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+;;; ob-ebnf.el --- org-babel functions for ebnf evaluation
+
+;; Copyright (C) 2013 Free Software Foundation, Inc.
+
+;; Author: Michael Gauland
+;; Keywords: literate programming, reproducible research
+;; Homepage: http://orgmode.org
+;; Version: 1.00
+
+;;; License:
+
+;; 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, 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 GNU Emacs; see the file COPYING.  If not, write to the
+;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+;; Boston, MA 02110-1301, USA.
+
+;;; Commentary:
+
+;;; Org-Babel support for using ebnf2ps to generate encapsulated postscript
+;;; railroad diagrams. It recogises these arguments:
+;;;
+;;;     :file is required; it must include the extension '.eps.' All the rules
+;;;           in the block will be drawn in the same file. This is done by
+;;;           inserting a '[<file>' comment at the start of the block (see the
+;;;           documentation for ebnf-eps-buffer for more information).
+;;;
+;;;     :style specifies a value in ebnf-style-database. This provides the
+;;;            ability to customise the output. The style can also specify the
+;;;            grammar syntax (by setting ebnf-syntax); note that only ebnf,
+;;;            iso-ebnf, and yacc are supported by this file.
+
+;;; Requirements:
+
+;;; Code:
+(require 'ob)
+(require 'ebnf2ps)
+
+;; optionally declare default header arguments for this language
+(defvar org-babel-default-header-args:ebnf '((:style . nil)))
+
+;; Use ebnf-eps-buffer to produce an encapsulated postscript file.
+;;
+(defun org-babel-execute:ebnf (body params)
+  "Execute a block of Ebnf code with org-babel.  This function is
+called by `org-babel-execute-src-block'"
+  (save-excursion
+    (let* ((dest-file (cdr (assoc :file params)))
+	   (dest-dir (file-name-directory dest-file))
+	   (dest-root (file-name-sans-extension
+		       (file-name-nondirectory dest-file)))
+           (dest-ext  (file-name-extension dest-file))
+	   (style (cdr (assoc :style params)))
+	   (current-dir default-directory)
+	   (result nil))
+      (with-temp-buffer
+	(when style (ebnf-push-style style))
+	(let ((comment-format
+	       (cond ((string= ebnf-syntax 'yacc) "/*%s*/")
+		     ((string= ebnf-syntax 'ebnf) ";%s")
+		     ((string= ebnf-syntax 'iso-ebnf) "(*%s*)")
+		     (t (setq result
+			      (format "EBNF error: format %s not supported."
+				      ebnf-syntax))))))
+	  (setq ebnf-eps-prefix dest-dir)
+	  (insert (format comment-format (format "[%s" dest-root)))
+	  (newline)
+	  (insert body)
+	  (newline)
+	  (insert (format comment-format (format "]%s" dest-root)))
+	  (ebnf-eps-buffer)
+	  (when style (ebnf-pop-style))))
+      result)))
+
+(provide 'ob-ebnf)
+;;; ob-ebnf.el ends here