com.google.errorprone.bugpatterns.overloading.InconsistentOverloads 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.overloading;
import static com.google.common.collect.ImmutableList.sortedCopyOf;
import static com.google.common.collect.ImmutableList.toImmutableList;
import static com.google.errorprone.util.ASTHelpers.getSymbol;
import static java.util.Comparator.comparingInt;
import static java.util.stream.Collectors.groupingBy;
import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableList;
import com.google.errorprone.BugPattern;
import com.google.errorprone.BugPattern.SeverityLevel;
import com.google.errorprone.VisitorState;
import com.google.errorprone.bugpatterns.BugChecker;
import com.google.errorprone.bugpatterns.BugChecker.ClassTreeMatcher;
import com.google.errorprone.fixes.SuggestedFix;
import com.google.errorprone.matchers.Description;
import com.google.errorprone.util.ASTHelpers;
import com.sun.source.tree.ClassTree;
import com.sun.source.tree.MethodTree;
import com.sun.source.tree.Tree;
import com.sun.tools.javac.code.Symbol.MethodSymbol;
import com.sun.tools.javac.tree.JCTree;
import java.util.Collection;
import java.util.Comparator;
import java.util.List;
import java.util.Optional;
/**
* A {@link BugChecker} that detects inconsistently overloaded methods in Java classes.
*
* The bug checker works in several stages. First, it group the class methods by name. Then each
* group is processed separately (and violations are reported on per-group basis).
*
*
The group is processed by building a {@link ParameterTrie}. This trie is an archetype built
* from methods of lower arity used to determine ordering of methods of higher arity. After ordering
* of arguments of particular method has been determined (using the archetype) it is then added to
* the trie and serves as basis for methods of even higher arity.
*
*
If the determined ordering is different the original parameter ordering a {@link
* ParameterOrderingViolation} is reported. It is essentially a list of expected parameter and list
* of actual parameters then used to build a {@link SuggestedFix} object.
*
* @author [email protected] (Łukasz Hanuszczak)
*/
@BugPattern(
summary =
"The ordering of parameters in overloaded methods should be as consistent as possible (when"
+ " viewed from left to right)",
severity = SeverityLevel.WARNING)
public final class InconsistentOverloads extends BugChecker implements ClassTreeMatcher {
@Override
public Description matchClass(ClassTree classTree, VisitorState state) {
processClassMethods(getClassTreeMethods(classTree, state), state);
/*
* We want to report inconsistencies per method group. There is no "method group" unit in the
* Java AST, so we match on the class, group its methods to method groups and process each group
* separately.
*
* Because of this we return no match for the class itself but we report policy violations for
* each group after it is processed.
*/
return Description.NO_MATCH;
}
private void processClassMethods(List classMethodTrees, VisitorState state) {
for (List groupMethods : getMethodGroups(classMethodTrees)) {
processGroupMethods(groupMethods, state);
}
}
private void processGroupMethods(List groupMethodTrees, VisitorState state) {
Preconditions.checkArgument(!groupMethodTrees.isEmpty());
for (ParameterOrderingViolation violation : getViolations(groupMethodTrees)) {
MethodSymbol methodSymbol = getSymbol(violation.methodTree());
if (ASTHelpers.findSuperMethods(methodSymbol, state.getTypes()).isEmpty()) {
Description.Builder description = buildDescription(violation.methodTree());
description.setMessage(violation.getDescription());
state.reportMatch(description.build());
}
}
}
private static ImmutableList getViolations(
List groupMethodTrees) {
ImmutableList.Builder result = ImmutableList.builder();
ParameterTrie trie = new ParameterTrie();
for (MethodTree methodTree : sortedByArity(groupMethodTrees)) {
Optional violation = trie.extendAndComputeViolation(methodTree);
violation.ifPresent(result::add);
}
return result.build();
}
private static ImmutableList sortedByArity(Iterable methodTrees) {
return sortedCopyOf(comparingArity().thenComparing(comparingPositions()), methodTrees);
}
private static Comparator comparingPositions() {
return comparingInt(InconsistentOverloads::getStartPosition);
}
private static Comparator comparingArity() {
return comparingInt(ParameterTrie::getMethodTreeArity);
}
/**
* Returns a collection of method groups for given list of {@code classMethods}.
*
* A method group is a list of methods with the same name.
*
*
It is assumed that given {@code classMethods} really do belong to the same class. The
* returned collection does not guarantee any particular group ordering.
*/
private static Collection> getMethodGroups(List classMethods) {
return classMethods.stream().collect(groupingBy(MethodTree::getName)).values();
}
/**
* Returns a list of {@link MethodTree} declared in the given {@code classTree}.
*
* Only method trees that belong to the {@code classTree} are returned, so methods declared in
* nested classes are not going to be considered.
*/
private ImmutableList getClassTreeMethods(ClassTree classTree, VisitorState state) {
List members = classTree.getMembers();
return members.stream()
.filter(MethodTree.class::isInstance)
.map(MethodTree.class::cast)
.filter(m -> !isSuppressed(m, state))
.collect(toImmutableList());
}
/**
* Returns a start position of given {@code tree}.
*
* The only purpose of this method is to avoid doing a hacky casting to {@link JCTree}.
*/
private static int getStartPosition(Tree tree) {
return ASTHelpers.getStartPosition(tree);
}
}