Add a rule for matching packages.

RELNOTES=n/a
PiperOrigin-RevId: 456576706

core/src/main/java/com/google/errorprone/bugpatterns/checkreturnvalue/PackagesRule.java

@@ -0,0 +1,66 @@
+/*
+ * Copyright 2022 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.checkreturnvalue;
+
+import com.google.common.collect.ImmutableMap;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.bugpatterns.checkreturnvalue.ResultUseRule.SymbolRule;
+import com.sun.tools.javac.code.Symbol;
+import com.sun.tools.javac.code.Symbol.PackageSymbol;
+import com.sun.tools.javac.util.Name;
+import java.util.Optional;
+
+/**
+ * A rule that enables checking for methods belonging to a set of packages or any of their
+ * subpackages.
+ */
+final class PackagesRule extends SymbolRule {
+
+  private final ImmutableMap<Name, Boolean> packages;
+
+  public PackagesRule(VisitorState state, Iterable<String> patterns) {
+    ImmutableMap.Builder<Name, Boolean> builder = ImmutableMap.builder();
+    for (String pattern : patterns) {
+      if (pattern.charAt(0) == '-') {
+        builder.put(state.getName(pattern.substring(1)), false);
+      } else {
+        builder.put(state.getName(pattern), true);
+      }
+    }
+    this.packages = builder.buildOrThrow();
+  }
+
+  @Override
+  public final String id() {
+    return "Packages";
+  }
+
+  @Override
+  public Optional<ResultUsePolicy> evaluate(Symbol symbol, VisitorState state) {
+    while (symbol instanceof PackageSymbol) {
+      Boolean value = packages.get(((PackageSymbol) symbol).fullname);
+      if (value != null) {
+        return value
+            ? Optional.of(ResultUsePolicy.EXPECTED)
+            // stop evaluating if the package matched a negative pattern
+            : Optional.empty();
+      }
+      symbol = symbol.owner;
+    }
+    return Optional.empty();
+  }
+}