Limit max number of files to maxsize (1000)

The paths in .vis-cursors are now sorted in a least used order and limited
to a maxsize, currently set to 1000, but can however be changed using M.maxsize.

Based on PR by @leorosa :
https://github.com/erf/vis-cursors/pull/8

2 files changed, 50 insertions, 17 deletions

diff --git a/README.md b/README.md
index 1965d85..494ff59 100644
--- a/README.md
+++ b/README.md
@@ -2,6 +2,11 @@
 
 A [vis](https://github.com/martanne/vis) [plugin](https://github.com/martanne/vis/wiki/Plugins) for saving cursor position per file.
 
+The file positions are ordered by latest used first.
+
+You can set a `maxsize` which defaults to 1000 files.
+
 Default save path is `{XDG_CACHE_HOME|HOME}/.vis-cursors`
 
-Set a custom path with `M.path`
\ No newline at end of file
+Set a custom path with `M.path`
+
diff --git a/init.lua b/init.lua
index 7fd5ee0..c33abb4 100644
--- a/init.lua
+++ b/init.lua
@@ -1,6 +1,9 @@
 local M = {}
 local cursors = {}
+local files = {}
+M.maxsize = 1000
 
+-- get the default system cache directory
 local get_default_cache_path = function()
 	local HOME = os.getenv('HOME')
 	local XDG_CACHE_HOME = os.getenv('XDG_CACHE_HOME')
@@ -10,33 +13,59 @@ end
 
 M.path = get_default_cache_path()
 
-local read_cursors = function()
+-- read cursors from file on init
+local on_init = function()
+
+	-- read file
 	local f = io.open(M.path)
 	if f == nil then
 		return
 	end
+
 	-- read positions per file path
 	for line in f:lines() do
 		for path, pos in string.gmatch(line, '(.+)[,%s](%d+)') do
 			cursors[path] = pos
+			table.insert(files, path)
 		end
 	end
+
 	f:close()
 end
 
-local apply_cursor_pos = function(win)
+-- apply cursor pos on win open
+local on_win_open = function(win)
+
 	if win.file == nil or win.file.path == nil then
 		return
 	end
+
+	-- remove old occurences of path
+	for i, path in ipairs(files) do
+		if path == win.file.path then
+			table.remove(files, i)
+			break
+		end
+	end
+
+	-- insert current path to top of files
+	table.insert(files, 1, win.file.path)
+
+	-- 
 	local pos = cursors[win.file.path]
 	if pos == nil then
+		cursors[win.file.path] = win.selection.pos
 		return
 	end
+
 	win.selection.pos = tonumber(pos)
+
 	vis:feedkeys("zz")
 end
 
-local set_cursor_pos = function(win)
+-- set cursor pos on close
+local on_win_close = function(win)
+
 	if win.file == nil or win.file.path == nil then
 		return
 	end
@@ -44,33 +73,32 @@ local set_cursor_pos = function(win)
 	cursors[win.file.path] = win.selection.pos
 end
 
-local write_cursors = function()
+-- write cursors to file on quit
+local on_quit = function()
 
 	local f = io.open(M.path, 'w+')
 	if f == nil then
 		return
 	end
 
-	-- sort paths
-	local paths = {}
-	for path in pairs(cursors) do
-		table.insert(paths, path)
-	end
-	table.sort(paths)
-
 	-- buffer cursors string
 	local t = {}
-	for i, path in ipairs(paths) do
+	local n = 0
+	for i, path in ipairs(files) do
 		table.insert(t, string.format('%s,%d', path, cursors[path]))
+		n = n + 1
+		if M.maxsize and n >= M.maxsize then
+			break
+		end
 	end
 	local s = table.concat(t, '\n')
 	f:write(s)
 	f:close()
 end
 
-vis.events.subscribe(vis.events.INIT, read_cursors)
-vis.events.subscribe(vis.events.WIN_OPEN, apply_cursor_pos)
-vis.events.subscribe(vis.events.WIN_CLOSE, set_cursor_pos)
-vis.events.subscribe(vis.events.QUIT, write_cursors)
+vis.events.subscribe(vis.events.INIT, on_init)
+vis.events.subscribe(vis.events.WIN_OPEN, on_win_open)
+vis.events.subscribe(vis.events.WIN_CLOSE, on_win_close)
+vis.events.subscribe(vis.events.QUIT, on_quit)
 
 return M