lisp/ob-tangle.el

   1 ;;; ob-tangle.el --- extract source code from org-mode files
   2
   3 ;; Copyright (C) 2009-2016 Free Software Foundation, Inc.
   4
   5 ;; Author: Eric Schulte
   6 ;; Keywords: literate programming, reproducible research
   7 ;; Homepage: http://orgmode.org
   8
   9 ;; This file is part of GNU Emacs.
  10
  11 ;; GNU Emacs is free software: you can redistribute it and/or modify
  12 ;; it under the terms of the GNU General Public License as published by
  13 ;; the Free Software Foundation, either version 3 of the License, or
  14 ;; (at your option) any later version.
  15
  16 ;; GNU Emacs is distributed in the hope that it will be useful,
  17 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  18 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19 ;; GNU General Public License for more details.
  20
  21 ;; You should have received a copy of the GNU General Public License
  22 ;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
  23
  24 ;;; Commentary:
  25
  26 ;; Extract the code from source blocks out into raw source-code files.
  27
  28 ;;; Code:
  29 (require 'org-src)
  30
  31 (declare-function make-directory "files" (dir &optional parents))
  32 (declare-function org-at-heading-p "org" (&optional ignored))
  33 (declare-function org-babel-update-block-body "ob-core" (new-body))
  34 (declare-function org-back-to-heading "org" (&optional invisible-ok))
  35 (declare-function org-before-first-heading-p "org" ())
  36 (declare-function org-edit-special "org" (&optional arg))
  37 (declare-function org-element-at-point "org-element" ())
  38 (declare-function org-element-type "org-element" (element))
  39 (declare-function org-fill-template "org" (template alist))
  40 (declare-function org-heading-components "org" ())
  41 (declare-function org-in-commented-heading-p "org" (&optional no-inheritance))
  42 (declare-function org-link-escape "org" (text &optional table merge))
  43 (declare-function org-open-link-from-string "org" (s &optional arg reference-buffer))
  44 (declare-function org-store-link "org" (arg))
  45 (declare-function org-string-nw-p "org-macs" (s))
  46 (declare-function outline-previous-heading "outline" ())
  47
  48 (defvar org-link-types-re)
  49
  50 (defcustom org-babel-tangle-lang-exts
  51   '(("emacs-lisp" . "el")
  52     ("elisp" . "el"))
  53   "Alist mapping languages to their file extensions.
  54 The key is the language name, the value is the string that should
  55 be inserted as the extension commonly used to identify files
  56 written in this language.  If no entry is found in this list,
  57 then the name of the language is used."
  58   :group 'org-babel-tangle
  59   :version "24.1"
  60   :type '(repeat
  61           (cons
  62            (string "Language name")
  63            (string "File Extension"))))
  64
  65 (defcustom org-babel-tangle-use-relative-file-links t
  66   "Use relative path names in links from tangled source back the Org-mode file."
  67   :group 'org-babel-tangle
  68   :type 'boolean)
  69
  70 (defcustom org-babel-post-tangle-hook nil
  71   "Hook run in code files tangled by `org-babel-tangle'."
  72   :group 'org-babel
  73   :version "24.1"
  74   :type 'hook)
  75
  76 (defcustom org-babel-pre-tangle-hook '(save-buffer)
  77   "Hook run at the beginning of `org-babel-tangle'."
  78   :group 'org-babel
  79   :version "24.1"
  80   :type 'hook)
  81
  82 (defcustom org-babel-tangle-body-hook nil
  83   "Hook run over the contents of each code block body."
  84   :group 'org-babel
  85   :version "24.1"
  86   :type 'hook)
  87
  88 (defcustom org-babel-tangle-comment-format-beg "[[%link][%source-name]]"
  89   "Format of inserted comments in tangled code files.
  90 The following format strings can be used to insert special
  91 information into the output using `org-fill-template'.
