Searchable stack data structure

It is like Stack but one can search without popping

git-svn-id: svn+ssh://scm.gforge.inria.fr/svn/coq/trunk@16670 85f007b7-540e-0410-9357-904b9bb8a0f7

3 files changed, 51 insertions, 0 deletions

diff --git a/lib/lib.mllib b/lib/lib.mllib
index fec18486f..14a835872 100644
--- a/lib/lib.mllib
+++ b/lib/lib.mllib
@@ -2,6 +2,7 @@ Xml_lexer
 Xml_parser
 Xml_printer
 Errors
+Searchstack
 Bigint
 Dyn
 Segmenttree
diff --git a/lib/searchstack.ml b/lib/searchstack.ml
new file mode 100644
index 000000000..8d160e572
--- /dev/null
+++ b/lib/searchstack.ml
@@ -0,0 +1,25 @@
+(************************************************************************)
+(*  v      *   The Coq Proof Assistant  /  The Coq Development Team     *)
+(* <O___,, *   INRIA - CNRS - LIX - LRI - PPS - Copyright 1999-2010     *)
+(*   \VV/  **************************************************************)
+(*    //   *      This file is distributed under the terms of the       *)
+(*         *       GNU Lesser General Public License Version 2.1        *)
+(************************************************************************)
+
+type 'a t = 'a list ref
+type ('a,'b) search = [ `Stop of 'b | `Cont of 'a ]
+
+let create () = ref []
+let push x l = l := x :: !l
+let pop l = match !l with [] -> raise Stack.Empty | x::xs -> l := xs; x
+let top l = match !l with [] -> raise Stack.Empty | x::_ -> x
+let find f i l =
+  let rec aux i = function
+    | [] -> raise Not_found
+    | x::xs -> match f i x with `Stop x -> x | `Cont i -> aux i xs in
+  aux i !l
+let is_empty l = match !l with [] -> true | _ -> false
+let iter f l = List.iter f !l
+let clear l = l := []
+let length l = List.length !l
+let to_list l = !l
diff --git a/lib/searchstack.mli b/lib/searchstack.mli
new file mode 100644
index 000000000..6c81a2a9c
--- /dev/null
+++ b/lib/searchstack.mli
@@ -0,0 +1,25 @@
+(************************************************************************)
+(*  v      *   The Coq Proof Assistant  /  The Coq Development Team     *)
+(* <O___,, *   INRIA - CNRS - LIX - LRI - PPS - Copyright 1999-2010     *)
+(*   \VV/  **************************************************************)
+(*    //   *      This file is distributed under the terms of the       *)
+(*         *       GNU Lesser General Public License Version 2.1        *)
+(************************************************************************)
+
+type 'a t
+type ('a,'b) search = [ `Stop of 'b | `Cont of 'a ]
+
+val create : unit -> 'a t
+val push : 'a -> 'a t -> unit
+val find : ('c -> 'a -> ('c, 'b) search) -> 'c -> 'a t -> 'b
+val is_empty : 'a t -> bool
+val iter : ('a -> unit) -> 'a t -> unit
+val clear : 'a t -> unit
+val length : 'a t -> int
+
+(* may raise Stack.Empty *)
+val pop  : 'a t -> 'a
+val top  : 'a t -> 'a
+
+(* Extra *)
+val to_list : 'a t -> 'a list