added a is_empty function for FHashtbl;

more tests for FHashtbl

fHashtbl.ml

@@ -41,6 +41,8 @@ module type S = sig
   val empty : int -> 'a t
     (** The empty hashtable (with sub-hashtables of given size) *)
 
+  val is_empty : _ t -> bool
+
   val find : 'a t -> key -> 'a
     (** Find the binding for this key, or raise Not_found *)
 
@@ -159,6 +161,15 @@ module Tree(X : HASH) = struct
     let size = max size 4 in  (* size >= 4 *)
     Table (empty_buckets size)
 
+  let rec is_empty_array a i =
+    if i = Array.length a then true
+    else (a.(i) = Empty || a.(i) = Deleted) && is_empty_array a (i+1)
+
+  let rec is_empty t =
+    match t with
+    | Split (l, r) -> is_empty l && is_empty r
+    | Table a -> is_empty_array (PArray.reroot a) 0
+
   (** The address in a bucket array, after probing [i] times *)
   let addr n h i = ((h land max_int) + i) mod n
 
@@ -358,6 +369,12 @@ module Flat(X : HASH) = struct
       size = 0;
     }
 
+  let rec is_empty_array a i =
+    if i = Array.length a then true
+    else (a.(i) = Empty || a.(i) = Deleted) && is_empty_array a (i+1)
+
+  let is_empty t = is_empty_array (PArray.reroot t.buckets) 0
+
   (** Index of slot, for i-th probing starting from hash [h] in
       a table of length [n] *)
   let addr h n i = ((h land max_int) + i) mod n

fHashtbl.mli

@@ -41,6 +41,8 @@ module type S = sig
   val empty : int -> 'a t
     (** The empty hashtable (with sub-hashtables of given size) *)
 
+  val is_empty : _ t -> bool
+
   val find : 'a t -> key -> 'a
     (** Find the binding for this key, or raise Not_found *)
 

tests/test_fHashtbl.ml

@@ -2,7 +2,6 @@
 open OUnit
 
 module Test(SomeHashtbl : FHashtbl.S with type key = int) = struct
-
   let test_add () =
     let h = SomeHashtbl.empty 32 in
     let h = SomeHashtbl.replace h 42 "foo" in
@@ -79,6 +78,17 @@ module Test(SomeHashtbl : FHashtbl.S with type key = int) = struct
     (* test that 2 has been removed *)
     OUnit.assert_raises Not_found (fun () -> SomeHashtbl.find h 2)
 
+  let test_size () =
+    let open Sequence.Infix in
+    let n = 10000 in
+    let seq = Sequence.map (fun i -> i, string_of_int i) (0 -- n) in
+    let h = SomeHashtbl.of_seq seq in
+    OUnit.assert_equal (n+1) (SomeHashtbl.size h);
+    let h = Sequence.fold (fun h i -> SomeHashtbl.remove h i) h (0 -- 500) in
+    OUnit.assert_equal (n-500) (SomeHashtbl.size h);
+    OUnit.assert_bool "is_empty" (SomeHashtbl.is_empty (SomeHashtbl.empty 16));
+    ()
+
   let suite =
     "test_FHashtbl" >:::
       [ "test_add" >:: test_add;
@@ -88,6 +98,7 @@ module Test(SomeHashtbl : FHashtbl.S with type key = int) = struct
         "test_persistent" >:: test_persistent;
         "test_big" >:: test_big;
         "test_remove" >:: test_remove;
+        "test_size" >:: test_size;
       ]
 end