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package org.checkerframework.framework.flow;
import com.sun.source.tree.ClassTree;
import com.sun.source.tree.MethodTree;
import com.sun.source.tree.Tree;
import com.sun.source.tree.VariableTree;
import com.sun.source.util.TreePath;
import com.sun.tools.javac.code.Symbol.ClassSymbol;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import javax.lang.model.element.AnnotationMirror;
import javax.lang.model.element.Element;
import javax.lang.model.element.ElementKind;
import javax.lang.model.element.ExecutableElement;
import javax.lang.model.element.VariableElement;
import javax.lang.model.type.TypeMirror;
import org.checkerframework.checker.nullness.qual.Nullable;
import org.checkerframework.dataflow.analysis.ConditionalTransferResult;
import org.checkerframework.dataflow.analysis.FlowExpressions;
import org.checkerframework.dataflow.analysis.FlowExpressions.ClassName;
import org.checkerframework.dataflow.analysis.FlowExpressions.FieldAccess;
import org.checkerframework.dataflow.analysis.FlowExpressions.LocalVariable;
import org.checkerframework.dataflow.analysis.FlowExpressions.Receiver;
import org.checkerframework.dataflow.analysis.FlowExpressions.ThisReference;
import org.checkerframework.dataflow.analysis.RegularTransferResult;
import org.checkerframework.dataflow.analysis.TransferFunction;
import org.checkerframework.dataflow.analysis.TransferInput;
import org.checkerframework.dataflow.analysis.TransferResult;
import org.checkerframework.dataflow.cfg.UnderlyingAST;
import org.checkerframework.dataflow.cfg.UnderlyingAST.CFGLambda;
import org.checkerframework.dataflow.cfg.UnderlyingAST.CFGMethod;
import org.checkerframework.dataflow.cfg.UnderlyingAST.Kind;
import org.checkerframework.dataflow.cfg.node.AbstractNodeVisitor;
import org.checkerframework.dataflow.cfg.node.ArrayAccessNode;
import org.checkerframework.dataflow.cfg.node.AssignmentNode;
import org.checkerframework.dataflow.cfg.node.CaseNode;
import org.checkerframework.dataflow.cfg.node.ClassNameNode;
import org.checkerframework.dataflow.cfg.node.ConditionalNotNode;
import org.checkerframework.dataflow.cfg.node.EqualToNode;
import org.checkerframework.dataflow.cfg.node.FieldAccessNode;
import org.checkerframework.dataflow.cfg.node.LambdaResultExpressionNode;
import org.checkerframework.dataflow.cfg.node.LocalVariableNode;
import org.checkerframework.dataflow.cfg.node.MethodInvocationNode;
import org.checkerframework.dataflow.cfg.node.NarrowingConversionNode;
import org.checkerframework.dataflow.cfg.node.Node;
import org.checkerframework.dataflow.cfg.node.NotEqualNode;
import org.checkerframework.dataflow.cfg.node.ObjectCreationNode;
import org.checkerframework.dataflow.cfg.node.ReturnNode;
import org.checkerframework.dataflow.cfg.node.StringConcatenateAssignmentNode;
import org.checkerframework.dataflow.cfg.node.StringConversionNode;
import org.checkerframework.dataflow.cfg.node.TernaryExpressionNode;
import org.checkerframework.dataflow.cfg.node.ThisLiteralNode;
import org.checkerframework.dataflow.cfg.node.VariableDeclarationNode;
import org.checkerframework.dataflow.cfg.node.WideningConversionNode;
import org.checkerframework.framework.source.Result;
import org.checkerframework.framework.type.AnnotatedTypeFactory;
import org.checkerframework.framework.type.AnnotatedTypeMirror;
import org.checkerframework.framework.type.AnnotatedTypeMirror.AnnotatedDeclaredType;
import org.checkerframework.framework.type.AnnotatedTypeMirror.AnnotatedExecutableType;
import org.checkerframework.framework.type.GenericAnnotatedTypeFactory;
import org.checkerframework.framework.util.AnnotatedTypes;
import org.checkerframework.framework.util.ContractsUtils;
import org.checkerframework.framework.util.ContractsUtils.ConditionalPostcondition;
import org.checkerframework.framework.util.ContractsUtils.Contract;
import org.checkerframework.framework.util.ContractsUtils.Postcondition;
import org.checkerframework.framework.util.ContractsUtils.Precondition;
import org.checkerframework.framework.util.FlowExpressionParseUtil;
import org.checkerframework.framework.util.FlowExpressionParseUtil.FlowExpressionContext;
import org.checkerframework.framework.util.FlowExpressionParseUtil.FlowExpressionParseException;
import org.checkerframework.javacutil.ElementUtils;
import org.checkerframework.javacutil.Pair;
import org.checkerframework.javacutil.TreeUtils;
/**
* The default analysis transfer function for the Checker Framework propagates information through
* assignments and uses the {@link AnnotatedTypeFactory} to provide checker-specific logic how to
* combine types (e.g., what is the type of a string concatenation, given the types of the two
* operands) and as an abstraction function (e.g., determine the annotations on literals).
*
* Design note: CFAbstractTransfer and its subclasses are supposed to act as transfer functions.
* But, since the AnnotatedTypeFactory already existed and performed checker-independent type
* propagation, CFAbstractTransfer delegates work to it instead of duplicating some logic in
* CFAbstractTransfer. The checker-specific subclasses of CFAbstractTransfer do implement transfer
* function logic themselves.
