org-mode/contrib/babel/lisp/org-babel-ref.el

;;; org-babel-ref.el --- org-babel functions for referencing external data

;; Copyright (C) 2009 Eric Schulte, Dan Davison

;; Author: Eric Schulte, Dan Davison
;; Keywords: literate programming, reproducible research
;; Homepage: http://orgmode.org
;; Version: 0.01

;;; 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
;; 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; see the file COPYING.  If not, write to the
;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
;; Boston, MA 02110-1301, USA.

;;; Commentary:

;; Functions for referencing data from the header arguments of a
;; org-babel block.  The syntax of such a reference should be
;;
;;   #+VAR: variable-name=file:resource-id
;;
;; - variable-name :: the name of the variable to which the value
;;                    will be assigned
;;                    
;; - file :: path to the file containing the resource, or omitted if
;;           resource is in the current file
;;
;; - resource-id :: the id or name of the resource
;;
;; So an example of a simple src block referencing table data in the
;; same file would be
;;
;;  #+TBLNAME: sandbox
;;  | 1 |       2 | 3 |
;;  | 4 | org-babel | 6 |
;;
;;  #+begin_src emacs-lisp :var table=sandbox
;;  (message table)
;;  #+end_src
;;

;;; Code:
(require 'org-babel)

(defun org-babel-ref-variables (params)
  "Takes a parameter alist, and return an alist of variable
names, and the emacs-lisp representation of the related value."
  (let ((assignments
	 (delq nil (mapcar (lambda (pair) (if (eq (car pair) :var) (cdr pair))) params)))
	(others
         (delq nil (mapcar (lambda (pair) (unless (eq :var (car pair)) pair)) params))))
    (mapcar (lambda (assignment) (org-babel-ref-parse assignment)) assignments)))

(defvar org-babel-ref-split-regexp
  "[ \f\t\n\r\v]*\\(.+?\\)[ \f\t\n\r\v]*=[ \f\t\n\r\v]*\\(.+\\)[ \f\t\n\r\v]*")

(defun org-babel-ref-parse (assignment &optional params)
  "Parse a variable ASSIGNMENT in a header argument.  If the
right hand side of the assignment has a literal value return that
value, otherwise interpret as a reference to an external resource
and find it's value using `org-babel-ref-resolve-reference'.
Return a list with two elements.  The first element of the list
will be the name of the variable, and the second will be an
emacs-lisp representation of the value of the variable."
  (if (string-match org-babel-ref-split-regexp assignment)
      (let ((var (match-string 1 assignment))
            (ref (match-string 2 assignment)))
        (cons (intern var)
              (or (org-babel-ref-literal ref)
                  (org-babel-ref-resolve-reference ref params))))))

(defun org-babel-ref-literal (ref)
  "Determine if the right side of a header argument variable
assignment is a literal value or is a reference to some external
resource.  If REF is literal then return it's value, otherwise
return nil."
  (let ((out (org-babel-read ref)))
    (if (equal out ref)
        (if (string-match "^\".+\"$" ref)
            (read ref))
      out)))

