Added Optional emptiness handler

nullaway/src/main/java/com/uber/nullaway/ErrorMessage.java

@@ -0,0 +1,33 @@
+package com.uber.nullaway;
+
+/** Contains error message string to be displayed and the message type from {@link MessageTypes}. */
+public class ErrorMessage {
+  MessageTypes messageType;
+  String message;
+
+  ErrorMessage(MessageTypes messageType, String message) {
+    this.messageType = messageType;
+    this.message = message;
+  }
+
+  public void updateErrorMessage(MessageTypes messageType, String message) {
+    this.messageType = messageType;
+    this.message = message;
+  }
+
+  public enum MessageTypes {
+    DEREFERENCE_NULLABLE,
+    RETURN_NULLABLE,
+    PASS_NULLABLE,
+    ASSIGN_FIELD_NULLABLE,
+    WRONG_OVERRIDE_RETURN,
+    WRONG_OVERRIDE_PARAM,
+    METHOD_NO_INIT,
+    FIELD_NO_INIT,
+    UNBOX_NULLABLE,
+    NONNULL_FIELD_READ_BEFORE_INIT,
+    ANNOTATION_VALUE_INVALID,
+    CAST_TO_NONNULL_ARG_NONNULL,
+    GET_ON_EMPTY_OPTIONAL;
+  }
+}

nullaway/src/main/java/com/uber/nullaway/NullAway.java

@@ -88,6 +88,7 @@
 import com.sun.tools.javac.code.Types;
 import com.sun.tools.javac.processing.JavacProcessingEnvironment;
 import com.sun.tools.javac.tree.JCTree;
+import com.uber.nullaway.ErrorMessage.MessageTypes;
 import com.uber.nullaway.dataflow.AccessPathNullnessAnalysis;
 import com.uber.nullaway.dataflow.EnclosingEnvironmentNullness;
 import com.uber.nullaway.handlers.Handler;
@@ -366,7 +367,7 @@ private void updateEnvironmentMapping(Tree tree, VisitorState state) {
     // 2. we keep info on all locals rather than just effectively final ones for simplicity
     EnclosingEnvironmentNullness.instance(state.context)
         .addEnvironmentMapping(
-            tree, analysis.getLocalVarInfoBefore(state.getPath(), state, handler));
+            tree, analysis.getNullnessInfoBeforeNewContext(state.getPath(), state, handler));
   }
 
   private Symbol.MethodSymbol getSymbolOfSuperConstructor(
@@ -1937,7 +1938,7 @@ private Description matchDereference(
           "dereferenced expression " + baseExpression.toString() + " is @Nullable";
       ErrorMessage errorMessage = new ErrorMessage(MessageTypes.DEREFERENCE_NULLABLE, message);
 
-      handler.getErrorMessage(baseExpression, state, errorMessage);
+      handler.onPrepareErrorMessage(baseExpression, state, errorMessage);
 
       return createErrorDescriptionForNullAssignment(
           errorMessage.messageType,
@@ -1960,7 +1961,10 @@ private Description matchDereference(
    * @return the error description
    */
   private Description createErrorDescription(
-      MessageTypes errorType, Tree errorLocTree, String message, TreePath path) {
+      com.uber.nullaway.ErrorMessage.MessageTypes errorType,
+      Tree errorLocTree,
+      String message,
+      TreePath path) {
     Tree enclosingSuppressTree = suppressibleNode(path);
     return createErrorDescription(errorType, errorLocTree, message, enclosingSuppressTree);
   }
@@ -2330,37 +2334,6 @@ public void setComputedNullness(ExpressionTree e, Nullness nullness) {
     computedNullnessMap.put(e, nullness);
   }
 
-  public enum MessageTypes {
-    DEREFERENCE_NULLABLE,
-    RETURN_NULLABLE,
-    PASS_NULLABLE,
-    ASSIGN_FIELD_NULLABLE,
-    WRONG_OVERRIDE_RETURN,
-    WRONG_OVERRIDE_PARAM,
-    METHOD_NO_INIT,
-    FIELD_NO_INIT,
-    UNBOX_NULLABLE,
-    NONNULL_FIELD_READ_BEFORE_INIT,
-    ANNOTATION_VALUE_INVALID,
-    CAST_TO_NONNULL_ARG_NONNULL,
-    GET_ON_EMPTY_OPTIONAL;
-  }
-
-  public static class ErrorMessage {
-    MessageTypes messageType;
-    String message;
-
-    ErrorMessage(MessageTypes messageType, String message) {
-      this.messageType = messageType;
-      this.message = message;
-    }
-
-    public void updateErrorMessage(MessageTypes messageType, String message) {
-      this.messageType = messageType;
-      this.message = message;
-    }
-  }
-
   @AutoValue
   abstract static class FieldInitEntities {
 

nullaway/src/main/java/com/uber/nullaway/dataflow/AccessPathNullnessAnalysis.java

