feat(persistence): pre_save option to call before saving (#22)

* feat(persistence): `pre_save` option to call before saving

This commit adds the `pre_save` option, which is a `fun()|nil` that will
be called (if present) before saving the current session. Use cases
include filtering buffers, executing `User` autocmds, etc.

* docs: `pre_save` option

README.md

@@ -52,6 +52,7 @@ Persistence comes with the following defaults:
 {
   dir = vim.fn.expand(vim.fn.stdpath("state") .. "/sessions/"), -- directory where session files are saved
   options = { "buffers", "curdir", "tabpages", "winsize" }, -- sessionoptions used for saving
+  pre_save = nil, -- a function to call before saving the session
 }
 ```
 

doc/persistence.nvim.txt

@@ -71,6 +71,7 @@ Persistence comes with the following defaults:
     {
       dir = vim.fn.expand(vim.fn.stdpath("state") .. "/sessions/"), -- directory where session files are saved
       options = { "buffers", "curdir", "tabpages", "winsize" }, -- sessionoptions used for saving
+      pre_save = nil, -- a function to call before saving the session
     }
 <
 

doc/persistence.txt

@@ -71,6 +71,7 @@ Persistence comes with the following defaults:
     {
       dir = vim.fn.expand(vim.fn.stdpath("state") .. "/sessions/"), -- directory where session files are saved
       options = { "buffers", "curdir", "tabpages", "winsize" }, -- sessionoptions used for saving
+      pre_save = nil, -- a function to call before saving the session
     }
 <
 

lua/persistence/config.lua

@@ -1,6 +1,7 @@
 local M = {}
 
 ---@class PersistenceOptions
+---@field pre_save? fun()
 local defaults = {
   dir = vim.fn.expand(vim.fn.stdpath("state") .. "/sessions/"), -- directory where session files are saved
   options = { "buffers", "curdir", "tabpages", "winsize" }, -- sessionoptions used for saving

lua/persistence/init.lua

@@ -30,6 +30,10 @@ function M.start()
   vim.api.nvim_create_autocmd("VimLeavePre", {
     group = vim.api.nvim_create_augroup("persistence", { clear = true }),
     callback = function()
+      if Config.options.pre_save then
+        Config.options.pre_save()
+      end
+
       M.save()
     end,
   })