[JavaClassName] Introduce a function to strip out anonymous class suffix from a class

Summary:
We will use it in follow up diffs.

From many perspectives, if the function belongs to an anonymous class,
it is useful to know the original user-defined class.

This function makes this distinction clear.

Thanks to ngorogiannis, whos work on refactoring `Typ.name` made this module
easy enough so we can introduce unit tests!

Reviewed By: ngorogiannis

Differential Revision: D20389311

fbshipit-source-id: 408d95660

infer/src/IR/JavaClassName.ml

@@ -10,7 +10,11 @@ module F = Format
 module L = Logging
 
 (** invariant: if [package = Some str] then [not (String.equal str "")] *)
-type t = {classname: string; package: string option} [@@deriving compare]
+type t = {classname: string; package: string option} [@@deriving compare, equal]
+
+let make ~package ~classname =
+  match package with Some "" -> {package= None; classname} | _ -> {package; classname}
+
 
 let from_string str =
   match String.rsplit2 str ~on:'.' with
@@ -40,19 +44,39 @@ let package {package} = package
 
 let classname {classname} = classname
 
-let is_anonymous_inner_class_name {classname} =
-  match String.rsplit2 classname ~on:'$' with
-  | Some (_, s) ->
-      let is_int =
-        try
-          ignore (int_of_string (String.strip s)) ;
-          true
-        with Failure _ -> false
-      in
-      is_int
-  | None ->
-      false
+let is_int s =
+  try
+    ignore (int_of_string s) ;
+    true
+  with Failure _ -> false
+
+
+(* Strips $<int> suffixes from the class name, and return how many were stripped *)
+let strip_anonymous_suffixes_if_present classname =
+  let rec strip_recursively classname nesting_level =
+    match String.rsplit2 classname ~on:'$' with
+    | Some (outer, suffix) when is_int (String.strip suffix) ->
+        (* Suffix is an integer - that was an anonymous class.
+           But it could be nested inside another anonymous class as well *)
+        strip_recursively outer (nesting_level + 1)
+    | _ ->
+        (* Suffix is not an integer or not present - not an anonymous class *)
+        (classname, nesting_level)
+  in
+  strip_recursively classname 0
+
+
+(*
+ Anonymous classes have suffixes in form of $<int>; but they can be nested inside of each other.
+ Also non-anonymous (user-defined) name can be nested as well (Class$NestedClass).
+ So in general case anonymous class name looks something like
+ Class$NestedClass$1$17$5, and we need to return Class$NestedClass *)
+let get_user_defined_class_if_anonymous_inner {package; classname} =
+  let outer_class_name, nesting_level = strip_anonymous_suffixes_if_present classname in
+  if nesting_level > 0 then Some {package; classname= outer_class_name} else None
+
 
+let is_anonymous_inner_class_name t = get_user_defined_class_if_anonymous_inner t |> is_some
 
 let is_external_via_config t =
   let package = package t in

infer/src/IR/JavaClassName.mli

@@ -7,7 +7,9 @@
 
 open! IStd
 
-type t [@@deriving compare]
+type t [@@deriving compare, equal]
+
+val make : package:string option -> classname:string -> t
 
 val from_string : string -> t
 
@@ -28,3 +30,13 @@ val is_external_via_config : t -> bool
 val is_anonymous_inner_class_name : t -> bool
 (** True if it is anonymous Java class:
     https://docs.oracle.com/javase/tutorial/java/javaOO/anonymousclasses.html *)
+
+val get_user_defined_class_if_anonymous_inner : t -> t option
+(** If the current class is anonymous ([is_anonymous_inner_class_name] is true), Return the
+    corresponding user defined (not anonymous) class this anonymous class belongs to.
+
+    In general case, BOTH anonymous classes and user-defined classes can be nested, so the most
+    general example looks like So in general case anonymous class name looks something like
+    Class$NestedClass$1$17$5. This function should return Class$NestedClass for this case.
+
+    If this is not an anonymous class, returns [None]. *)

