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;;; *0 peano.el --- Giuseppe Peano-style document structure
;; _ __ ___ __ _ _ __ ___
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;; | |_) | __/ (_| | | | | (_) |
;; | .__/ \___|\__,_|_| |_|\___/
;; |_|
;; Copyright (C) 2007 Dave O'Toole
;; Author: Dave O'Toole <>
;; Package-Version: 0.01
;; Version: $Id: peano.el,v 1.1 2007/09/20 20:35:01 dto Exp dto $
;; Time-stamp: <2007-09-22 00:01:36 dto>
;; Keywords: outlines, convenience, tools
;; This file 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 file 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.
;;; *1 Preface
;; Giuseppe Peano (1858-1932) was a mathematician and philosopher.
;; The subject of this essay is not really him, but rather one in
;; particular of his many notational ideas.
;; If you want to learn more about Peano himself, I suggest starting
;; with the wikipedia page about him:
;;; *1.1 Status
;; Pre-alpha release.
;;; *2 Overview
;; Peano was a prolific writer of mathematical papers and books. In
;; order to keep everything organized, he invented a universal scheme
;; for numbering and indexing the sections, paragraphs, formulae,
;; figures, and other components of an arbitrarily long and complex
;; document. His system was later adopted by Bertrand Russell and
;; Alfred North Whitehead for their "Principia Mathematica", and also
;; by Wittgenstein for his 1921 "Tractatus Logico-Philisophicus".
;;; *2.1
;; This file implements an Emacs minor mode that can automatically
;; number, cross-reference, and browse any kind of plain-text document
;; in an extended version of the Principia Mathematica addressing
;; system. Optional font-locking is provided for the notation.
;;; *2.2
;; This file is (as you may already suspect) organized according to
;; the system it implements. To try it out, evaluate this file or put
;; it in your load-path and do
;; (require 'peano)
;; Then do M-x peano-mode RET to view the source code.
;;; *3 Document Structure
;; A document is a plain text file divided into short "blocks". A
;; block consists of a formatted header line, followed by zero or more
;; lines of any text whatsoever. Blank lines in the file are ignored.
;;; *3.1 Block Numbers
;; Every block is assigned a unique decimal number such as 3.1 or
;; 1.256. Unlike the typical LaTeX numbering system, in which creating
;; a new section can cause subsequent section numbers to change, here
;; we use decimals so that it is always possible to insert new blocks
;; between others without changing their numbers.
;;; *3.11
;; This last step is important; we can annotate any block by inserting
;; a new block immediately following the first, and annotate the
;; annotations ad infinitum. Furthermore we can use the number as a
;; unnique and permanent identifier for the block. This simplifies the
;; cross-referencing of documents and imposes a consistent structure.
;;; *3.2 Header Formatting
;; A header line consists of a prefix string, followed by a block
;; number, and then finally an optional label. All three are
;; separated from one another by single spaces. The entire header line
;; is part of the block.
;;; *3.21 Prefix String
;; The prefix string may be any string matching the local
;; `outline-regexp'; this makes it easy to use `orgstruct-mode' to
;; obtain folded overviews, navigation, and structure editing.
;;; *3.22 Block Number Formatting
;; Block numbers are always written in base-10, prefixed with an
;; asterisk, like this: *7.2 The decimal point may be ommitted in the
;; case of whole numbers.
;;; *3.23 Labels
;; The label extends to the end of the header line. Labels are
;; subject to change, and therefore do not identify blocks---only the
;; numbers do.
;;; *3.3 Chapters
;; The only other unit of document organization provided by this
;; system is the "chapter". A chapter is a series of blocks whose
;; numbers are in increasing order. The integer part of a block
;; number identifies the chapter it belongs to. We write *1 to refer
;; to the first chapter, *2 for the second, and so on.
;;; *3.4 Notes
;; Notes and other optional readings are written in-line, and are
;; marked with two asterisks before the number instead of one. There
;; are no footnotes or endnotes of any kind.
;;; *3.5 Appendices
;; Numbers of appendices are prefixed with *A instead of * or **. All
;; the *A numbers must follow all the * and ** numbers; this ensures
;; that a document's body can grow without limit using all available
;; numbers, while still keeping all the appendices at the end of the
;; document.
;;; *3.6 Preamble
;; Any text before the first block in a file is ignored.
;;; *3.7 Postamble
;; After the appendices, the optional last section in a document is
;; called *Z. A header line whose number is *Z begins a block
;; containing the rest of the file.
;;; *3.71
;; So *0 and *Z are the like the covers of a book, and are also useful
;; when you need to put some text at the beginning or at the end of a
;; file for technical reasons (i.e. file-local variables.)
;;; **3.99 Additional Conventions
;; These are optional.
;;; **3.991
;; Chapter *0 should contain authorship and copyright information, and
;; any needed tags or preamble text (such as those used in the Emacs
;; Lisp coding standards.) The label should be of the form:
;; filename.extension --- short description of contents
;; TODO provide custom auto-insert-mode
;;; **3.992
;; Chapter *1 should introduce the work to the reader and provide an
;; overview of its contents. Within *1, The following block names are
;; standardized:
;; Overview
;; Conventions
;; History
;; Status
;; Installation
;; Roadmap
;; Other names are ignored.