*/
public abstract class CFAbstractTransfer<
V extends CFAbstractValue,
S extends CFAbstractStore,
T extends CFAbstractTransfer>
extends AbstractNodeVisitor, TransferInput>
implements TransferFunction {
/** The analysis class this store belongs to. */
protected final CFAbstractAnalysis analysis;
/**
* Should the analysis use sequential Java semantics (i.e., assume that only one thread is
* running at all times)?
*/
protected final boolean sequentialSemantics;
/** Indicates that the whole-program inference is on. */
private final boolean infer;
public CFAbstractTransfer(CFAbstractAnalysis analysis) {
this.analysis = analysis;
this.sequentialSemantics = !analysis.checker.hasOption("concurrentSemantics");
this.infer = analysis.checker.hasOption("infer");
}
/**
* Constructor that allows forcing concurrent semantics to be on for this instance of
* CFAbstractTransfer.
*
* @param forceConcurrentSemantics whether concurrent semantics should be forced to be on. If
* false, concurrent semantics are turned off by default, but the user can still turn them
* on via {@code -AconcurrentSemantics}. If true, the user cannot turn off concurrent
* semantics.
*/
public CFAbstractTransfer(
CFAbstractAnalysis analysis, boolean forceConcurrentSemantics) {
this.analysis = analysis;
this.sequentialSemantics =
!(forceConcurrentSemantics || analysis.checker.hasOption("concurrentSemantics"));
this.infer = analysis.checker.hasOption("infer");
}
/**
* @return true if the transfer function uses sequential semantics, false if it uses concurrent
* semantics. Useful when creating an empty store, since a store makes different decisions
* depending on whether sequential or concurrent semantics are used.
*/
public boolean usesSequentialSemantics() {
return sequentialSemantics;
}
/**
* This method is called before returning the abstract value {@code value} as the result of the
* transfer function. By default, the value is not changed but subclasses might decide to
* implement some functionality. The store at this position is also passed.
*/
protected V finishValue(V value, S store) {
return value;
}
/**
* This method is called before returning the abstract value {@code value} as the result of the
* transfer function. By default, the value is not changed but subclasses might decide to
* implement some functionality. The store at this position is also passed (two stores, as the
* result is a {@link ConditionalTransferResult}.
*/
protected V finishValue(V value, S thenStore, S elseStore) {
return value;
}
/**
* @return the abstract value of a non-leaf tree {@code tree}, as computed by the {@link
* AnnotatedTypeFactory}.
*/
protected V getValueFromFactory(Tree tree, Node node) {
GenericAnnotatedTypeFactory> factory =
analysis.atypeFactory;
Tree preTree = analysis.getCurrentTree();
Pair preCtxt = factory.getVisitorState().getAssignmentContext();
analysis.setCurrentTree(tree);
// is there an assignment context node available?
if (node != null && node.getAssignmentContext() != null) {
// get the declared type of the assignment context by looking up the
// assignment context tree's type in the factory while flow is
// disabled.
Tree contextTree = node.getAssignmentContext().getContextTree();
AnnotatedTypeMirror assCtxt = null;
if (contextTree != null) {
assCtxt = factory.getAnnotatedTypeLhs(contextTree);
} else {
Element assCtxtElement = node.getAssignmentContext().getElementForType();
if (assCtxtElement != null) {
// if contextTree is null, use the element to get the type
assCtxt = factory.getAnnotatedType(assCtxtElement);
}
}
if (assCtxt != null) {
if (assCtxt instanceof AnnotatedExecutableType) {
// For a MethodReturnContext, we get the full type of the
// method, but we only want the return type.
assCtxt = ((AnnotatedExecutableType) assCtxt).getReturnType();
}
factory.getVisitorState()
.setAssignmentContext(
Pair.of(node.getAssignmentContext().getContextTree(), assCtxt));
}
}
AnnotatedTypeMirror at = factory.getAnnotatedType(tree);
analysis.setCurrentTree(preTree);
factory.getVisitorState().setAssignmentContext(preCtxt);
return analysis.createAbstractValue(at);
}
/**
* @return an abstract value with the given {@code type} and the annotations from {@code
* annotatedValue}.
