Added `workspace` plugin

2 files changed, 149 insertions, 0 deletions

diff --git a/README.md b/README.md
index 143429d..9d6fa5b 100644
--- a/README.md
+++ b/README.md
@@ -50,4 +50,5 @@ Plugin | Description
 [`todotreeview`](https://github.com/drmargarido/TodoTreeView)* | Todo tree viewer for annotations in code like `TODO`, `BUG`, `FIX`, `IMPROVEMENT`
 [`togglesnakecamel`](plugins/togglesnakecamel.lua?raw=1) | Toggles symbols between `snake_case` and `camelCase`
 [`unboundedscroll`](plugins/unboundedscroll.lua?raw=1) | Allows scrolling outside the bounds of a document
+[`workspace`](plugins/workspace.lua?raw=1) | Retains project's layout and open documents between sessions
 
diff --git a/plugins/workspace.lua b/plugins/workspace.lua
new file mode 100644
index 0000000..03304a9
--- /dev/null
+++ b/plugins/workspace.lua
@@ -0,0 +1,148 @@
+local core = require "core"
+local DocView = require "core.docview"
+
+local workspace_filename = core.project_dir .. "/.lite_workspace.lua"
+
+
+local function serialize(val)
+  if type(val) == "string" then
+    return string.format("%q", val)
+  elseif type(val) == "table" then
+    local t = {}
+    for k, v in pairs(val) do
+      table.insert(t, "[" .. serialize(k) .. "]=" .. serialize(v))
+    end
+    return "{" .. table.concat(t, ",") .. "}"
+  end
+  return tostring(val)
+end
+
+
+local function has_no_locked_children(node)
+  if node.locked then return false end
+  if node.type == "leaf" then return true end
+  return has_no_locked_children(node.a) and has_no_locked_children(node.b)
+end
+
+
+local function get_unlocked_root(node)
+  if node.type == "leaf" then
+    return not node.locked and node
+  end
+  if has_no_locked_children(node) then
+    return node
+  end
+  return get_unlocked_root(node.a) or get_unlocked_root(node.b)
+end
+
+
+local function save_path(filename)
+  local proj = system.absolute_path(core.project_dir)
+  filename = system.absolute_path(filename)
+  if filename:sub(1, #proj) == proj then
+    return "." .. filename:sub(#proj + 1)
+  end
+  return filename
+end
+
+
+local function load_path(filename)
+  return filename:gsub("^%.", core.project_dir)
+end
+
+
+local function save_docview(dv)
+  return {
+    filename = save_path(dv.doc.filename),
+    selection = { dv.doc:get_selection() },
+    scroll = { x = dv.scroll.to.x, y = dv.scroll.to.y }
+  }
+end
+
+
+local function load_docview(t)
+  local ok, doc = pcall(core.open_doc, load_path(t.filename))
+  if not ok then
+    return DocView(core.open_doc())
+  end
+  local dv = DocView(doc)
+  doc:set_selection(table.unpack(t.selection))
+  dv:update() -- prevents scrolling-to-make-caret-visible on initial frame
+  dv.scroll.x, dv.scroll.to.x = t.scroll.x, t.scroll.x
+  dv.scroll.y, dv.scroll.to.y = t.scroll.y, t.scroll.y
+  return dv
+end
+
+
+local function save_node(node)
+  local res = {}
+  res.type = node.type
+  if node.type == "leaf" then
+    res.views = {}
+    for _, view in ipairs(node.views) do
+      if getmetatable(view) == DocView and view.doc.filename then
+        table.insert(res.views, save_docview(view))
+        if node.active_view == view then
+          res.active_view = #res.views
+        end
+      end
+    end
+  else
+    res.divider = node.divider
+    res.a = save_node(node.a)
+    res.b = save_node(node.b)
+  end
+  return res
+end
+
+
+local function load_node(node, t)
+  if t.type == "leaf" then
+    for _, dv in ipairs(t.views) do
+      node:add_view(load_docview(dv))
+    end
+    if t.active_view then
+      node:set_active_view(node.views[t.active_view])
+    end
+  else
+    node:split(t.type == "hsplit" and "right" or "down")
+    node.divider = t.divider
+    load_node(node.a, t.a)
+    load_node(node.b, t.b)
+  end
+end
+
+
+local function save_workspace()
+  local root = get_unlocked_root(core.root_view.root_node)
+  local fp = io.open(workspace_filename, "w")
+  fp:write("return ", serialize(save_node(root)), "\n")
+  fp:close()
+end
+
+
+local function load_workspace()
+  local ok, t = pcall(dofile, workspace_filename)
+  if ok then
+    local root = get_unlocked_root(core.root_view.root_node)
+    load_node(root, t)
+  end
+end
+
+
+local run = core.run
+
+function core.run(...)
+  if #core.docs == 0 then
+    load_workspace()
+
+    local exit = os.exit
+    function os.exit(...)
+      save_workspace()
+      exit(...)
+    end
+  end
+
+  core.run = run
+  return core.run(...)
+end