com.google.errorprone.bugpatterns.SubstringOfZero Maven / Gradle / Ivy
/*
* Copyright 2018 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 com.google.errorprone.BugPattern;
import com.google.errorprone.VisitorState;
import com.google.errorprone.bugpatterns.BugChecker.MethodInvocationTreeMatcher;
import com.google.errorprone.fixes.Fix;
import com.google.errorprone.fixes.SuggestedFix;
import com.google.errorprone.matchers.Description;
import com.google.errorprone.matchers.Matcher;
import com.google.errorprone.matchers.Matchers;
import com.google.errorprone.util.ASTHelpers;
import com.sun.source.tree.ExpressionTree;
import com.sun.source.tree.MethodInvocationTree;
import java.util.Objects;
/** Check for calls to String's {@code foo.substring(0)}. */
@BugPattern(
summary = "String.substring(0) returns the original String",
explanation =
"String.substring(int) gives you the substring from the index to the end, inclusive."
+ " Calling that method with an index of 0 will return the same String.",
severity = ERROR)
public final class SubstringOfZero extends BugChecker implements MethodInvocationTreeMatcher {
private static final Matcher SUBSTRING_CALLS =
Matchers.instanceMethod()
.onExactClass("java.lang.String")
.named("substring")
.withParameters("int");
private static final Matcher ARGUMENT_IS_ZERO =
Matchers.argument(0, (tree, state) -> Objects.equals(ASTHelpers.constValue(tree), 0));
private static final Matcher SUBSTRING_CALLS_WITH_ZERO_ARG =
Matchers.allOf(SUBSTRING_CALLS, ARGUMENT_IS_ZERO);
@Override
public Description matchMethodInvocation(MethodInvocationTree tree, VisitorState state) {
if (!SUBSTRING_CALLS_WITH_ZERO_ARG.matches(tree, state)) {
return Description.NO_MATCH;
}
return describeMatch(tree, removeSubstringCall(tree, state));
}
private static Fix removeSubstringCall(MethodInvocationTree tree, VisitorState state) {
ExpressionTree originalString = ASTHelpers.getReceiver(tree);
return SuggestedFix.replace(tree, state.getSourceForNode(originalString));
}
}