From d48c6cfaea74da36e8268888cce3429a883a8395 Mon Sep 17 00:00:00 2001
From: Xavier Leroy <xavier.leroy@inria.fr>
Date: Fri, 28 Jul 2000 12:24:25 +0000
Subject: [PATCH] Ajout de Hashtbl.replace.  Pas d'allocation dans Hashtbl.find

git-svn-id: http://caml.inria.fr/svn/ocaml/trunk@3262 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02
---
 stdlib/hashtbl.ml  | 61 ++++++++++++++++++++++++++++++++++------------
 stdlib/hashtbl.mli |  8 ++++++
 2 files changed, 53 insertions(+), 16 deletions(-)

diff --git a/stdlib/hashtbl.ml b/stdlib/hashtbl.ml
index 9be4a1906..d39fd28a2 100644
--- a/stdlib/hashtbl.ml
+++ b/stdlib/hashtbl.ml
@@ -79,6 +79,12 @@ let remove h key =
   let i = (hash key) mod (Array.length h.data) in
   h.data.(i) <- remove_bucket h.data.(i)
 
+let rec find_rec key = function
+    Empty ->
+      raise Not_found
+  | Cons(k, d, rest) ->
+      if key = k then d else find_rec key rest
+
 let find h key =
   match h.data.((hash key) mod (Array.length h.data)) with
     Empty -> raise Not_found
@@ -91,14 +97,7 @@ let find h key =
           match rest2 with
             Empty -> raise Not_found
           | Cons(k3, d3, rest3) ->
-              if key = k3 then d3 else begin
-                let rec find = function
-                    Empty ->
-                      raise Not_found
-                  | Cons(k, d, rest) ->
-                      if key = k then d else find rest
-                in find rest3
-              end
+              if key = k3 then d3 else find_rec key rest3
 
 let find_all h key =
   let rec find_in_bucket = function
@@ -108,6 +107,21 @@ let find_all h key =
       if k = key then d :: find_in_bucket rest else find_in_bucket rest in
   find_in_bucket h.data.((hash key) mod (Array.length h.data))
 
+let replace h key info =
+  let rec replace_bucket = function
+      Empty ->
+        raise Not_found
+    | Cons(k, i, next) ->
+        if k = key
+        then Cons(k, info, next)
+        else Cons(k, i, replace_bucket next) in
+  let i = (hash key) mod (Array.length h.data) in
+  let l = h.data.(i) in
+  try
+    h.data.(i) <- replace_bucket l
+  with Not_found ->
+    h.data.(i) <- Cons(key, info, l)
+
 let mem h key =
   let rec mem_in_bucket = function
   | Empty ->
@@ -146,6 +160,7 @@ module type S =
     val remove: 'a t -> key -> unit
     val find: 'a t -> key -> 'a
     val find_all: 'a t -> key -> 'a list
+    val replace : 'a t -> key -> 'a -> unit
     val mem : 'a t -> key -> bool
     val iter: (key -> 'a -> unit) -> 'a t -> unit
   end
@@ -175,6 +190,12 @@ module Make(H: HashedType): (S with type key = H.t) =
       let i = (H.hash key) mod (Array.length h.data) in
       h.data.(i) <- remove_bucket h.data.(i)
 
+    let rec find_rec key = function
+        Empty ->
+          raise Not_found
+      | Cons(k, d, rest) ->
+          if H.equal key k then d else find_rec key rest
+
     let find h key =
       match h.data.((H.hash key) mod (Array.length h.data)) with
         Empty -> raise Not_found
@@ -187,14 +208,7 @@ module Make(H: HashedType): (S with type key = H.t) =
               match rest2 with
                 Empty -> raise Not_found
               | Cons(k3, d3, rest3) ->
-                  if H.equal key k3 then d3 else begin
-                    let rec find = function
-                        Empty ->
-                          raise Not_found
-                      | Cons(k, d, rest) ->
-                          if H.equal key k then d else find rest
-                    in find rest3
-                  end
+                  if H.equal key k3 then d3 else find_rec key rest3
 
     let find_all h key =
       let rec find_in_bucket = function
@@ -206,6 +220,21 @@ module Make(H: HashedType): (S with type key = H.t) =
           else find_in_bucket rest in
       find_in_bucket h.data.((H.hash key) mod (Array.length h.data))
 
+    let replace h key info =
+      let rec replace_bucket = function
+          Empty ->
+            raise Not_found
+        | Cons(k, i, next) ->
+            if H.equal k key
+            then Cons(k, info, next)
+            else Cons(k, i, replace_bucket next) in
+      let i = (H.hash key) mod (Array.length h.data) in
+      let l = h.data.(i) in
+      try
+        h.data.(i) <- replace_bucket l
+      with Not_found ->
+        h.data.(i) <- Cons(key, info, l)
+
     let mem h key =
       let rec mem_in_bucket = function
       | Empty ->
diff --git a/stdlib/hashtbl.mli b/stdlib/hashtbl.mli
index 41ab86df8..04bcab320 100644
--- a/stdlib/hashtbl.mli
+++ b/stdlib/hashtbl.mli
@@ -56,6 +56,13 @@ val remove : ('a, 'b) t -> 'a -> unit
            restoring the previous binding if it exists.
            It does nothing if [x] is not bound in [tbl]. *)
 
+val replace : ('a, 'b) t -> key:'a -> data:'b -> unit
+        (* [Hashtbl.replace tbl x y] replaces the current binding of [x]
+           in [tbl] by a binding of [x] to [y].  If [x] is unbound in [tbl],
+           a binding of [x] to [y] is added to [tbl].
+           This is functionally equivalent to [Hashtbl.remove tbl x]
+           followed by [Hashtbl.add tbl x y]. *)
+
 val iter : f:(key:'a -> data:'b -> unit) -> ('a, 'b) t -> unit
         (* [Hashtbl.iter f tbl] applies [f] to all bindings in table [tbl].
            [f] receives the key as first argument, and the associated value
@@ -94,6 +101,7 @@ module type S =
     val remove: 'a t -> key -> unit
     val find: 'a t -> key -> 'a
     val find_all: 'a t -> key -> 'a list
+    val replace : 'a t -> key:key -> data:'a -> unit
     val mem: 'a t -> key -> bool
     val iter: f:(key:key -> data:'a -> unit) -> 'a t -> unit
   end