This implements the nG key map--functionally the same as vi(1) and
less(1)--to navigate to line n in the diff and blame views.

As the diff view is a pager, we make nG behave like less(1) such that
line n will be the first line on the page.

And because the blame view is more like an editor with navigation, we
make nG behave like vi(1) such that line n is centered in the middle of
the page--except for when n < view->nlines / 2. In this case, line
n will be the nth line on the page (excluding the header).

The alternative is to make them both either place line n at the top
[like less(1)] or the middle [like vi(1)] of the page. If we go that
route, I'm partial to centering the line.

I didn't think it made sense to add this to the log, tree, and ref
views; but if you think we should make it global, I'm happy to expand
it.

naddy suggested a while back that this makes the g key map somewhat
redundant as 1G satisfies this use case, so we could be more like
vi(1) and remove g; however, less(1) provides g so there's precedent for
both. And given this only adds nG to two views, we probably want to keep
g unless expanding nG to all views.

diff refs/heads/main refs/heads/dev/gline
commit - 2525dccb913c5e7f293cfcad103af7a761d32b34
commit + 3539279418de788b5fbc216b5fc6ba14f67cfe91
blob - 4ec26b8962b911a5c478faf7aebc3d0686931d6e
blob + 3dee27c9da2e151c418d27f26dbfec60d1f27f47
--- tog/tog.1
+++ tog/tog.1
@@ -286,8 +286,10 @@ Scroll down N half pages (default: 1).
 Scroll up N half pages (default: 1).
 .It Cm Home, g
 Scroll to the top of the view.
-.It Cm End, G
+.It Cm End
 Scroll to the bottom of the view.
+.It Cm G
+Go to line N in the diff (default: last line).
 .It Cm \&[
 Reduce diff context by N lines (default: 1).
 .It Cm \&]
@@ -384,8 +386,10 @@ Move the selection cursor down N half pages (default: 
 Move the selection cursor up N half pages (default: 1).
 .It Cm Home, g
 Move the selection cursor to the first line of the file.
-.It Cm End, G
+.It Cm End
 Move the selection cursor to the last line of the file.
+.It Cm G
+Go to line N in the file (default: last line).
 .It Cm Enter
 Open a
 .Cm diff
blob - 41a38da73b3c99dd62ddda5ae9e19708dea2b862
blob + b04bb37cdd7c24649cca3ddc8764f73970374122
--- tog/tog.c
+++ tog/tog.c
@@ -516,6 +516,7 @@ struct tog_view {
 	int maxx, x; /* max column and current start column */
 	int lines, cols; /* copies of LINES and COLS */
 	int nscrolled, offset; /* lines scrolled and hsplit line offset */
+	int gline; /* navigate to this nG line */
 	int ch, count; /* current keymap and count prefix */
 	int resize; /* set when in a resize event */
 	int focussed; /* Only set on one parent or child view at a time. */
@@ -1224,7 +1225,6 @@ get_compound_key(struct tog_view *view, int c)
 		v = view->parent;

 	view->count = 0;
-	cbreak();  /* block for input */
 	wmove(v->window, v->nlines - 1, 0);
 	wclrtoeol(v->window);
 	waddch(v->window, ':');
@@ -1283,15 +1283,14 @@ view_input(struct tog_view **new, int *done, struct to
 		return NULL;
 	}

-	nodelay(view->window, FALSE);
+	cbreak();
+	nodelay(view->window, TRUE);
 	/* Allow threads to make progress while we are waiting for input. */
 	errcode = pthread_mutex_unlock(&tog_mutex);
 	if (errcode)
 		return got_error_set_errno(errcode, "pthread_mutex_unlock");
 	/* If we have an unfinished count, let C-g or backspace abort. */
 	if (view->count && --view->count) {
-		cbreak();
-		nodelay(view->window, TRUE);
 		ch = wgetch(view->window);
 		if (ch == CTRL('g') || ch == KEY_BACKSPACE)
 			view->count = 0;
@@ -1299,13 +1298,19 @@ view_input(struct tog_view **new, int *done, struct to
 			ch = view->ch;
 	} else {
 		ch = wgetch(view->window);
-		if (ch >= '1' && ch  <= '9')
+		if (ch >= '1' && ch  <= '9') {
+			nodelay(view->window, FALSE);
 			view->ch = ch = get_compound_key(view, ch);
+			if (ch == 'G') {
+				view->gline = view->count;
+				view->ch = ch = 0;
+				view->count = 0;
+			}
+		}
 	}
 	errcode = pthread_mutex_lock(&tog_mutex);
 	if (errcode)
 		return got_error_set_errno(errcode, "pthread_mutex_lock");
-	nodelay(view->window, TRUE);

 	if (tog_sigwinch_received || tog_sigcont_received) {
 		tog_resizeterm();
@@ -3859,13 +3864,70 @@ done:
 	return err;
 }

