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Consolidate checks for reference equality
RELNOTES: N/A ------------- Created by MOE: https://github.com/google/moe MOE_MIGRATED_REVID=122224435
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core/src/main/java/com/google/errorprone/bugpatterns/AbstractReferenceEquality.java
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| /* | ||
| * Copyright 2015 Google Inc. All Rights Reserved. | ||
| * | ||
| * Licensed under the Apache License, Version 2.0 (the "License"); | ||
| * you may not use this file except in compliance with the License. | ||
| * You may obtain a copy of the License at | ||
| * | ||
| * http://www.apache.org/licenses/LICENSE-2.0 | ||
| * | ||
| * Unless required by applicable law or agreed to in writing, software | ||
| * distributed under the License is distributed on an "AS IS" BASIS, | ||
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| * See the License for the specific language governing permissions and | ||
| * limitations under the License. | ||
| */ | ||
|
|
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| package com.google.errorprone.bugpatterns; | ||
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| import static com.google.errorprone.dataflow.nullnesspropagation.Nullness.NONNULL; | ||
| import static com.google.errorprone.dataflow.nullnesspropagation.Nullness.NULL; | ||
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| import com.google.errorprone.VisitorState; | ||
| import com.google.errorprone.bugpatterns.BugChecker.BinaryTreeMatcher; | ||
| import com.google.errorprone.dataflow.nullnesspropagation.Nullness; | ||
| import com.google.errorprone.fixes.SuggestedFix; | ||
| import com.google.errorprone.matchers.Description; | ||
| import com.google.errorprone.util.ASTHelpers; | ||
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|
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| import com.sun.source.tree.BinaryTree; | ||
| import com.sun.source.tree.ExpressionTree; | ||
| import com.sun.source.tree.Tree.Kind; | ||
| import com.sun.source.util.TreePath; | ||
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|
||
| /** | ||
| * Abstract implementation of a BugPattern that detects the use of reference equality to compare | ||
| * classes with value semantics. | ||
| * | ||
| * <p>See e.g. {@link NumericEquality}, {@link OptionalEquality}, | ||
| * {@link ProtoStringFieldReferenceEquality}, and {@link StringEquality}. | ||
| * | ||
| * @author cushon@google.com (Liam Miller-Cushon) | ||
| */ | ||
| public abstract class AbstractReferenceEquality extends BugChecker implements BinaryTreeMatcher { | ||
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| protected abstract boolean matchArgument(ExpressionTree tree, VisitorState state); | ||
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| @Override | ||
| public final Description matchBinary(BinaryTree tree, VisitorState state) { | ||
| switch (tree.getKind()) { | ||
| case EQUAL_TO: | ||
| case NOT_EQUAL_TO: | ||
| break; | ||
| default: | ||
| return Description.NO_MATCH; | ||
| } | ||
| if (tree.getLeftOperand().getKind() == Kind.NULL_LITERAL | ||
| || !matchArgument(tree.getLeftOperand(), state)) { | ||
| return Description.NO_MATCH; | ||
| } | ||
| if (tree.getRightOperand().getKind() == Kind.NULL_LITERAL | ||
| || !matchArgument(tree.getRightOperand(), state)) { | ||
| return Description.NO_MATCH; | ||
| } | ||
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| Description.Builder builder = buildDescription(tree); | ||
| addFixes(builder, tree, state); | ||
| return builder.build(); | ||
| } | ||
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| protected void addFixes(Description.Builder builder, BinaryTree tree, VisitorState state) { | ||
| ExpressionTree lhs = tree.getLeftOperand(); | ||
| ExpressionTree rhs = tree.getRightOperand(); | ||
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| // Swap the order (e.g. rhs.equals(lhs) if the rhs is a non-null constant, and the lhs is not | ||
| if (ASTHelpers.constValue(lhs) == null && ASTHelpers.constValue(rhs) != null) { | ||
| ExpressionTree tmp = lhs; | ||
| lhs = rhs; | ||
| rhs = tmp; | ||
| } | ||
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| String prefix = tree.getKind() == Kind.NOT_EQUAL_TO ? "!" : ""; | ||
| String lhsSource = state.getSourceForNode(lhs); | ||
| String rhsSource = state.getSourceForNode(rhs); | ||
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| Nullness nullness = getNullness(lhs, state); | ||
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| // If the lhs is possibly-null, provide both options. | ||
| if (nullness != NONNULL) { | ||
| builder.addFix( | ||
| SuggestedFix.builder() | ||
| .replace( | ||
| tree, String.format("%sObjects.equals(%s, %s)", prefix, lhsSource, rhsSource)) | ||
| .addImport("java.util.Objects") | ||
| .build()); | ||
| } | ||
| if (nullness != NULL) { | ||
| builder.addFix( | ||
| SuggestedFix.replace( | ||
| tree, | ||
| String.format( | ||
| "%s%s.equals(%s)", | ||
| prefix, | ||
| lhs instanceof BinaryTree ? String.format("(%s)", lhsSource) : lhsSource, | ||
| rhsSource))); | ||
| } | ||
| } | ||
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| private Nullness getNullness(ExpressionTree expr, VisitorState state) { | ||
| TreePath pathToExpr = new TreePath(state.getPath(), expr); | ||
| return state.getNullnessAnalysis().getNullness(pathToExpr, state.context); | ||
| } | ||
| } |
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