feat(autocmd): deprecate ^<.+> pattern in sym/list to set Lua callb…

…ack (#197)

* refactor(utils): add `vim-callback-format?`

* refactor(autocmd): split `<command>` detection to deprecate it later

* feat(autocmd): deprecate `^<.+>` pattern as Lua callback

* test(autocmd): ensure compatibility on `<Cmd>format-callback`

fnl/nvim-laurel/macros.fnl

@@ -112,6 +112,18 @@
   (and (list? x) ;
        (contains? [`fn `hashfn `lambda `partial] (first x))))
 
+(fn vim-callback-format? [callback]
+  "Tell if `callback` is to be interpreted in Vim script just by the
+  `callback` format.
+  @param callback any
+  @return boolean"
+  ;; TODO: Include the `str?` check after removing the deprecated formats.
+  (or ;; (str? callback) ;
+      (and (sym? callback) ;
+           (-> (->str callback) (: :match "^<.+>")))
+      (and (list? callback) ;
+           (-> (->str (first callback)) (: :match "^<.+>")))))
+
 ;; Specific Utils ///1
 
 (lambda error* [msg]
@@ -350,8 +362,16 @@
         (when (and (or extra-opts.<command> extra-opts.ex)
                    (or extra-opts.<callback> extra-opts.cb))
           (error* "cannot set both <command>/ex and <callback>/cb."))
-        (if (or extra-opts.<command> extra-opts.ex vim?)
+        (var vim-cb? false)
+        (if ;; TODO: Deprecate `<command>` option.
+            (or extra-opts.<command> extra-opts.ex)
+            (set extra-opts.command callback)
+            vim?
             (set extra-opts.command callback)
+            (vim-callback-format? callback)
+            ;; TODO: Remove vim-cb? check on v0.6.0.
+            ;; (set extra-opts.command callback)
+            (set vim-cb? true)
             (or extra-opts.<callback> extra-opts.cb ;
                 (sym? callback) ;
                 (anonymous-function? callback) ;
@@ -371,8 +391,22 @@
         (assert-compile (nand extra-opts.pattern extra-opts.buffer)
                         "cannot set both pattern and buffer for the same autocmd"
                         extra-opts)
-        (let [api-opts (merge-api-opts (autocmd/->compatible-opts! extra-opts)
-                                       ?api-opts)]
+        (let [api-opts ;
+              (merge-api-opts (autocmd/->compatible-opts! extra-opts)
+                              ;; TODO: Remove all the if-expr except `?api-opts` here to set `callback` to `command`.
+                              (if vim-cb?
+                                  `(vim.tbl_extend :keep (or ,?api-opts {})
+                                                   (let [cb# ,callback
+                                                         str?# (= :string
+                                                                  (type cb#))]
+                                                     {:command (when str?#
+                                                                 cb#)
+                                                      :callback (when (not str?#)
+                                                                  ,(deprecate "symbol which, or list whose first symbol, matches \"^<.+>\" to set Lua callback"
+                                                                              "another name"
+                                                                              :v0.6.0
+                                                                              `cb#))}))
+                                  ?api-opts))]
           `(vim.api.nvim_create_autocmd ,events ,api-opts)))))
 
 (fn autocmd? [args]

tests/spec/autocmd_spec.fnl

@@ -13,6 +13,11 @@
 (local default-command :default-command)
 (local default {:multi {:sym #:default.multi.sym}})
 
+(local <default>-command :<default>-command)
+;; TODO: Remove it on removing the support for Lua callback.
+(local <default>-str-callback #:<default>-str-callback)
+(local <default>-callback-callback ##:<default>-callback-callback)
+
 (lambda get-autocmds [?opts]
   (let [opts (collect [k v (pairs (or ?opts {})) ;
                        &into {:group default-augroup}]
@@ -187,12 +192,32 @@
         (let [cb :callback
               opts {:nested true}]
           (autocmd! default-augroup default-event cb opts)))))
+  (describe :<Cmd>pattern
+    (it "symbol will be set to 'command'"
+      (au! default-augroup default-event [:pat1] <default>-command)
+      (let [au (get-first-autocmd {:pattern :pat1})]
+        (assert.is.same <default>-command au.command)))
+    (it "list will be set to 'command'"
+      (au! default-augroup default-event [:pat1] (<default>-str-callback))
+      (let [au (get-first-autocmd {:pattern :pat1})]
+        (assert.is.same (<default>-str-callback) au.command))))
   (describe "with &vim indicator"
     (it "set callback to `command`"
       (au! default-augroup default-event [:pat1] &vim default-command)
       (let [[autocmd1] (get-autocmds {:pattern :pat1})]
         (assert.is.same default-command autocmd1.command))))
-  (describe "(deprecated)"
+  (describe "(Deprecated, v0.6.0 will not support it)"
+    (describe :<Cmd>pattern
+      (it "symbol can set Lua function as callback"
+        (au! default-augroup default-event [:pat1] <default>-str-callback)
+        (let [au (get-first-autocmd {:pattern :pat1})]
+          (assert.is.same <default>-str-callback au.callback)))
+      (it "list can set Lua function as callback"
+        (let [desc :<default>]
+          (au! default-augroup default-event [:pat1] [:desc desc]
+               (<default>-callback-callback))
+          (let [au (get-first-autocmd {:pattern :pat1})]
+            (assert.is.same desc au.desc)))))
     (describe :augroup+
       (it "gets an existing augroup id"
         (let [id (augroup! default-augroup)]