Detector to suggest more efficient collections. (749789d2) · Commits · e / os / android_frameworks_base

errorprone/java/com/google/errorprone/bugpatterns/android/EfficientCollectionsChecker.java

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		/*
		* Copyright (C) 2020 The Android Open Source Project
		*
		* 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.android;

		import static com.google.errorprone.BugPattern.SeverityLevel.WARNING;
		import static com.google.errorprone.matchers.Matchers.isSubtypeOf;

		import com.google.auto.service.AutoService;
		import com.google.errorprone.BugPattern;
		import com.google.errorprone.VisitorState;
		import com.google.errorprone.bugpatterns.BugChecker;
		import com.google.errorprone.bugpatterns.BugChecker.NewClassTreeMatcher;
		import com.google.errorprone.matchers.Description;
		import com.google.errorprone.matchers.Matcher;
		import com.google.errorprone.util.ASTHelpers;
		import com.sun.source.tree.NewClassTree;
		import com.sun.source.tree.Tree;
		import com.sun.tools.javac.code.Type;

		import java.util.Collections;
		import java.util.List;

		/**
		* Android offers several efficient alternatives to some upstream
		* {@link Collections} containers, such as {@code SparseIntArray} instead of
		* {@code Map<Integer, Integer>}.
		*/
		@AutoService(BugChecker.class)
		@BugPattern(
		name = "AndroidFrameworkEfficientCollections",
		summary = "Verifies efficient collections best-practices",
		severity = WARNING)
		public final class EfficientCollectionsChecker extends BugChecker implements NewClassTreeMatcher {
		private static final Matcher<Tree> IS_LIST = isSubtypeOf("java.util.List");
		private static final Matcher<Tree> IS_MAP = isSubtypeOf("java.util.Map");

		private static final String INTEGER = "java.lang.Integer";
		private static final String LONG = "java.lang.Long";
		private static final String BOOLEAN = "java.lang.Boolean";

		@Override
		public Description matchNewClass(NewClassTree tree, VisitorState state) {
		final List<Type> types = ASTHelpers.getType(tree).getTypeArguments();
		if (IS_LIST.matches(tree, state) && types != null && types.size() == 1) {
		final Type first = types.get(0);
		if (ASTHelpers.isSameType(first, state.getTypeFromString(INTEGER), state)) {
		return buildDescription(tree)
		.setMessage("Consider replacing with IntArray for efficiency")
		.build();
		} else if (ASTHelpers.isSameType(first, state.getTypeFromString(LONG), state)) {
		return buildDescription(tree)
		.setMessage("Consider replacing with LongArray for efficiency")
		.build();
		}
		} else if (IS_MAP.matches(tree, state) && types != null && types.size() == 2) {
		final Type first = types.get(0);
		final Type second = types.get(1);
		if (ASTHelpers.isSameType(first, state.getTypeFromString(INTEGER), state)) {
		if (ASTHelpers.isSameType(second, state.getTypeFromString(INTEGER), state)) {
		return buildDescription(tree)
		.setMessage("Consider replacing with SparseIntArray for efficiency")
		.build();
		} else if (ASTHelpers.isSameType(second, state.getTypeFromString(LONG), state)) {
		return buildDescription(tree)
		.setMessage("Consider replacing with SparseLongArray for efficiency")
		.build();
		} else if (ASTHelpers.isSameType(second, state.getTypeFromString(BOOLEAN), state)) {
		return buildDescription(tree)
		.setMessage("Consider replacing with SparseBooleanArray for efficiency")
		.build();
		} else {
		return buildDescription(tree)
		.setMessage("Consider replacing with SparseArray for efficiency")
		.build();
		}
		} else if (ASTHelpers.isSameType(first, state.getTypeFromString(LONG), state)) {
		return buildDescription(tree)
		.setMessage("Consider replacing with LongSparseArray for efficiency")
		.build();
		}
		}
		return Description.NO_MATCH;
		}
		}

errorprone/tests/java/com/google/errorprone/bugpatterns/android/EfficientCollectionsCheckerTest.java

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		/*
		* Copyright (C) 2020 The Android Open Source Project
		*
		* 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.android;

		import com.google.errorprone.CompilationTestHelper;

		import org.junit.Before;
		import org.junit.Test;
		import org.junit.runner.RunWith;
		import org.junit.runners.JUnit4;

		@RunWith(JUnit4.class)
		public class EfficientCollectionsCheckerTest {
		private CompilationTestHelper compilationHelper;

		@Before
		public void setUp() {
		compilationHelper = CompilationTestHelper.newInstance(
		EfficientCollectionsChecker.class, getClass());
		}

		@Test
		public void testMap() {
		compilationHelper
		.addSourceLines("Example.java",
		"import java.util.HashMap;",
		"public class Example {",
		" public void exampleInteger() {",
		" // BUG: Diagnostic contains:",
		" HashMap<Integer, Integer> a = new HashMap<>();",
		" // BUG: Diagnostic contains:",
		" HashMap<Integer, Long> b = new HashMap<>();",
		" // BUG: Diagnostic contains:",
		" HashMap<Integer, Boolean> c = new HashMap<>();",
		" // BUG: Diagnostic contains:",
		" HashMap<Integer, String> d = new HashMap<>();",
		" }",
		" public void exampleLong() {",
		" // BUG: Diagnostic contains:",
		" HashMap<Long, String> res = new HashMap<>();",
		" }",
		" public void exampleOther() {",
		" HashMap<String, String> res = new HashMap<>();",
		" }",
		"}")
		.doTest();
		}

		@Test
		public void testList() {
		compilationHelper
		.addSourceLines("Example.java",
		"import java.util.ArrayList;",
		"public class Example {",
		" public void exampleInteger() {",
		" // BUG: Diagnostic contains:",
		" ArrayList<Integer> res = new ArrayList<>();",
		" }",
		" public void exampleLong() {",
		" // BUG: Diagnostic contains:",
		" ArrayList<Long> res = new ArrayList<>();",
		" }",
		" public void exampleOther() {",
		" ArrayList<String> res = new ArrayList<>();",
		" }",
		"}")
		.doTest();
		}

		@Test
		public void testErasure() {
		compilationHelper
		.addSourceLines("Example.java",
		"import java.util.HashMap;",
		"public class Example {",
		" public void example() {",
		" HashMap a = new HashMap();",
		" }",
		"}")
		.doTest();
		}
		}