*/
protected V getValueWithSameAnnotations(TypeMirror type, V annotatedValue) {
if (annotatedValue == null) {
return null;
}
return analysis.createAbstractValue(annotatedValue.getAnnotations(), type);
}
private S fixedInitialStore = null;
/** Set a fixed initial Store. */
public void setFixedInitialStore(S s) {
fixedInitialStore = s;
}
/** The initial store maps method formal parameters to their currently most refined type. */
@Override
public S initialStore(
UnderlyingAST underlyingAST, @Nullable List parameters) {
if (underlyingAST.getKind() != Kind.LAMBDA && underlyingAST.getKind() != Kind.METHOD) {
if (fixedInitialStore != null) {
return fixedInitialStore;
} else {
return analysis.createEmptyStore(sequentialSemantics);
}
}
S info;
if (underlyingAST.getKind() == Kind.METHOD) {
if (fixedInitialStore != null) {
// copy knowledge
info = analysis.createCopiedStore(fixedInitialStore);
} else {
info = analysis.createEmptyStore(sequentialSemantics);
}
AnnotatedTypeFactory factory = analysis.getTypeFactory();
for (LocalVariableNode p : parameters) {
AnnotatedTypeMirror anno = factory.getAnnotatedType(p.getElement());
info.initializeMethodParameter(p, analysis.createAbstractValue(anno));
}
// add properties known through precondition
CFGMethod method = (CFGMethod) underlyingAST;
MethodTree methodTree = method.getMethod();
ExecutableElement methodElem = TreeUtils.elementFromDeclaration(methodTree);
addInformationFromPreconditions(info, factory, method, methodTree, methodElem);
final ClassTree classTree = method.getClassTree();
addFieldValues(info, factory, classTree, methodTree);
addFinalLocalValues(info, methodElem);
if (shouldPerformWholeProgramInference(methodTree, methodElem)) {
Map overriddenMethods =
AnnotatedTypes.overriddenMethods(
analysis.atypeFactory.getElementUtils(),
analysis.atypeFactory,
methodElem);
for (Map.Entry pair :
overriddenMethods.entrySet()) {
AnnotatedExecutableType overriddenMethod =
AnnotatedTypes.asMemberOf(
analysis.atypeFactory.getProcessingEnv().getTypeUtils(),
analysis.atypeFactory,
pair.getKey(),
pair.getValue());
// Infers parameter and receiver types of the method based
// on the overridden method.
analysis.atypeFactory
.getWholeProgramInference()
.updateInferredMethodParameterTypes(
methodTree,
methodElem,
overriddenMethod,
analysis.getTypeFactory());
analysis.atypeFactory
.getWholeProgramInference()
.updateInferredMethodReceiverType(
methodTree,
methodElem,
overriddenMethod,
analysis.getTypeFactory());
}
}
} else if (underlyingAST.getKind() == Kind.LAMBDA) {
// Create a copy and keep only the field values (nothing else applies).
info = analysis.createCopiedStore(fixedInitialStore);
// Allow that local variables are retained; they are effectively final,
// otherwise Java wouldn't allow access from within the lambda.
// TODO: what about the other information? Can code further down be simplified?
// info.localVariableValues.clear();
info.classValues.clear();
info.arrayValues.clear();
info.methodValues.clear();
AnnotatedTypeFactory factory = analysis.getTypeFactory();
for (LocalVariableNode p : parameters) {
AnnotatedTypeMirror anno = factory.getAnnotatedType(p.getElement());
info.initializeMethodParameter(p, analysis.createAbstractValue(anno));
}
CFGLambda lambda = (CFGLambda) underlyingAST;
Tree enclosingTree =
TreeUtils.enclosingOfKind(
factory.getPath(lambda.getLambdaTree()),
new HashSet<>(
Arrays.asList(
Tree.Kind.METHOD,
// Tree.Kind for which TreeUtils.isClassTree is true
Tree.Kind.CLASS,
Tree.Kind.INTERFACE,
Tree.Kind.ANNOTATION_TYPE,
Tree.Kind.ENUM)));
Element enclosingElement = null;
if (enclosingTree.getKind() == Tree.Kind.METHOD) {
// If it is in an initializer, we need to use locals from the initializer.
enclosingElement = TreeUtils.elementFromTree(enclosingTree);
} else if (TreeUtils.isClassTree(enclosingTree)) {
// Try to find an enclosing initializer block
// Would love to know if there was a better way
// Find any enclosing element of the lambda (using trees)
// Then go up the elements to find an initializer element (which can't be found with
// the tree).
TreePath loopTree = factory.getPath(lambda.getLambdaTree()).getParentPath();
Element anEnclosingElement = null;
while (loopTree.getLeaf() != enclosingTree) {
Element sym = TreeUtils.elementFromTree(loopTree.getLeaf());
if (sym != null) {
anEnclosingElement = sym;
break;
}
loopTree = loopTree.getParentPath();
}
while (anEnclosingElement != null
&& !anEnclosingElement.equals(TreeUtils.elementFromTree(enclosingTree))) {
if (anEnclosingElement.getKind() == ElementKind.INSTANCE_INIT
|| anEnclosingElement.getKind() == ElementKind.STATIC_INIT) {
enclosingElement = anEnclosingElement;
break;
}
anEnclosingElement = anEnclosingElement.getEnclosingElement();
}
}
if (enclosingElement != null) {
addFinalLocalValues(info, enclosingElement);
}
// We want the initialization stuff, but need to throw out any refinements.
