com.google.errorprone.bugpatterns.RandomCast Maven / Gradle / Ivy
/*
* Copyright 2017 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.ERROR;
import static com.google.errorprone.matchers.Description.NO_MATCH;
import static com.google.errorprone.matchers.Matchers.anyOf;
import static com.google.errorprone.matchers.Matchers.staticMethod;
import static com.google.errorprone.matchers.method.MethodMatchers.instanceMethod;
import com.google.errorprone.BugPattern;
import com.google.errorprone.VisitorState;
import com.google.errorprone.bugpatterns.BugChecker.MethodInvocationTreeMatcher;
import com.google.errorprone.matchers.Description;
import com.google.errorprone.matchers.Matcher;
import com.google.errorprone.util.ASTHelpers;
import com.sun.source.tree.ExpressionTree;
import com.sun.source.tree.MethodInvocationTree;
import com.sun.source.tree.ParenthesizedTree;
import com.sun.source.tree.Tree;
import com.sun.source.tree.TypeCastTree;
import com.sun.source.util.TreePath;
import com.sun.tools.javac.code.Type;
import java.util.EnumSet;
import java.util.Set;
import javax.lang.model.type.TypeKind;
/** A {@link BugChecker}; see the associated {@link BugPattern} annotation for details. */
@BugPattern(
name = "RandomCast",
summary =
"Casting a random number in the range [0.0, 1.0) to an integer or long always results"
+ " in 0.",
severity = ERROR)
public class RandomCast extends BugChecker implements MethodInvocationTreeMatcher {
private static final Matcher MATCHER =
anyOf(
instanceMethod().onExactClass("java.util.Random").namedAnyOf("nextFloat", "nextDouble"),
staticMethod().onClass("java.lang.Math").named("random"));
private static final Set INTEGRAL = EnumSet.of(TypeKind.LONG, TypeKind.INT);
@Override
public Description matchMethodInvocation(MethodInvocationTree tree, VisitorState state) {
if (!MATCHER.matches(tree, state)) {
return NO_MATCH;
}
TreePath parentPath = state.getPath().getParentPath();
while (parentPath.getLeaf() instanceof ParenthesizedTree) {
parentPath = parentPath.getParentPath();
}
Tree parent = parentPath.getLeaf();
if (!(parent instanceof TypeCastTree)) {
return NO_MATCH;
}
Type type = ASTHelpers.getType(parent);
if (type == null || !INTEGRAL.contains(type.getKind())) {
return NO_MATCH;
}
return describeMatch(tree);
}
}