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Add a check to reverse Yoda conditions.
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core/src/main/java/com/google/errorprone/bugpatterns/YodaCondition.java
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,112 @@ | ||
| /* | ||
| * Copyright 2023 The Error Prone Authors. | ||
| * | ||
| * 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. | ||
| */ | ||
|
|
||
| package com.google.errorprone.bugpatterns; | ||
|
|
||
| import static com.google.errorprone.BugPattern.SeverityLevel.WARNING; | ||
| import static com.google.errorprone.fixes.SuggestedFixes.qualifyType; | ||
| import static com.google.errorprone.matchers.Description.NO_MATCH; | ||
| import static com.google.errorprone.matchers.Matchers.instanceEqualsInvocation; | ||
| import static com.google.errorprone.matchers.Matchers.staticEqualsInvocation; | ||
| import static com.google.errorprone.util.ASTHelpers.constValue; | ||
| import static com.google.errorprone.util.ASTHelpers.getReceiver; | ||
| import static com.google.errorprone.util.ASTHelpers.getSymbol; | ||
| import static java.lang.String.format; | ||
|
|
||
| import com.google.errorprone.BugPattern; | ||
| import com.google.errorprone.VisitorState; | ||
| import com.google.errorprone.bugpatterns.BugChecker.BinaryTreeMatcher; | ||
| import com.google.errorprone.bugpatterns.BugChecker.MethodInvocationTreeMatcher; | ||
| import com.google.errorprone.fixes.SuggestedFix; | ||
| import com.google.errorprone.matchers.Description; | ||
| import com.sun.source.tree.BinaryTree; | ||
| import com.sun.source.tree.MethodInvocationTree; | ||
| import com.sun.source.tree.Tree; | ||
| import com.sun.tools.javac.code.Symbol.VarSymbol; | ||
| import java.util.Objects; | ||
|
|
||
| /** See the summary. */ | ||
| @BugPattern( | ||
| summary = "The non-constant portion of an equals check generally comes first.", | ||
| severity = WARNING) | ||
| public final class YodaCondition extends BugChecker | ||
| implements BinaryTreeMatcher, MethodInvocationTreeMatcher { | ||
| @Override | ||
| public Description matchBinary(BinaryTree tree, VisitorState state) { | ||
| switch (tree.getKind()) { | ||
| case EQUAL_TO: | ||
| case NOT_EQUAL_TO: | ||
| return fix( | ||
| tree, | ||
| tree.getLeftOperand(), | ||
| tree.getRightOperand(), | ||
| /* provideNullSafeFix= */ false, | ||
| state); | ||
| default: | ||
| return NO_MATCH; | ||
| } | ||
| } | ||
|
|
||
| @Override | ||
| public Description matchMethodInvocation(MethodInvocationTree tree, VisitorState state) { | ||
| if (staticEqualsInvocation().matches(tree, state)) { | ||
| return fix( | ||
| tree, | ||
| tree.getArguments().get(0), | ||
| tree.getArguments().get(1), | ||
| /* provideNullSafeFix= */ false, | ||
| state); | ||
| } | ||
| if (instanceEqualsInvocation().matches(tree, state)) { | ||
| return fix( | ||
| tree, | ||
| getReceiver(tree), | ||
| tree.getArguments().get(0), | ||
| /* provideNullSafeFix= */ true, | ||
| state); | ||
| } | ||
| return NO_MATCH; | ||
| } | ||
|
|
||
| private Description fix( | ||
| Tree tree, Tree lhs, Tree rhs, boolean provideNullSafeFix, VisitorState state) { | ||
| if (seemsConstant(lhs) && !seemsConstant(rhs)) { | ||
| var description = buildDescription(lhs).addFix(SuggestedFix.swap(lhs, rhs)); | ||
| if (provideNullSafeFix) { | ||
| var fix = SuggestedFix.builder().setShortDescription("null-safe fix"); | ||
| description.addFix( | ||
| fix.replace( | ||
| tree, | ||
| format( | ||
| "%s.equals(%s, %s)", | ||
| qualifyType(state, fix, Objects.class.getName()), | ||
| state.getSourceForNode(rhs), | ||
