Implementation of a new backtracking system, that allow to go back

anywhere in a script (provided no suspend/resume is used):

* the command "Backtrack n m p" (vernac_bactrack) performs the
  following operation:

** do abort p times,
** do undo on the current proof (after the aborts) in order to reach a
   stack depth of m (see vernac_undo_todepth)
** resets the global state to state labelled with n.

* The coq prompt in emacs mode has more informations, it contains:

** the usual coq prompt plus:
** the state number (global state label)
** the depth of the current proof stack
** the names of all pending proofs, in *unspecified* order, separated by '|'

 Example:

     state                        proof stack
      num                           depth
       __                              _
 aux < 12 |aux|SmallStepAntiReflexive| 4 < ù
 ^^^^^^   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^     ^
 usual           pending proofs           usual
                                          special char


git-svn-id: svn+ssh://scm.gforge.inria.fr/svn/coq/trunk@6947 85f007b7-540e-0410-9357-904b9bb8a0f7

1 files changed, 7 insertions, 0 deletions

diff --git a/lib/edit.mli b/lib/edit.mli
index 0bd802fcc3..d13d9c6f69 100644
--- a/lib/edit.mli
+++ b/lib/edit.mli
@@ -54,3 +54,10 @@ val delete : ('a,'b,'c) t -> 'a -> unit
 val dom : ('a,'b,'c) t -> 'a list
 
 val clear : ('a,'b,'c) t -> unit
+
+(* [depth e] Returns the depth of the focused proof stack of [e], this
+   is used to put informations in coq prompt (in emacs mode). *)
+val depth : ('a,'b,'c) t -> int
+
+(* [undo_todepth e n] Undoes focused proof of [e] to reach depth [n] *)
+val undo_todepth : ('a,'b,'c) t -> int -> unit