implemented the ^Q command for converting between line and glyph positions

* As known from DEC TECO, but extended to convert absolute positions to line numbers as well.
  :^Q returns the current line.
* Especially useful in macros that accept line arguments,
  as it is much shorter than something like
  ^E@ES/LINEFROMPOSITION//+Q.l@ES/POSITIONFROMLINE//:^E-.
* On the other hand, the fact that ^Q checks the line range means we cannot
  easily replace lexer.checkheader with something like
  [:J 0,^Q::S...$ ]:
  Using SCI_POSITIONFROMLINE still has the advantage that it returns `Z` for out-of-bounds ranges
  which would be cumbersome to write with the current ^Q.
* Perhaps there should be a separate command for converting between absolute lines and positions
  and :^Q should be repurposed to return a failure boolean for out-of-range values?
* fnkeys.tes could be simplified.

4 files changed, 76 insertions, 7 deletions

diff --git a/lib/fnkeys.tes b/lib/fnkeys.tes
index fd6b332..ab78025 100644
--- a/lib/fnkeys.tes
+++ b/lib/fnkeys.tes
@@ -36,7 +36,7 @@
  *!
 
 @[HOME]{
-  ESLINEFROMPOSITIONESPOSITIONFROMLINE:U.p
+  0+.U.p
   Q.pU.l <Q.l-."U 1; ' Q.l-.AU.c Q.c- "N Q.c-9"N Q.lU.p 1; '' %.l>
   Q.pESGETCOLUMN,4EJ
   Q.p-.M#c
@@ -45,7 +45,7 @@
 1U[HOME]
 
 @[END]{
-  ESLINEFROMPOSITIONESGETLINEENDPOSITIONU.p
+  :-1ESGETLINEENDPOSITIONU.p
   Q.pESGETCOLUMN,4EJ
   Q.p:-.M#c
 }
@@ -54,7 +54,7 @@
 
 @[NPAGE]{
   0,4EJ
-  ESLINEFROMPOSITION+(ESLINESONSCREEN)
+  :-1+ESLINESONSCREEN
   ESPOSITIONFROMLINEU.p
   Q.p"< Z | Q.p: '-.M#c
 }
@@ -63,7 +63,7 @@
 
 @[PPAGE]{
   0,4EJ
-  ESLINEFROMPOSITION-(ESLINESONSCREEN)U.l
+  :-1-ESLINESONSCREENU.l
   Q.l"< 0 | Q.lESPOSITIONFROMLINE: '-.M#c
 }
 @[PPAGE]{(M[PPAGE]}
@@ -102,13 +102,13 @@
 1U[SRIGHT]
 
 @[UP]{
-  4EJ(ESLINEFROMPOSITION-1)ESFINDCOLUMN:-.M#c
+  4EJ,:-2ESFINDCOLUMN:-.M#c
 }
 @[UP]{(M[UP]}
 1U[UP]
 
 @[DOWN]{
-  4EJ(ESLINEFROMPOSITION+1)ESFINDCOLUMN:-.M#c
+  4EJ,:ESFINDCOLUMN:-.M#c
 }
 @[DOWN]{(M[DOWN]}
 1U[DOWN]
diff --git a/lib/scite2co.lua b/lib/scite2co.lua
index 7c49aaa..ab3ccf4 100755
--- a/lib/scite2co.lua
+++ b/lib/scite2co.lua
@@ -107,7 +107,7 @@ local file_patterns = expand(props["file.patterns."..language])
 io.write([=[
 @[lexer.test.]=], language:lower(), [=[]{
 ]=])
-if shbang then io.write([=[  _#!M]=], shbang, [=[M[lexer.checkheader]"S -1 '
+if shbang then io.write([=[  _#!M]=], shbang, [=[:M[lexer.checkheader]"S -1 '
 ]=]) end
 local patterns = {}
 for pattern in file_patterns:gmatch("[^;]+") do
diff --git a/src/core-commands.c b/src/core-commands.c
index 6e39d9a..2f473ce 100644
--- a/src/core-commands.c
+++ b/src/core-commands.c
@@ -1672,6 +1672,9 @@ teco_state_control_negate(teco_machine_main_t *ctx, GError **error)
 {
 	teco_int_t v;
 
