StreamOptionalGetWithoutFilter

baseline-error-prone/src/main/java/com/palantir/baseline/errorprone/StreamOptionalGetWithoutFilter.java

@@ -0,0 +1,99 @@
+/*
+ * (c) Copyright 2024 Palantir Technologies 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.palantir.baseline.errorprone;
+
+import com.google.auto.service.AutoService;
+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.matchers.ChildMultiMatcher.MatchType;
+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.Optional;
+import java.util.function.Function;
+import java.util.function.Predicate;
+import java.util.stream.Stream;
+
+@AutoService(BugChecker.class)
+@BugPattern(
+        link = "https://github.com/palantir/gradle-baseline#baseline-error-prone-checks",
+        linkType = BugPattern.LinkType.CUSTOM,
+        severity = SeverityLevel.WARNING,
+        summary = "Stream<Optional<?>> should call filter(Optional::isPresent) before "
+                + "map(Optional::get) or map(Optional::orElseThrow)",
+        explanation = "Calling map(Optional::get) on a Stream<Optional<?>> without first calling "
+                + "filter(Optional::isPresent) can cause NoSuchElementException.")
+public final class StreamOptionalGetWithoutFilter extends BugChecker implements BugChecker.MethodInvocationTreeMatcher {
+
+    private static final Matcher<ExpressionTree> OPTIONAL_GET_METHOD = Matchers.staticMethod()
+            .onClass(Optional.class.getName())
+            .named("get")
+            .withNoParameters();
+    private static final Matcher<ExpressionTree> OPTIONAL_OR_ELSE_THROW_METHOD = Matchers.staticMethod()
+            .onClass(Optional.class.getName())
+            .named("orElseThrow")
+            .withNoParameters();
+
+    private static final Matcher<ExpressionTree> OPTIONAL_UNWRAP_METHOD =
+            Matchers.anyOf(OPTIONAL_GET_METHOD, OPTIONAL_OR_ELSE_THROW_METHOD);
+
+    private static final Matcher<ExpressionTree> STREAM_MAP_METHOD = Matchers.instanceMethod()
+            .onDescendantOf(Stream.class.getName())
+            .named("map")
+            .withParameters(Function.class.getName());
+
+    private static final Matcher<ExpressionTree> STREAM_FILTER_METHOD = Matchers.instanceMethod()
+            .onDescendantOf(Stream.class.getName())
+            .named("filter")
+            .withParameters(Predicate.class.getName());
+
+    private static final Matcher<ExpressionTree> OPTIONAL_IS_PRESENT_METHOD = Matchers.instanceMethod()
+            .onDescendantOf(Optional.class.getName())
+            .named("isPresent")
+            .withNoParameters();
+
+    private static final Matcher<ExpressionTree> STREAM_FILTER_IS_PRESENT =
+            Matchers.methodInvocation(STREAM_FILTER_METHOD, MatchType.LAST, OPTIONAL_IS_PRESENT_METHOD);
+
+    private static final Matcher<ExpressionTree> STREAM_MAP_OPTIONAL_GET =
+            Matchers.methodInvocation(STREAM_MAP_METHOD, MatchType.LAST, OPTIONAL_UNWRAP_METHOD);
+
+    @Override
+    public Description matchMethodInvocation(MethodInvocationTree tree, VisitorState state) {
+        if (STREAM_MAP_OPTIONAL_GET.matches(tree, state)) {
+            ExpressionTree receiver = ASTHelpers.getReceiver(tree);
+            if (receiver != null && !hasFilterIsPresent(receiver, state)) {
+                return describeMatch(tree);
+            }
+        }
+        return Description.NO_MATCH;
+    }
+
+    private static boolean hasFilterIsPresent(ExpressionTree receiver, VisitorState state) {
+        if (receiver instanceof MethodInvocationTree) {
+            MethodInvocationTree methodInvocationTree = (MethodInvocationTree) receiver;
+            return STREAM_FILTER_IS_PRESENT.matches(methodInvocationTree, state)
+                    || hasFilterIsPresent(methodInvocationTree.getMethodSelect(), state);
+        }
+        return false;
+    }
+}

baseline-error-prone/src/test/java/com/palantir/baseline/errorprone/StreamOptionalGetWithoutFilterTest.java

