path: root/src/guile/skribilo/reader/outline.scm

;;; outline.scm  --  A reader for Emacs' outline syntax.
;;;
;;; Copyright 2006  Ludovic Court�s <ludovic.courtes@laas.fr>
;;;
;;;
;;; 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 2 of the License, 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 this program; if not, write to the Free Software
;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
;;; USA.

(define-module (skribilo reader outline)
  :use-module (skribilo utils syntax)
  :use-module (skribilo reader)
  :use-module (ice-9 optargs)
  :use-module (srfi srfi-11)

  :autoload   (ice-9 rdelim) (read-line)
  :autoload   (ice-9 regex) (make-regexp)

  :export (reader-specification
           make-outline-reader))

(fluid-set! current-reader %skribilo-module-reader)

;;; Author:  Ludovic Court�s
;;;
;;; Commentary:
;;;
;;; A reader for Emacs' outline-mode syntax.
;;;
;;; Code:

;;; TODO:
;;;
;;; - add source position information;
;;; - handle `blockquote' (indented paragraph);
;;; - handle sublists (indented lists) --- optional;
;;; - handle inline Skribe code: `\n{skribe\n(table (tr ... ))\n}\n'




;;;
;;; Tools.
;;;

(define (apply-any procs args)
  "Apply the procedure listed in @var{procs} to @var{args} until one of these
procedure returns true."
  (let loop ((procs procs))
    (if (null? procs)
	#f
	(let ((result (apply (car procs) args)))
	  (if result result (loop (cdr procs)))))))

(define (make-markup name body)
  "Return a clean markup form, i.e., an s-exp whose @code{car} is a symbol
equal to @var{name}, a markup name."
  (cond ((list? body)
	 (cond ((null? body) `(,name))
	       ((symbol? (car body)) `(,name ,body))
	       (else `(,name ,@body))))
	(else
	 (list name body))))


(define (append-trees . trees)
  "Append markup trees @var{trees}.  Trees whose car is a symbol (e.g.,
@code{(bold \"paf\")} will be considered as sub-trees of the resulting tree."
  (let loop ((trees trees)
	     (result '()))
    (if (null? trees)
	result
	(let ((tree (car trees)))
	  (loop (cdr trees)
		(append result
			(if (list? tree)
			    (cond ((null? tree) '())
				  ((symbol? (car tree)) (list tree))
				  (else tree))
			    (list tree))))))))

(define (null-string? s)
  (and (string? s) (string=? s "")))


(define empty-line-rx (make-regexp "^([[:space:]]*|;.*)$"))
(define (empty-line? s)
  "Return true if string @var{s} denotes an ``empty'' line, i.e., a blank
line or a line comment."
  (regexp-exec empty-line-rx s))



;;;
;;; In-line markup, i.e., markup that doesn't span over multiple lines.
;;;

(define %inline-markup
  ;; Note: the order matters because, for instance, URLs must be searched for
  ;; _before_ italics (`/italic/').
  `(("_([^_]+)_" .
     ,(lambda (m)
	(values (match:prefix m)                           ;; before
		(match:substring m 1)                      ;; body
		(match:suffix m)                           ;; after
		(lambda (body) `(emph ,body)))))           ;; process-body
    ("(f|ht)tp://[a-zA-Z0-9\\._~%/-]+" .
     ,(lambda (m)
	(values (match:prefix m)
		(match:substring m)
		(match:suffix m)
		(lambda (url) `(ref :url ,url)))))
    ("\\/([^\\/]+)\\/" .
     ,(lambda (m)
	(values (match:prefix m)
		(match:substring m 1)
		(match:suffix m)
		(lambda (body) `(it ,body)))))
    ("\\*([^\\*]+)\\*" .
     ,(lambda (m)
	(values (match:prefix m)
		(match:substring m 1)
		(match:suffix m)
		(lambda (body) `(bold ,body)))))
    ("``(([^`^'])+)''" .
     ,(lambda (m)
	(values (match:prefix m)
		(match:substring m 1)
		(match:suffix m)
		(lambda (body) `(q ,body)))))
    ("`(([^`^'])+)'" .
     ,(lambda (m)
	(values (match:prefix m)
		(match:substring m 1)
		(match:suffix m)
		(lambda (body) `(tt ,body)))))))