Map fieldValuesClone = new HashMap<>(info.fieldValues);
for (Entry fieldValue : fieldValuesClone.entrySet()) {
AnnotatedTypeMirror declaredType =
factory.getAnnotatedType(fieldValue.getKey().getField());
V lubbedValue =
analysis.createAbstractValue(declaredType)
.leastUpperBound(fieldValue.getValue());
info.fieldValues.put(fieldValue.getKey(), lubbedValue);
}
} else {
assert false : "Unexpected tree: " + underlyingAST;
info = null;
}
return info;
}
private void addFieldValues(
S info, AnnotatedTypeFactory factory, ClassTree classTree, MethodTree methodTree) {
// Add knowledge about final fields, or values of non-final fields
// if we are inside a constructor (information about initializers)
TypeMirror classType = TreeUtils.typeOf(classTree);
List> fieldValues = analysis.getFieldValues();
for (Pair p : fieldValues) {
VariableElement element = p.first;
V value = p.second;
if (ElementUtils.isFinal(element) || TreeUtils.isConstructor(methodTree)) {
Receiver receiver;
if (ElementUtils.isStatic(element)) {
receiver = new ClassName(classType);
} else {
receiver = new ThisReference(classType);
}
TypeMirror fieldType = ElementUtils.getType(element);
Receiver field = new FieldAccess(receiver, fieldType, element);
info.insertValue(field, value);
}
}
// add properties about fields (static information from type)
boolean isNotFullyInitializedReceiver = isNotFullyInitializedReceiver(methodTree);
if (isNotFullyInitializedReceiver && !TreeUtils.isConstructor(methodTree)) {
// cannot add information about fields if the receiver isn't initialized
// and the method isn't a constructor
return;
}
for (Tree member : classTree.getMembers()) {
if (member instanceof VariableTree) {
VariableTree vt = (VariableTree) member;
final VariableElement element = TreeUtils.elementFromDeclaration(vt);
AnnotatedTypeMirror type =
((GenericAnnotatedTypeFactory) factory).getAnnotatedTypeLhs(vt);
TypeMirror fieldType = ElementUtils.getType(element);
Receiver receiver;
if (ElementUtils.isStatic(element)) {
receiver = new ClassName(classType);
} else {
receiver = new ThisReference(classType);
}
V value = analysis.createAbstractValue(type);
if (value == null) {
continue;
}
if (TreeUtils.isConstructor(methodTree)) {
// if we are in a constructor,
// then we can still use the static type, but only
// if there is also an initializer that already does
// some initialization.
boolean found = false;
for (Pair fieldValue : fieldValues) {
if (fieldValue.first.equals(element)) {
value = value.leastUpperBound(fieldValue.second);
found = true;
break;
}
}
if (!found) {
// no initializer found, cannot use static type
continue;
}
}
Receiver field = new FieldAccess(receiver, fieldType, element);
info.insertValue(field, value);
}
}
}
private void addFinalLocalValues(S info, Element enclosingElement) {
// add information about effectively final variables (from outer scopes)
for (Entry e : analysis.atypeFactory.getFinalLocalValues().entrySet()) {
Element elem = e.getKey();
// TODO: There is a design flaw where the values of final local values leaks
// into other methods of the same class. For example, in
// class a { void b() {...} void c() {...} }
// final local values from b() would be visible in the store for c(),
// even though they should only be visible in b() and in classes
// defined inside the method body of b().
// This is partly because GenericAnnotatedTypeFactory.performFlowAnalysis
// does not call itself recursively to analyze inner classes, but instead
// pops classes off of a queue, and the information about known final local
// values is stored by GenericAnnotatedTypeFactory.analyze in
// GenericAnnotatedTypeFactory.flowResult, which is visible to all classes
// in the queue regardless of their level of recursion.
// We work around this here by ensuring that we only add a final
// local value to a method's store if that method is enclosed by
// the method where the local variables were declared.
// Find the enclosing method of the element
Element enclosingMethodOfVariableDeclaration = elem.getEnclosingElement();
if (enclosingMethodOfVariableDeclaration != null) {
// Now find all the enclosing methods of the code we are analyzing. If any one of
// them matches the above, then the final local variable value applies.
Element enclosingMethodOfCurrentMethod = enclosingElement;
while (enclosingMethodOfCurrentMethod != null) {
if (enclosingMethodOfVariableDeclaration.equals(
enclosingMethodOfCurrentMethod)) {
LocalVariable l = new LocalVariable(elem);
info.insertValue(l, e.getValue());
break;
}
enclosingMethodOfCurrentMethod =
enclosingMethodOfCurrentMethod.getEnclosingElement();
}
}
}
}
/** Returns true if the receiver of a method might not yet be fully initialized. */
protected boolean isNotFullyInitializedReceiver(MethodTree methodTree) {
return TreeUtils.isConstructor(methodTree);
}
/**
* Add the information from all the preconditions of the method {@code method} with
* corresponding tree {@code methodTree} to the store {@code info}.
*/
protected void addInformationFromPreconditions(
S info,
AnnotatedTypeFactory factory,
CFGMethod method,
MethodTree methodTree,
ExecutableElement methodElement) {
ContractsUtils contracts = ContractsUtils.getInstance(analysis.atypeFactory);
FlowExpressionContext flowExprContext = null;
Set preconditions = contracts.getPreconditions(methodElement);
for (Precondition p : preconditions) {
String expression = p.expression;
AnnotationMirror annotation = p.annotation;
if (flowExprContext == null) {
flowExprContext =
FlowExpressionContext.buildContextForMethodDeclaration(
methodTree, method.getClassTree(), analysis.checker.getContext());
}
TreePath localScope = analysis.atypeFactory.getPath(methodTree);
annotation = standardizeAnnotationFromContract(annotation, flowExprContext, localScope);
try {
// TODO: currently, these expressions are parsed at the
// declaration (i.e. here) and for every use. this could
// be optimized to store the result the first time.
