/*
* Copyright (c) 2017 Uber Technologies, Inc.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.uber.nullaway.dataflow;
import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableList;
import com.google.errorprone.util.ASTHelpers;
import com.sun.source.tree.LiteralTree;
import com.sun.source.tree.MethodInvocationTree;
import com.sun.source.tree.Tree;
import com.sun.tools.javac.code.Symbol;
import com.sun.tools.javac.code.Type;
import com.sun.tools.javac.code.Types;
import java.util.ArrayList;
import java.util.List;
import javax.annotation.Nullable;
import javax.lang.model.element.Element;
import org.checkerframework.dataflow.cfg.node.FieldAccessNode;
import org.checkerframework.dataflow.cfg.node.LocalVariableNode;
import org.checkerframework.dataflow.cfg.node.MethodAccessNode;
import org.checkerframework.dataflow.cfg.node.MethodInvocationNode;
import org.checkerframework.dataflow.cfg.node.Node;
import org.checkerframework.dataflow.cfg.node.ThisLiteralNode;
import org.checkerframework.dataflow.cfg.node.VariableDeclarationNode;
import org.checkerframework.javacutil.TreeUtils;
/**
* Represents an extended notion of an access path, which we track for nullness.
*
* <p>Typically, access paths are of the form x.f.g.h, where x is a variable and f, g, and h are
* field names. Here, we also allow no-argument methods to appear in the access path, as well as
* method calls passed only statically constant parameters, so an AP can be of the form
* x.f().g.h([int_expr|string_expr]) in general.
*
* <p>We do not allow array accesses in access paths for the moment.
*/
public final class AccessPath {
private final Root root;
private final ImmutableList<AccessPathElement> elements;
/**
* if present, the argument to the map get() method call that is the final element of this path
*/
@Nullable private final AccessPath mapGetArgAccessPath;
AccessPath(Root root, List<AccessPathElement> elements) {
this.root = root;
this.elements = ImmutableList.copyOf(elements);
this.mapGetArgAccessPath = null;
}
private AccessPath(Root root, List<AccessPathElement> elements, AccessPath mapGetArgAccessPath) {
this.root = root;
this.elements = ImmutableList.copyOf(elements);
this.mapGetArgAccessPath = mapGetArgAccessPath;
}
/**
* Construct the access path of a local.
*
* @param node the local
* @return access path representing the local
*/
static AccessPath fromLocal(LocalVariableNode node) {
return new AccessPath(new Root(node.getElement()), ImmutableList.of());
}
/**
* Construct the access path of a variable declaration.
*
* @param node the variable declaration
* @return access path representing the variable declaration
*/
static AccessPath fromVarDecl(VariableDeclarationNode node) {
Element elem = TreeUtils.elementFromDeclaration(node.getTree());
return new AccessPath(new Root(elem), ImmutableList.of());
}
/**
* Construct the access path of a field access.
*
* @param node the field access
* @return access path for the field access, or <code>null</code> if it cannot be represented
*/
@Nullable
static AccessPath fromFieldAccess(FieldAccessNode node) {
List<AccessPathElement> elements = new ArrayList<>();
Root root = populateElementsRec(node, elements);
return (root != null) ? new AccessPath(root, elements) : null;
}
/**
* Construct the access path of a method call.
*
* @param node the method call
* @return access path for the method call, or <code>null</code> if it cannot be represented
*/
@Nullable
static AccessPath fromMethodCall(MethodInvocationNode node, @Nullable Types types) {
if (types != null && isMapGet(ASTHelpers.getSymbol(node.getTree()), types)) {
return fromMapGetCall(node);
}
return fromVanillaMethodCall(node);
}
@Nullable
private static AccessPath fromVanillaMethodCall(MethodInvocationNode node) {
List<AccessPathElement> elements = new ArrayList<>();
Root root = populateElementsRec(node, elements);
return (root != null) ? new AccessPath(root, elements) : null;
}
/**
* Construct the access path given a {@code base.element} structure.
*
* @param base the base expression for the access path
* @param element the final element of the access path (a field or method)
* @return the {@link AccessPath} {@code base.element}
*/
@Nullable
public static AccessPath fromBaseAndElement(Node base, Element element) {
List<AccessPathElement> elements = new ArrayList<>();
Root root = populateElementsRec(base, elements);
if (root == null) {
return null;
}
elements.add(new AccessPathElement(element));
return new AccessPath(root, elements);
}
/**
* Construct the access path for <code>map.get(x)</code> from an invocation of <code>put(x)</code>
* or <code>containsKey(x)</code>.