@@ -0,0 +1,93 @@
+/*
+ * (c) Copyright 2024 Palantir Technologies 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.palantir.baseline.errorprone;
+
+import com.google.errorprone.CompilationTestHelper;
+import org.junit.jupiter.api.Test;
+
+class StreamOptionalGetWithoutFilterTest {
+    @Test
+    public void testPositive() {
+        compile()
+                .addSourceLines(
+                        "Test.java",
+                        "import java.util.Optional;",
+                        "import java.util.stream.Stream;",
+                        "public class Test {",
+                        "    Stream<String> test1(Stream<Optional<String>> stream) {",
+                        "        // BUG: Diagnostic contains filter(Optional::isPresent) before map(Optional::get)",
+                        "        return stream.map(Optional::get);",
+                        "    }",
+                        "    Stream<String> test2(Stream<Optional<String>> stream) {",
+                        "        // BUG: Diagnostic contains filter(Optional::isPresent) before map(Optional::get)",
+                        "        return stream.map(opt -> opt.get());",
+                        "    }",
+                        "    Stream<String> test3(Stream<Optional<String>> stream) {",
+                        "        // BUG: Diagnostic contains filter(Optional::isPresent) before map(Optional::get)"
+                                + " or map(Optional::orElseThrow)",
+                        "        return stream.map(opt -> opt.orElseThrow());",
+                        "    }",
+                        "    Stream<String> test4(Stream<Optional<String>> stream) {",
+                        "        // BUG: Diagnostic contains filter(Optional::isPresent) before map(Optional::get)"
+                                + " or map(Optional::orElseThrow)",
+                        "        return stream.map(Optional::orElseThrow);",
+                        "    }",
+                        "}")
+                .doTest();
+    }
+
+    @Test
+    public void testNegative() {
+        compile()
+                .addSourceLines(
+                        "Test.java",
+                        "import java.util.Optional;",
+                        "import java.util.stream.Stream;",
+                        "public class Test {",
+                        "    Stream<String> test1(Stream<Optional<String>> stream) {",
+                        "        return stream.filter(Optional::isPresent)",
+                        "                .map(Optional::get);",
+                        "    }",
+                        "    Stream<String> test2(Stream<Optional<String>> stream) {",
+                        "        return stream.filter(opt -> opt.isPresent())",
+                        "                .map(opt -> opt.get());",
+                        "    }",
+                        "    Stream<String> test3(Stream<Optional<String>> stream) {",
+                        "        return stream.filter(opt -> opt.isPresent())",
+                        "                .map(Optional::get);",
+                        "    }",
+                        "    Stream<String> test4(Stream<Optional<String>> stream) {",
+                        "        return stream.filter(opt -> opt.isPresent())",
+                        "                .map(opt -> opt.get())",
+                        "                .filter(s -> s.length() > 2);",
+                        "    }",
+                        "    Stream<String> test5(Stream<Optional<String>> stream) {",
+                        "        return stream.filter(opt -> opt.isPresent())",
+                        "                .map(Optional::orElseThrow);",
+                        "    }",
+                        "    Stream<String> test6(Stream<Optional<String>> stream) {",
+                        "        return stream.filter(opt -> opt.isPresent())",
+                        "                .map(opt -> opt.orElseThrow());",
+                        "    }",
+                        "}")
+                .doTest();
+    }
+
+    private CompilationTestHelper compile() {
+        return CompilationTestHelper.newInstance(StreamOptionalGetWithoutFilter.class, getClass());
+    }
+}