;;; ement-macros.el --- Ement macros                 -*- lexical-binding: t; -*-

;; Copyright (C) 2020  Adam Porter

;; Author: Adam Porter <adam@alphapapa.net>
;; Keywords:

;; This program is free software; you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.

;; This program is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU General Public License for more details.

;; You should have received a copy of the GNU General Public License
;; along with this program.  If not, see <https://www.gnu.org/licenses/>.

;;; Commentary:

;;

;;; Code:

;;;; Requirements

(require 'map)

;;;; Debugging

(eval-and-compile
  (setq-local warning-minimum-log-level nil)
  (setq-local warning-minimum-log-level :debug))

(cl-defmacro ement-debug (&rest args)
  "Display a debug warning showing the runtime value of ARGS.
The warning automatically includes the name of the containing
function, and it is only displayed if `warning-minimum-log-level'
is `:debug' at expansion time (otherwise the macro expands to nil
and is eliminated by the byte-compiler).  When debugging, the
form also returns nil so, e.g. it may be used in a conditional in
place of nil.

Each of ARGS may be a string, which is displayed as-is, or a
symbol, the value of which is displayed prefixed by its name, or
a Lisp form, which is displayed prefixed by its first symbol.

Before the actual ARGS arguments, you can write keyword
arguments, i.e. alternating keywords and values.  The following
keywords are supported:

  :buffer BUFFER   Name of buffer to pass to `display-warning'.
  :level  LEVEL    Level passed to `display-warning', which see.
                   Default is :debug."
  (pcase-let* ((fn-name (with-current-buffer
                            (or byte-compile-current-buffer (current-buffer))
                          ;; This is a hack, but a nifty one.
                          (save-excursion
                            (beginning-of-defun)
                            (cl-second (read (current-buffer))))))
               (plist-args (cl-loop while (keywordp (car args))
                                    collect (pop args)
                                    collect (pop args)))
               ((map (:buffer buffer) (:level level)) plist-args)
               (level (or level :debug))
               (string (cl-loop for arg in args
                                concat (pcase arg
                                         ((pred stringp) "%S ")
                                         ((pred symbolp)
                                          (concat (upcase (symbol-name arg)) ":%S "))
                                         ((pred listp)
                                          (concat "(" (upcase (symbol-name (car arg)))
                                                  (pcase (length arg)
                                                    (1 ")")
                                                    (_ "...)"))
                                                  ":%S "))))))
    (when (eq :debug warning-minimum-log-level)
      `(progn
         (display-warning ',fn-name (format ,string ,@args) ,level ,buffer)
         nil))))

;;;; Macros

(defmacro ement-alist (&rest pairs)
  "Expand to an alist of the keys and values in PAIRS."
  `(list ,@(cl-loop for (key value) on pairs by #'cddr
                    collect `(cons ,key ,value))))



;;;; Variables


;;;; Customization


;;;; Commands


;;;; Functions


;;;; Footer

(provide 'ement-macros)

;;; ement-macros.el ends here