Vimode: fix cursor position after using undo

vimode/src/Makefile.am

@@ -35,7 +35,9 @@ vi_srcs = \
 	cmds/edit.h \
 	cmds/edit.c \
 	cmds/excmds.h \
-	cmds/excmds.c
+	cmds/excmds.c \
+	cmds/undo.h \
+	cmds/undo.c
 
 vimode_la_SOURCES = \
 	backends/backend-geany.c \

vimode/src/cmds/edit.c

@@ -17,6 +17,7 @@
  */
 
 #include "cmds/edit.h"
+#include "cmds/undo.h"
 #include "utils.h"
 
 
@@ -161,13 +162,7 @@ void cmd_del_word_left(CmdContext *c, CmdParams *p)
 
 void cmd_undo(CmdContext *c, CmdParams *p)
 {
-	gint i;
-	for (i = 0; i < p->num; i++)
-	{
-		if (!SSM(p->sci, SCI_CANUNDO, 0, 0))
-			break;
-		SSM(p->sci, SCI_UNDO, 0, 0);
-	}
+	undo_apply(c, p->num);
 }
 
 

vimode/src/cmds/excmds.c

@@ -18,6 +18,7 @@
 
 #include "cmds/excmds.h"
 #include "cmds/edit.h"
+#include "cmds/undo.h"
 #include "utils.h"
 
 void excmd_save(CmdContext *c, ExCmdParams *p)
@@ -93,7 +94,7 @@ void excmd_put(CmdContext *c, ExCmdParams *p)
 
 void excmd_undo(CmdContext *c, ExCmdParams *p)
 {
-	SSM(c->sci, SCI_UNDO, 0, 0);
+	undo_apply(c, 1);
 }
 
 

vimode/src/cmds/undo.c

@@ -0,0 +1,59 @@
+/*
+ * Copyright 2024 Sylvain Cresto <[email protected]>
+ *
+ * This program 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 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+#include "undo.h"
+#include "utils.h"
+
+void undo_update(CmdContext *c, gint pos)
+{
+	c->undo_pos = pos;
+}
+
+
+static gboolean is_start_of_line(ScintillaObject *sci, gint pos)
+{
+	gint line = SSM(sci, SCI_LINEFROMPOSITION, pos, 0);
+	gint line_pos = SSM(sci, SCI_POSITIONFROMLINE, line, 0);
+
+	return pos == line_pos;
+}
+
+
+void undo_apply(CmdContext *c, gint num)
+{
+	ScintillaObject *sci = c->sci;
+	gint i;
+
+	c->undo_pos = -1;
+
+	for (i = 0; i < num; i++)
+	{
+		if (!SSM(sci, SCI_CANUNDO, 0, 0))
+			break;
+		SSM(sci, SCI_UNDO, 0, 0);
+	}
+
+	/* exit when no undo has been applied */
+	if (c->undo_pos == -1)
+		return;
+
+	if (is_start_of_line(sci, c->undo_pos))
+		goto_nonempty(sci, SSM(sci, SCI_LINEFROMPOSITION, c->undo_pos, 0), FALSE);
+	else
+		SET_POS(sci, c->undo_pos, FALSE);
+}

vimode/src/cmds/undo.h

@@ -0,0 +1,27 @@
+/*
+ * Copyright 2024 Sylvain Cresto <[email protected]>
+ *
+ * This program 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 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+#ifndef __UNDO_H__
+#define __UNDO_H__
+
+#include "context.h"
+
+void undo_update(CmdContext *c, gint pos);
+void undo_apply(CmdContext *c, gint num);
+
+#endif

vimode/src/context.h

@@ -57,6 +57,9 @@ typedef struct
 	 * copied N times when e.g. 'i' is preceded by a number or when using '.' */
 	gchar insert_buf[INSERT_BUF_LEN];
 	gint insert_buf_len;
+
+	/* cursor position to restore after undo */
+	gint undo_pos;
 } CmdContext;
 
 #endif

vimode/src/utils.c

@@ -210,6 +210,7 @@ gint get_line_number_rel(ScintillaObject *sci, gint shift)
 	return new_line;
 }
 
+
 void goto_nonempty(ScintillaObject *sci, gint line, gboolean scroll)
 {
 	gint line_end_pos = SSM(sci, SCI_GETLINEENDPOSITION, line, 0);

vimode/src/vi.c

@@ -21,6 +21,7 @@
 #include "utils.h"
 #include "keypress.h"
 #include "excmd-prompt.h"
+#include "cmds/undo.h"
 
 #include <gdk/gdkkeysyms.h>
 
@@ -51,7 +52,8 @@ CmdContext ctx =
 	NULL, NULL, NULL,
 	FALSE, FALSE,
 	0, 1,
-	"", 0 
+	"", 0,
+	-1
 };
 
 
@@ -306,6 +308,10 @@ gboolean vi_notify_sci(SCNotification *nt)
 		}
 	}
 
+	/* Keep position of undo operation */
+	if (nt->nmhdr.code == SCN_MODIFIED && (nt->modificationType & SC_MOD_BEFOREINSERT && nt->modificationType & SC_PERFORMED_UNDO) && nt->length > 1)
+		undo_update(&ctx, nt->position);
+
 	/* This makes sure that when we click behind the end of line in command mode,
 	 * the cursor is not placed BEHIND the last character but ON the last character.
 	 * We want to ignore this when doing selection with mouse as it breaks things. */