instead of relying on Scintilla undo actions, use SciTECO undo tokens exclusivelyHEADmaster-fmsbw-cimaster

Previously we were using both Scintilla undo actions and our own undo tokens
and both had to be coordinated via `undo__teco_interface_ssm(SCI_UNDO, 0, 0)`.
This was error prone since we have to predict when an undo action is actually
generated. Furthermore, you had to update SCI_SETUNDOCOLLECTION on all buffers
and the Q-Reg view whenever switching to and from interactive mode.
Also, this probably wasted memory for the doubled undo bookkeeping.
Now, we always set SCI_SETUNDOCOLLECTION(FALSE), even in interactive mode.
teco_undo_view_insert() was introduced to undo text deletions.
While this saves almost no lines of code, it's just a clearer and simpler
architecture.

1 files changed, 52 insertions, 6 deletions

diff --git a/src/view.c b/src/view.c
index 43cdd3f..d866a5e 100644
--- a/src/view.c
+++ b/src/view.c
@@ -65,10 +65,9 @@ teco_view_setup(teco_view_t *ctx)
 	              SC_MOD_INSERTTEXT | SC_MOD_BEFOREDELETE, 0);
 
 	/*
-	 * Start with or without undo collection,
-	 * depending on teco_undo_enabled.
+	 * We are exclusively using SciTECO's undo tokens.
 	 */
-	teco_view_ssm(ctx, SCI_SETUNDOCOLLECTION, teco_undo_enabled, 0);
+	teco_view_ssm(ctx, SCI_SETUNDOCOLLECTION, FALSE, 0);
 
 	teco_view_ssm(ctx, SCI_SETFOCUS, TRUE, 0);
 
@@ -248,7 +247,6 @@ teco_view_load_from_channel(teco_view_t *ctx, GIOChannel *channel,
 		teco_view_ssm(ctx, SCI_RELEASELINECHARACTERINDEX,
 		              SC_LINECHARACTERINDEX_UTF32, 0);
 
-	teco_view_ssm(ctx, SCI_BEGINUNDOACTION, 0, 0);
 	if (clear) {
 		teco_view_ssm(ctx, SCI_CLEARALL, 0, 0);
 
@@ -322,8 +320,6 @@ teco_view_load_from_channel(teco_view_t *ctx, GIOChannel *channel,
 		                   "Inconsistent EOL styles normalized");
 
 cleanup:
-	teco_view_ssm(ctx, SCI_ENDUNDOACTION, 0, 0);
-
 	if (cp == SC_CP_UTF8)
 		teco_view_ssm(ctx, SCI_ALLOCATELINECHARACTERINDEX,
 		              SC_LINECHARACTERINDEX_UTF32, 0);
@@ -835,6 +831,56 @@ teco_view_get_character(teco_view_t *ctx, gsize pos, gsize len)
 	return rc < 0 ? rc-1 : rc;
 }
 
+typedef struct {
+	teco_view_t *view;
+	/** dot in bytes before the deletion */
+	gsize dot_bytes;
+	gsize position, length;
+	gchar text[];
+} teco_undo_view_insert_t;
+
+static void
+teco_undo_view_insert_action(teco_undo_view_insert_t *ctx, gboolean run)
+{
+	if (!run)
+		return;
+	teco_view_ssm(ctx->view, SCI_GOTOPOS, ctx->position, 0);
+	teco_view_ssm(ctx->view, SCI_ADDTEXT, ctx->length, (sptr_t)ctx->text);
+	teco_view_ssm(ctx->view, SCI_GOTOPOS, ctx->dot_bytes, 0);
+}
+
+/**
+ * During undo, insert a string from the given view.
+ * This can be used to undo text deletions.
+ *
+ * @param view The view that contains the string
+ * @param pos Beginning of string in bytes
+ * @param len Length of string in bytes
+ */
+void
+teco_undo_view_insert(teco_view_t *view, gsize pos, gsize len)
+{
+	if (!len)
+		return;
+
+	teco_undo_view_insert_t *ctx;
+	ctx = teco_undo_push_size((teco_undo_action_t)teco_undo_view_insert_action,
+	                          sizeof(*ctx) + len + 1);
+	if (!ctx)
+		return;
+
+	ctx->view = view;
+	ctx->dot_bytes = teco_view_ssm(view, SCI_GETCURRENTPOS, 0, 0);
+	ctx->position = pos;
+	ctx->length = len;
+
+	struct Sci_TextRangeFull range = {
+		.chrg = {pos, pos + len},
+		.lpstrText = ctx->text
+	};
+	teco_view_ssm(view, SCI_GETTEXTRANGEFULL, 0, (sptr_t)&range);
+}
+
 void
 teco_view_process_notify(teco_view_t *ctx, const SCNotification *notify)
 {