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-rw-r--r--CHANGES3
-rw-r--r--doc/refman/RefMan-ltac.tex18
-rw-r--r--theories/Init/Tactics.v11
3 files changed, 32 insertions, 0 deletions
diff --git a/CHANGES b/CHANGES
index 7ea23eeb7..9dcd07eba 100644
--- a/CHANGES
+++ b/CHANGES
@@ -54,6 +54,9 @@ Tactics
with let bindings in the parameters.
- The tactic "dtauto" now handles some inductives such as
"@sigT A (fun _ => B)" as non-dependent conjunctions.
+- Added tactics "assert_succeeds tac" and "assert_fails tac" to ensure
+ properties of the executation of a tactic without keeping the effect
+ of the execution.
Focusing
diff --git a/doc/refman/RefMan-ltac.tex b/doc/refman/RefMan-ltac.tex
index c4c0435c5..921e80743 100644
--- a/doc/refman/RefMan-ltac.tex
+++ b/doc/refman/RefMan-ltac.tex
@@ -156,6 +156,8 @@ is understood as
& | & {\tt type\_term} {\term}\\
& | & {\tt numgoals} \\
& | & {\tt guard} {\it test}\\
+& | & {\tt assert\_fails} {\tacexprpref}\\
+& | & {\tt assert\_succeds} {\tacexprpref}\\
& | & \atomictac\\
& | & {\qualid} \nelist{\tacarg}{}\\
& | & {\atom}
@@ -598,6 +600,22 @@ The experimental status of this tactic pertains to the fact if $v$ performs side
\ErrMsg \errindex{This tactic has more than one success}
+\subsubsection[Checking the failure]{Checking the failure\tacindex{assert\_fails}\index{Tacticals!assert\_fails@{\tt assert\_fails}}}
+
+Coq provides a derived tactic to check that a tactic \emph{fails}:
+\begin{quote}
+{\tt assert\_fails} {\tacexpr}
+\end{quote}
+This behaves like {\tt tryif {\tacexpr} then fail 0 tac "succeeds" else idtac}.
+
+\subsubsection[Checking the success]{Checking the success\tacindex{assert\_succeeds}\index{Tacticals!assert\_succeeds@{\tt assert\_succeeds}}}
+
+Coq provides a derived tactic to check that a tactic has \emph{at least one} success:
+\begin{quote}
+{\tt assert\_succeeds} {\tacexpr}
+\end{quote}
+This behaves like {\tt tryif (assert\_fails tac) then fail 0 tac "fails" else idtac}.
+
\subsubsection[Solving]{Solving\tacindex{solve}
\index{Tacticals!solve@{\tt solve}}}
diff --git a/theories/Init/Tactics.v b/theories/Init/Tactics.v
index 47a971ef0..287b44fd0 100644
--- a/theories/Init/Tactics.v
+++ b/theories/Init/Tactics.v
@@ -313,3 +313,14 @@ Ltac time_constr tac :=
let ret := tac () in
let eval_early := match goal with _ => finish_timing ( "Tactic evaluation" ) end in
ret.
+
+(** Useful combinators *)
+
+Ltac assert_fails tac :=
+ tryif tac then fail 0 tac "succeeds" else idtac.
+Ltac assert_succeeds tac :=
+ tryif (assert_fails tac) then fail 0 tac "fails" else idtac.
+Tactic Notation "assert_succeeds" tactic3(tac) :=
+ assert_succeeds tac.
+Tactic Notation "assert_fails" tactic3(tac) :=
+ assert_fails tac.