trident-mode.el

;;; trident-mode.el --- Live Parenscript interaction -*- lexical-binding: t -*-

;; This is free and unencumbered software released into the public domain.

;; Author: John Mastro <john.b.mastro@gmail.com>
;; URL: https://github.com/johnmastro/trident-mode.el
;; Version: 0.9.1
;; Keywords: languages, lisp, processes, tools
;; Package-Requires: ((emacs "24") (slime "20130526") (skewer-mode "1.5.0") (dash "1.0.3"))

;;; Commentary:

;; This is an Emacs minor mode and collection of commands for working with
;; Parenscript code in SLIME and sending it to the browser via Skewer. The goal
;; is to create an environment for hacking Parenscript which fits as naturally
;; as possible into the Lisp style of interactive development.

;; ** Installation

;; Trident is available on MELPA, meaning a simple =M-x package-install RET
;; trident-mode RET= will install both it and its dependencies.

;; To enable MELPA, if you haven't already, add something like the following to
;; your Emacs configuration:

;;   (require 'package)
;;   (add-to-list 'package-archives
;;                '("melpa" . "http://melpa.milkbox.net/packages/") t)
;;   (package-initialize)

;; The dependencies that will be installed are:
;;   - SLIME
;;   - Skewer
;;   - dash.el

;; Trident also requires a Common Lisp implementation and Parenscript.
;; Quicklisp is the best way to install Parenscript.

;; ** Setup

;; To enable trident-mode in a SLIME buffer: M-x trident-mode.

;; To have lisp-mode, slime-mode, and trident-mode all enable automatically for
;; any file with an extension of ".paren":

;;   (add-to-list 'auto-mode-alist (cons "\\.paren\\'" 'lisp-mode))
;;   (add-hook 'lisp-mode-hook
;;             #'(lambda ()
;;                 (when (and buffer-file-name
;;                            (string-match-p "\\.paren\\>" buffer-file-name))
;;                   (unless (slime-connected-p)
;;                     (save-excursion (slime)))
;;                   (trident-mode +1))))

;; Parenscript must be loaded in your Common Lisp image, and you'll probably
;; also want to import its symbols:

;;   (ql:quickload :parenscript)
;;   (use-package :parenscript)

;; With the above taken care of it's time to skewer the browser. See Skewer's
;; README for detailed information on the multiple ways you can connect to a
;; site - including sites on servers you don't control.

;; The fastest way to simply try things out is to run M-x run-skewer. Skewer
;; will load an empty page in your browser and connect to it. You can
;; immediately begin using Trident's evaluation commands (described below); to
;; additionally open a JavaScript REPL you can run M-x skewer-repl.

;; ** Commands

;; *** Code expansion commands

;; These commands generate JavaScript from the Parenscript code and display it
;; but don't send it to the browser for evaluation:

;;    - trident-expand-sexp
;;    - trident-expand-last-expression
;;    - trident-expand-defun
;;    - trident-expand-region
;;    - trident-expand-buffer
;;    - trident-expand-dwim

;; From within an expansion buffer you can press e to send the JavaScript to
;; the browser, w to copy it to the kill ring, s to save it to a file (you'll
;; be prompted for the destination) or q to dismiss the buffer. The copy
;; command, w, acts on the region if it's active or the entire buffer
;; otherwise.

;; Additionally, you can use M-x trident-compile-buffer-to-file to expand the
;; current buffer and save the generated code directly to a file.

;; *** Code evaluation commands

;; These commands first compile the Parenscript code to JavaScript and then
;; immediately send to it the browser to be evaluated:

;;    - trident-eval-sexp
;;    - trident-eval-last-expression
;;    - trident-eval-defun
;;    - trident-eval-region
;;    - trident-eval-buffer
;;    - trident-eval-dwim

;; ** Key bindings

;; The traditional set of code evaluation key bindings is a poor fit for
;; Trident,since they would shadow SLIME's equivalent commands and that's
;; probably not what you want. That leaves us without a clear convention to
;; follow, so by default we don't establish any key bindings at all. However,
;; the function trident-add-keys-with-prefix will add two-key key bindings for
;; all commands behind a prefix of your choice.