| state.getSourceForNode(lhs))) | ||
| .build()); | ||
| } | ||
| return description.build(); | ||
| } | ||
| return NO_MATCH; | ||
| } | ||
|
|
||
| private static boolean seemsConstant(Tree tree) { | ||
| if (constValue(tree) != null) { | ||
| return true; | ||
| } | ||
| var symbol = getSymbol(tree); | ||
| return symbol instanceof VarSymbol && symbol.isEnum(); | ||
| } | ||
| } |
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136
core/src/test/java/com/google/errorprone/bugpatterns/YodaConditionTest.java
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,136 @@ | ||
| /* | ||
| * Copyright 2023 The Error Prone Authors. | ||
| * | ||
| * 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. | ||
| */ | ||
|
|
||
| package com.google.errorprone.bugpatterns; | ||
|
|
||
| import com.google.errorprone.BugCheckerRefactoringTestHelper; | ||
| import com.google.errorprone.BugCheckerRefactoringTestHelper.FixChoosers; | ||
| import org.junit.Test; | ||
| import org.junit.runner.RunWith; | ||
| import org.junit.runners.JUnit4; | ||
|
|
||
| @RunWith(JUnit4.class) | ||
| public final class YodaConditionTest { | ||
| private final BugCheckerRefactoringTestHelper refactoring = | ||
| BugCheckerRefactoringTestHelper.newInstance(YodaCondition.class, getClass()); | ||
|
|
||
| @Test | ||
| public void primitive() { | ||
| refactoring | ||
| .addInputLines( | ||
| "Test.java", | ||
| "class Test {", | ||
| " boolean yoda(int a) {", | ||
| " return 4 == a;", | ||
| " }", | ||
| " boolean notYoda(int a) {", | ||
| " return a == 4;", | ||
| " }", | ||
| "}") | ||
| .addOutputLines( | ||
| "Test.java", | ||
| "class Test {", | ||
| " boolean yoda(int a) {", | ||
| " return a == 4;", | ||
| " }", | ||
| " boolean notYoda(int a) {", | ||
| " return a == 4;", | ||
| " }", | ||
| "}") | ||
| .doTest(); | ||
| } | ||
|
|
||
| @Test | ||
| public void enums() { | ||
| refactoring | ||
| .addInputLines( | ||
| "E.java", | ||
| "enum E {", | ||
| " A, B;", | ||
| " boolean foo(E e) {", | ||
| " return this == e;", | ||
| " }", | ||
| "}") | ||
| .expectUnchanged() | ||
| .addInputLines( | ||
| "Test.java", | ||
| "class Test {", | ||
| " boolean yoda(E a) {", | ||
| " return E.A == a;", | ||
| " }", | ||
| " boolean notYoda(E a) {", | ||
| " return a == E.A;", | ||
| " }", | ||
| "}") | ||
| .addOutputLines( | ||
| "Test.java", | ||
| "class Test {", | ||
| " boolean yoda(E a) {", | ||
| " return a == E.A;", | ||
| " }", | ||
| " boolean notYoda(E a) {", | ||
| " return a == E.A;", | ||
| " }", | ||
| "}") | ||
| .doTest(); | ||
| } | ||
|
|
||
| @Test | ||
| public void nullUnsafeFix() { | ||
| refactoring | ||
| .addInputLines("E.java", "enum E {A, B}") | ||
| .expectUnchanged() | ||
| .addInputLines( | ||
| "Test.java", | ||
| "class Test {", | ||
| " boolean yoda(E a) {", | ||
| " return E.A.equals(a);", | ||
| " }", | ||
| "}") | ||
| .addOutputLines( | ||
| "Test.java", | ||
| "class Test {", | ||
| " boolean yoda(E a) {", | ||
| " return a.equals(E.A);", | ||
| " }", | ||
| "}") | ||
| .doTest(); | ||
| } | ||
|
|
||
| @Test | ||
| public void nullSafeFix() { | ||
| refactoring | ||
| .addInputLines("E.java", "enum E {A, B}") | ||
| .expectUnchanged() | ||
| .addInputLines( | ||
| "Test.java", | ||
| "class Test {", | ||
| " boolean yoda(E a) {", | ||
| " return E.A.equals(a);", | ||
| " }", | ||
| "}") | ||
| .addOutputLines( | ||
| "Test.java", | ||
| "import java.util.Objects;", | ||
| "class Test {", | ||
| " boolean yoda(E a) {", | ||
| " return Objects.equals(a, E.A);", | ||
| " }", | ||
| "}") | ||
| .setFixChooser(FixChoosers.SECOND) | ||
| .doTest(); | ||
| } | ||
| } |