;;; litorgy-R.el --- litorgy functions for R code evaluation

;; Copyright (C) 2009 Eric Schulte, Dan Davison, Austin F. Frank

;; Author: Eric Schulte, Dan Davison, Austin F. Frank
;; 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:

;; Litorgy support for evaluating R code

;;; Code:
(require 'litorgy)

(litorgy-add-interpreter "R")

(defun litorgy-execute:R (body params)
  "Execute a block of R code with litorgy.  This function is
called by `litorgy-execute-src-block'."
  (let (results)
    (message "executing R code block...")
    (litorgy-initiate-R-buffer)
    (mapc (lambda (line) (litorgy-R-input-command line)) (butlast (split-string body "[\r\n]")))
    (litorgy-R-last-output)))

;; Maybe the following be replaced with a method using `ess-execute',
;; I went with the following functions because I wrote them and they
;; are what I know
;;
;; (not the best reasons for making design decisions)

(defvar litorgy-R-buffer nil
  "Holds the buffer for the current R process")

(defun litorgy-initiate-R-buffer ()
  "If there is not a current R process then create one."
  (unless (and (buffer-live-p litorgy-R-buffer) (get-buffer litorgy-R-buffer))
    (save-excursion
      (R)
      (setf litorgy-R-buffer (current-buffer))
      (litorgy-R-wait-for-output)
      (litorgy-R-input-command ""))))

(defun litorgy-R-command-to-string (command)
  "Send a command to R, and return the results as a string."
  (litorgy-R-input-command command)
  (litorgy-R-last-output))

(defun litorgy-R-input-command (command)
  "Pass COMMAND to the R process running in `litorgy-R-buffer'."
  (save-excursion
    (save-match-data
      (set-buffer litorgy-R-buffer)
      (goto-char (process-mark (get-buffer-process (current-buffer))))
      (insert command)
      (comint-send-input)
      (litorgy-R-wait-for-output))))

(defun litorgy-R-wait-for-output ()
  "Wait until output arrives"
  (save-excursion
    (save-match-data
      (set-buffer litorgy-R-buffer)
      (while (progn
	       (goto-char comint-last-input-end)
	       (not (re-search-forward comint-prompt-regexp nil t)))
	(accept-process-output (get-buffer-process (current-buffer)))))))

(defun litorgy-R-last-output ()
  "Return the last R output as a string"
  (save-excursion
    (save-match-data
      (set-buffer litorgy-R-buffer)
      (goto-char (process-mark (get-buffer-process (current-buffer))))
      (forward-line 0)
      (let ((raw (buffer-substring comint-last-input-end (- (point) 1))))
	(if (string-match "\n" raw)
	    raw
	  (and (string-match "\\[[[:digit:]+]\\] *\\(.*\\)$" raw)
	       (message raw)
	       (message (match-string 1 raw))
	       (match-string 1 raw)))))))

(provide 'litorgy-R)
;;; litorgy-R.el ends here