[lib] Split auxiliary libraries into Coq-specific and general.

Up to this point the `lib` directory contained two different library
archives, `clib.cma` and `lib.cma`, which a rough splitting between
Coq-specific libraries and general-purpose ones.

We know split the directory in two, as to make the distinction clear:

- `clib`: contains libraries that are not Coq specific and implement
  common data structures and programming patterns. These libraries
  could be eventually replace with external dependencies and the rest
  of the code base wouldn't notice much.

- `lib`: contains Coq-specific common libraries in widespread use
  along the codebase, but that are not considered part of other
  components. Examples are printing, error handling, or flags.

In some cases we have coupling due to utility files depending on Coq
specific flags, however this commit doesn't modify any files, but only
moves them around, further cleanup is welcome, as indeed a few files
in `lib` should likely be placed in `clib`.

Also note that `Deque` is not used ATM.

1 files changed, 97 insertions, 0 deletions

diff --git a/clib/deque.ml b/clib/deque.ml
new file mode 100644
index 000000000..373269b4f
--- /dev/null
+++ b/clib/deque.ml
@@ -0,0 +1,97 @@
+(************************************************************************)
+(*  v      *   The Coq Proof Assistant  /  The Coq Development Team     *)
+(* <O___,, *   INRIA - CNRS - LIX - LRI - PPS - Copyright 1999-2017     *)
+(*   \VV/  **************************************************************)
+(*    //   *      This file is distributed under the terms of the       *)
+(*         *       GNU Lesser General Public License Version 2.1        *)
+(************************************************************************)
+
+exception Empty
+
+type 'a t = {
+  face : 'a list;
+  rear : 'a list;
+  lenf : int;
+  lenr : int;
+}
+
+let rec split i accu l = match l with
+| [] ->
+  if Int.equal i 0 then (accu, []) else invalid_arg "split"
+| t :: q ->
+  if Int.equal i 0 then (accu, l)
+  else split (pred i) (t :: accu) q
+
+let balance q =
+  let avg = (q.lenf + q.lenr) / 2 in
+  let dif = q.lenf + q.lenr - avg in
+  if q.lenf > succ (2 * q.lenr) then
+    let (ff, fr) = split avg [] q.face in
+    { face = List.rev ff ; rear = q.rear @ List.rev fr; lenf = avg; lenr = dif }
+  else if q.lenr > succ (2 * q.lenf) then
+    let (rf, rr) = split avg [] q.rear in
+    { face = q.face @ List.rev rr ; rear = List.rev rf; lenf = dif; lenr = avg }
+  else q
+
+let empty = {
+  face = [];
+  rear = [];
+  lenf = 0;
+  lenr = 0;
+}
+
+let lcons x q =
+  balance { q with lenf = succ q.lenf; face = x :: q.face }
+
+let lhd q = match q.face with
+| [] ->
+  begin match q.rear with
+  | [] -> raise Empty
+  | t :: _ -> t
+  end
+| t :: _ -> t
+
+let ltl q = match q.face with
+| [] ->
+  begin match q.rear with
+  | [] -> raise Empty
+  | t :: _ -> empty
+  end
+| t :: r -> balance { q with lenf = pred q.lenf; face = r }
+
+let rcons x q =
+  balance { q with lenr = succ q.lenr; rear = x :: q.rear }
+
+let rhd q = match q.rear with
+| [] ->
+  begin match q.face with
+  | [] -> raise Empty
+  | t :: r -> t
+  end
+| t :: _ -> t
+
+let rtl q = match q.rear with
+| [] ->
+  begin match q.face with
+  | [] -> raise Empty
+  | t :: r -> empty
+  end
+| t :: r ->
+  balance { q with lenr = pred q.lenr; rear = r }
+
+let rev q = {
+  face = q.rear;
+  rear = q.face;
+  lenf = q.lenr;
+  lenr = q.lenf;
+}
+
+let length q = q.lenf + q.lenr
+
+let is_empty q = Int.equal (length q) 0
+
+let filter f q =
+  let fold (accu, len) x = if f x then (x :: accu, succ len) else (accu, len) in
+  let (rf, lenf) = List.fold_left fold ([], 0) q.face in
+  let (rr, lenr) = List.fold_left fold ([], 0) q.rear in
+  balance { face = List.rev rf; rear = List.rev rr; lenf = lenf; lenr = lenr }