  92 %start-line --- the line number at the start of the code block
  93 %file --------- the file from which the code block was tangled
  94 %link --------- Org-mode style link to the code block
  95 %source-name -- name of the code block
  96
  97 Upon insertion the formatted comment will be commented out, and
  98 followed by a newline.  To inhibit this post-insertion processing
  99 set the `org-babel-tangle-uncomment-comments' variable to a
 100 non-nil value.
 101
 102 Whether or not comments are inserted during tangling is
 103 controlled by the :comments header argument."
 104   :group 'org-babel
 105   :version "24.1"
 106   :type 'string)
 107
 108 (defcustom org-babel-tangle-comment-format-end "%source-name ends here"
 109   "Format of inserted comments in tangled code files.
 110 The following format strings can be used to insert special
 111 information into the output using `org-fill-template'.
 112 %start-line --- the line number at the start of the code block
 113 %file --------- the file from which the code block was tangled
 114 %link --------- Org-mode style link to the code block
 115 %source-name -- name of the code block
 116
 117 Upon insertion the formatted comment will be commented out, and
 118 followed by a newline.  To inhibit this post-insertion processing
 119 set the `org-babel-tangle-uncomment-comments' variable to a
 120 non-nil value.
 121
 122 Whether or not comments are inserted during tangling is
 123 controlled by the :comments header argument."
 124   :group 'org-babel
 125   :version "24.1"
 126   :type 'string)
 127
 128 (defcustom org-babel-tangle-uncomment-comments nil
 129   "Inhibits automatic commenting and addition of trailing newline
 130 of tangle comments.  Use `org-babel-tangle-comment-format-beg'
 131 and `org-babel-tangle-comment-format-end' to customize the format
 132 of tangled comments."
 133   :group 'org-babel
 134   :type 'boolean)
 135
 136 (defcustom org-babel-process-comment-text #'org-remove-indentation
 137   "Function called to process raw Org-mode text collected to be
 138 inserted as comments in tangled source-code files.  The function
 139 should take a single string argument and return a string
 140 result.  The default value is `org-remove-indentation'."
 141   :group 'org-babel
 142   :version "24.1"
 143   :type 'function)
 144
 145 (defun org-babel-find-file-noselect-refresh (file)
 146   "Find file ensuring that the latest changes on disk are
 147 represented in the file."
 148   (find-file-noselect file 'nowarn)
 149   (with-current-buffer (get-file-buffer file)
 150     (revert-buffer t t t)))
 151
 152 (defmacro org-babel-with-temp-filebuffer (file &rest body)
 153   "Open FILE into a temporary buffer execute BODY there like
 154 `progn', then kill the FILE buffer returning the result of
 155 evaluating BODY."
 156   (declare (indent 1))
 157   (let ((temp-path (make-symbol "temp-path"))
 158         (temp-result (make-symbol "temp-result"))
 159         (temp-file (make-symbol "temp-file"))
 160         (visited-p (make-symbol "visited-p")))
 161     `(let* ((,temp-path ,file)
 162             (,visited-p (get-file-buffer ,temp-path))
 163             ,temp-result ,temp-file)
 164        (org-babel-find-file-noselect-refresh ,temp-path)
 165        (setf ,temp-file (get-file-buffer ,temp-path))
 166        (with-current-buffer ,temp-file
 167          (setf ,temp-result (progn ,@body)))
 168        (unless ,visited-p (kill-buffer ,temp-file))
 169        ,temp-result)))
 170 (def-edebug-spec org-babel-with-temp-filebuffer (form body))
 171
 172 ;;;###autoload
 173 (defun org-babel-tangle-file (file &optional target-file lang)
 174   "Extract the bodies of source code blocks in FILE.
 175 Source code blocks are extracted with `org-babel-tangle'.
 176 Optional argument TARGET-FILE can be used to specify a default
 177 export file for all source blocks.  Optional argument LANG can be
 178 used to limit the exported source code blocks by language.
