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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:
+;; 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
+;; 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