From 5bffb50207f8d8ba873f4c40dde4859179153001 Mon Sep 17 00:00:00 2001
From: Leo Tenenbaum <pommicket@gmail.com>
Date: Wed, 10 Feb 2021 10:55:51 -0500
Subject: chain replace all into one undo event

---
 buffer.c | 40 ++++++++++++++++++++++++++++++++++++----
 find.c   |  2 ++
 main.c   |  3 +--
 ted.h    |  3 +++
 4 files changed, 42 insertions(+), 6 deletions(-)

diff --git a/buffer.c b/buffer.c
index 7cb1208..640e64c 100644
--- a/buffer.c
+++ b/buffer.c
@@ -446,6 +446,8 @@ static void buffer_print_undo_history(TextBuffer *buffer) {
 static void buffer_edit(TextBuffer *buffer, BufferPos start, u32 prev_len, u32 new_len) {
 	BufferEdit edit = {0};
 	if (buffer_edit_create(buffer, &edit, start, prev_len, new_len)) {
+		edit.chain = buffer->chaining_edits;
+		if (buffer->will_chain_edits) buffer->chaining_edits = true;
 		buffer_append_edit(buffer, &edit);
 	}
 }
@@ -489,10 +491,11 @@ static bool buffer_edit_does_anything(TextBuffer *buffer, BufferEdit *edit) {
 
 // has enough time passed since the last edit that we should create a new one?
 static bool buffer_edit_split(TextBuffer *buffer) {
-	double curr_time = time_get_seconds();
-	double undo_time_cutoff = buffer_settings(buffer)->undo_save_time; // only keep around edits for this long (in seconds).
 	BufferEdit *last_edit = arr_lastp(buffer->undo_history);
 	if (!last_edit) return true;
+	if (buffer->chaining_edits) return false;
+	double curr_time = time_get_seconds();
+	double undo_time_cutoff = buffer_settings(buffer)->undo_save_time; // only keep around edits for this long (in seconds).
 	return curr_time - last_edit->time > undo_time_cutoff;
 }
 
@@ -1632,12 +1635,18 @@ static void buffer_cursor_to_edit(TextBuffer *buffer, BufferEdit *edit) {
 	buffer_center_cursor(buffer); // whenever we undo an edit, put the cursor in the center, to make it clear where the undo happened
 }
 
+// a <-b <-c
+// c <-b <-a
+
 void buffer_undo(TextBuffer *buffer, i64 ntimes) {
+	bool chain_next = false;
 	for (i64 i = 0; i < ntimes; ++i) {
 		BufferEdit *edit = arr_lastp(buffer->undo_history);
 		if (edit) {
+			bool chain = edit->chain;
 			BufferEdit inverse = {0};
 			if (buffer_undo_edit(buffer, edit, &inverse)) {
+				inverse.chain = chain_next;
 				if (i == ntimes - 1) {
 					// if we're on the last undo, put cursor where edit is
 					buffer_cursor_to_edit(buffer, edit);
@@ -1647,16 +1656,21 @@ void buffer_undo(TextBuffer *buffer, i64 ntimes) {
 				buffer_edit_free(edit);
 				arr_remove_last(buffer->undo_history);
 			}
-		}
+			if (chain) --i;
+			chain_next = chain;
+		} else break;
 	}
 }
 
 void buffer_redo(TextBuffer *buffer, i64 ntimes) {
+	bool chain_next = false;
 	for (i64 i = 0; i < ntimes; ++i) {
 		BufferEdit *edit = arr_lastp(buffer->redo_history);
 		if (edit) {
+			bool chain = edit->chain;
 			BufferEdit inverse = {0};
 			if (buffer_undo_edit(buffer, edit, &inverse)) {
+				inverse.chain = chain_next;
 				if (i == ntimes - 1)
 					buffer_cursor_to_edit(buffer, edit);
 				
@@ -1667,7 +1681,9 @@ void buffer_redo(TextBuffer *buffer, i64 ntimes) {
 				buffer_edit_free(edit);
 				arr_remove_last(buffer->redo_history);
 			}
-		}
+			if (chain) --i;
+			chain_next = chain;
+		} else break;
 	}
 }
 
@@ -2176,3 +2192,19 @@ void buffer_render(TextBuffer *buffer, Rect r) {
 		}
 	}
 }
+
+// if you do:
+//  buffer_start_edit_chain(buffer)
+//  buffer_insert_text_at_pos(buffer, some position, "text1")
+//  buffer_insert_text_at_pos(buffer, another position, "text2")
+//  buffer_end_edit_chain(buffer)
+// pressing ctrl+z will undo both the insertion of text1 and text2.
+static void buffer_start_edit_chain(TextBuffer *buffer) {
+	assert(!buffer->chaining_edits);
+	assert(!buffer->will_chain_edits);
+	buffer->will_chain_edits = true;
+}
+
+static void buffer_end_edit_chain(TextBuffer *buffer) {
+	buffer->chaining_edits = buffer->will_chain_edits = false;
+}
diff --git a/find.c b/find.c
index 48a9299..805210a 100644
--- a/find.c
+++ b/find.c
@@ -272,11 +272,13 @@ static void find_replace_all(Ted *ted) {
 				FindResult *last_result = arr_lastp(ted->find_results);
 				buffer_cursor_move_to_pos(buffer, last_result->start);
 			}
+			buffer_start_edit_chain(buffer);
 			// NOTE: we don't need to increment i because the matches will be removed from the find_results array.
 			for (u32 i = match_idx; i < arr_len(ted->find_results); ) {
 				if (!find_replace_match(ted, i))
 					break;
 			}
+			buffer_end_edit_chain(buffer);
 			find_update(ted, true);
 		}
 	}
diff --git a/main.c b/main.c
index 4036a1f..790c461 100644
--- a/main.c
+++ b/main.c
@@ -1,7 +1,6 @@
 // @TODO:
-// - chained undos (replace all = one undo action)
-// - highlight matching parentheses
 // - indent/dedent region
+// - highlight matching parentheses
 // - split
 // - completion
 // - view-only
diff --git a/ted.h b/ted.h
index b1d5554..60cb06d 100644
--- a/ted.h
+++ b/ted.h
@@ -114,6 +114,7 @@ typedef struct {
 
 // this refers to replacing prev_len characters (found in prev_text) at pos with new_len characters
 typedef struct BufferEdit {
+	bool chain; // should this + the next edit be treated as one?
 	BufferPos pos;
 	u32 new_len;
 	u32 prev_len;
@@ -134,6 +135,8 @@ typedef struct {
 	// This is set to true whenever a change is made to the buffer, and never set to false by buffer_ functions.
 	// (Distinct from buffer_unsaved_changes)
 	bool modified;
+	bool will_chain_edits;
+	bool chaining_edits; // are we chaining undo events together?
 	float x1, y1, x2, y2;
 	u32 nlines;
 	u32 lines_capacity;
-- 
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