// (same for other annotations)
FlowExpressions.Receiver expr =
FlowExpressionParseUtil.parse(
expression, flowExprContext, localScope, false);
info.insertValue(expr, annotation);
} catch (FlowExpressionParseException e) {
// Errors are reported by BaseTypeVisitor.checkContractsAtMethodDeclaration()
}
}
}
/** Standardize a type qualifier annotation obtained from a contract. */
private AnnotationMirror standardizeAnnotationFromContract(
AnnotationMirror annoFromContract,
FlowExpressionContext flowExprContext,
TreePath path) {
// TODO: common implementation with BaseTypeVisitor.standardizeAnnotationFromContract
if (analysis.dependentTypesHelper != null) {
return analysis.dependentTypesHelper.standardizeAnnotation(
flowExprContext, path, annoFromContract, false);
// BaseTypeVisitor checks the validity of the annotaiton. Errors are reported there
// when called from BaseTypeVisitor.checkContractsAtMethodDeclaration().
} else {
return annoFromContract;
}
}
/**
* The default visitor returns the input information unchanged, or in the case of conditional
* input information, merged.
*/
@Override
public TransferResult visitNode(Node n, TransferInput in) {
V value = null;
// TODO: handle implicit/explicit this and go to correct factory method
Tree tree = n.getTree();
if (tree != null) {
if (TreeUtils.canHaveTypeAnnotation(tree)) {
value = getValueFromFactory(tree, n);
}
}
if (in.containsTwoStores()) {
S thenStore = in.getThenStore();
S elseStore = in.getElseStore();
return new ConditionalTransferResult<>(
finishValue(value, thenStore, elseStore), thenStore, elseStore);
} else {
S info = in.getRegularStore();
return new RegularTransferResult<>(finishValue(value, info), info);
}
}
@Override
public TransferResult visitClassName(ClassNameNode n, TransferInput in) {
// The tree underlying a class name is a type tree.
V value = null;
Tree tree = n.getTree();
if (tree != null) {
if (TreeUtils.canHaveTypeAnnotation(tree)) {
GenericAnnotatedTypeFactory>
factory = analysis.atypeFactory;
analysis.setCurrentTree(tree);
AnnotatedTypeMirror at = factory.getAnnotatedTypeFromTypeTree(tree);
analysis.setCurrentTree(null);
value = analysis.createAbstractValue(at);
}
}
if (in.containsTwoStores()) {
S thenStore = in.getThenStore();
S elseStore = in.getElseStore();
return new ConditionalTransferResult<>(
finishValue(value, thenStore, elseStore), thenStore, elseStore);
} else {
S info = in.getRegularStore();
return new RegularTransferResult<>(finishValue(value, info), info);
}
}
@Override
public TransferResult visitFieldAccess(FieldAccessNode n, TransferInput p) {
S store = p.getRegularStore();
V storeValue = store.getValue(n);
// look up value in factory, and take the more specific one
// TODO: handle cases, where this is not allowed (e.g. constructors in
// non-null type systems)
V factoryValue = getValueFromFactory(n.getTree(), n);
V value = moreSpecificValue(factoryValue, storeValue);
return new RegularTransferResult<>(finishValue(value, store), store);
}
@Override
public TransferResult visitArrayAccess(ArrayAccessNode n, TransferInput p) {
S store = p.getRegularStore();
V storeValue = store.getValue(n);
// look up value in factory, and take the more specific one
V factoryValue = getValueFromFactory(n.getTree(), n);
V value = moreSpecificValue(factoryValue, storeValue);
return new RegularTransferResult<>(finishValue(value, store), store);
}
/** Use the most specific type information available according to the store. */
@Override
public TransferResult visitLocalVariable(LocalVariableNode n, TransferInput in) {
S store = in.getRegularStore();
V valueFromStore = store.getValue(n);
V valueFromFactory = getValueFromFactory(n.getTree(), n);
V value = moreSpecificValue(valueFromFactory, valueFromStore);
return new RegularTransferResult<>(finishValue(value, store), store);
}
@Override
public TransferResult visitThisLiteral(ThisLiteralNode n, TransferInput in) {
S store = in.getRegularStore();
V valueFromStore = store.getValue(n);
V valueFromFactory = null;
V value = null;
Tree tree = n.getTree();
if (tree != null && TreeUtils.canHaveTypeAnnotation(tree)) {
valueFromFactory = getValueFromFactory(tree, n);
}
if (valueFromFactory == null) {
value = valueFromStore;
} else {
value = moreSpecificValue(valueFromFactory, valueFromStore);
}
return new RegularTransferResult<>(finishValue(value, store), store);
}
/** The resulting abstract value is the merge of the 'then' and 'else' branch. */
@Override
public TransferResult visitTernaryExpression(
TernaryExpressionNode n, TransferInput p) {
TransferResult result = super.visitTernaryExpression(n, p);
S store = result.getRegularStore();
V thenValue = p.getValueOfSubNode(n.getThenOperand());
V elseValue = p.getValueOfSubNode(n.getElseOperand());
V resultValue = null;
if (thenValue != null && elseValue != null) {
resultValue = thenValue.leastUpperBound(elseValue);
}
return new RegularTransferResult<>(finishValue(resultValue, store), store);
}
/** Reverse the role of the 'thenStore' and 'elseStore'. */
@Override
public TransferResult visitConditionalNot(ConditionalNotNode n, TransferInput p) {
TransferResult result = super.visitConditionalNot(n, p);
S thenStore = result.getThenStore();
S elseStore = result.getElseStore();
return new ConditionalTransferResult<>(result.getResultValue(), elseStore, thenStore);
}
@Override
public TransferResult visitEqualTo(EqualToNode n, TransferInput p) {
TransferResult res = super.visitEqualTo(n, p);
Node leftN = n.getLeftOperand();
Node rightN = n.getRightOperand();
V leftV = p.getValueOfSubNode(leftN);
V rightV = p.getValueOfSubNode(rightN);
// if annotations differ, use the one that is more precise for both
// sides (and add it to the store if possible)
res = strengthenAnnotationOfEqualTo(res, leftN, rightN, leftV, rightV, false);
res = strengthenAnnotationOfEqualTo(res, rightN, leftN, rightV, leftV, false);
return res;
}
@Override
public TransferResult visitNotEqual(NotEqualNode n, TransferInput p) {
TransferResult res = super.visitNotEqual(n, p);
Node leftN = n.getLeftOperand();
Node rightN = n.getRightOperand();
V leftV = p.getValueOfSubNode(leftN);
V rightV = p.getValueOfSubNode(rightN);
// if annotations differ, use the one that is more precise for both
// sides (and add it to the store if possible)
res = strengthenAnnotationOfEqualTo(res, leftN, rightN, leftV, rightV, true);
res = strengthenAnnotationOfEqualTo(res, rightN, leftN, rightV, leftV, true);
return res;
}
/**
* Refine the annotation of {@code secondNode} if the annotation {@code secondValue} is less
* precise than {@code firstvalue}. This is possible, if {@code secondNode} is an expression
* that is tracked by the store (e.g., a local variable or a field).