 179 Return a list whose CAR is the tangled file name."
 180   (interactive "fFile to tangle: \nP")
 181   (let ((visited-p (get-file-buffer (expand-file-name file)))
 182         to-be-removed)
 183     (prog1
 184         (save-window-excursion
 185           (find-file file)
 186           (setq to-be-removed (current-buffer))
 187           (mapcar #'expand-file-name (org-babel-tangle nil target-file lang)))
 188       (unless visited-p
 189         (kill-buffer to-be-removed)))))
 190
 191 (defun org-babel-tangle-publish (_ filename pub-dir)
 192   "Tangle FILENAME and place the results in PUB-DIR."
 193   (unless (file-exists-p pub-dir)
 194     (make-directory pub-dir t))
 195   (mapc (lambda (el) (copy-file el pub-dir t)) (org-babel-tangle-file filename)))
 196
 197 ;;;###autoload
 198 (defun org-babel-tangle (&optional arg target-file lang)
 199   "Write code blocks to source-specific files.
 200 Extract the bodies of all source code blocks from the current
 201 file into their own source-specific files.
 202 With one universal prefix argument, only tangle the block at point.
 203 When two universal prefix arguments, only tangle blocks for the
 204 tangle file of the block at point.
 205 Optional argument TARGET-FILE can be used to specify a default
 206 export file for all source blocks.  Optional argument LANG can be
 207 used to limit the exported source code blocks by language."
 208   (interactive "P")
 209   (run-hooks 'org-babel-pre-tangle-hook)
 210   ;; Possibly Restrict the buffer to the current code block
 211   (save-restriction
 212     (save-excursion
 213       (when (equal arg '(4))
 214         (let ((head (org-babel-where-is-src-block-head)))
 215           (if head
 216               (goto-char head)
 217             (user-error "Point is not in a source code block"))))
 218       (let ((block-counter 0)
 219             (org-babel-default-header-args
 220              (if target-file
 221                  (org-babel-merge-params org-babel-default-header-args
 222                                          (list (cons :tangle target-file)))
 223                org-babel-default-header-args))
 224             (tangle-file
 225              (when (equal arg '(16))
 226                (or (cdr (assoc :tangle (nth 2 (org-babel-get-src-block-info 'light))))
 227                    (user-error "Point is not in a source code block"))))
 228             path-collector)
 229         (mapc ;; map over all languages
 230          (lambda (by-lang)
 231            (let* ((lang (car by-lang))
 232                   (specs (cdr by-lang))
 233                   (ext (or (cdr (assoc lang org-babel-tangle-lang-exts)) lang))
 234                   (lang-f (intern
 235                            (concat
 236                             (or (and (cdr (assoc lang org-src-lang-modes))
 237                                      (symbol-name
 238                                       (cdr (assoc lang org-src-lang-modes))))
 239                                 lang)
 240                             "-mode")))
 241                   she-banged)
 242              (mapc
 243               (lambda (spec)
 244                 (let ((get-spec (lambda (name) (cdr (assoc name (nth 4 spec))))))
 245                   (let* ((tangle (funcall get-spec :tangle))
 246                          (she-bang (let ((sheb (funcall get-spec :shebang)))
 247                                      (when (> (length sheb) 0) sheb)))
 248                          (tangle-mode (funcall get-spec :tangle-mode))
 249                          (base-name (cond
 250                                      ((string= "yes" tangle)
 251                                       (file-name-sans-extension
 252                                        (nth 1 spec)))
 253                                      ((string= "no" tangle) nil)
 254                                      ((> (length tangle) 0) tangle)))
 255                          (file-name (when base-name
 256                                       ;; decide if we want to add ext to base-name
 257                                       (if (and ext (string= "yes" tangle))
 258                                           (concat base-name "." ext) base-name))))
 259                     (when file-name
 260                       ;; Possibly create the parent directories for file.
