[Fix #498] Implement scratch buffer functionality

Author: Bozhidar Batsov

CHANGELOG.md

@@ -21,6 +21,7 @@ cider-nrepl's info middleware for jump-to-definition.
 * New inspector inspired by SLIME's inspector
 * STDERR ouput is now font-locked with `cider-repl-err-output-face` to make it
 visually distinctive from `cider-repl-output-face` (used for STDOUT output).
+* New interactive command `cider-scratch`.
 
 ### Changes
 

cider-scratch.el

@@ -0,0 +1,69 @@
+;;; cider-scratch.el --- *scratch* buffer for Clojure -*- lexical-binding: t -*-
+
+;; Copyright © 2014 Bozhidar Batsov
+;;
+;; Author: Tim King <[email protected]>
+;;         Phil Hagelberg <[email protected]>
+;;         Bozhidar Batsov <[email protected]>
+;;         Hugo Duncan <[email protected]>
+;;         Steve Purcell <[email protected]>
+
+;; 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 <http://www.gnu.org/licenses/>.
+
+;; This file is not part of GNU Emacs.
+
+;;; Commentary:
+
+;; Imitate Emacs's *scratch* buffer.
+
+;;; Code:
+
+(require 'cider-interaction)
+(require 'clojure-mode)
+
+(defvar cider-scratch-mode-map
+  (let ((map (make-sparse-keymap)))
+    (set-keymap-parent map clojure-mode-map)
+    (define-key map (kbd "C-j") 'cider-eval-print-last-sexp)
+    map))
+
+(defconst cider-scratch-buffer-name "*cider-scratch*")
+
+;;;###autoload
+(defun cider-scratch ()
+  "Create a scratch buffer."
+  (interactive)
+  (pop-to-buffer (cider-find-or-create-scratch-buffer)))
+
+(defun cider-find-or-create-scratch-buffer ()
+  "Find or create the scratch buffer."
+  (or (get-buffer cider-scratch-buffer-name)
+      (cider-create-scratch-buffer)))
+
+(defun cider-create-scratch-buffer ()
+  "Create a new scratch buffer."
+  (with-current-buffer (get-buffer-create cider-scratch-buffer-name)
+    (clojure-mode)
+    (insert ";; This buffer is for Clojure experiments and evaluation.\n")
+    (insert ";; Press C-j to evaluate the last expression.")
+    (use-local-map cider-scratch-mode-map)
+    (current-buffer)))
+
+(provide 'cider-scratch)
+
+;; Local Variables:
+;; indent-tabs-mode: nil
+;; End:
+
+;;; cider-scratch.el ends here