*
* Note that when overriding this method, when a new type is inserted into the store,
* splitAssignments should be called, and the new type should be inserted into the store for
* each of the resulting nodes.
*
* @param res the previous result
* @param notEqualTo if true, indicates that the logic is flipped (i.e., the information is
* added to the {@code elseStore} instead of the {@code thenStore}) for a not-equal
* comparison.
* @return the conditional transfer result (if information has been added), or {@code null}.
*/
protected TransferResult strengthenAnnotationOfEqualTo(
TransferResult res,
Node firstNode,
Node secondNode,
V firstValue,
V secondValue,
boolean notEqualTo) {
if (firstValue != null) {
// Only need to insert if the second value is actually different.
if (!firstValue.equals(secondValue)) {
List secondParts = splitAssignments(secondNode);
for (Node secondPart : secondParts) {
Receiver secondInternal =
FlowExpressions.internalReprOf(analysis.getTypeFactory(), secondPart);
if (CFAbstractStore.canInsertReceiver(secondInternal)) {
S thenStore = res.getThenStore();
S elseStore = res.getElseStore();
if (notEqualTo) {
elseStore.insertValue(secondInternal, firstValue);
} else {
thenStore.insertValue(secondInternal, firstValue);
}
// To handle `(a = b = c) == x`, repeat for all insertable receivers of
// splitted assignments instead of returning.
res =
new ConditionalTransferResult<>(
res.getResultValue(), thenStore, elseStore);
}
}
}
}
return res;
}
/**
* Takes a node, and either returns the node itself again (as a singleton list), or if the node
* is an assignment node, returns the lhs and rhs (where splitAssignments is applied recursively
* to the rhs -- that is, the rhs may not appear in the result, but rather its lhs and rhs may).
*/
protected List splitAssignments(Node node) {
if (node instanceof AssignmentNode) {
List result = new ArrayList<>();
AssignmentNode a = (AssignmentNode) node;
result.add(a.getTarget());
result.addAll(splitAssignments(a.getExpression()));
return result;
} else {
return Collections.singletonList(node);
}
}
@Override
public TransferResult visitAssignment(AssignmentNode n, TransferInput in) {
Node lhs = n.getTarget();
Node rhs = n.getExpression();
S info = in.getRegularStore();
V rhsValue = in.getValueOfSubNode(rhs);
if (shouldPerformWholeProgramInference(n.getTree(), lhs.getTree())) {
if (lhs instanceof FieldAccessNode) {
// Updates inferred field type
analysis.atypeFactory
.getWholeProgramInference()
.updateInferredFieldType(
(FieldAccessNode) lhs,
rhs,
analysis.getContainingClass(n.getTree()),
analysis.getTypeFactory());
} else if (lhs instanceof LocalVariableNode
&& ((LocalVariableNode) lhs).getElement().getKind() == ElementKind.PARAMETER) {
analysis.atypeFactory
.getWholeProgramInference()
.updateInferredParameterType(
(LocalVariableNode) lhs,
rhs,
analysis.getContainingClass(n.getTree()),
analysis.getContainingMethod(n.getTree()),
analysis.getTypeFactory());
}
}
processCommonAssignment(in, lhs, rhs, info, rhsValue);
return new RegularTransferResult<>(finishValue(rhsValue, info), info);
}
@Override
public TransferResult visitReturn(ReturnNode n, TransferInput p) {
if (shouldPerformWholeProgramInference(n.getTree())) {
// Retrieves class containing the method
ClassTree classTree = analysis.getContainingClass(n.getTree());
ClassSymbol classSymbol = (ClassSymbol) TreeUtils.elementFromTree(classTree);
// Updates the inferred return type of the method
analysis.atypeFactory
.getWholeProgramInference()
.updateInferredMethodReturnType(
n,
classSymbol,
analysis.getContainingMethod(n.getTree()),
analysis.getTypeFactory());
}
return super.visitReturn(n, p);
}
@Override
public TransferResult visitLambdaResultExpression(
LambdaResultExpressionNode n, TransferInput in) {
return n.getResult().accept(this, in);
}
@Override
public TransferResult visitStringConcatenateAssignment(
StringConcatenateAssignmentNode n, TransferInput in) {
// This gets the type of LHS + RHS
TransferResult result = super.visitStringConcatenateAssignment(n, in);
Node lhs = n.getLeftOperand();
Node rhs = n.getRightOperand();
// update the results store if the assignment target is something we can
// process
S info = result.getRegularStore();
// ResultValue is the type of LHS + RHS
V resultValue = result.getResultValue();
if (lhs instanceof FieldAccessNode
&& shouldPerformWholeProgramInference(n.getTree(), lhs.getTree())) {
// Updates inferred field type
analysis.atypeFactory
.getWholeProgramInference()
.updateInferredFieldType(
(FieldAccessNode) lhs,
rhs,
analysis.getContainingClass(n.getTree()),
analysis.getTypeFactory());
}
processCommonAssignment(in, lhs, rhs, info, resultValue);
return new RegularTransferResult<>(finishValue(resultValue, info), info);
}
/**
* Determine abstract value of right-hand side and update the store accordingly to the
* assignment.