 261                       (let ((m (funcall get-spec :mkdirp))
 262                             (fnd (file-name-directory file-name)))
 263                         (and m fnd (not (string= m "no"))
 264                              (make-directory fnd 'parents)))
 265                       ;; delete any old versions of file
 266                       (and (file-exists-p file-name)
 267                            (not (member file-name (mapcar #'car path-collector)))
 268                            (delete-file file-name))
 269                       ;; drop source-block to file
 270                       (with-temp-buffer
 271                         (when (fboundp lang-f) (ignore-errors (funcall lang-f)))
 272                         (when (and she-bang (not (member file-name she-banged)))
 273                           (insert (concat she-bang "\n"))
 274                           (setq she-banged (cons file-name she-banged)))
 275                         (org-babel-spec-to-string spec)
 276                         ;; We avoid append-to-file as it does not work with tramp.
 277                         (let ((content (buffer-string)))
 278                           (with-temp-buffer
 279                             (if (file-exists-p file-name)
 280                                 (insert-file-contents file-name))
 281                             (goto-char (point-max))
 282                             ;; Handle :padlines unless first line in file
 283                             (unless (or (string= "no" (cdr (assoc :padline (nth 4 spec))))
 284                                         (= (point) (point-min)))
 285                               (insert "\n"))
 286                             (insert content)
 287                             (write-region nil nil file-name))))
 288                       ;; if files contain she-bangs, then make the executable
 289                       (when she-bang
 290                         (unless tangle-mode (setq tangle-mode #o755)))
 291                       ;; update counter
 292                       (setq block-counter (+ 1 block-counter))
 293                       (add-to-list 'path-collector
 294                                    (cons file-name tangle-mode)
 295                                    nil
 296                                    (lambda (a b) (equal (car a) (car b))))))))
 297               specs)))
 298          (if (equal arg '(4))
 299              (org-babel-tangle-single-block 1 t)
 300            (org-babel-tangle-collect-blocks lang tangle-file)))
 301         (message "Tangled %d code block%s from %s" block-counter
 302                  (if (= block-counter 1) "" "s")
 303                  (file-name-nondirectory
 304                   (buffer-file-name
 305                    (or (buffer-base-buffer) (current-buffer)))))
 306         ;; run `org-babel-post-tangle-hook' in all tangled files
 307         (when org-babel-post-tangle-hook
 308           (mapc
 309            (lambda (file)
 310              (org-babel-with-temp-filebuffer file
 311                (run-hooks 'org-babel-post-tangle-hook)))
 312            (mapcar #'car path-collector)))
 313         ;; set permissions on tangled files
 314         (mapc (lambda (pair)
 315                 (when (cdr pair) (set-file-modes (car pair) (cdr pair))))
 316               path-collector)
 317         (mapcar #'car path-collector)))))
 318
 319 (defun org-babel-tangle-clean ()
 320   "Remove comments inserted by `org-babel-tangle'.
 321 Call this function inside of a source-code file generated by
 322 `org-babel-tangle' to remove all comments inserted automatically
 323 by `org-babel-tangle'.  Warning, this comment removes any lines
 324 containing constructs which resemble org-mode file links or noweb
 325 references."
 326   (interactive)
 327   (goto-char (point-min))
 328   (while (or (re-search-forward "\\[\\[file:.*\\]\\[.*\\]\\]" nil t)
 329              (re-search-forward (org-babel-noweb-wrap) nil t))
 330     (delete-region (save-excursion (beginning-of-line 1) (point))
 331                    (save-excursion (end-of-line 1) (forward-char 1) (point)))))
 332
 333 (defvar org-stored-links)
 334 (defvar org-bracket-link-regexp)
 335 (defun org-babel-spec-to-string (spec)
 336   "Insert SPEC into the current file.
