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org.openrewrite.staticanalysis.NoEqualityInForCondition Maven / Gradle / Ivy

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/*
 * Copyright 2024 the original author or authors.
 * 

* Licensed under the Moderne Source Available License (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at *

* https://docs.moderne.io/licensing/moderne-source-available-license *

* 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 org.openrewrite.staticanalysis; import org.openrewrite.ExecutionContext; import org.openrewrite.Recipe; import org.openrewrite.TreeVisitor; import org.openrewrite.java.JavaVisitor; import org.openrewrite.java.tree.Expression; import org.openrewrite.java.tree.J; import org.openrewrite.java.tree.JavaType; import java.time.Duration; import java.util.Collections; import java.util.Set; public class NoEqualityInForCondition extends Recipe { @Override public String getDisplayName() { return "Use comparison rather than equality checks in for conditions"; } @Override public String getDescription() { return "Testing for loop termination using an equality operator (`==` and `!=`) is dangerous, because it could set up an infinite loop. Using a relational operator instead makes it harder to accidentally write an infinite loop."; } @Override public Set getTags() { return Collections.singleton("RSPEC-S888"); } @Override public Duration getEstimatedEffortPerOccurrence() { return Duration.ofMinutes(2); } @Override public TreeVisitor getVisitor() { return new JavaVisitor() { @Override public J visitForControl(J.ForLoop.Control control, ExecutionContext ctx) { if (control.getCondition() instanceof J.Binary) { J.Binary condition = (J.Binary) control.getCondition(); if (isNumericalType(condition) && control.getUpdate().size() == 1 && control.getUpdate().get(0) instanceof J.Unary) { J.Unary update = (J.Unary) control.getUpdate().get(0); if (updatedExpressionInConditional(update.getExpression(), condition)) { if (condition.getOperator() == J.Binary.Type.NotEqual) { switch (update.getOperator()) { case PreIncrement: case PostIncrement: return control.withCondition(condition.withOperator(J.Binary.Type.LessThan)); case PreDecrement: case PostDecrement: return control.withCondition(condition.withOperator(J.Binary.Type.GreaterThan)); } } } } } return super.visitForControl(control, ctx); } private boolean updatedExpressionInConditional(Expression updatedExpression, J.Binary condition) { final String simpleName; if (updatedExpression instanceof J.Identifier) { simpleName = ((J.Identifier) updatedExpression).getSimpleName(); } else if (updatedExpression instanceof J.FieldAccess) { simpleName = ((J.FieldAccess) updatedExpression).getSimpleName(); } else { return false; } if (condition.getLeft() instanceof J.Identifier) { return simpleName.equals(((J.Identifier) condition.getLeft()).getSimpleName()); } else if (condition.getLeft() instanceof J.FieldAccess) { return simpleName.equals(((J.FieldAccess) condition.getLeft()).getSimpleName()); } else if (condition.getRight() instanceof J.Identifier) { return simpleName.equals(((J.Identifier) condition.getRight()).getSimpleName()); } else if (condition.getRight() instanceof J.FieldAccess) { return simpleName.equals(((J.FieldAccess) condition.getRight()).getSimpleName()); } return false; } private boolean isNumericalType(J.Binary condition) { JavaType type = condition.getRight().getType(); return type == JavaType.Primitive.Short || type == JavaType.Primitive.Byte || type == JavaType.Primitive.Int || type == JavaType.Primitive.Long; } }; } }





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