+	if (!teco_expressions_eval(FALSE, error))
+		return;
+
 	if (!teco_expressions_args()) {
 		teco_error_argexpected_set(error, "^_");
 		return;
@@ -1788,6 +1791,67 @@ teco_state_control_radix(teco_machine_main_t *ctx, GError **error)
 	}
 }
 
+/*$ ^Q lines2glyphs glyphs2lines
+ * [n]^Q -> glyphs -- Convert between lines and glyph lengths or positions
+ * [position]:^Q -> line
+ *
+ * Converts between line and glyph arguments.
+ * It returns the number of glyphs between dot and the <n>-th next
+ * line (or previous line if <n> is negative).
+ * Consequently \(lq^QC\(rq is equivalent to \(lqL\(rq, but less efficient.
+ *
+ * If colon-modified, an absolute buffer position is converted to the line that
+ * contains this position, beginning with 1.
+ * Without arguments, \(lq:^Q\(rq returns the current line.
+ */
+/*
+ * FIXME: Perhaps there should be a way to convert an absolute line to an
+ * absolute position.
+ */
+static void
+teco_state_control_lines2glyphs(teco_machine_main_t *ctx, GError **error)
+{
+	if (!teco_expressions_eval(FALSE, error))
+		return;
+
+	if (teco_machine_main_eval_colon(ctx)) {
+		gssize pos;
+
+		if (!teco_expressions_args()) {
+			pos = teco_interface_ssm(SCI_GETCURRENTPOS, 0, 0);
+		} else {
+			teco_int_t v;
+
+			if (!teco_expressions_pop_num_calc(&v, 0, error))
+				return;
+
+			pos = teco_interface_glyphs2bytes(v);
+			if (pos < 0) {
+				teco_error_range_set(error, "^Q");
+				return;
+			}
+		}
+
+		teco_expressions_push(teco_interface_ssm(SCI_LINEFROMPOSITION, pos, 0)+1);
+	} else {
+		teco_int_t v;
+
+		if (!teco_expressions_pop_num_calc(&v, teco_num_sign, error))
+			return;
+
+		sptr_t pos = teco_interface_ssm(SCI_GETCURRENTPOS, 0, 0);
+		sptr_t line = teco_interface_ssm(SCI_LINEFROMPOSITION, pos, 0) + v;
+
+		if (!teco_validate_line(line)) {
+			teco_error_range_set(error, "^Q");
+			return;
+		}
+
+		sptr_t line_pos = teco_interface_ssm(SCI_POSITIONFROMLINE, line, 0);
+		teco_expressions_push(teco_interface_bytes2glyphs(line_pos) - teco_interface_bytes2glyphs(pos));
+	}
+}
+
 /*$ ^E glyphs2bytes bytes2glyphs
  * glyphs^E -> bytes -- Translate between glyph and byte indexes
  * bytes:^E -> glyphs
@@ -1975,6 +2039,7 @@ teco_state_control_input(teco_machine_main_t *ctx, gunichar chr, GError **error)
 		['O']  = {&teco_state_start, teco_state_control_octal},
 		['D']  = {&teco_state_start, teco_state_control_decimal},
 		['R']  = {&teco_state_start, teco_state_control_radix},
+		['Q']  = {&teco_state_start, teco_state_control_lines2glyphs},
 		['E']  = {&teco_state_start, teco_state_control_glyphs2bytes},
 		['X']  = {&teco_state_start, teco_state_control_search_mode},
 		['Y']  = {&teco_state_start, teco_state_control_last_range},
diff --git a/tests/testsuite.at b/tests/testsuite.at
index 00861dc..ffb3941 100644
--- a/tests/testsuite.at
+++ b/tests/testsuite.at
@@ -109,6 +109,10 @@ AT_CHECK([$SCITECO -e "[[\$ @FG'..' ]]\$ :Q\$-1Q\$-^^r\"=(0/0)'"], 0, ignore, ig
 AT_CHECK([$SCITECO -e "[[: @I/XXX/ ]]: .\"N(0/0)'"], 0, ignore, ignore)
 AT_CLEANUP
 
+AT_SETUP([Convert between line and glyph positions])
+AT_CHECK([$SCITECO -e "@I/1^J2^J3/J 2^QC :^Q-3\"N(0/0)'"], 0, ignore, ignore)
+AT_CLEANUP
+
 AT_SETUP([Searches])
 # FIXME: We cannot currently easily insert a single ASCII 5 (^E), as it must be followed
 # by a 2nd character. It can be quoted, but cannot be written as Caret+E.