 337
 338 Insert the source-code specified by SPEC into the current source
 339 code file.  This function uses `comment-region' which assumes
 340 that the appropriate major-mode is set.  SPEC has the form:
 341
 342   (start-line file link source-name params body comment)"
 343   (let* ((start-line (nth 0 spec))
 344          (info (nth 4 spec))
 345          (file (if org-babel-tangle-use-relative-file-links
 346                    (file-relative-name (nth 1 spec))
 347                  (nth 1 spec)))
 348          (link (let ((link (nth 2 spec)))
 349                  (if org-babel-tangle-use-relative-file-links
 350                      (when (string-match org-link-types-re link)
 351                        (let ((type (match-string 0 link))
 352                              (link (substring link (match-end 0))))
 353                          (concat
 354                           type
 355                           (file-relative-name
 356                            link
 357                            (file-name-directory (cdr (assq :tangle info)))))))
 358                    link)))
 359          (source-name (nth 3 spec))
 360          (body (nth 5 spec))
 361          (comment (nth 6 spec))
 362          (comments (cdr (assq :comments info)))
 363          (link-p (or (string= comments "both") (string= comments "link")
 364                      (string= comments "yes") (string= comments "noweb")))
 365          (link-data (mapcar (lambda (el)
 366                               (cons (symbol-name el)
 367                                     (let ((le (eval el)))
 368                                       (if (stringp le) le (format "%S" le)))))
 369                             '(start-line file link source-name)))
 370          (insert-comment (lambda (text)
 371                            (when (and comments
 372                                       (not (string= comments "no"))
 373                                       (org-string-nw-p text))
 374                              (if org-babel-tangle-uncomment-comments
 375                                  ;; Plain comments: no processing.
 376                                  (insert text)
 377                                ;; Ensure comments are made to be
 378                                ;; comments, and add a trailing
 379                                ;; newline.  Also ignore invisible
 380                                ;; characters when commenting.
 381                                (comment-region
 382                                 (point)
 383                                 (progn (insert (org-no-properties text))
 384                                        (point)))
 385                                (end-of-line)
 386                                (insert "\n"))))))
 387     (when comment (funcall insert-comment comment))
 388     (when link-p
 389       (funcall
 390        insert-comment
 391        (org-fill-template org-babel-tangle-comment-format-beg link-data)))
 392     (insert
 393      (format
 394       "%s\n"
 395       (org-unescape-code-in-string
 396        (org-babel-trim body (if org-src-preserve-indentation "[\f\n\r\v]")))))
 397     (when link-p
 398       (funcall
 399        insert-comment
 400        (org-fill-template org-babel-tangle-comment-format-end link-data)))))
 401
 402 (defun org-babel-tangle-collect-blocks (&optional language tangle-file)
 403   "Collect source blocks in the current Org file.
 404 Return an association list of source-code block specifications of
 405 the form used by `org-babel-spec-to-string' grouped by language.
 406 Optional argument LANGUAGE can be used to limit the collected
 407 source code blocks by language.  Optional argument TANGLE-FILE
 408 can be used to limit the collected code blocks by target file."
 409   (let ((counter 0) last-heading-pos blocks)
 410     (org-babel-map-src-blocks (buffer-file-name)
 411       (let ((current-heading-pos
 412              (org-with-wide-buffer
 413               (org-with-limited-levels (outline-previous-heading)))))
 414         (if (eq last-heading-pos current-heading-pos) (incf counter)
 415           (setq counter 1)
 416           (setq last-heading-pos current-heading-pos)))
 417       (unless (org-in-commented-heading-p)
 418         (let* ((info (org-babel-get-src-block-info 'light))
 419                (src-lang (nth 0 info))
 420                (src-tfile (cdr (assq :tangle (nth 2 info)))))
 421           (unless (or (string= src-tfile "no")
 422                       (and tangle-file (not (equal tangle-file src-tfile)))
 423                       (and language (not (string= language src-lang))))
 424             ;; Add the spec for this block to blocks under its
 425             ;; language.
 426             (let ((by-lang (assoc src-lang blocks))
 427                   (block (org-babel-tangle-single-block counter)))
 428               (if by-lang (setcdr by-lang (cons block (cdr by-lang)))
 429                 (push (cons src-lang (list block)) blocks)))))))
 430     ;; Ensure blocks are in the correct order.
