Toggle between test and implementation files for scala project by Maven2

toggle-scala.el

;;; toggle-scala.el --- Toggle between test and implementation files.

;; Author: MIZUNO Hiroki<mzp.ppp_at_gmail.com>
;; Keywords: tools

;;;  Usage:
;;   Insert into your .emacs file the following line, (and eval it for
;;  immediate usage:
;;
;;   (require 'toggle-scala)
;;   (add-hook 'scala-mode-hook
;;      (lambda ()
;;         (define-key scala-mode-map "\M-t" 'toggle-scala))))
;;

;;
;;   Optionally byte compile this file, and change the default
;;  keybinding.

;;; History:
;;   0.1 :  Initial version.

;;; Code:
(defun toggle-scala-pom (try s)
  (cond
   ((= 0 try)  nil)
   ((file-exists-p (expand-file-name "pom.xml" s))
    s)
   (t
    (toggle-scala-pom (- try 1)
		      (expand-file-name ".." s)))))

(defun toggle-scala-src-p (s)
  (string-match "^src/main/" s))

(defun toggle-scala-src->test (s)
  (let ((base
	 (replace-regexp-in-string "^src/main/" "src/test/" s)))
    (list
     (replace-regexp-in-string "¥¥.scala$" "Test.scala" base)
     (replace-regexp-in-string "¥¥.scala$" "Spec.scala" base))))

(defun toggle-scala-test->src (s)
  (let ((base
	 (replace-regexp-in-string "^src/test/" "src/main/" s)))
    (list
     (replace-regexp-in-string "Test¥¥|Spec¥¥.scala$" ".scala" base))))

(defun toggle-scala-find (p xs)
  (if (consp xs)
      (if (funcall p (car xs))
	  (car xs)
	(toggle-scala-find p (cdr xs)))
    nil))

(defun toggle-scala-test-p (s)
  (string-match "^src/test/" s))

(defun toggle-scala-other-file (path)
  (let* ((base (toggle-scala-pom 10 path))
	 (file (file-relative-name path base)))
    (toggle-scala-find (function file-exists-p)
		       (mapcar (lambda (x)
				 (expand-file-name x base))
			       (if (toggle-scala-src-p file)
				   (toggle-scala-src->test file)
				 (toggle-scala-test->src file))))))

(defun toggle-scala ()
  (interactive)
  (when (buffer-file-name)
    (let ((file (toggle-scala-other-file (buffer-file-name))))
      (when file
	(find-file file)))))

(provide 'toggle-scala)