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org-mode/lisp/ob-ebnf.el
2021-01-01 14:59:01 -05:00

82 lines
2.9 KiB
EmacsLisp

;;; ob-ebnf.el --- Babel Functions for EBNF -*- lexical-binding: t; -*-
;; Copyright (C) 2013-2021 Free Software Foundation, Inc.
;; Author: Michael Gauland
;; Keywords: literate programming, reproducible research
;; Homepage: https://orgmode.org
;; This file is part of GNU Emacs.
;; GNU Emacs 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.
;; GNU Emacs 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. If not, see <https://www.gnu.org/licenses/>.
;;; Commentary:
;; Org-Babel support for using ebnf2ps to generate encapsulated postscript
;; railroad diagrams. It recognizes 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 customize 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 (assq :file params)))
(dest-dir (file-name-directory dest-file))
(dest-root (file-name-sans-extension
(file-name-nondirectory dest-file)))
(style (cdr (assq :style params)))
(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