 431     (mapcar (lambda (b) (cons (car b) (nreverse (cdr b)))) blocks)))
 432
 433 (defun org-babel-tangle-single-block
 434   (block-counter &optional only-this-block)
 435   "Collect the tangled source for current block.
 436 Return the list of block attributes needed by
 437 `org-babel-tangle-collect-blocks'.
 438 When ONLY-THIS-BLOCK is non-nil, return the full association
 439 list to be used by `org-babel-tangle' directly."
 440   (let* ((info (org-babel-get-src-block-info))
 441          (start-line
 442           (save-restriction (widen)
 443                             (+ 1 (line-number-at-pos (point)))))
 444          (file (buffer-file-name (buffer-base-buffer)))
 445          (src-lang (nth 0 info))
 446          (params (nth 2 info))
 447          (extra (nth 3 info))
 448          (cref-fmt (or (and (string-match "-l \"\\(.+\\)\"" extra)
 449                             (match-string 1 extra))
 450                        org-coderef-label-format))
 451          (link (let ((link (org-no-properties
 452                             (org-store-link nil))))
 453                  (and (string-match org-bracket-link-regexp link)
 454                       (match-string 1 link))))
 455          (source-name
 456           (intern (or (nth 4 info)
 457                       (format "%s:%d"
 458                               (or (ignore-errors (nth 4 (org-heading-components)))
 459                                   "No heading")
 460                               block-counter))))
 461          (expand-cmd
 462           (intern (concat "org-babel-expand-body:" src-lang)))
 463          (assignments-cmd
 464           (intern (concat "org-babel-variable-assignments:" src-lang)))
 465          (body
 466           ;; Run the tangle-body-hook.
 467           (let* ((body ;; Expand the body in language specific manner.
 468                   (if (org-babel-noweb-p params :tangle)
 469                       (org-babel-expand-noweb-references info)
 470                     (nth 1 info)))
 471                  (body
 472                   (if (assoc :no-expand params)
 473                       body
 474                     (if (fboundp expand-cmd)
 475                         (funcall expand-cmd body params)
 476                       (org-babel-expand-body:generic
 477                        body params
 478                        (and (fboundp assignments-cmd)
 479                             (funcall assignments-cmd params)))))))
 480             (with-temp-buffer
 481               (insert body)
 482               (when (string-match "-r" extra)
 483                 (goto-char (point-min))
 484                 (while (re-search-forward
 485                         (replace-regexp-in-string "%s" ".+" cref-fmt) nil t)
 486                   (replace-match "")))
 487               (run-hooks 'org-babel-tangle-body-hook)
 488               (buffer-string))))
 489          (comment
 490           (when (or (string= "both" (cdr (assoc :comments params)))
 491                     (string= "org" (cdr (assoc :comments params))))
 492             ;; From the previous heading or code-block end
 493             (funcall
 494              org-babel-process-comment-text
 495              (buffer-substring
 496               (max (condition-case nil
 497                        (save-excursion
 498                          (org-back-to-heading t)  ; Sets match data
 499                          (match-end 0))
 500                      (error (point-min)))
 501                    (save-excursion
 502                      (if (re-search-backward
 503                           org-babel-src-block-regexp nil t)
 504                          (match-end 0)
 505                        (point-min))))
 506               (point)))))
 507          (result
 508           (list start-line file link source-name params body comment)))
 509     (if only-this-block
 510         (list (cons src-lang (list result)))
 511       result)))
 512
 513 (defun org-babel-tangle-comment-links ( &optional info)
 514   "Return a list of begin and end link comments for the code block at point."