infer/src/unit/JavaClassNameTests.ml

@@ -0,0 +1,92 @@
+(*
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *)
+
+open! IStd
+open OUnit2
+open JavaClassName
+module F = Format
+
+let assert_equal_to classname ~expected_package ~expected_classname =
+  assert_equal ~printer:JavaClassName.to_string classname
+    (make ~package:expected_package ~classname:expected_classname)
+
+
+let assert_some = function Some a -> a | None -> assert_failure "Expected Some, got None"
+
+let assert_none = function Some _ -> assert_failure "Expected None, got Some" | None -> ()
+
+let test_from_string =
+  "test_from_string"
+  >:: fun _ ->
+  assert_equal_to
+    (from_string "some.package.SomeClass")
+    ~expected_package:(Some "some.package") ~expected_classname:"SomeClass" ;
+  assert_equal_to (from_string "SomeClass") ~expected_package:None ~expected_classname:"SomeClass" ;
+  assert_equal_to
+    (from_string "some.package.SomeClass$NestedClass")
+    ~expected_package:(Some "some.package") ~expected_classname:"SomeClass$NestedClass" ;
+  assert_equal_to
+    (from_string "SomeClass$NestedClass")
+    ~expected_package:None ~expected_classname:"SomeClass$NestedClass" ;
+  (* anonymous classes *)
+  assert_equal_to
+    (from_string "some.package.SomeClass$1")
+    ~expected_package:(Some "some.package") ~expected_classname:"SomeClass$1" ;
+  (* anonymous classes can be of nested levels *)
+  assert_equal_to
+    (from_string "some.package.SomeClass$1$3")
+    ~expected_package:(Some "some.package") ~expected_classname:"SomeClass$1$3" ;
+  (* anonymous classes can be inside nested *)
+  assert_equal_to
+    (from_string "SomeClass$NestedClass$1$3")
+    ~expected_package:None ~expected_classname:"SomeClass$NestedClass$1$3"
+
+
+let test_anonymous =
+  "test_from_string"
+  >:: fun _ ->
+  (* If it is not an anonymous class, we expect this to return None *)
+  get_user_defined_class_if_anonymous_inner
+    (make ~package:(Some "some.package") ~classname:"SomeClass")
+  |> assert_none ;
+  get_user_defined_class_if_anonymous_inner (make ~package:None ~classname:"SomeClass")
+  |> assert_none ;
+  get_user_defined_class_if_anonymous_inner
+    (make ~package:(Some "some.package") ~classname:"SomeClass$SomeNestedClass$AgainNestedClass")
+  |> assert_none ;
+  (* If it is an anonymous class, we expect this to be detected *)
+  get_user_defined_class_if_anonymous_inner
+    (make ~package:(Some "some.package") ~classname:"SomeClass$17")
+  |> assert_some
+  |> assert_equal_to ~expected_package:(Some "some.package") ~expected_classname:"SomeClass" ;
+  (* Can be several nested anonymous classes *)
+  get_user_defined_class_if_anonymous_inner
+    (make ~package:(Some "some.package") ~classname:"SomeClass$17$23$1")
+  |> assert_some
+  |> assert_equal_to ~expected_package:(Some "some.package") ~expected_classname:"SomeClass" ;
+  (* Can be nested class with anonymous class *)
+  get_user_defined_class_if_anonymous_inner
+    (make ~package:(Some "some.package") ~classname:"SomeClass$NestedClass$AgainNestedClass$17")
+  |> assert_some
+  |> assert_equal_to ~expected_package:(Some "some.package")
+       ~expected_classname:"SomeClass$NestedClass$AgainNestedClass" ;
+  (* Can be nested class AND several nested anonymous classes *)
+  get_user_defined_class_if_anonymous_inner
+    (make ~package:(Some "some.package")
+       ~classname:"SomeClass$NestedClass$AgainNestedClass$17$23$1")
+  |> assert_some
+  |> assert_equal_to ~expected_package:(Some "some.package")
+       ~expected_classname:"SomeClass$NestedClass$AgainNestedClass" ;
+  (* If package was empty, everything should still work *)
+  get_user_defined_class_if_anonymous_inner
+    (make ~package:None ~classname:"SomeClass$NestedClass$AgainNestedClass$17$23$1")
+  |> assert_some
+  |> assert_equal_to ~expected_package:None
+       ~expected_classname:"SomeClass$NestedClass$AgainNestedClass"
+
+
+let tests = "JavaClassNameTests" >::: [test_from_string; test_anonymous]

infer/src/unit/inferunit.ml

@@ -35,6 +35,7 @@ let () =
         ; DifferentialTests.tests
         ; FileDiffTests.tests
         ; IListTests.tests
+        ; JavaClassNameTests.tests
         ; JavaProfilerSamplesTest.tests
         ; LivenessTests.tests
         ; LRUHashtblTests.tests