;; For example: (trident-add-keys-with-prefix "C-c C-e"). The key sequence for
;; trident-eval-region is "e r", so it's now bound to "C-c" "C-e er"

;; The full list of key bindings trident-add-keys-with-prefix will establish
;; is:

;;    - "e RET" -- trident-eval-sexp
;;    - "e e" -- trident-eval-last-expression
;;    - "e d" -- trident-eval-defun
;;    - "e r" -- trident-eval-region
;;    - "e b" -- trident-eval-buffer
;;    - "e SPC" -- trident-eval-dwim
;;    - "x RET" -- trident-expand-sexp
;;    - "x e" -- trident-expand-last-expression
;;    - "x d" -- trident-expand-defun
;;    - "x r" -- trident-expand-region
;;    - "x b" -- trident-expand-buffer
;;    - "x SPC" -- trident-expand-dwim

;; Evaluation commands begin with an "e", expansion commands with "x". The
;; second letter is generally mnemonic but not always. The -sexp commands use
;; RET in correspondence to slime-expand-1, and the -dwim commands use the
;; space bar because it's easy and comfortable to hit.

;; Please consider these keys provisional, and let me know if you have any
;; ideas for improving the arrangement.

;; If you really want to shadow SLIME's key bindings in buffers where
;; trident-mode is active you could do something like this:

;;   (defun steal-slime-keys-for-trident! ()
;;     ;; Don't affect all SLIME buffers, just where invoked
;;     (make-local-variable 'slime-mode-map)
;;     (let ((map slime-mode-map))
;;       (define-key map (kbd "C-x C-e") nil)
;;       (define-key map (kbd "C-c C-r") nil)
;;       (define-key map (kbd "C-M-x")   nil)
;;       (define-key map (kbd "C-c C-k") nil)
;;       (define-key map (kbd "C-c C-m") nil))
;;     (let ((map trident-mode-map))
;;       (define-key map (kbd "C-x C-e") 'trident-eval-last-expression)
;;       (define-key map (kbd "C-c C-r") 'trident-eval-region)
;;       (define-key map (kbd "C-M-x")   'trident-eval-defun)
;;       (define-key map (kbd "C-c C-k") 'trident-eval-buffer)
;;       (define-key map (kbd "C-c C-m") 'trident-expand-sexp)))
;;
;;   (add-hook 'trident-mode-hook 'steal-slime-keys-for-trident!)

;; ** Other amenities

;; slime-selector is a great feature and Trident can optionally integrate with
;; it. If you call trident-add-slime-selector-methods, two entries related to
;; trident-mode will be added. One, invoked with p, will take you to the most
;; recently visited buffer where trident-mode is active (excluding buffers
;; which are already visible). The other, on P, will take you to a scratch
;; buffer with trident-mode enabled, creating the buffer if necessary.

;; Speaking of the scratch buffer, the trident-scratch command will take you
;; straight there.

;; ** Still do be done

;;    - Add some tests.
;;    - Better documentation.
;;    - Look into adding a REPL.
;;    - See if more integration with SLIME is possible.
;;    - Command(s) for compiling to a file.
;;    - Similar support for CL-WHO and/or CSS-LITE?
;;    - Add support for Customize.

;; ** Contributing

;; Contributions are very welcome. Since I've just started working on this and
;; don't have everything figured out yet, please first contact me on GitHub or
;; send me an email so we can talk before you start working on something.

;;; Code:

(require 'slime)
(require 'skewer-mode)
(require 'dash)

;;;; Vars

(defvar trident-mode-map (make-sparse-keymap)
  "Keymap for trident-mode.
This keymap is initialized empty. You can optionally use
`trident-add-keys-with-prefix' to add bindings for all commands
on two-key sequences behind a prefix of your choice.")

