ocamlbuild,minor,improvement: Digest commands in such a way that one don't make too big strings.

git-svn-id: http://caml.inria.fr/svn/ocaml/trunk@8713 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02

ocamlbuild/command.ml

@@ -317,7 +317,21 @@ let rec reduce x =
   | [x] -> x
   | xs -> S xs
 
-let to_string_for_digest = to_string
+let digest =
+  let list = List.fold_right in
+  let text x acc = Digest.string x :: acc in
+  let rec cmd =
+    function
+    | Cmd spec -> fun acc -> string_of_command_spec spec :: acc
+    | Seq seq -> list cmd seq
+    | Nop -> fun acc -> acc
+    | Echo(texts, dest_path) -> list text (dest_path :: texts)
+  in
+  fun x ->
+    match cmd x [] with
+    | [x] -> x
+    | xs  -> Digest.string ("["^String.concat ";" xs^"]")
+
 (*
 let to_string_for_digest x =
   let rec cmd_of_spec =

ocamlbuild/command.mli

@@ -23,8 +23,8 @@ val string_target_and_tags_of_command_spec : spec -> string * string * Tags.t
 
 val iter_tags : (Tags.t -> unit) -> t -> unit
 
-(** Same as [to_string]. *)
-val to_string_for_digest : t -> string
+(** Digest the given command. *)
+val digest : t -> Digest.t
 
 (** Maximum number of parallel jobs. *)
 val jobs : int ref

ocamlbuild/rule.ml

@@ -292,7 +292,7 @@ let rule name ?(tags=[]) ?(prods=[]) ?(deps=[]) ?prod ?dep ?stamp ?(insert = `bo
   let prods = res_add Resource.import_pattern prods prod in
   let code env build =
     let cmd = code env build in
-    { digest  = Command.to_string_for_digest cmd
+    { digest  = Command.digest cmd
     ; command = cmd }
   in
   add_rule insert

ocamlbuild/signatures.mli

@@ -221,10 +221,10 @@ module type COMMAND = sig
       into command-line options. *)
   val reduce : spec -> spec
 
-  (** Print a command. *)
+  (** Print a command (the format is not suitable to running the command). *)
   val print : Format.formatter -> t -> unit
 
-  (** Convert a command to a string. *)
+  (** Convert a command to a string (same format as print). *)
   val to_string : t -> string
 
   (** Build a string representation of a command that can be passed to the