# HG changeset patch
# User wenzelm
# Date 1181685725 -7200
# Node ID de1476695aa6f0809222771a63e22d3157f176d8
# Parent  df3d21caad2c4cc1e24da45a451c1c258573cd9f
added map_current;
simplified internal type proof;

diff -r df3d21caad2c -r de1476695aa6 src/Pure/Isar/proof_history.ML
--- a/src/Pure/Isar/proof_history.ML	Wed Jun 13 00:02:04 2007 +0200
+++ b/src/Pure/Isar/proof_history.ML	Wed Jun 13 00:02:05 2007 +0200
@@ -11,6 +11,7 @@
   val position: T -> int
   val init: int option -> Proof.state -> T
   val is_initial: T -> bool
+  val map_current: (Proof.state -> Proof.state) -> T -> T
   val current: T -> Proof.state
   val previous: T -> Proof.state option
   val clear: int -> T -> T
@@ -31,20 +32,22 @@
   Proof.state *                 (*first result*)
   Proof.state Seq.seq;          (*alternative results*)
 
-type proof = node * node list;
+type proof = node * int;        (*proof node, proof position*)
 
 datatype T = ProofHistory of proof History.T;
 
 fun app f (ProofHistory x) = ProofHistory (f x);
 fun hist_app f = app (History.apply f);
+fun hist_map f = app (History.map_current f);
 
-fun position (ProofHistory prf) = length (snd (History.current prf));
+fun position (ProofHistory prf) = snd (History.current prf);
 
 
 (* generic history operations *)
 
-fun init lim st = ProofHistory (History.init lim ((st, Seq.empty), []));
+fun init lim st = ProofHistory (History.init lim ((st, Seq.empty), 0));
 fun is_initial (ProofHistory prf) = History.is_initial prf;
+fun map_current f = hist_map (apfst (apfst f));
 fun current (ProofHistory prf) = fst (fst (History.current prf));
 fun previous (ProofHistory prf) = Option.map (fst o fst) (History.previous prf);
 val clear = app o History.clear;
@@ -54,18 +57,18 @@
 
 (* backtracking *)
 
-val back = hist_app (fn ((_, stq), nodes) =>
+val back = hist_app (fn ((_, stq), position) =>
   (case Seq.pull stq of
     NONE => error "back: no alternatives"
-  | SOME result => (result, nodes)));
+  | SOME result => (result, position)));
 
 
 (* apply transformer *)
 
-fun applys f = hist_app (fn (node as (st, _), nodes) =>
+fun applys f = hist_app (fn (node as (st, _), position) =>
   (case Seq.pull (f st) of
     NONE => error "empty result sequence -- proof command failed"
-  | SOME results => (results, node :: nodes)));
+  | SOME results => (results, position + 1)));
 
 fun apply f = applys (Seq.single o f);