*
* @param node a node invoking containsKey() or put() on a map
* @return an AccessPath representing invoking get() on the same type of map as from node, passing
* the same first argument as is passed in node
*/
@Nullable
public static AccessPath getForMapInvocation(MethodInvocationNode node) {
// For the receiver type for get, use the declared type of the receiver of the containsKey()
// call.
// Note that this may differ from the containing class of the resolved containsKey() method,
// which
// can be in a superclass (e.g., LinkedHashMap does not override containsKey())
// assumption: map type will not both override containsKey() and inherit get()
return fromMapGetCall(node);
}
@Nullable
private static AccessPath fromMapGetCall(MethodInvocationNode node) {
Node argument = node.getArgument(0);
AccessPath argAccessPath = getAccessPathForNodeNoMapGet(argument);
if (argAccessPath == null) {
return null;
}
MethodAccessNode target = node.getTarget();
Node receiver = target.getReceiver();
List<AccessPathElement> elements = new ArrayList<>();
Root root = populateElementsRec(receiver, elements);
if (root == null) {
return null;
}
return new AccessPath(root, elements, argAccessPath);
}
/**
* Gets corresponding AccessPath for node, if it exists. Does <emph>not</emph> handle calls to
* <code>Map.get()</code>
*
* @param node AST node
* @return corresponding AccessPath if it exists; <code>null</code> otherwise
*/
@Nullable
public static AccessPath getAccessPathForNodeNoMapGet(Node node) {
return getAccessPathForNodeWithMapGet(node, null);
}
/**
* Gets corresponding AccessPath for node, if it exists. Handles calls to <code>Map.get()
* </code>
*
* @param node AST node
* @param types javac {@link Types}
* @return corresponding AccessPath if it exists; <code>null</code> otherwise
*/
@Nullable
public static AccessPath getAccessPathForNodeWithMapGet(Node node, @Nullable Types types) {
if (node instanceof LocalVariableNode) {
return fromLocal((LocalVariableNode) node);
} else if (node instanceof FieldAccessNode) {
return fromFieldAccess((FieldAccessNode) node);
} else if (node instanceof MethodInvocationNode) {
return fromMethodCall((MethodInvocationNode) node, types);
} else {
return null;
}
}
private static boolean isBoxingMethod(Symbol.MethodSymbol methodSymbol) {
return methodSymbol.isStatic()
&& methodSymbol.getSimpleName().contentEquals("valueOf")
&& methodSymbol.enclClass().packge().fullname.contentEquals("java.lang");
}
@Nullable
private static Root populateElementsRec(Node node, List<AccessPathElement> elements) {
Root result;
if (node instanceof FieldAccessNode) {
FieldAccessNode fieldAccess = (FieldAccessNode) node;
if (fieldAccess.isStatic()) {
// this is the root
result = new Root(fieldAccess.getElement());
} else {
// instance field access
result = populateElementsRec(fieldAccess.getReceiver(), elements);
elements.add(new AccessPathElement(fieldAccess.getElement()));
}
} else if (node instanceof MethodInvocationNode) {
MethodInvocationNode invocation = (MethodInvocationNode) node;
AccessPathElement accessPathElement;
MethodAccessNode accessNode = invocation.getTarget();
if (invocation.getArguments().size() == 0) {
accessPathElement = new AccessPathElement(accessNode.getMethod());
} else {
List<String> constantArgumentValues = new ArrayList<>();
for (Node argumentNode : invocation.getArguments()) {
Tree tree = argumentNode.getTree();
if (tree == null) {
return null; // Not an AP
} else if (tree.getKind().equals(Tree.Kind.METHOD_INVOCATION)) {
// Check for boxing call
MethodInvocationTree methodInvocationTree = (MethodInvocationTree) tree;
if (methodInvocationTree.getArguments().size() == 1
&& isBoxingMethod(ASTHelpers.getSymbol(methodInvocationTree))) {
tree = methodInvocationTree.getArguments().get(0);
}
}
switch (tree.getKind()) {
case BOOLEAN_LITERAL:
case CHAR_LITERAL:
case DOUBLE_LITERAL:
case FLOAT_LITERAL:
case INT_LITERAL:
case LONG_LITERAL:
case STRING_LITERAL:
constantArgumentValues.add(((LiteralTree) tree).getValue().toString());
break;
case NULL_LITERAL:
// Um, probably not? Cascade to default for now.