;;; **3.993
;; Chapter *Z may contain notes, local variables for Emacs, or other
;; text.
;;; **3.994
;; In a living document there are always things to do. The string
;; "TODO " makes the rest of the line into the text of a todo-list
;; item. Other such "annotations" may be added in the future.
;;; *4 Requirements
(require 'cl)
(require 'rx)
(require 'org)
(require 'font-lock)
;;; *5 Headers
;;; *5.1 Syntax
(defvar peano-header-regexp "" "Regular expression matching headers."))
(defun peano-set-header-regexp ()
"Set `peano-header-regexp' to its canonical value."
(setf peano-header-regexp
(rx (sequence space "*"
;; 1. type symbol
(group (zero-or-one (any "ZA*")))
;; 2. block number
;; 3. chapter
(group (zero-or-more digit))
(zero-or-one "."
;; 4. verse
(zero-or-more digit)))
(zero-or-one space
;; 5. label
(group (zero-or-more not-newline)))
;;; *5.1 Parsing Headers
(defun* peano-read-next-header (&optional &key bound backward)
"Return a property list with data from the next header.
Return nil if there is no next header. Point is left where
the search leaves it."
(let ((search-function (if backward
(when (funcall search-function peano-header-regexp bound :noerror)
(labels ((group (n)
(match-string-no-properties n))
(ngroup (n)
(let ((s (group n)))
(if (stringp s)
(string-to-number s)
(goto-char (point-at-eol))
(list :type-symbol (group 1)
:block-number (ngroup 2)
:chapter (ngroup 3)
:verse (ngroup 4)
:label (group 5))))))
;;; *5.2 Formatting Headers
;; TODO Finish this
(defvar peano-header-prefix nil "Prefix to use when inserting headers"))
(defun* peano-insert-header (&key (block-number
(format "%d.%d"
chapter verse)))
(when (not (stringp peano-header-prefix))
(error "You must set `peano-header-prefix' before inserting headers."))
(insert peano-header-prefix " *")
(when type-symbol
(insert type-symbol))
(when chapter
(insert (number-to-string chapter))
(when verse
(insert (concat "."
(number-to-string verse)))))
(when label
(insert (concat " " label))))
;;; *5.3 Interactive Commands for Headers
;; (defun peano-chapter-and-verse (chapter verse type)
;; (let* ((chapter-string (number-to-string chapter))
;; (verse-string (number-to-string verse))
;; (new-verse-maybe (+ 1 verse))
;; (new-verse (if (> (length (number-to-string new-verse-maybe))
;; (length verse-string))
;; (+ 1 (* 10 verse))
;; new-verse-maybe)))
;; (case type
;; (:sibling (list chapter (+ 1 verse)))
;; (:child (list chapter
;; TODO add 1 to verse if it's a sibling,
;; TODO append "1" to verse-string if it's a child
(defun peano-insert-sibling ()
"Insert a sibling header following the current block."
(let ((block-info
(peano-read-next-header :backward t)))
(when (null block-info)
(error "Cannot insert sibling; no previous header."))
(destructuring-bind (&key chapter verse &allow-other-keys)
(insert "\n")
(peano-insert-header :chapter chapter :verse (+ 1 verse)))
(insert "\n")))
;;; *5.5
;(defun peano-insert-child
(defun org-cycle-global ()
(org-cycle t))
(defun org-cycle-local ()
(move-beginning-of-line nil)
;; TODO standardized keybindings for minor mode: M-_
;; (global-set-key (kbd "M-[") 'org-cycle-global)
;; (global-set-key (kbd "M-]") 'org-cycle-local)
;; (add-hook 'emacs-lisp-mode-hook #'orgstruct-mode)
;;;; Fontifying todo items outside of org-mode
(defface todo-comment-face '((t (:background "red" :foreground "yellow" :weight bold :bold t))) "Face for TODO in code buffers.")
(defvar todo-comment-face 'todo-comment-face)
(defun fontify-todo ()
(font-lock-add-keywords nil '(("\\<\\(TODO\\)\\>"
(1 todo-comment-face t)))))
(add-hook 'emacs-lisp-mode-hook #'fontify-todo)
(defface headline-face '((t (:foreground "white" :underline "white" :background "navyblue"))) "Face for headlines.")
(defvar headline-face 'headline-face)
(defun fontify-headline ()
(font-lock-add-keywords nil '(("^;;;;* \\(.*\\)\\>"
(1 headline-face t)))))
(add-hook 'emacs-lisp-mode-hook #'fontify-headline)
;;; *Z
;;; **10.1 Glyphs
(defface eon-form-feed-face
'((t (:foreground "white" :background "blue" :bold
t :weight bold :underline "red")))
"Face for form-feed characters.")
(defvar eon-form-feed-face 'eon-form-feed-face)
;; TODO fix this stuff
(defun eon-do-glyphs ()
"Highlight certain characters."
(let ((form-feed (make-glyph-code ? 'eon-form-feed-face)))
(aset standard-display-table ?\^L (vector form-feed))))
;; Local Variables:
;; peano-header-prefix: ";;;"
;; End:
(provide 'peano)
;;; peano.el ends here
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