(define (make-markup-processor rx proc)
  (lambda (line)
    (let ((match (regexp-exec rx line)))
      (if match
	  (proc match)
	  #f))))

(define (make-line-processor markup-alist)
  "Returns a @dfn{line processor}.  A line processor is a procedure that
takes a string and returns a list."
  (let* ((markups (map (lambda (rx+proc)
			 (cons (make-regexp (car rx+proc) regexp/extended)
			       (cdr rx+proc)))
		       markup-alist))
	 (procs (map (lambda (rx+proc)
		       (make-markup-processor (car rx+proc) (cdr rx+proc)))
		     markups)))
    (lambda (line)
      (let self ((line line))
	;;(format #t "self: ~a~%" line)
	(cond ((string? line)
	       (let ((result (apply-any procs (list line))))
		 (if result
		     (let-values (((before body after proc-body)
				   result))
		       (let ((body+
			      (if (string=? (string-append before body after)
					    line)
				  body (self body))))
			 (if (and (null-string? before)
				  (null-string? after))
			     (proc-body body+)
			     (append-trees (self before)
					   (proc-body body+)
					   (self after)))))
		     line)))
	      (else
	       (error "line-processor: internal error" line)))))))

(define %line-processor
  (make-line-processor %inline-markup))



;;;
;;; Large-scale structures: paragraphs, chapters, sections, etc.
;;;

(define (process-paragraph line line-proc port)
  (let loop ((line line)
	     (result '()))
    (if (or (eof-object? line) (empty-line? line))
	(cons 'p result)
	(loop (read-line port)
	      (let ((line (line-proc line)))
		(append-trees result line "\n"))))))

(define (make-list-processor rx node-type extract-line-proc line-proc
			     end-of-node?)
  "Return a procedure (a @dfn{list processor}) that takes a line and a port
and returns an AST node of type @var{node-type} (a symbol, typically
@code{itemize} or @code{enumerate}) along with a line.  If the processor is
not triggered, i.e., it is passed a line that does not match @var{rx}, then
it returns @code{#f}."
  (lambda (line port)
    (let ((match (regexp-exec rx line)))
      (if (not match)
	  #f
	  (let loop ((line line)
		     (contiguous-empty-lines 0)
		     (item '())
		     (body '()))
	      (if (eof-object? line)
		  (let ((body (if (null? item)
				  body
				  (cons `(item ,@(reverse! item)) body))))
		    (values line `(,node-type ,@(reverse! body))))
		  (let ((match (regexp-exec rx line)))
		    (cond (match
			   ;; reading the first line of an item
			   (loop (read-line port) 0
				 (append-trees
				  (line-proc (extract-line-proc match)))
				 body))

			  ((and (procedure? end-of-node?)
				(end-of-node? line))
			   (values line
				   `(,node-type ,@(reverse! body))))

			  ((empty-line? line)
			   (cond ((>= contiguous-empty-lines 1)
				  ;; end of list
				  (values line
					  `(,node-type ,@(reverse! body))))

				 ((= contiguous-empty-lines 0)
				  ;; end of item: add ITEM to BODY
				  (loop (read-line port) 1 '()
					(cons (make-markup 'item item)
					      body)))

				 (else
				  ;; skipping empty line
				  (loop (read-line port)
					(+ 1 contiguous-empty-lines)
					item body))))

			  (else
			   ;; reading an item: add LINE to ITEM
			   (loop (read-line port) 0
				 (append-trees item (line-proc line))
				 body))))))))))

(define (make-node-processor rx node-type title-proc line-proc
			     subnode-procs end-of-node?)
  "Return a procedure that reads the given string and return an AST node of
type @var{node-type} or @code{#f}.  When the original string matches the node
header, then the rest of the node is read from @var{port}.
@var{subnode-procs} is a list of node processors for node types subordinate
to @var{node-type}."
  (lambda (line port)
    (let ((match (regexp-exec rx line)))
      (if (not match)
	  #f
	  (let ((title (line-proc (title-proc match))))
	    (let loop ((line (read-line port))
		       (body '()))

	      (let ((subnode (and (not (eof-object? line))
				  (apply-any subnode-procs
					     (list line port)))))
		(cond (subnode
		       (let-values (((line node) subnode))
			 (loop line (cons node body))))