*/
protected void processCommonAssignment(
TransferInput in, Node lhs, Node rhs, S info, V rhsValue) {
// update information in the store
info.updateForAssignment(lhs, rhsValue);
}
@Override
public TransferResult visitObjectCreation(ObjectCreationNode n, TransferInput p) {
if (shouldPerformWholeProgramInference(n.getTree())) {
ExecutableElement constructorElt =
analysis.getTypeFactory()
.constructorFromUse(n.getTree())
.executableType
.getElement();
analysis.atypeFactory
.getWholeProgramInference()
.updateInferredConstructorParameterTypes(
n, constructorElt, analysis.getTypeFactory());
}
return super.visitObjectCreation(n, p);
}
@Override
public TransferResult visitMethodInvocation(
MethodInvocationNode n, TransferInput in) {
S store = in.getRegularStore();
ExecutableElement method = n.getTarget().getMethod();
V factoryValue = null;
Tree tree = n.getTree();
if (tree != null) {
// look up the value from factory
factoryValue = getValueFromFactory(tree, n);
}
// look up the value in the store (if possible)
V storeValue = store.getValue(n);
V resValue = moreSpecificValue(factoryValue, storeValue);
store.updateForMethodCall(n, analysis.atypeFactory, resValue);
// add new information based on postcondition
processPostconditions(n, store, method, tree);
S thenStore = store;
S elseStore = thenStore.copy();
// add new information based on conditional postcondition
processConditionalPostconditions(n, method, tree, thenStore, elseStore);
if (shouldPerformWholeProgramInference(n.getTree(), method)) {
// Finds the receiver's type
Tree receiverTree = n.getTarget().getReceiver().getTree();
if (receiverTree == null) {
// If there is no receiver, then get the class being visited.
// This happens when the receiver corresponds to "this".
receiverTree = analysis.getContainingClass(n.getTree());
// receiverTree could still be null after the call above. That
// happens when the method is called from a static context.
}
// Updates the inferred parameter type of the invoked method
analysis.atypeFactory
.getWholeProgramInference()
.updateInferredMethodParameterTypes(
n, receiverTree, method, analysis.getTypeFactory());
}
return new ConditionalTransferResult<>(
finishValue(resValue, thenStore, elseStore), thenStore, elseStore);
}
/**
* Returns true if whole-program inference should be performed. If the tree is in the scope of
* a @SuppressWarning, then this method returns false.
*/
private boolean shouldPerformWholeProgramInference(Tree tree) {
return infer && (tree == null || !analysis.checker.shouldSuppressWarnings(tree, null));
}
/**
* Returns true if whole-program inference should be performed. If the expressionTree or lhsTree
* is in the scope of a @SuppressWarning, then this method returns false.
*/
private boolean shouldPerformWholeProgramInference(Tree expressionTree, Tree lhsTree) {
// Check that infer is true and the tree isn't in scope of a @SuppressWarning
// before calling InternalUtils.symbol(lhs)
if (!shouldPerformWholeProgramInference(expressionTree)) {
return false;
}
Element elt = TreeUtils.elementFromTree(lhsTree);
return !analysis.checker.shouldSuppressWarnings(elt, null);
}
/**
* Returns true if whole-program inference should be performed. If the tree or element is in the
* scope of a @SuppressWarning, then this method returns false.
*/
private boolean shouldPerformWholeProgramInference(Tree tree, Element elt) {
return shouldPerformWholeProgramInference(tree)
&& !analysis.checker.shouldSuppressWarnings(elt, null);
}
/**
* Add information based on all postconditions of method {@code n} with tree {@code tree} and
* element {@code method} to the store {@code store}.
*/
protected void processPostconditions(
MethodInvocationNode n, S store, ExecutableElement methodElement, Tree tree) {
ContractsUtils contracts = ContractsUtils.getInstance(analysis.atypeFactory);
Set postconditions = contracts.getPostconditions(methodElement);
processPostconditionsAndConditionalPostconditions(n, tree, store, null, postconditions);
}
/**
* Add information based on all conditional postconditions of method {@code n} with tree {@code
* tree} and element {@code method} to the appropriate store.
