--- a/src/Pure/goal.ML Wed Jun 26 18:38:03 2013 +0200
+++ b/src/Pure/goal.ML Wed Jun 26 21:48:23 2013 +0200
@@ -9,6 +9,7 @@
val skip_proofs: bool Unsynchronized.ref
val parallel_proofs: int Unsynchronized.ref
val SELECT_GOAL: tactic -> int -> tactic
+ val PREFER_GOAL: tactic -> int -> tactic
val CONJUNCTS: tactic -> int -> tactic
val PRECISE_CONJUNCTS: int -> tactic -> int -> tactic
val PARALLEL_CHOICE: tactic list -> tactic
@@ -52,6 +53,8 @@
({prems: thm list, context: Proof.context} -> tactic) -> thm
val extract: int -> int -> thm -> thm Seq.seq
val retrofit: int -> int -> thm -> thm -> thm Seq.seq
+ val restrict: int -> int -> thm -> thm
+ val unrestrict: int -> thm -> thm
val conjunction_tac: int -> tactic
val precise_conjunction_tac: int -> int -> tactic
val recover_conjunction_tac: tactic
@@ -361,9 +364,25 @@
|> Thm.bicompose {flatten = false, match = false, incremented = false}
(false, conclude st', Thm.nprems_of st') i;
+
+(* rearrange subgoals *)
+
+fun restrict i n st =
+ if i < 1 orelse n < 1 orelse i + n - 1 > Thm.nprems_of st
+ then raise THM ("Goal.restrict", i, [st])
+ else rotate_prems (i - 1) st |> protect n;
+
+fun unrestrict i = conclude #> rotate_prems (1 - i);
+
+(*with structural marker*)
fun SELECT_GOAL tac i st =
if Thm.nprems_of st = 1 andalso i = 1 then tac st
- else Seq.lifts (retrofit i 1) (Seq.maps tac (extract i 1 st)) st;
+ else (PRIMITIVE (restrict i 1) THEN tac THEN PRIMITIVE (unrestrict i)) st;
+
+(*without structural marker*)
+fun PREFER_GOAL tac i st =
+ if i < 1 orelse i > Thm.nprems_of st then Seq.empty
+ else (PRIMITIVE (rotate_prems (i - 1)) THEN tac THEN PRIMITIVE (rotate_prems (1 - i))) st;
(* multiple goals *)