		      ((or (eof-object? line)
			   (regexp-exec rx line)
			   (and (procedure? end-of-node?)
				(end-of-node? line)))
		       (values line
			       `(,node-type :title ,title ,@(reverse! body))))

		      ((empty-line? line)
		       (loop (read-line port) body))

		      (else
			   (let ((par (process-paragraph line line-proc port)))
			     (loop (read-line port)
				   (cons par body))))))))))))


(define (node-markup-line? line)
  (define node-rx (make-regexp "^\\*+ (.+)$" regexp/extended))
  (regexp-exec node-rx line))

(define %list-processors
  (list (make-list-processor (make-regexp "^[-~o] (.+)$" regexp/extended)
			     'itemize
			     (lambda (m) (match:substring m 1))
			     %line-processor
			     node-markup-line?)
	(make-list-processor (make-regexp "^([0-9]+)\\.? (.+)$"
					  regexp/extended)
			     'enumerate
			     (lambda (m) (match:substring m 2))
			     %line-processor
			     node-markup-line?)))

(define %node-processors
  (let* ((subsubsection-proc
	  (make-node-processor (make-regexp "^\\*\\*\\*\\* (.+)$"
					    regexp/extended)
			       'subsection
			       (lambda (m) (match:substring m 1))
			       %line-processor
			       %list-processors ;; no further subnodes
			       node-markup-line?))
	 (subsection-proc
	  (make-node-processor (make-regexp "^\\*\\*\\* (.+)$"
					    regexp/extended)
			       'subsection
			       (lambda (m) (match:substring m 1))
			       %line-processor
			       (append %list-processors
				       (list subsubsection-proc))
			       node-markup-line?))
	 (section-proc
	  (make-node-processor (make-regexp "^\\*\\* (.+)$" regexp/extended)
			       'section
			       (lambda (m) (match:substring m 1))
			       %line-processor
			       (append %list-processors
				       (list subsection-proc))
			       node-markup-line?)))
    (list (make-node-processor (make-regexp "^\\* (.+)$" regexp/extended)
			       'chapter
			       (lambda (m) (match:substring m 1))
			       %line-processor
			       (append %list-processors
				       (list section-proc))
			       #f))))




;;;
;;; The top-level parser.
;;;

(define (make-document-processor node-procs line-proc)
  (lambda (line port)
    (let self ((line line)
	       (doc '()))
      ;;(format #t "doc-proc: ~a~%" line)
      (if (eof-object? line)
	  (if (null? doc)
	      line
	      (reverse! doc))
	  (if (empty-line? line)
	      (self (read-line port) doc)
	      (let ((result (apply-any node-procs (list line port))))
		(if result
		    (let-values (((line node) result))
		      (self line (cons node doc)))
		    (let ((par (process-paragraph line line-proc port)))
		      (self (read-line port)
			    (cons par doc))))))))))


(define* (outline-reader :optional (port (current-input-port)))
  (define modeline-rx
    (make-regexp "^[[:space:]]*-\\*- [a-zA-Z-]+ -\\*-[[:space:]]*$"))
  (define title-rx (make-regexp "^[Tt]itle: (.+)$" regexp/extended))
  (define author-rx (make-regexp "^[Aa]uthor: (.+)$" regexp/extended))

  (let ((doc-proc (make-document-processor %node-processors %line-processor)))

    (let loop ((title #f)
	       (author #f)
	       (line (read-line port)))

      (if (eof-object? line)
	  (if (or title author)
	      `(document :title ,title :author (author :name ,author) '())
	      line)
	  (if (or (empty-line? line)
		  (regexp-exec modeline-rx line))
	      (loop title author (read-line port))
	      (let ((title-match (regexp-exec title-rx line)))
		(if title-match
		    (loop (match:substring title-match 1)
			  author (read-line port))
		    (let ((author-match (regexp-exec author-rx line)))
		      (if author-match
			  (loop title (match:substring author-match 1)
				(read-line port))

			  ;; Let's go.
			  `(document :title ,title
				     :author (author :name ,author)
				     ,@(doc-proc line port)))))))))))


(define* (make-outline-reader :optional (version "0.1"))
  outline-reader)



;;; The reader specification.

(define-reader outline "0.1" make-outline-reader)


;;; arch-tag: 53473e73-c811-4eed-a0b4-22ada4d6ef08

;;; outline.scm ends here