 515   (let* ((start-line (org-babel-where-is-src-block-head))
 516          (file (buffer-file-name))
 517          (link (org-link-escape (progn (call-interactively 'org-store-link)
 518                                        (org-no-properties
 519                                         (car (pop org-stored-links))))))
 520          (source-name (nth 4 (or info (org-babel-get-src-block-info 'light))))
 521          (link-data (mapcar (lambda (el)
 522                               (cons (symbol-name el)
 523                                     (let ((le (eval el)))
 524                                       (if (stringp le) le (format "%S" le)))))
 525                             '(start-line file link source-name))))
 526     (list (org-fill-template org-babel-tangle-comment-format-beg link-data)
 527           (org-fill-template org-babel-tangle-comment-format-end link-data))))
 528
 529 ;; de-tangling functions
 530 (defvar org-bracket-link-analytic-regexp)
 531 (defun org-babel-detangle (&optional source-code-file)
 532   "Propagate changes in source file back original to Org-mode file.
 533 This requires that code blocks were tangled with link comments
 534 which enable the original code blocks to be found."
 535   (interactive)
 536   (save-excursion
 537     (when source-code-file (find-file source-code-file))
 538     (goto-char (point-min))
 539     (let ((counter 0) new-body end)
 540       (while (re-search-forward org-bracket-link-analytic-regexp nil t)
 541         (when (re-search-forward
 542                (concat " " (regexp-quote (match-string 5)) " ends here"))
 543           (setq end (match-end 0))
 544           (forward-line -1)
 545           (save-excursion
 546             (when (setq new-body (org-babel-tangle-jump-to-org))
 547               (org-babel-update-block-body new-body)))
 548           (setq counter (+ 1 counter)))
 549         (goto-char end))
 550       (prog1 counter (message "Detangled %d code blocks" counter)))))
 551
 552 (defun org-babel-tangle-jump-to-org ()
 553   "Jump from a tangled code file to the related Org mode file."
 554   (interactive)
 555   (let ((mid (point))
 556         start body-start end done
 557         target-buffer target-char link path block-name body)
 558     (save-window-excursion
 559       (save-excursion
 560         (while (and (re-search-backward org-bracket-link-analytic-regexp nil t)
 561                     (not ; ever wider searches until matching block comments
 562                      (and (setq start (line-beginning-position))
 563                           (setq body-start (line-beginning-position 2))
 564                           (setq link (match-string 0))
 565                           (setq path (match-string 3))
 566                           (setq block-name (match-string 5))
 567                           (save-excursion
 568                             (save-match-data
 569                               (re-search-forward
 570                                (concat " " (regexp-quote block-name)
 571                                        " ends here") nil t)
 572                               (setq end (line-beginning-position))))))))
 573         (unless (and start (< start mid) (< mid end))
 574           (error "Not in tangled code"))
 575         (setq body (buffer-substring body-start end)))
 576       (when (string-match "::" path)
 577         (setq path (substring path 0 (match-beginning 0))))
 578       (find-file path)
 579       (setq target-buffer (current-buffer))
 580       ;; Go to the beginning of the relative block in Org file.
 581       (org-open-link-from-string link)
 582       (if (string-match "[^ \t\n\r]:\\([[:digit:]]+\\)" block-name)
 583           (let ((n (string-to-number (match-string 1 block-name))))
 584             (if (org-before-first-heading-p) (goto-char (point-min))
 585               (org-back-to-heading t))
 586             ;; Do not skip the first block if it begins at point min.
 587             (cond ((or (org-at-heading-p)
 588                        (not (eq (org-element-type (org-element-at-point))
 589                                 'src-block)))
 590                    (org-babel-next-src-block n))
 591                   ((= n 1))
 592                   (t (org-babel-next-src-block (1- n)))))
 593         (org-babel-goto-named-src-block block-name))
 594       (goto-char (org-babel-where-is-src-block-head))
 595       ;; Preserve location of point within the source code in tangled
 596       ;; code file.
 597       (forward-line 1)
 598       (forward-char (- mid body-start))
 599       (setq target-char (point)))
 600     (org-src-switch-to-buffer target-buffer t)
 601     (prog1 body (goto-char target-char))))
 602
 603 (provide 'ob-tangle)
 604
 605 ;; Local variables:
 606 ;; generated-autoload-file: "org-loaddefs.el"
 607 ;; End:
 608
 609 ;;; ob-tangle.el ends here