*/
protected void processConditionalPostconditions(
MethodInvocationNode n,
ExecutableElement methodElement,
Tree tree,
S thenStore,
S elseStore) {
ContractsUtils contracts = ContractsUtils.getInstance(analysis.atypeFactory);
Set conditionalPostconditions =
contracts.getConditionalPostconditions(methodElement);
processPostconditionsAndConditionalPostconditions(
n, tree, thenStore, elseStore, conditionalPostconditions);
}
private void processPostconditionsAndConditionalPostconditions(
MethodInvocationNode n,
Tree tree,
S thenStore,
S elseStore,
Set postconditions) {
FlowExpressionContext flowExprContext = null;
for (Contract p : postconditions) {
String expression = p.expression;
AnnotationMirror anno = p.annotation;
if (flowExprContext == null) {
flowExprContext =
FlowExpressionContext.buildContextForMethodUse(
n, analysis.checker.getContext());
}
TreePath localScope = analysis.atypeFactory.getPath(tree);
anno = standardizeAnnotationFromContract(anno, flowExprContext, localScope);
try {
FlowExpressions.Receiver r =
FlowExpressionParseUtil.parse(
expression, flowExprContext, localScope, false);
if (p.kind == Contract.Kind.CONDITIONALPOSTCONDTION) {
if (((ConditionalPostcondition) p).annoResult) {
thenStore.insertValue(r, anno);
} else {
elseStore.insertValue(r, anno);
}
} else {
thenStore.insertValue(r, anno);
}
} catch (FlowExpressionParseException e) {
Result result;
if (e.isFlowParseError()) {
Object[] args = new Object[e.args.length + 1];
args[0] = ElementUtils.getSimpleName(TreeUtils.elementFromUse(n.getTree()));
System.arraycopy(e.args, 0, args, 1, e.args.length);
result = Result.failure("flowexpr.parse.error.postcondition", args);
} else {
result = e.getResult();
}
// report errors here
analysis.checker.report(result, tree);
}
}
}
/**
* A case produces no value, but it may imply some facts about the argument to the switch
* statement.
*/
@Override
public TransferResult visitCase(CaseNode n, TransferInput in) {
S store = in.getRegularStore();
TransferResult result =
new ConditionalTransferResult<>(
finishValue(null, store), in.getThenStore(), in.getElseStore(), false);
V caseValue = in.getValueOfSubNode(n.getCaseOperand());
AssignmentNode assign = (AssignmentNode) n.getSwitchOperand();
V switchValue =
store.getValue(
FlowExpressions.internalReprOf(
analysis.getTypeFactory(), assign.getTarget()));
result =
strengthenAnnotationOfEqualTo(
result,
n.getCaseOperand(),
assign.getExpression(),
caseValue,
switchValue,
false);
// Update value of switch temporary variable
result =
strengthenAnnotationOfEqualTo(
result,
n.getCaseOperand(),
assign.getTarget(),
caseValue,
switchValue,
false);
return result;
}
/**
* In a cast {@code (@A C) e} of some expression {@code e} to a new type {@code @A C}, we
* usually take the annotation of the type {@code C} (here {@code @A}). However, if the inferred
* annotation of {@code e} is more precise, we keep that one.
*/
// @Override
// public TransferResult visitTypeCast(TypeCastNode n,
// TransferInput p) {
// TransferResult result = super.visitTypeCast(n, p);
// V value = result.getResultValue();
// V operandValue = p.getValueOfSubNode(n.getOperand());
// // Normally we take the value of the type cast node. However, if the old
// // flow-refined value was more precise, we keep that value.
// V resultValue = moreSpecificValue(value, operandValue);
// result.setResultValue(resultValue);
// return result;
// }
/**
* Returns the abstract value of {@code (value1, value2)} that is more specific. If the two are
* incomparable, then {@code value1} is returned.
*/
public V moreSpecificValue(V value1, V value2) {
if (value1 == null) {
return value2;
}
if (value2 == null) {
return value1;
}
return value1.mostSpecific(value2, value1);
}
@Override
public TransferResult visitVariableDeclaration(
VariableDeclarationNode n, TransferInput p) {
S store = p.getRegularStore();
return new RegularTransferResult<>(finishValue(null, store), store);
}
@Override
public TransferResult visitNarrowingConversion(
NarrowingConversionNode n, TransferInput p) {
TransferResult result = super.visitNarrowingConversion(n, p);
// Combine annotations from the operand with the narrow type
V operandValue = p.getValueOfSubNode(n.getOperand());
V narrowedValue = getValueWithSameAnnotations(n.getType(), operandValue);
result.setResultValue(narrowedValue);
return result;
}
@Override
public TransferResult visitWideningConversion(
WideningConversionNode n, TransferInput p) {
TransferResult result = super.visitWideningConversion(n, p);
// Combine annotations from the operand with the wide type
V operandValue = p.getValueOfSubNode(n.getOperand());
V widenedValue = getValueWithSameAnnotations(n.getType(), operandValue);
result.setResultValue(widenedValue);
return result;
}
@Override
public TransferResult visitStringConversion(
StringConversionNode n, TransferInput p) {
TransferResult result = super.visitStringConversion(n, p);
result.setResultValue(p.getValueOfSubNode(n.getOperand()));
return result;
}
}