;;; ob-ebnf.el --- Babel Functions for EBNF -*- lexical-binding: t; -*-
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;; Copyright (C) 2013-2018 Free Software Foundation, Inc.
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;; Author: Michael Gauland
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;; Keywords: literate programming, reproducible research
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;; Homepage: https://orgmode.org
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;; Version: 1.00
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;; This file is part of GNU Emacs.
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;; GNU Emacs is free software: you can redistribute it and/or modify
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;; it under the terms of the GNU General Public License as published by
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;; the Free Software Foundation, either version 3 of the License, or
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;; (at your option) any later version.
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;; GNU Emacs is distributed in the hope that it will be useful,
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;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;; GNU General Public License for more details.
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;; You should have received a copy of the GNU General Public License
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;; along with GNU Emacs. If not, see <https://www.gnu.org/licenses/>.
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;;; Commentary:
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;;; Org-Babel support for using ebnf2ps to generate encapsulated postscript
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;;; railroad diagrams. It recognizes these arguments:
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;;;
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;;; :file is required; it must include the extension '.eps.' All the rules
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;;; in the block will be drawn in the same file. This is done by
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;;; inserting a '[<file>' comment at the start of the block (see the
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;;; documentation for ebnf-eps-buffer for more information).
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;;;
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;;; :style specifies a value in ebnf-style-database. This provides the
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;;; ability to customize the output. The style can also specify the
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;;; grammar syntax (by setting ebnf-syntax); note that only ebnf,
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;;; iso-ebnf, and yacc are supported by this file.
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;;; Requirements:
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;;; Code:
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(require 'ob)
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(require 'ebnf2ps)
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;; optionally declare default header arguments for this language
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(defvar org-babel-default-header-args:ebnf '((:style . nil)))
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;; Use ebnf-eps-buffer to produce an encapsulated postscript file.
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;;
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(defun org-babel-execute:ebnf (body params)
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"Execute a block of Ebnf code with org-babel. This function is
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called by `org-babel-execute-src-block'"
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(save-excursion
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(let* ((dest-file (cdr (assq :file params)))
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(dest-dir (file-name-directory dest-file))
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(dest-root (file-name-sans-extension
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(file-name-nondirectory dest-file)))
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(style (cdr (assq :style params)))
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(result nil))
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(with-temp-buffer
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(when style (ebnf-push-style style))
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(let ((comment-format
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(cond ((string= ebnf-syntax 'yacc) "/*%s*/")
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((string= ebnf-syntax 'ebnf) ";%s")
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((string= ebnf-syntax 'iso-ebnf) "(*%s*)")
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(t (setq result
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(format "EBNF error: format %s not supported."
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ebnf-syntax))))))
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(setq ebnf-eps-prefix dest-dir)
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(insert (format comment-format (format "[%s" dest-root)))
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(newline)
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(insert body)
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(newline)
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(insert (format comment-format (format "]%s" dest-root)))
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(ebnf-eps-buffer)
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(when style (ebnf-pop-style))))
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result)))
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(provide 'ob-ebnf)
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;;; ob-ebnf.el ends here
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