From cb1507bdd44c7e79fcd96b0c87b53cbd357e30a1 Mon Sep 17 00:00:00 2001
From: rexy712 <rexy712@protonmail.com>
Date: Sat, 1 Apr 2023 12:35:48 -0700
Subject: [PATCH] add folding.c

---
 src/folding.c | 138 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 138 insertions(+)
 create mode 100644 src/folding.c

diff --git a/src/folding.c b/src/folding.c
new file mode 100644
index 00000000..646d0353
--- /dev/null
+++ b/src/folding.c
@@ -0,0 +1,138 @@
+/**************************************************************************
+ *   folding.c  --  This file is part of GNU nano.                        *
+ *                                                                        *
+ *   Copyright (C) 2022 rexy712                                           *
+ *                                                                        *
+ *   GNU nano is free software: you can redistribute it and/or modify     *
+ *   it under the terms of the GNU General Public License as published    *
+ *   by the Free Software Foundation, either version 3 of the License,    *
+ *   or (at your option) any later version.                               *
+ *                                                                        *
+ *   GNU nano is distributed in the hope that it will be useful,          *
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty          *
+ *   of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.              *
+ *   See the GNU General Public License for more details.                 *
+ *                                                                        *
+ *   You should have received a copy of the GNU General Public License    *
+ *   along with this program.  If not, see http://www.gnu.org/licenses/.  *
+ *                                                                        *
+ **************************************************************************/
+
+#include "prototypes.h"
+
+#include <ctype.h>
+	/* isspace */
+
+#ifdef ENABLE_FOLDING
+
+/* Remove a folded segment from the given line until end of segment */
+void unfold_folded_segment_from(linestruct *line)
+{
+	if (line != NULL)
+		refresh_needed = TRUE;
+	for(;line != NULL && line->folded;line = line->next)
+		line->folded = FALSE;
+}
+
+/* Remove a folded segment containing the given line */
+void unfold_folded_segment(linestruct *line)
+{
+	unfold_folded_segment_from(get_start_of_folded_segment(line));
+}
+
+/* Get the first member of the folded segment */
+linestruct *get_start_of_folded_segment(linestruct *line)
+{
+	if (!line->folded)
+		return line;
+
+	while (line->prev != NULL && line->prev->folded)
+		line = line->prev;
+
+	return line;
+}
+/* Get the last member of the folded segment */
+linestruct *get_end_of_folded_segment(linestruct *line)
+{
+	if (!line->folded)
+		return line;
+
+	while (line->next != NULL && line->next->folded)
+		line = line->next;
+
+	return line;
+}
+
+/* Get the span length of a folded_segment */
+int get_folded_segment_length(linestruct *line)
+{
+	int i = 1;
+
+	if (!line->folded)
+		return 0;
+
+	line = get_start_of_folded_segment(line);
+	for (;line->next != NULL && line->next->folded;line = line->next)
+		++i;
+	return i;
+}
+
+
+/* Remove any folded_segments within the range [top, bottom].
+ * Returns true if any segments are removed. */
+bool do_unfold_segment(linestruct *line)
+{
+	/* Attempt to find a bracketed region first.
+	 * If not, top is unmodified. */
+	if (!line->folded) {
+		linestruct *bot;
+		find_bracketed_region(openfile->current, &line, &bot);
+	}
+
+	if (line->folded) {
+		unfold_folded_segment(line);
+		move_cursor_to_proper_column();
+		return TRUE;
+	}
+
+	return FALSE;
+}
+
+/* Fold the currently selected lines unless the current selection
+ * already contains a folded_segment. In that case, remove any
+ * segments that are selected. */
+void do_fold_segment(void)
+{
+	linestruct *top, *bot;
+	get_range(&top, &bot);
+
+	if (top == bot) {
+		/* First try to unfold if this line/bracketed region is folded */
+		if (do_unfold_segment(top))
+			return;
+
+		/* When not selecting multiple lines, try to find bounding
+		 * brackets to act as top and bot. */
+		if (!find_bracketed_region(openfile->current, &top, &bot)) {
+			statusline(AHEM, _("No valid region found for automatic fold"));
+			return;
+		}
+	}
+
+	for (linestruct* line = top;line != bot->next;line = line->next)
+		line->folded = TRUE;
+
+	if (top->lineno < openfile->edittop->lineno &&
+	    bot->lineno > openfile->edittop->lineno)
+		openfile->edittop = top;
+
+	/* Place the cursor at the start of the fold segment.
+	 * Anywhere else within the segment is invalid. */
+	if (openfile->current->folded)
+		openfile->current = get_start_of_folded_segment(top);
+	openfile->mark = NULL;
+
+	refresh_needed = TRUE;
+}
+
+#endif /* ENABLE_FOLDING */