(defvar trident-expansion-mode-map
  (let ((map (make-sparse-keymap)))
    (define-key map (kbd "e") 'trident-send-expanded-code)
    (define-key map (kbd "w") 'trident-kill-ring-save-dwim)
    (define-key map (kbd "s") 'write-file)
    (define-key map (kbd "q") 'quit-window)
    map)
  "Keymap for `trident-expansion-mode' buffers.")

(defvar trident-scratch-mode-map (make-sparse-keymap)
  "Keymap for the *trident-scratch* buffer.")

(defvar trident-expansion-major-mode 'javascript-mode
  "The major mode to enable in expansion buffers.
Note that are currently serious problems when using js2-mode in
expansion buffers. Avoid it for the time being.")

;;;; Code expansion

(defun trident-wrap-in-ps-form (string)
  "Return Parenscript STRING wrapped in a PS:PS form."
  (format "(ps:ps %s)" string))

(defun trident-call-with-expansion (fn string)
  "Call FN on the result of expanding Parenscript STRING.

Note that FN will be called asynchronously and its return value
discarded; it must work through side effects alone.

See also `trident-with-expansion'."
  (let ((string (trident-wrap-in-ps-form string)))
    (slime-eval-async `(swank:eval-and-grab-output ,string)
      #'(lambda (result)
          (funcall fn (read (cadr result))))
      (slime-current-package))))

(defmacro trident-with-expansion (name-and-string &rest body)
  "Expand a Parenscript string and execute BODY.

NAME-AND-STRING should be a two-item list, with the second item
the string to be expanded and the first item the name to which to
bind the result of the expansion. Note that BODY will be executed
asynchronously and its return value discarded; it must work
through side effects alone.

See also `trident-call-with-expansion'."
  (let ((name (car name-and-string))
        (string (cadr name-and-string))
        (rv (make-symbol "rv")))
    `(slime-eval-async
         `(swank:eval-and-grab-output ,(trident-wrap-in-ps-form ,string))
       #'(lambda (,rv)
           (let ((,name (read (cadr ,rv))))
             ,@body))
       (slime-current-package))))

(put 'trident-with-expansion 'lisp-indent-function 1)

(defun trident-expand (string)
  "Display the JavaScript generated from Parenscript STRING.

The resulting JavaScript is displayed in a temporary buffer. The
buffer's major mode is determined by the variable
`trident-expansion-major-mode' (`javascript-mode' by default).
`trident-expansion-mode' is enabled as an additional minor mode."
  (trident-with-expansion (code string)
    (slime-with-popup-buffer ("*Parenscript generated JavaScript*")
      (setq buffer-read-only nil)
      (erase-buffer)
      (insert code)
      (funcall trident-expansion-major-mode)
      (trident-expansion-mode 1)
      (font-lock-fontify-buffer)
      (goto-char (point-min))
      (setq buffer-read-only t)
      (pop-to-buffer (current-buffer)))))

(defun trident-compile-buffer-to-file ()
  "Compile the current buffer and write the result.
Prompts for the destination. If a file already exists at the
destination it's overwritten."
  (interactive)
  (when (and (buffer-modified-p)
             (y-or-n-p "Save buffer? "))
    (save-buffer))
  (let* ((this buffer-file-name)
         (dir (and this (file-name-directory this)))
         (initial (and this (concat (file-name-base this) ".js")))
         (destination (read-file-name "Destination: " dir nil nil initial nil))
         (string (buffer-substring-no-properties (point-min) (point-max))))
    (trident-with-expansion (code string)
      (with-temp-buffer
        (erase-buffer)
        (insert code)
        (write-region 1 (point-max) destination)))))

(defun trident-expand-sexp ()
  "Display the expansion of the form at point."
  (interactive)
  (trident-expand (slime-sexp-at-point)))

