Allow multiple startup options to be tried in order (#126)

Author: nuchs

README.md

@@ -12,14 +12,14 @@ The plugin saves the sessions in the specified folder (see [configuration](#conf
 
 Use the command `:SessionManager[!]` with one of the following arguments:
 
-| Argument                     | Description                                                                                  |
-| -----------------------------| -------------------------------------------------------------------------------------------- |
-| `load_session`               | Select and load session. (Your current session won't appear on the list).                    |
-| `load_last_session`          | Will remove all buffers and `:source` the last saved session.                                |
-| `load_current_dir_session`   | Will remove all buffers and `:source` the last saved session file of the current directory.  |
-| `save_current_session`       | Works like `:mksession`, but saves/creates current directory as a session in `sessions_dir`. |
-| `delete_session`             | Select and delete session.                                                                   |
-| `delete_current_dir_session`| Deletes the session associated with the current directory.                                   |
+| Argument                     | Description                                                                                                                                                        |
+| -----------------------------| ------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
+| `load_session`               | Select and load session. (Your current session won't appear on the list).                                                                                          |
+| `load_last_session`          | Removes all buffers and tries to `:source` the last saved session. Returns `true` if the session was restored and `false` otherwise.                               |
+| `load_current_dir_session`   | Removes all buffers and tries to `:source` the last saved session file of the current directory. Returns `true` if the session was restored and `false` otherwise. |
+| `save_current_session`       | Works like `:mksession`, but saves/creates current directory as a session in `sessions_dir`.                                                                       |
+| `delete_session`             | Select and delete session.                                                                                                                                         |
+| `delete_current_dir_session` | Deletes the session associated with the current directory.                                                                                                         |
 
 When `!` is specified, the modified buffers will not be saved.
 
@@ -36,7 +36,7 @@ require('session_manager').setup({
   sessions_dir = Path:new(vim.fn.stdpath('data'), 'sessions'), -- The directory where the session files will be saved.
   session_filename_to_dir = session_filename_to_dir, -- Function that replaces symbols into separators and colons to transform filename into a session directory.
   dir_to_session_filename = dir_to_session_filename, -- Function that replaces separators and colons into special symbols to transform session directory into a filename. Should use `vim.uv.cwd()` if the passed `dir` is `nil`.
-  autoload_mode = config.AutoloadMode.LastSession, -- Define what to do when Neovim is started without arguments. Possible values: Disabled, CurrentDir, LastSession
+  autoload_mode = config.AutoloadMode.LastSession, -- Define what to do when Neovim is started without arguments. See "Autoload mode" section below.
   autosave_last_session = true, -- Automatically save last session on exit and on session switch.
   autosave_ignore_not_normal = true, -- Plugin will not save a session when no buffers are opened, or all of them aren't writable or listed.
   autosave_ignore_dirs = {}, -- A list of directories where the session will not be autosaved.
@@ -50,6 +50,26 @@ require('session_manager').setup({
 })
 ```
 
+### Autoload mode
+
+If Neovim is started without arguments the value of the autoload_mode option is used to determine which session to initially load. The following modes are supported:
+
+| Mode        | Description                                                  |
+| ----------- | ------------------------------------------------------------ |
+| Disabled    | No session will be loaded.                                   |
+| CurrentDir  | The session in the current working directory will be loaded. |
+| LastSession | The last session will be loaded. This is the default.        |
+
+`autoload_mode` can be set to either a single mode or an array of modes, in which
+case each mode will be tried until one succeeds e.g.
+
+```lua
+autoload_mode = { config.AutoloadMode.CurrentDir, config.AutoloadMode.LastSession }
+```
+
+Would attempt to load the current directory session and then fallback to the last session.
+
+
 ## Autocommands
 
 You can specify commands to be executed automatically after saving or loading a session using the following events:

lua/session_manager/init.lua

@@ -40,24 +40,30 @@ function session_manager.load_session(discard_current)
   end)
 end
 
---- Loads saved used session.
+--- Tries to load the last saved session.
 ---@param discard_current boolean?: If `true`, do not check for unsaved buffers.
+---@return boolean: `true` if session was loaded, `false` otherwise.
 function session_manager.load_last_session(discard_current)
   local last_session = utils.get_last_session_filename()
   if last_session then
     utils.load_session(last_session, discard_current)
+    return true
   end
+  return false
 end
 
---- Loads a session for the current working directory.
+--- Tries to load a session for the current working directory.
+---@return boolean: `true` if session was loaded, `false` otherwise.
 function session_manager.load_current_dir_session(discard_current)
   local cwd = vim.uv.cwd()
   if cwd then
     local session = config.dir_to_session_filename(cwd)
     if session:exists() then
       utils.load_session(session.filename, discard_current)
+      return true
     end
   end
+  return false
 end
 
 --- Saves a session for the current working directory.
@@ -68,13 +74,26 @@ function session_manager.save_current_session()
   end
 end
 
+local autoloaders = {
+  [AutoloadMode.Disabled] = function() return true end,
+  [AutoloadMode.CurrentDir] = session_manager.load_current_dir_session,
+  [AutoloadMode.LastSession] = session_manager.load_last_session,
+}
+
 --- Loads a session based on settings. Executed after starting the editor.
 function session_manager.autoload_session()
-  if config.autoload_mode ~= AutoloadMode.Disabled and vim.fn.argc() == 0 and not vim.g.started_with_stdin then
-    if config.autoload_mode == AutoloadMode.CurrentDir then
-      session_manager.load_current_dir_session()
-    elseif config.autoload_mode == AutoloadMode.LastSession then
-      session_manager.load_last_session()
+  if vim.fn.argc() > 0 or vim.g.started_with_stdin then
+    return
+  end
+
+  local modes = config.autoload_mode
+  if not vim.isarray(config.autoload_mode) then
+    modes = { config.autoload_mode }
+  end
+
+  for _, mode in ipairs(modes) do
+    if autoloaders[mode]() then
+      return
     end
   end
 end