Make inf-clojure-completions a defcustom

The motivation behind this change is that now the user can provide a custom
parsing function and therefore has complete freedom in what to use for
completion. I foresee a module that sets compliment completion for instance, or
even use directly what cider provides.

Author: arichiardi

inf-clojure.el

@@ -1210,7 +1210,7 @@ prefix argument PROMPT-FOR-NS, it prompts for a namespace name."
 
 (defun inf-clojure-set-ns (prompt-for-ns)
   "Set the ns of the inferior Clojure process to NS.
-See variable `inf-clojure-set-ns-form`.  It defaults to the ns of
+See variable `inf-clojure-set-ns-form'.  It defaults to the ns of
 the current buffer.  When invoked with a prefix argument
 PROMPT-FOR-NS, it prompts for a namespace name."
   (interactive "P")
@@ -1254,15 +1254,43 @@ See variable `inf-clojure-buffer'."
   "Return DATA if and only if it is a list."
   (when (listp data) data))
 
-(defun inf-clojure-completions (expr)
-  "Return a list of completions for the Clojure expression starting with EXPR."
+(defun inf-clojure-list-completions (expr)
+  "Return completions for the Clojure expression starting with EXPR.
+
+Its only ability is to parse a list of candidate strings, every
+other EXPR will be discarded and nil will be returned."
   (when (not (string-blank-p expr))
     (thread-first
         (format (inf-clojure-completion-form) (substring-no-properties expr))
       (inf-clojure--process-response (inf-clojure-proc) "(" ")")
       (inf-clojure--read-or-nil)
       (inf-clojure--list-or-nil))))
 
+(defcustom inf-clojure-completions 'inf-clojure-list-completions
+  "The function that parses completion results.
+
+It is a single-arity function that will receive the REPL
+evaluation result of \\[inf-clojure-completion-form] as string and
+should return elisp data compatible with your completion mode.
+
+The easiest possible data passed in input is a list of
+candidates (e.g.: (\"def\" \"defn\")) but more complex libraries
+like `alexander-yakushev/compliment' can return other things like
+edn.
+
+The expected return depends on the mode that you use for
+completion: `company-mode' for instance allows metadata along
+with the candidates completion. See \\[completion-table-dynamic]
+for more details.
+
+The default value is the `inf-clojure-list-completions' function,
+which is able to parse results in list form only.  You can peek
+at its implementation for getting to know some utility functions
+you might want to use in your customization."
+  :type 'function
+  :safe #'functionp
+  :package-version '(inf-clojure . "2.1.0"))
+
 (defconst inf-clojure-clojure-expr-break-chars " \t\n\"\'`><,;|&{()[]")
 
 (defun inf-clojure-completion-bounds-of-expr-at-point ()
@@ -1288,8 +1316,8 @@ Returns the selected completion or nil."
     (when bounds
       (list (car bounds) (cdr bounds)
             (if (fboundp 'completion-table-with-cache)
-                (completion-table-with-cache #'inf-clojure-completions)
-              (completion-table-dynamic #'inf-clojure-completions))))))
+                (completion-table-with-cache inf-clojure-completions)
+              (completion-table-dynamic inf-clojure-completions))))))
 
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