throw error instead of assertion when loop is closed (>) or continued (F>) without a corresponding loop start (<)

 * assertions were introduced very early when there was no proper error handling
   in SciTECO. However it points to a macro programming error instead of
   a SciTECO programming error and should not crash the editor.
 * Perhaps it would be best to check for this kind of "syntax" error also
   in parse-only modes. This is not done currently.
 * part of the solution to issue #3

1 files changed, 9 insertions, 2 deletions

diff --git a/src/parser.cpp b/src/parser.cpp
index e5d1f22..384c42d 100644
--- a/src/parser.cpp
+++ b/src/parser.cpp
@@ -858,7 +858,9 @@ StateStart::custom(gchar chr)
 			tecoInt loop_pc, loop_cnt;
 
 			expressions.discard_args();
-			g_assert(expressions.pop_op() == Expressions::OP_LOOP);
+			if (expressions.pop_op() != Expressions::OP_LOOP)
+				throw Error("Loop end without corresponding "
+				            "loop start command");
 			loop_pc = expressions.pop_num();
 			loop_cnt = expressions.pop_num();
 
@@ -1482,6 +1484,9 @@ StateFCommand::custom(gchar chr)
 	 * In interactive mode, if the loop is incomplete and must
 	 * be exited, you can type in the loop's remaining commands
 	 * without them being executed (but they are parsed).
+	 *
+	 * Calling \fBF\>\fP outside of a loop will throw an
+	 * error.
 	 */
 	case '>': {
 		tecoInt loop_pc, loop_cnt;
@@ -1489,7 +1494,9 @@ StateFCommand::custom(gchar chr)
 		BEGIN_EXEC(&States::start);
 		/* FIXME: what if in brackets? */
 		expressions.discard_args();
-		g_assert(expressions.pop_op() == Expressions::OP_LOOP);
+		if (expressions.pop_op() != Expressions::OP_LOOP)
+			throw Error("Jump to loop end without corresponding "
+			            "loop start command");
 		loop_pc = expressions.pop_num();
 		loop_cnt = expressions.pop_num();