added an utility function

[helm.git] / helm / software / components / extlib / hExtlib.ml

diff --git a/helm/software/components/extlib/hExtlib.ml b/helm/software/components/extlib/hExtlib.ml
index b36a4d89db2630f5d0d192454f706d86fa1054d3..d9b24c2eb38d92bd4377bbafcf08d4ab6322700c 100644 (file)
--- a/helm/software/components/extlib/hExtlib.ml
+++ b/helm/software/components/extlib/hExtlib.ml
@@ -153,6 +153,28 @@ let rec filter_map f =
       | None -> filter_map f tl
       | Some v -> v :: filter_map f tl)
 
+let list_rev_map_filter f l =
+   let rec aux a = function
+      | []       -> a
+      | hd :: tl -> 
+         begin match f hd with
+           | None   -> aux a tl
+           | Some b -> aux (b :: a) tl 
+         end
+   in 
+   aux [] l
+
+let list_rev_map_filter_fold f v l =
+   let rec aux v a = function
+      | []       -> v, a
+      | hd :: tl -> 
+         begin match f v hd with
+           | v, None   -> aux v a tl
+           | v, Some b -> aux v (b :: a) tl 
+         end
+   in 
+   aux v [] l
+
 let list_concat ?(sep = []) =
   let rec aux acc =
     function
@@ -172,6 +194,19 @@ let rec list_findopt f l =
   in
   aux l
 
+let split_nth n l =
+  let rec aux acc n l =
+    match n, l with
+    | 0, _ -> List.rev acc, l
+    | n, [] -> raise (Failure "HExtlib.split_nth")
+    | n, hd :: tl -> aux (hd :: acc) (n - 1) tl in
+  aux [] n l
+
+let list_last l =
+  let l = List.rev l in 
+  try List.hd l with exn -> raise (Failure "HExtlib.list_last")
+;;
+  
 (** {2 File predicates} *)
 
 let is_dir fname =
@@ -179,11 +214,28 @@ let is_dir fname =
     (Unix.stat fname).Unix.st_kind = Unix.S_DIR
   with Unix.Unix_error _ -> false
 
+let writable_dir path =
+  try
+    let file = path ^ "/prova_matita" in
+    let oc = open_out file in
+    close_out oc;
+    Sys.remove file;
+    true
+  with Sys_error _ -> false
+
+
 let is_regular fname =
   try
     (Unix.stat fname).Unix.st_kind = Unix.S_REG
   with Unix.Unix_error _ -> false
 
+let is_executable fname =
+  try
+    let stat = (Unix.stat fname) in
+    stat.Unix.st_kind = Unix.S_REG &&
+    (stat.Unix.st_perm land 0o001 > 0)
+  with Unix.Unix_error _ -> false
+
 let mkdir path =
   let components = split ~sep:'/' path in
   let rec aux where = function
@@ -314,13 +366,16 @@ let find ?(test = fun _ -> true) path =
 let safe_remove fname = if Sys.file_exists fname then Sys.remove fname
 
 let is_dir_empty d =
- let od = Unix.opendir d in
- let rec aux () =
-  let name = Unix.readdir od in
-  if name <> "." && name <> ".." then false else aux () in
- let res = try aux () with End_of_file -> true in
-  Unix.closedir od;
-  res
+ try
+  let od = Unix.opendir d in
+  let rec aux () =
+   let name = Unix.readdir od in
+   if name <> "." && name <> ".." then false else aux () in
+  let res = try aux () with End_of_file -> true in
+   Unix.closedir od;
+   res
+ with
+  Unix.Unix_error _ -> true (* raised by Unix.opendir, we hope :-) *)
 
 let safe_rmdir d = try Unix.rmdir d with Unix.Unix_error _ -> ()