/
OptionalEmptinessHandler.java
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/
OptionalEmptinessHandler.java
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/*
* Copyright (c) 2018 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.handlers;
import com.google.common.base.Preconditions;
import com.google.errorprone.VisitorState;
import com.google.errorprone.util.ASTHelpers;
import com.sun.source.tree.ClassTree;
import com.sun.source.tree.ExpressionTree;
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 com.sun.tools.javac.util.Context;
import com.uber.nullaway.NullAway;
import com.uber.nullaway.Nullness;
import com.uber.nullaway.dataflow.AccessPath;
import com.uber.nullaway.dataflow.AccessPathNullnessPropagation;
import java.util.Optional;
import javax.annotation.Nullable;
import javax.lang.model.element.Element;
import javax.lang.model.element.ElementKind;
import org.checkerframework.dataflow.cfg.node.MethodInvocationNode;
import org.checkerframework.dataflow.cfg.node.Node;
/**
* Handler to better handle {@code isPresent()} methods in code generated for Optionals. With this
* handler, we learn appropriate Emptiness facts about the relevant property from these calls.
*/
public class OptionalEmptinessHandler extends BaseNoOpHandler {
private static String OPTIONAL_PATH = "java.util.Optional";
@Nullable private Optional<Type> optionalType;
@Override
public boolean onOverrideMayBeNullExpr(
NullAway analysis, ExpressionTree expr, VisitorState state, boolean exprMayBeNull) {
if (expr.getKind() == Tree.Kind.METHOD_INVOCATION
&& optionalIsGetCall((Symbol.MethodSymbol) ASTHelpers.getSymbol(expr), state.getTypes())) {
return true;
}
return exprMayBeNull;
}
@Override
public void onMatchTopLevelClass(
NullAway analysis, ClassTree tree, VisitorState state, Symbol.ClassSymbol classSymbol) {
if (optionalType == null) {
optionalType =
Optional.ofNullable(state.getTypeFromString(OPTIONAL_PATH))
.map(state.getTypes()::erasure);
}
}
@Override
public NullnessHint onDataflowVisitMethodInvocation(
MethodInvocationNode node,
Types types,
Context context,
AccessPathNullnessPropagation.SubNodeValues inputs,
AccessPathNullnessPropagation.Updates thenUpdates,
AccessPathNullnessPropagation.Updates elseUpdates,
AccessPathNullnessPropagation.Updates bothUpdates) {
Symbol.MethodSymbol symbol = ASTHelpers.getSymbol(node.getTree());
if (optionalIsGetCall(symbol, types)) {
return NullnessHint.HINT_NULLABLE;
} else if (optionalIsPresentCall(symbol, types)) {
Element getter = null;
Node base = node.getTarget().getReceiver();
for (Symbol elem : symbol.owner.getEnclosedElements()) {
if (elem.getKind().equals(ElementKind.METHOD)
&& elem.getSimpleName().toString().equals("get")) {
getter = elem;
}
}
updateNonNullAPsForElement(thenUpdates, getter, base);
}
return NullnessHint.UNKNOWN;
}
private void updateNonNullAPsForElement(
AccessPathNullnessPropagation.Updates updates, @Nullable Element elem, Node base) {
if (elem != null) {
AccessPath ap = AccessPath.fromBaseAndElement(base, elem);
if (ap != null) {
updates.set(ap, Nullness.NONNULL);
}
}
}
private boolean optionalIsPresentCall(Symbol.MethodSymbol symbol, Types types) {
Preconditions.checkNotNull(optionalType);
// noinspection ConstantConditions
return optionalType.isPresent()
&& symbol.getSimpleName().toString().equals("isPresent")
&& symbol.getParameters().length() == 0
&& types.isSubtype(symbol.owner.type, optionalType.get());
}
private boolean optionalIsGetCall(Symbol.MethodSymbol symbol, Types types) {
Preconditions.checkNotNull(optionalType);
// noinspection ConstantConditions
return optionalType.isPresent()
&& symbol.getSimpleName().toString().equals("get")
&& symbol.getParameters().length() == 0
&& types.isSubtype(symbol.owner.type, optionalType.get());
}
}