store produced if no exception is thrown by the {@link Node}
* corresponding to this transfer function result
*/
public S getRegularStore() {
if (store == null) {
return thenStore.leastUpperBound(elseStore);
} else {
return store;
}
}
/**
* @return the result store produced if the {@link Node} this result belongs to evaluates to
* {@code true}.
*/
public S getThenStore() {
if (store == null) {
return thenStore;
}
return store;
}
/**
* @return the result store produced if the {@link Node} this result belongs to evaluates to
* {@code false}.
*/
public S getElseStore() {
if (store == null) {
return elseStore;
}
// copy the store such that it is the same as the result of getThenStore
// (that is, identical according to equals), but two different objects.
return store.copy();
}
/**
* @return {@code true} if and only if this transfer input contains two stores that are
* potentially not equal. Note that the result {@code true} does not imply that {@code
* getRegularStore} cannot be called (or vice versa for {@code false}). Rather, it indicates
* that {@code getThenStore} or {@code getElseStore} can be used to give more precise
* results. Otherwise, if the result is {@code false}, then all three methods {@code
* getRegularStore}, {@code getThenStore}, and {@code getElseStore} return equivalent
* stores.
*/
public boolean containsTwoStores() {
return (thenStore != null && elseStore != null);
}
/** @return an exact copy of this store. */
public TransferInput<A, S> copy() {
return new TransferInput<>(this);
}
/**
* Compute the least upper bound of two stores.
*
* <p><em>Important</em>: This method must fulfill the same contract as {@code leastUpperBound}
* of {@link Store}.
*/
public TransferInput<A, S> leastUpperBound(TransferInput<A, S> other) {
if (store == null) {
S newThenStore = thenStore.leastUpperBound(other.getThenStore());
S newElseStore = elseStore.leastUpperBound(other.getElseStore());
return new TransferInput<>(node, analysis, newThenStore, newElseStore);
} else {
if (other.store == null) {
// make sure we do not lose precision and keep two stores if at
// least one of the two TransferInput's has two stores.
return other.leastUpperBound(this);
}
return new TransferInput<>(
node, analysis, store.leastUpperBound(other.getRegularStore()));
}
}
@Override
public boolean equals(Object o) {
if (o != null && o instanceof TransferInput) {
@SuppressWarnings("unchecked")
TransferInput<A, S> other = (TransferInput<A, S>) o;
if (containsTwoStores()) {
if (other.containsTwoStores()) {
return getThenStore().equals(other.getThenStore())
&& getElseStore().equals(other.getElseStore());
}
} else {
if (!other.containsTwoStores()) {
return getRegularStore().equals(other.getRegularStore());
}
}
}
return false;
}
@Override
public int hashCode() {
return HashCodeUtils.hash(
this.analysis, this.node, this.store, this.thenStore, this.elseStore);
}
@Override
public String toString() {
if (store == null) {
return "[then=" + thenStore + ", else=" + elseStore + "]";
} else {
return "[" + store + "]";
}
}
}