use delimcc in a new module, SequenceInvert, in order

to reverse the control flow (here with conversion to Gen)

META

@@ -1,6 +1,6 @@
 # OASIS_START
-# DO NOT EDIT (digest: 8fe7646cd958ccfd4ec565a95fe6b68c)
+# DO NOT EDIT (digest: 1e28d93f3671e8db9acf63b73cdbca82)
-version = "0.3.7"
+version = "0.4.1"
 description = "Simple sequence (iterator) datatype and combinators"
 archive(byte) = "sequence.cma"
 archive(byte, plugin) = "sequence.cma"

_oasis

@@ -1,6 +1,6 @@
 OASISFormat: 0.4
 Name:        sequence
-Version:     0.3.7
+Version:     0.4.1
 Homepage:    https://github.com/c-cube/sequence
 Authors:     Simon Cruanes
 License:     BSD-2-clause
@@ -19,10 +19,23 @@ Flag bench
     Description: enable benchmarks (require library Benchmark)
     Default: false
 
+Flag invert
+    Description: build sequence.invert (requires Delimcc)
+    Default: false
+
 Library "sequence"
   Path:             .
   Modules:          Sequence 
 
+Library "invert"
+  Path:             invert
+  Build$:           flag(invert)
+  Install$:         flag(invert)
+  Modules:          SequenceInvert
+  FindlibName:      invert
+  FindlibParent:    sequence
+  BuildDepends:     sequence,delimcc
+
 Document sequence
   Title:                Sequence docs
   Type:                 ocamlbuild (0.3)

_tags

@@ -1,5 +1,5 @@
 # OASIS_START
-# DO NOT EDIT (digest: 34c62fcaf6a79f081a2b2c5cf44cbe05)
+# DO NOT EDIT (digest: ffd3fbaf00b431777fea1b8279203bf9)
 # Ignore VCS directories, you can use the same kind of rule outside
 # OASIS_START/STOP if you want to exclude directories that contains
 # useless stuff for the build process
@@ -15,5 +15,16 @@
 "_darcs": not_hygienic
 # Library sequence
 "sequence.cmxs": use_sequence
+# Executable benchs
+"bench/benchs.native": pkg_benchmark
+"bench/benchs.native": use_sequence
+# Executable bench_persistent
+"bench/bench_persistent.native": pkg_benchmark
+"bench/bench_persistent.native": use_sequence
+# Executable bench_persistent_read
+"bench/bench_persistent_read.native": pkg_benchmark
+"bench/bench_persistent_read.native": use_sequence
+<bench/*.ml{,i}>: pkg_benchmark
+<bench/*.ml{,i}>: use_sequence
 # OASIS_STOP
 true: bin_annot

invert/.merlin

@@ -0,0 +1,2 @@
+REC
+PKG delimcc

invert/sequenceInvert.ml

@@ -0,0 +1,62 @@
+(*
+Copyright (c) 2014, Simon Cruanes
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+Redistributions of source code must retain the above copyright notice, this
+list of conditions and the following disclaimer.  Redistributions in binary
+form must reproduce the above copyright notice, this list of conditions and the
+following disclaimer in the documentation and/or other materials provided with
+the distribution.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*)
+
+(** {1 Interface to Delimcc (Invert control flow)} *)
+
+type 'a gen = unit -> 'a option
+
+type 'a res =
+  | Start
+  | Yield of 'a
+  | Stop
+
+let _ret_none () = None
+let _ret_unit () = ()
+
+let to_gen seq =
+  let p = Delimcc.new_prompt () in
+  let _next = ref None in
+  ignore (Delimcc.push_prompt p
+    (fun () ->
+      Delimcc.take_subcont p (fun c () -> _next := Some c; Start);
+      seq
+        (fun x ->
+          Delimcc.take_subcont p (fun c () -> _next := Some c; Yield x)
+        );
+      _next := None;
+      Stop
+    ));
+  (* call next subcont *)
+  let rec next () =
+    match !_next with
+    | None -> None
+    | Some f ->
+        begin match Delimcc.push_delim_subcont f _ret_unit with
+        | Start -> next ()
+        | Yield x -> Some x
+        | Stop -> None
+        end
+  in
+  next

invert/sequenceInvert.mli

@@ -0,0 +1,32 @@
+(*
+Copyright (c) 2014, Simon Cruanes
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+Redistributions of source code must retain the above copyright notice, this
+list of conditions and the following disclaimer.  Redistributions in binary
+form must reproduce the above copyright notice, this list of conditions and the
+following disclaimer in the documentation and/or other materials provided with
+the distribution.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*)
+
+(** {1 Interface to Delimcc (Invert control flow)} *)
+
+type 'a gen = unit -> 'a option
+
+val to_gen : 'a Sequence.t -> 'a gen
+(** Use delimited continuations to iterate on the sequence step by step.
+    Relatively costly but still useful *)