com.google.errorprone.bugpatterns.MissingCasesInEnumSwitch Maven / Gradle / Ivy
/*
* Copyright 2014 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.common.collect.ImmutableSet.toImmutableSet;
import static com.google.errorprone.BugPattern.SeverityLevel.WARNING;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Sets;
import com.google.errorprone.BugPattern;
import com.google.errorprone.VisitorState;
import com.google.errorprone.bugpatterns.BugChecker.SwitchTreeMatcher;
import com.google.errorprone.matchers.Description;
import com.google.errorprone.util.ASTHelpers;
import com.google.errorprone.util.RuntimeVersion;
import com.sun.source.tree.CaseTree;
import com.sun.source.tree.ExpressionTree;
import com.sun.source.tree.IdentifierTree;
import com.sun.source.tree.SwitchTree;
import com.sun.tools.javac.code.Type;
import java.util.List;
import java.util.Set;
import java.util.stream.Collectors;
import java.util.stream.Stream;
import javax.lang.model.element.ElementKind;
/** A {@link BugChecker}; see the associated {@link BugPattern} annotation for details. */
@BugPattern(
summary = "Switches on enum types should either handle all values, or have a default case.",
severity = WARNING)
public class MissingCasesInEnumSwitch extends BugChecker implements SwitchTreeMatcher {
public static final int MAX_CASES_TO_PRINT = 5;
@Override
public Description matchSwitch(SwitchTree tree, VisitorState state) {
Type switchType = ASTHelpers.getType(tree.getExpression());
if (switchType.asElement().getKind() != ElementKind.ENUM) {
return Description.NO_MATCH;
}
// default case is present
if (tree.getCases().stream().anyMatch(c -> c.getExpression() == null)) {
return Description.NO_MATCH;
}
ImmutableSet handled =
tree.getCases().stream()
.flatMap(MissingCasesInEnumSwitch::getExpressions)
.filter(IdentifierTree.class::isInstance)
.map(e -> ((IdentifierTree) e).getName().toString())
.collect(toImmutableSet());
Set unhandled = Sets.difference(ASTHelpers.enumValues(switchType.asElement()), handled);
if (unhandled.isEmpty()) {
return Description.NO_MATCH;
}
return buildDescription(tree).setMessage(buildMessage(unhandled)).build();
}
/**
* Build the diagnostic message.
*
* Examples:
*
*
* - Non-exhaustive switch, expected cases for: FOO
*
- Non-exhaustive switch, expected cases for: FOO, BAR, BAZ, and 42 others.
*
*/
private static String buildMessage(Set unhandled) {
StringBuilder message =
new StringBuilder(
"Non-exhaustive switch; either add a default or handle the remaining cases: ");
int numberToShow =
unhandled.size() > MAX_CASES_TO_PRINT
? 3 // if there are too many to print, only show three examples.
: unhandled.size();
message.append(unhandled.stream().limit(numberToShow).collect(Collectors.joining(", ")));
if (numberToShow < unhandled.size()) {
message.append(String.format(", and %d others", unhandled.size() - numberToShow));
}
return message.toString();
}
@SuppressWarnings("unchecked")
private static Stream getExpressions(CaseTree caseTree) {
try {
if (RuntimeVersion.isAtLeast12()) {
return ((List)
CaseTree.class.getMethod("getExpressions").invoke(caseTree))
.stream();
} else {
return Stream.of(caseTree.getExpression());
}
} catch (ReflectiveOperationException e) {
throw new LinkageError(e.getMessage(), e);
}
}
}