(defun org-babel-ref-resolve-reference (ref &optional params)
  "Resolve the reference and return its value"
  (save-excursion
    (let ((case-fold-search t)
          type args new-refere new-referent result lob-info split-file split-ref
          index index-row index-col)
      ;; if ref is indexed grab the indices
      (when (string-match "\\[\\(.+\\)\\]" ref)
        (setq index (match-string 1 ref))
        (setq ref (substring ref 0 (match-beginning 0))))
      ;; assign any arguments to pass to source block
      (when (string-match "^\\(.+?\\)\(\\(.*\\)\)$" ref)
        (setq new-refere (match-string 1 ref))
        (setq new-referent (match-string 2 ref))
        ;; (message "new-refere=%S, new-referent=%S" new-refere new-referent) ;; debugging
        (when (> (length new-refere) 0)
          (if (> (length new-referent) 0)
              (setq args (mapcar (lambda (ref) (cons :var ref))
                                 (org-babel-ref-split-args new-referent))))
          ;; (message "args=%S" args) ;; debugging
          (setq ref new-refere)))
      (when (string-match "^\\(.+\\):\\(.+\\)$" ref)
        (setq split-file (match-string 1 ref))
        (setq split-ref (match-string 2 ref))
        (find-file split-file) (setq ref split-ref))
      (goto-char (point-min))
      (if (let ((result_regexp (concat "^#\\+\\(TBLNAME\\|RESNAME\\|RESULTS\\):[ \t]*"
                                       (regexp-quote ref) "[ \t]*$"))
                (regexp (concat org-babel-source-name-regexp
                                (regexp-quote ref) "\\(\(.*\)\\)?" "[ \t]*$")))
            ;; goto ref in the current buffer
            (or (and (not args)
                     (or (re-search-forward result_regexp nil t)
                         (re-search-backward result_regexp nil t)))
                (re-search-forward regexp nil t)
                (re-search-backward regexp nil t)
                ;; check the Library of Babel
                (setq lob-info (cdr (assoc (intern ref) org-babel-library-of-babel)))))
          (unless lob-info (goto-char (match-beginning 0)))
        ;; ;; TODO: allow searching for names in other buffers
        ;; (setq id-loc (org-id-find ref 'marker)
        ;;       buffer (marker-buffer id-loc)
        ;;       loc (marker-position id-loc))
        ;; (move-marker id-loc nil)
        (progn (message (format "reference '%s' not found in this buffer" ref))
               (error (format "reference '%s' not found in this buffer" ref))))
      (if lob-info
          (setq type 'lob)
        (while (not (setq type (org-babel-ref-at-ref-p)))
          (forward-line 1)
          (beginning-of-line)
          (if (or (= (point) (point-min)) (= (point) (point-max)))
              (error "reference not found"))))
      (setq params (org-babel-merge-params params args '((:results . "silent"))))
      (setq result
	    (case type
	      ('results-line (org-babel-read-result))
	      ('table (org-babel-read-table))
              ('file (org-babel-read-file))
	      ('source-block (org-babel-execute-src-block nil nil params))
	      ('lob (org-babel-execute-src-block nil lob-info params))))
      (if (symbolp result)
          (format "%S" result)
        (if (and index (listp result))
            (org-babel-ref-index-list index result)
          result)))))

(defun org-babel-ref-index-list (index lis)
  "Return the subset of LIS indexed by INDEX.  If INDEX is
separated by ,s then each PORTION is assumed to index into the
next deepest nesting or dimension.  A valid PORTION can consist
of either an integer index, or two integers separated by a : in
which case the entire range is returned."
  (if (string-match "^,?\\([^,]+\\)" index)
      (let ((length (length lis))
            (portion (match-string 1 index))
            (remainder (substring index (match-end 0))))
        (flet ((wrap (num) (if (< num 0) (+ length num) num)))
          (mapcar
           (lambda (sub-lis) (org-babel-ref-index-list remainder sub-lis))
           (if (string-match "\\(\\([-[:digit:]]+\\):\\([-[:digit:]]+\\)\\|\*\\)"
                             portion)
               (mapcar (lambda (n) (nth n lis))
                       (apply 'number-sequence
                              (if (match-string 2 portion)
                                  (list
                                   (wrap (string-to-number (match-string 2 portion)))
                                   (wrap (string-to-number (match-string 3 portion))))
                                (list (wrap 0) (wrap -1)))))
             (list (nth (wrap (string-to-number portion)) lis))))))
    lis))

(defun org-babel-ref-split-args (arg-string)
  "Split ARG-STRING into top-level arguments of balanced parenthesis."
  (let ((index 0) (depth 0) (buffer "") holder return)
    ;; crawl along string, splitting at any ","s which are on the top level
    (while (< index (length arg-string))
      (setq holder (substring arg-string index (+ 1 index)))
      (setq buffer (concat buffer holder))
      (setq index (+ 1 index))
      (cond
       ((string= holder ",")
        (when (= depth 0)
          (setq return (reverse (cons (substring buffer 0 -1) return)))
          (setq buffer "")))
       ((or (string= holder "(") (string= holder "[")) (setq depth (+ depth 1)))
       ((or (string= holder ")") (string= holder "]")) (setq depth (- depth 1)))))
    (mapcar #'org-babel-trim (reverse (cons buffer return)))))

(defun org-babel-ref-at-ref-p ()
  "Return the type of reference located at point or nil if none
of the supported reference types are found.  Supported reference
types are tables and source blocks."
  (cond ((org-at-table-p) 'table)
        ((looking-at "^#\\+BEGIN_SRC") 'source-block)
        ((looking-at org-bracket-link-regexp) 'file)
        ((looking-at org-babel-result-regexp) 'results-line)))

(provide 'org-babel-ref)
;;; org-babel-ref.el ends here