@@ -157,7 +157,8 @@ public Set<Element> getNonnullStaticFieldsBefore(TreePath path, Context context)
    * @param state visitor state
    * @return nullness info for local variables just before the node
    */
-  public NullnessStore getLocalVarInfoBefore(TreePath path, VisitorState state, Handler handler) {
+  public NullnessStore getNullnessInfoBeforeNewContext(
+      TreePath path, VisitorState state, Handler handler) {
     NullnessStore store = dataFlow.resultBefore(path, state.context, nullnessPropagation);
     if (store == null) {
       return NullnessStore.empty();
@@ -173,14 +174,14 @@ public NullnessStore getLocalVarInfoBefore(TreePath path, VisitorState state, Ha
             }
           }
 
-          return handler.filterApForLocalVarInfoBefore(ap, state);
+          return handler.includeApInfoInSavedContext(ap, state);
         });
   }
 
   /**
    * @param path tree path of static method, or initializer block
    * @param context Javac context
-   * @return fields guaranteed to be nonnull at exit of static method (or initialize r block)
+   * @return fields guaranteed to be nonnull at exit of static method (or initializer block)
    */
   public Set<Element> getNonnullStaticFieldsAtExit(TreePath path, Context context) {
     NullnessStore nullnessResult = dataFlow.finalResult(path, context, nullnessPropagation);

nullaway/src/main/java/com/uber/nullaway/handlers/BaseNoOpHandler.java

@@ -34,6 +34,7 @@
 import com.sun.tools.javac.code.Symbol;
 import com.sun.tools.javac.code.Types;
 import com.sun.tools.javac.util.Context;
+import com.uber.nullaway.ErrorMessage;
 import com.uber.nullaway.NullAway;
 import com.uber.nullaway.dataflow.AccessPath;
 import com.uber.nullaway.dataflow.AccessPathNullnessPropagation;
@@ -169,13 +170,13 @@ public void onDataflowVisitLambdaResultExpression(
   }
 
   @Override
-  public void getErrorMessage(
-      ExpressionTree expr, VisitorState state, NullAway.ErrorMessage errorMessage) {
+  public void onPrepareErrorMessage(
+      ExpressionTree expr, VisitorState state, ErrorMessage errorMessage) {
     // NoOp
   }
 
   @Override
-  public boolean filterApForLocalVarInfoBefore(AccessPath accessPath, VisitorState state) {
+  public boolean includeApInfoInSavedContext(AccessPath accessPath, VisitorState state) {
     return false;
   }
 }

nullaway/src/main/java/com/uber/nullaway/handlers/CompositeHandler.java

@@ -35,6 +35,7 @@
 import com.sun.tools.javac.code.Symbol;
 import com.sun.tools.javac.code.Types;
 import com.sun.tools.javac.util.Context;
+import com.uber.nullaway.ErrorMessage;
 import com.uber.nullaway.NullAway;
 import com.uber.nullaway.dataflow.AccessPath;
 import com.uber.nullaway.dataflow.AccessPathNullnessPropagation;
@@ -210,18 +211,18 @@ public void onDataflowVisitLambdaResultExpression(
   }
 
   @Override
-  public void getErrorMessage(
-      ExpressionTree expr, VisitorState state, NullAway.ErrorMessage errorMessage) {
+  public void onPrepareErrorMessage(
+      ExpressionTree expr, VisitorState state, ErrorMessage errorMessage) {
     for (Handler h : handlers) {
-      h.getErrorMessage(expr, state, errorMessage);
+      h.onPrepareErrorMessage(expr, state, errorMessage);
     }
   }
 