default:
return null; // Not an AP
}
}
accessPathElement = new AccessPathElement(accessNode.getMethod(), constantArgumentValues);
}
result = populateElementsRec(accessNode.getReceiver(), elements);
elements.add(accessPathElement);
} else if (node instanceof LocalVariableNode) {
result = new Root(((LocalVariableNode) node).getElement());
} else if (node instanceof ThisLiteralNode) {
result = new Root();
} else {
// don't handle any other cases
result = null;
}
return result;
}
@Override
public boolean equals(Object o) {
if (this == o) {
return true;
}
if (!(o instanceof AccessPath)) {
return false;
}
AccessPath that = (AccessPath) o;
if (!root.equals(that.root)) {
return false;
}
if (!elements.equals(that.elements)) {
return false;
}
return mapGetArgAccessPath != null
? (that.mapGetArgAccessPath != null && mapGetArgAccessPath.equals(that.mapGetArgAccessPath))
: that.mapGetArgAccessPath == null;
}
@Override
public int hashCode() {
int result = root.hashCode();
result = 31 * result + elements.hashCode();
result = 31 * result + (mapGetArgAccessPath != null ? mapGetArgAccessPath.hashCode() : 0);
return result;
}
public Root getRoot() {
return root;
}
public ImmutableList<AccessPathElement> getElements() {
return elements;
}
@Override
public String toString() {
return "AccessPath{" + "root=" + root + ", elements=" + elements + '}';
}
private static boolean isMapMethod(
Symbol.MethodSymbol symbol, Types types, String methodName, int numParams) {
if (!symbol.getSimpleName().toString().equals(methodName)) {
return false;
}
if (symbol.getParameters().size() != numParams) {
return false;
}
Symbol owner = symbol.owner;
if (owner.getQualifiedName().toString().equals("java.util.Map")) {
return true;
}
com.sun.tools.javac.util.List<Type> supertypes = types.closure(owner.type);
for (Type t : supertypes) {
if (t.asElement().getQualifiedName().toString().equals("java.util.Map")) {
return true;
}
}
return false;
}
private static boolean isMapGet(Symbol.MethodSymbol symbol, Types types) {
return isMapMethod(symbol, types, "get", 1);
}
public static boolean isContainsKey(Symbol.MethodSymbol symbol, Types types) {
return isMapMethod(symbol, types, "containsKey", 1);
}
public static boolean isMapPut(Symbol.MethodSymbol symbol, Types types) {
return isMapMethod(symbol, types, "put", 2);
}
/**
* root of an access path; either a variable {@link javax.lang.model.element.Element} or <code>
* this</code> (enclosing method receiver)
*/
public static final class Root {
/** does this represent the receiver? */
private final boolean isMethodReceiver;
@Nullable private final Element varElement;
Root(Element varElement) {
this.isMethodReceiver = false;
this.varElement = Preconditions.checkNotNull(varElement);
}
/** for case when it represents the receiver */
Root() {
this.isMethodReceiver = true;
this.varElement = null;
}
/**
* Get the variable element of this access path root, if not representing <code>this</code>.
*
* @return the variable, if not representing 'this'
*/
public Element getVarElement() {
return Preconditions.checkNotNull(varElement);
}
/**
* Check whether this access path root represents the receiver (i.e. <code>this</code>). s
*
* @return <code>true</code> if representing 'this', <code>false</code> otherwise
*/
public boolean isReceiver() {
return isMethodReceiver;
}
@Override
public boolean equals(Object o) {
if (this == o) {
return true;
}
if (o == null || getClass() != o.getClass()) {
return false;
}
Root root = (Root) o;
if (isMethodReceiver != root.isMethodReceiver) {
return false;
}
return varElement != null ? varElement.equals(root.varElement) : root.varElement == null;
}
@Override
public int hashCode() {
int result = (isMethodReceiver ? 1 : 0);
result = 31 * result + (varElement != null ? varElement.hashCode() : 0);
return result;
}
@Override
public String toString() {
return "Root{" + "isMethodReceiver=" + isMethodReceiver + ", varElement=" + varElement + '}';
}
}
}
