com.google.errorprone.bugpatterns.inject.dagger.PrivateConstructorForNoninstantiableModule.java Source code

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Here is the source code for com.google.errorprone.bugpatterns.inject.dagger.PrivateConstructorForNoninstantiableModule.java

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/*
 * Copyright 2016 Google Inc. All Rights Reserved.
 *
 * 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.inject.dagger;

import static com.google.errorprone.BugPattern.Category.DAGGER;
import static com.google.errorprone.BugPattern.SeverityLevel.SUGGESTION;
import static com.google.errorprone.bugpatterns.inject.dagger.DaggerAnnotations.isBindingDeclarationMethod;
import static com.google.errorprone.matchers.Description.NO_MATCH;
import static com.google.errorprone.matchers.Matchers.isStatic;
import static com.google.errorprone.util.ASTHelpers.getSymbol;
import static com.google.errorprone.util.ASTHelpers.isGeneratedConstructor;
import static com.sun.source.tree.Tree.Kind.CLASS;
import static com.sun.source.tree.Tree.Kind.METHOD;

import com.google.common.base.Predicate;
import com.google.common.base.Predicates;
import com.google.common.collect.FluentIterable;
import com.google.errorprone.BugPattern;
import com.google.errorprone.VisitorState;
import com.google.errorprone.bugpatterns.BugChecker;
import com.google.errorprone.bugpatterns.BugChecker.ClassTreeMatcher;
import com.google.errorprone.fixes.Fix;
import com.google.errorprone.fixes.SuggestedFixes;
import com.google.errorprone.matchers.Description;
import com.google.errorprone.matchers.Matcher;
import com.sun.source.tree.ClassTree;
import com.sun.source.tree.MethodTree;
import com.sun.source.tree.Tree;

/** @author gak@google.com (Gregory Kick) */
@BugPattern(name = "PrivateConstructorForNoninstantiableModuleTest", summary = "Add a private constructor to modules that will not be instantiated by Dagger.", explanation = "Modules that contain abstract binding methods (@Binds, @Multibinds) or only static"
        + " @Provides methods will not be instantiated by Dagger when they are included in a"
        + " component.  Adding a private constructor clearly conveys that the module will not be"
        + " used as an instance.", category = DAGGER,

        severity = SUGGESTION)
public class PrivateConstructorForNoninstantiableModule extends BugChecker implements ClassTreeMatcher {
    private static final Predicate<Tree> IS_CONSTRUCTOR = new Predicate<Tree>() {
        @Override
        public boolean apply(Tree tree) {
            return getSymbol(tree).isConstructor();
        }
    };

    @Override
    public Description matchClass(ClassTree classTree, VisitorState state) {
        if (!DaggerAnnotations.isAnyModule().matches(classTree, state)) {
            return NO_MATCH;
        }

        // if a module is declared as an interface, skip it
        if (!classTree.getKind().equals(CLASS)) {
            return NO_MATCH;
        }

        FluentIterable<? extends Tree> nonSyntheticMembers = FluentIterable.from(classTree.getMembers())
                .filter(Predicates.not(new Predicate<Tree>() {
                    @Override
                    public boolean apply(Tree tree) {
                        return tree.getKind().equals(METHOD) && isGeneratedConstructor((MethodTree) tree);
                    }
                }));

        // ignore empty modules
        if (nonSyntheticMembers.isEmpty()) {
            return NO_MATCH;
        }

        if (nonSyntheticMembers.anyMatch(IS_CONSTRUCTOR)) {
            return NO_MATCH;
        }

        boolean hasBindingDeclarationMethods = nonSyntheticMembers
                .anyMatch(matcherAsPredicate(isBindingDeclarationMethod(), state));

        if (hasBindingDeclarationMethods) {
            return describeMatch(classTree, addPrivateConstructor(classTree, state));
        }

        boolean allStaticMembers = nonSyntheticMembers.allMatch(matcherAsPredicate(isStatic(), state));

        if (allStaticMembers) {
            return describeMatch(classTree, addPrivateConstructor(classTree, state));
        }

        return NO_MATCH;
    }

    private Fix addPrivateConstructor(ClassTree classTree, VisitorState state) {
        return SuggestedFixes.addMembers(classTree, state, "private " + classTree.getSimpleName() + "() {}");
    }

    private static <T extends Tree> Predicate<T> matcherAsPredicate(final Matcher<? super T> matcher,
            final VisitorState state) {
        return new Predicate<T>() {
            @Override
            public boolean apply(T t) {
                return matcher.matches(t, state);
            }
        };
    }
}