+static int
+gotoline(struct tog_view *view, int *lineno, int *nprinted)
+{
+	FILE	*f = NULL;
+	int	*eof, *first, *selected;
+	int	 restart = 0;
+
+	if (view->type == TOG_VIEW_DIFF) {
+		struct tog_diff_view_state *s = &view->state.diff;
+
+		first = &s->first_displayed_line;
+		selected = &s->selected_line;
+		eof = &s->eof;
+		f = s->f;
+
+		/* Make gline the first line on the page like less(1). */
+		if (*first != 1 && *lineno > view->gline)
+			restart = 1;			/* after gline */
+		else if (*lineno < view->gline)		/* before gline */
+			return 0;
+		else
+			*selected = 1;			/* at gline */
+	} else if (view->type == TOG_VIEW_BLAME) {
+		struct tog_blame_view_state *s = &view->state.blame;
+
+		first = &s->first_displayed_line;
+		selected = &s->selected_line;
+		eof = &s->eof;
+		f = s->blame.f;
+
+		/* Center gline in the middle of the page like vi(1). */
+		if (*first != 1 &&
+		    (*lineno > view->gline - (view->nlines - 3) / 2))
+			restart = 1;
+		else if (*lineno < view->gline - (view->nlines - 3) / 2)
+			return 0;
+		else {
+			*selected = view->gline <= (view->nlines - 3) / 2 ?
+			    view->gline : (view->nlines - 3) / 2 + 1;
+		}
+	} else
+		return 0;
+
+	if (restart) {
+		rewind(f);
+		*eof = 0;
+		*first = 1;
+		*lineno = 0;
+		*nprinted = 0;
+		return 0;
+	}
+
+	view->gline = 0;
+
+	return 1;
+}
+
 static const struct got_error *
 draw_file(struct tog_view *view, const char *header)
 {
 	struct tog_diff_view_state *s = &view->state.diff;
 	regmatch_t *regmatch = &view->regmatch;
 	const struct got_error *err;
-	int nprinted = 0;
+	int lineno, nprinted = 0;
 	char *line;
 	size_t linesize = 0;
 	ssize_t linelen;
@@ -3876,12 +3938,16 @@ draw_file(struct tog_view *view, const char *header)
 	int nlines = s->nlines;
 	off_t line_offset;

+	lineno = s->first_displayed_line - 1;
 	line_offset = s->line_offsets[s->first_displayed_line - 1];
 	if (fseeko(s->f, line_offset, SEEK_SET) == -1)
 		return got_error_from_errno("fseek");

 	werase(view->window);

+	if (view->gline > s->nlines - 1)
+		view->gline = s->nlines - 1;
+
 	if (header) {
 		if (asprintf(&line, "[%d/%d] %s",
 		    s->first_displayed_line - 1 + s->selected_line, nlines,
@@ -3922,6 +3988,10 @@ draw_file(struct tog_view *view, const char *header)
 			return got_ferror(s->f, GOT_ERR_IO);
 		}

+		if (++lineno < s->first_displayed_line)
+			continue;
+		if (view->gline && !gotoline(view, &lineno, &nprinted))
+			continue;
 		/* Set view->maxx based on full line length. */
 		err = format_line(&wline, &width, NULL, line, 0, INT_MAX, 0,
 		    view->x ? 1 : 0);
@@ -3962,7 +4032,8 @@ draw_file(struct tog_view *view, const char *header)
 			    COLOR_PAIR(tc->colorpair), NULL);
 		if (width <= view->ncols - 1)
 			waddch(view->window, '\n');
-		nprinted++;
+		if (++nprinted == 1)
+			s->first_displayed_line = lineno;
 	}
 	free(line);
 	if (nprinted >= 1)
@@ -5077,6 +5148,9 @@ draw_blame(struct tog_view *view)
 	if (width < view->ncols - 1)
 		waddch(view->window, '\n');

+	if (view->gline > blame->nlines)
+		view->gline = blame->nlines;
+
 	if (asprintf(&line, "[%d/%d] %s%s",
 	    s->first_displayed_line - 1 + s->selected_line, blame->nlines,
 	    s->blame_complete ? "" : "annotating... ", s->path) == -1) {
@@ -5109,6 +5183,8 @@ draw_blame(struct tog_view *view)
 		}
 		if (++lineno < s->first_displayed_line)
 			continue;
+		if (view->gline && !gotoline(view, &lineno, &nprinted))
+			continue;

 		/* Set view->maxx based on full line length. */
 		err = format_line(&wline, &width, NULL, line, 0, INT_MAX, 9, 1);

-- 
Mark Jamsek <fnc.bsdbox.org>
GPG: F2FF 13DE 6A06 C471 CA80  E6E2 2930 DC66 86EE CF68