`A` without arguments is now equivalent to `0A`

* It was equivalent to `1A` which is almost never what you want.
  I doubt that any existing macros would be broken by this.
  But neither do I replace all `0A` in the existing code base (yet).
* `A` without arguments is a completely different "append" command in TECO-11,
  but it doesn't make sense in SciTECO and I don't see what else `A` could
  be repurposed for.
  It cannot be made an insertion command since it depends on the stack state
  which we don't track in parse-only mode.
* Added test case.

1 files changed, 12 insertions, 3 deletions

diff --git a/src/core-commands.c b/src/core-commands.c
index 32381f7..6c4ab58 100644
--- a/src/core-commands.c
+++ b/src/core-commands.c
@@ -621,7 +621,8 @@ teco_state_start_cmdline_pop(teco_machine_main_t *ctx, GError **error)
  *     immediately after dot.
  *   - If <n> is -1, return the <code> of the character
  *     immediately preceding dot, ecetera.
- *   - If <n> is omitted, the sign prefix is implied.
+ *   - If <n> is omitted, 0 is implied.
+ *     However \(lq-A\(rq is equivalent to \(lq-1A\(rq.
  *
  * If the position of the queried character is off-page,
  * the command will return -1.
@@ -630,11 +631,19 @@ teco_state_start_cmdline_pop(teco_machine_main_t *ctx, GError **error)
  * -2 is returned.
  * Incomplete byte sequences are returned as -3.
  */
+/*
+ * NOTE: `A` without arguments is the Append I/O
+ * command in TECO-11. It doesn't make sense in our case.
+ */
 static void
 teco_state_start_get(teco_machine_main_t *ctx, GError **error)
 {
-	teco_int_t v;
-	if (!teco_expressions_pop_num_calc(&v, teco_num_sign, error))
+	teco_int_t v = 0;
+
+	if (!teco_expressions_eval(FALSE, error))
+		return;
+	if ((teco_expressions_args() || teco_num_sign < 0) &&
+	    !teco_expressions_pop_num_calc(&v, teco_num_sign, error))
 		return;
 
 	gssize get_pos = teco_interface_glyphs2bytes_reldot(v);