refactor(animation): improve text change animation logic

Author: rachartier

lua/tiny-glimmer/animation/text_change.lua

@@ -1,118 +1,107 @@
 local M = {}
 
+---@param callback function|nil Function to call with the merged ranges
 ---@return nil
 function M.handle_text_change_animation(callback)
-	local detach_listener = false
 	local ranges = {}
-	local iter = 0
-
-	---Callback function for buffer changes
-	---@param event any Event type
-	---@param bufnr number Buffer number
-	---@param changedtick number Changed tick
-	---@param start_row number Starting row of change
-	---@param start_col number Starting column of change
-	---@param byte_offset number Byte offset
-	---@param old_end_row number Old end row
-	---@param old_end_col number Old end column
-	---@param old_byte_end number Old end byte
-	---@param new_end_row number New end row
-	---@param new_end_col number New end column
-	---@param new_byte_end number New end byte
-	function M.on_bytes(
-		event,
-		bufnr,
-		changedtick,
+	local final_ranges = {}
+
+	local insert = table.insert
+	local max = math.max
+
+	-- Flag to detach buffer listener
+	local detach_listener = false
+
+	local function on_bytes(
+		_, -- event
+		_, -- bufnr
+		_, -- changedtick
 		start_row,
 		start_col,
-		byte_offset,
-		old_end_row,
-		old_end_col,
-		old_byte_end,
+		_, -- byte_offset
+		_, -- old_end_row
+		_, -- old_end_col
+		_, -- old_byte_end
 		new_end_row,
 		new_end_col,
-		new_byte_end
+		_ -- new_byte_end
 	)
 		if detach_listener then
 			return true
 		end
 
 		-- Calculate the affected text range
-		local buffer_line_count = vim.api.nvim_buf_line_count(0)
 		local end_row = start_row + new_end_row
 		local end_col = start_col + new_end_col
 
-		-- Adjust end column for changes at buffer end
-		if end_row >= buffer_line_count then
+		if end_row >= vim.api.nvim_buf_line_count(0) then
 			local last_line = vim.api.nvim_buf_get_lines(0, -2, -1, false)[1]
-			end_col = #last_line
+			if last_line then
+				end_col = #last_line
+			end
 		end
 
-		local range = {
+		insert(ranges, {
 			start_line = start_row,
 			start_col = start_col,
 			end_line = end_row,
 			end_col = end_col,
-		}
-
-		table.insert(ranges, range)
-
-		iter = iter + 1
+		})
 	end
 
-	-- Attach buffer listener
 	vim.api.nvim_buf_attach(0, false, {
-		on_bytes = M.on_bytes,
+		on_bytes = on_bytes,
 	})
 
 	vim.schedule(function()
 		detach_listener = true
 
-		local final_ranges = {}
-
-		-- Sort ranges by start line and then by start column
-		table.sort(ranges, function(a, b)
-			if a.start_line == b.start_line then
-				return a.start_col < b.start_col
-			end
-			return a.start_line < b.start_line
-		end)
+		local range_count = #ranges
+		if range_count > 0 then
+			table.sort(ranges, function(a, b)
+				if a.start_line == b.start_line then
+					return a.start_col < b.start_col
+				end
+				return a.start_line < b.start_line
+			end)
 
-		if #ranges > 0 then
 			local current = ranges[1]
 
-			for i = 2, #ranges do
+			local is_empty_range = function(r)
+				return r.start_line == r.end_line and r.start_col == r.end_col
+			end
+
+			for i = 2, range_count do
 				local next_range = ranges[i]
 
 				-- Check if ranges overlap or are adjacent
 				if
 					current.end_line < next_range.start_line
 					or (current.end_line == next_range.start_line and current.end_col < next_range.start_col)
 				then
-					-- No overlap, add current range and start new one
-					if current.start_line ~= current.end_line or current.start_col ~= current.end_col then
-						table.insert(final_ranges, current)
+					-- No overlap, add current range if not empty
+					if not is_empty_range(current) then
+						insert(final_ranges, current)
 					end
 					current = next_range
 				else
-					-- Merge overlapping ranges
-					current.end_line = math.max(current.end_line, next_range.end_line)
+					-- Merge overlapping ranges (optimize the conditional)
+					current.end_line = max(current.end_line, next_range.end_line)
 					if current.end_line == next_range.end_line then
-						current.end_col = math.max(current.end_col, next_range.end_col)
+						current.end_col = max(current.end_col, next_range.end_col)
 					end
 				end
 			end
 
-			if current.start_line ~= current.end_line or current.start_col ~= current.end_col then
-				table.insert(final_ranges, current)
+			-- Add the last range if not empty
+			if not is_empty_range(current) then
+				insert(final_ranges, current)
 			end
 		end
 
-		vim.schedule(function()
-			if callback then
-				callback(final_ranges)
-			end
-		end)
+		if callback then
+			callback(final_ranges)
+		end
 	end)
 end