(defun trident-expand-last-expression ()
  "Display the expansion of the expression preceding point."
  (interactive)
  (trident-expand (slime-last-expression)))

(defun trident-expand-defun ()
  "Display the expansion of the current toplevel form."
  (interactive)
  (trident-expand (slime-defun-at-point)))

(defun trident-expand-region (beg end)
  "Display the expansion of the currently active region."
  (interactive "r")
  (trident-expand (buffer-substring-no-properties beg end)))

(defun trident-expand-buffer ()
  "Display the expansion of the current buffer."
  (interactive)
  (trident-expand-region (point-min) (point-max)))

(defun trident-expand-dwim ()
  "Display the expansion of the active region or toplevel form.
If the region is active this is equivalent to invoking
`trident-expand-region', otherwise it's equivalent to
`trident-expand-defun'."
  (interactive)
  (if (region-active-p)
      (trident-expand-region (region-beginning) (region-end))
    (trident-expand-defun)))

;;;; Code evaluation

(defun trident-eval (string)
  "Compile Parenscript STRING and evaluate it in the browser.

The code is first compiled to JavaScript in the CL image and then
sent to the browser via `skewer-eval'."
  (trident-with-expansion (code string)
    (skewer-eval code #'skewer-post-minibuffer)))

(defun trident-eval-sexp ()
  "Evaluate the expression at point as Parenscript."
  (interactive)
  (trident-eval (slime-sexp-at-point)))

(defun trident-eval-last-expression (&optional prefix)
  "Evaluate the expression preceding point as Parenscript. If
invoked with a prefix argument, insert the result into the
current buffer."
  (interactive "P")
  (if prefix
      (trident-eval-print-last-expression)
    (trident-eval (slime-last-expression))))

(defun trident-eval-print-last-expression ()
  "Evaluate sexp before point as Parenscript; print value into
the current buffer."
  (interactive)
  (cl-destructuring-bind (start end)
      (slime-region-for-defun-at-point)
    (let ((string (buffer-substring-no-properties start end)))
      (skewer-flash-region start end)
      (unless (zerop (current-column))
        (newline))
      (trident-with-expansion (code string)
        (let* ((request (skewer-eval code #'skewer-post-print :verbose t))
               (id (cdr (assoc 'id request)))
               (pos (cons (current-buffer) (point))))
          (setf (cache-table-get id skewer-eval-print-map) pos))))))

(defun trident-eval-defun ()
  "Evaluate the current toplevel form as Parenscript."
  (interactive)
  (trident-eval (slime-defun-at-point)))

(defun trident-eval-region (beg end)
  "Evaluate the currently active region as Parenscript."
  (interactive "r")
  (trident-eval (buffer-substring-no-properties beg end)))

(defun trident-eval-buffer ()
  "Evaluate the current buffer as Parenscript."
  (interactive)
  (prog1
      (trident-eval-region (point-min) (point-max))
    (when slime-highlight-edits-mode
      (slime-remove-edits (point-min) (point-max)))))

(defun trident-eval-dwim ()
  "Evaluate the active region or toplevel form.
If the region is active this is equivalent to invoking
`trident-eval-region', otherwise it's equivalent to
`trident-eval-defun'."
  (interactive)
  (if (region-active-p)
      (trident-eval-region (region-beginning) (region-end))
    (trident-eval-defun)))

;;;; Expansion buffer commands

(defun trident-send-expanded-code ()
  "Send the expanded code to the browser.
For use from `trident-expansion-mode' buffers."
  (interactive)
  (skewer-eval
   (buffer-substring-no-properties (point-min) (point-max))
   #'skewer-post-minibuffer))

(defun trident-kill-ring-save-dwim ()
  "Save the current buffer's content to the kill ring.
If the region is active, save it; otherwise save the entire
buffer."
  (interactive)
  (if (region-active-p)
      (kill-ring-save (region-beginning) (region-end))
    (kill-ring-save (point-min) (point-max))))

