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, ExecutionContext> 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;
}
};
}
}