   @Override
-  public boolean filterApForLocalVarInfoBefore(AccessPath accessPath, VisitorState state) {
+  public boolean includeApInfoInSavedContext(AccessPath accessPath, VisitorState state) {
     boolean shouldFilter = false;
     for (Handler h : handlers) {
-      shouldFilter |= h.filterApForLocalVarInfoBefore(accessPath, state);
+      shouldFilter |= h.includeApInfoInSavedContext(accessPath, state);
     }
     return shouldFilter;
   }

nullaway/src/main/java/com/uber/nullaway/handlers/ContractHandler.java

@@ -30,6 +30,7 @@
 import com.sun.tools.javac.code.Symbol;
 import com.sun.tools.javac.code.Types;
 import com.sun.tools.javac.util.Context;
+import com.uber.nullaway.ErrorMessage;
 import com.uber.nullaway.NullAway;
 import com.uber.nullaway.Nullness;
 import com.uber.nullaway.dataflow.AccessPath;
@@ -221,7 +222,10 @@ private void reportMatch(Tree errorLocTree, String message) {
     if (this.analysis != null && this.state != null) {
       this.state.reportMatch(
           this.analysis.createErrorDescription(
-              NullAway.MessageTypes.ANNOTATION_VALUE_INVALID, errorLocTree, message, errorLocTree));
+              ErrorMessage.MessageTypes.ANNOTATION_VALUE_INVALID,
+              errorLocTree,
+              message,
+              errorLocTree));
     }
   }
 

nullaway/src/main/java/com/uber/nullaway/handlers/Handler.java

@@ -34,6 +34,7 @@
 import com.sun.tools.javac.code.Symbol;
 import com.sun.tools.javac.code.Types;
 import com.sun.tools.javac.util.Context;
+import com.uber.nullaway.ErrorMessage;
 import com.uber.nullaway.NullAway;
 import com.uber.nullaway.Nullness;
 import com.uber.nullaway.dataflow.AccessPath;
@@ -279,18 +280,18 @@ void onDataflowVisitLambdaResultExpression(
    * @param errorMessage error message string and type of the error wrapped in {@link
    *     com.uber.nullaway.NullAway.ErrorMessage}.
    */
-  void getErrorMessage(ExpressionTree expr, VisitorState state, NullAway.ErrorMessage errorMessage);
+  void onPrepareErrorMessage(ExpressionTree expr, VisitorState state, ErrorMessage errorMessage);
 
   /**
    * Called when the store access paths are filtered for local variable information before an
    * expression.
    *
    * @param accessPath The access path that needs to be checked if filtered.
    * @param state The current visitor state.
-   * @return true if the accesspath should be filtered to be included in the local variable
-   *     information.
+   * @return true if the nullability information for this accesspath should be treated as part of
+   *     the surrounding context when processing a lambda expression or anonymous class declaration.
    */
-  boolean filterApForLocalVarInfoBefore(AccessPath accessPath, VisitorState state);
+  boolean includeApInfoInSavedContext(AccessPath accessPath, VisitorState state);
 
   /**
    * A three value enum for handlers implementing onDataflowVisitMethodInvocation to communicate

nullaway/src/main/java/com/uber/nullaway/handlers/OptionalEmptinessHandler.java

@@ -31,6 +31,7 @@
 import com.sun.tools.javac.code.Type;
 import com.sun.tools.javac.code.Types;
 import com.sun.tools.javac.util.Context;
+import com.uber.nullaway.ErrorMessage;
 import com.uber.nullaway.NullAway;
 import com.uber.nullaway.Nullness;
 import com.uber.nullaway.dataflow.AccessPath;
@@ -100,8 +101,8 @@ public NullnessHint onDataflowVisitMethodInvocation(
   }
 
   @Override
-  public void getErrorMessage(
-      ExpressionTree expr, VisitorState state, NullAway.ErrorMessage errorMessage) {
+  public void onPrepareErrorMessage(
+      ExpressionTree expr, VisitorState state, ErrorMessage errorMessage) {
     if (expr.getKind() == Tree.Kind.METHOD_INVOCATION
         && optionalIsGetCall((Symbol.MethodSymbol) ASTHelpers.getSymbol(expr), state.getTypes())) {
       final int exprStringSize = expr.toString().length();
@@ -110,12 +111,12 @@ && optionalIsGetCall((Symbol.MethodSymbol) ASTHelpers.getSymbol(expr), state.get
           "Optional "
               + expr.toString().substring(0, exprStringSize - 6)
               + " can be empty, dereferenced get() call on it";
-      errorMessage.updateErrorMessage(NullAway.MessageTypes.GET_ON_EMPTY_OPTIONAL, message);
+      errorMessage.updateErrorMessage(ErrorMessage.MessageTypes.GET_ON_EMPTY_OPTIONAL, message);
     }
   }
 
   @Override
-  public boolean filterApForLocalVarInfoBefore(AccessPath accessPath, VisitorState state) {
+  public boolean includeApInfoInSavedContext(AccessPath accessPath, VisitorState state) {
 
     if (accessPath.getElements().size() == 1) {
       AccessPath.Root root = accessPath.getRoot();