;;;; Keybindings

(defun trident-add-keys-with-prefix (p)
  "Add keybindings for `trident-mode' commands behind prefix P."
  (let ((map trident-mode-map)
        (prefix #'(lambda (keys) (read-kbd-macro (concat p " " keys)))))
    ;; Evaluation commands
    (define-key map (funcall prefix "e C-m") 'trident-eval-sexp)
    (define-key map (funcall prefix "e e")   'trident-eval-last-expression)
    (define-key map (funcall prefix "e d")   'trident-eval-defun)
    (define-key map (funcall prefix "e r")   'trident-eval-region)
    (define-key map (funcall prefix "e b")   'trident-eval-buffer)
    (define-key map (funcall prefix "e SPC") 'trident-eval-dwim)
    ;; Expansion commands
    (define-key map (funcall prefix "x C-m") 'trident-expand-sexp)
    (define-key map (funcall prefix "x e")   'trident-expand-last-expression)
    (define-key map (funcall prefix "x d")   'trident-expand-defun)
    (define-key map (funcall prefix "x r")   'trident-expand-region)
    (define-key map (funcall prefix "x b")   'trident-expand-buffer)
    (define-key map (funcall prefix "x SPC") 'trident-expand-dwim)))

;;;; Scratch buffer

(defun trident-scratch-buffer ()
  "Return the scratch buffer, creating it if necessary."
  (let ((name "*trident-scratch*"))
    (or (get-buffer name)
        (with-current-buffer (get-buffer-create name)
          (lisp-mode)
          (slime-mode t)
          (trident-mode 1)
          (trident-scratch-mode 1)
          (current-buffer)))))

(defun trident-switch-to-scratch-buffer ()
  "Jump to the *trident-scratch* buffer."
  (set-buffer (trident-scratch-buffer))
  (unless (eq (current-buffer) (window-buffer))
    (pop-to-buffer (current-buffer) t)))

(defun trident-scratch ()
  "Jump to the *trident-scratch* buffer."
  (interactive)
  (trident-switch-to-scratch-buffer))

;;;; A little extra SLIME integration

(defun trident-mode-buffer-p (buffer)
  "Return t if `trident-mode' is active in BUFFER."
  (with-current-buffer buffer
    (bound-and-true-p trident-mode)))

(defun trident-recently-visited-trident-buffer ()
  "Return the most recently visited `trident-mode' buffer.
Only considers buffers that are not already visible."
  (or (-first #'(lambda (b) (and (trident-mode-buffer-p b)
                                 (null (get-buffer-window b 'visible))))
              (buffer-list))
      (error "Can't find unshown buffer in trident-mode")))

(defun trident-add-slime-selector-methods ()
  "Add methods to `slime-selector' for `trident-mode' buffers.
Allows access to the most recently visited buffer with
trident-mode active via \"p\" and to the *trident-scratch* buffer
via \"P\"."
  (interactive)
  (def-slime-selector-method ?p
    "most recently visited buffer using trident-mode."
    (trident-recently-visited-trident-buffer))
  (def-slime-selector-method ?P
    "*trident-scratch* buffer."
    (trident-scratch-buffer)))

;;;; The minor modes

;;;###autoload
(define-minor-mode trident-mode
  "Minor mode for interactively evaluating Parenscript forms."
  :lighter " tri"
  :keymap  trident-mode-map)

;;;###autoload
(define-minor-mode trident-scratch-mode
  "Mode for trident-mode scratch buffer."
  :lighter nil
  :keymap  trident-scratch-mode-map)

(define-minor-mode trident-expansion-mode
  "Minor mode for displaying the code generated by Parenscript."
  :lighter nil
  :keymap  trident-expansion-mode-map)


(provide 'trident-mode)

;; Local Variables:
;; indent-tabs-mode: nil
;; coding: utf-8
;; End:

;;; trident-mode.el ends here