[PATCH] Add the ability to archive to the datetree.

[Andrew Hyatt <ahyatt@gmail.com>]

* org.el (org-archive-location): Add documentation on new datetree
option.
* org-archive.el (org-archive-subtree): Add special handling
of datetree options to archive to datetree.

---
 doc/org.texi        |   22 +++++++++++++---------
 lisp/org-archive.el |   21 +++++++++++++++++----
 lisp/org.el         |    7 +++++++
 3 files changed, 37 insertions(+), 13 deletions(-)

diff --git a/doc/org.texi b/doc/org.texi
index 143b184..128f966 100644
--- a/doc/org.texi
+++ b/doc/org.texi
@@ -6854,16 +6854,20 @@ is invoked, the level 1 trees will be checked.
 @cindex archive locations
 The default archive location is a file in the same directory as the
 current file, with the name derived by appending @file{_archive} to the
-current file name.  For information and examples on how to change this,
+current file name.  You can also choose what heading to file archived
+items under, with the possibility to add them to a datetree in a file.
+For information and examples on how to specify the file and the heading,
 see the documentation string of the variable
-@code{org-archive-location}.  There is also an in-buffer option for
-setting this variable, for example@footnote{For backward compatibility,
-the following also works: If there are several such lines in a file,
-each specifies the archive location for the text below it.  The first
-such line also applies to any text before its definition.  However,
-using this method is @emph{strongly} deprecated as it is incompatible
-with the outline structure of the document.  The correct method for
-setting multiple archive locations in a buffer is using properties.}:
+@code{org-archive-location}.
+
+There is also an in-buffer option for setting this variable, for
+example@footnote{For backward compatibility, the following also works:
+If there are several such lines in a file, each specifies the archive
+location for the text below it.  The first such line also applies to any
+text before its definition.  However, using this method is
+@emph{strongly} deprecated as it is incompatible with the outline
+structure of the document.  The correct method for setting multiple
+archive locations in a buffer is using properties.}:

 @cindex #+ARCHIVE
 @example
diff --git a/lisp/org-archive.el b/lisp/org-archive.el
index 16c35cf..35ef290 100644
--- a/lisp/org-archive.el
+++ b/lisp/org-archive.el
@@ -213,13 +213,14 @@ this heading."
 		 (current-time)))
 	  category todo priority ltags itags atags
 	  ;; end of variables that will be used for saving context
-	  location afile heading buffer level newfile-p infile-p visiting)
+	  location afile heading buffer level newfile-p infile-p visiting
+	  datetree-date)

       ;; Find the local archive location
       (setq location (org-get-local-archive-location)
 	    afile (org-extract-archive-file location)
 	    heading (org-extract-archive-heading location)
-	    infile-p (equal file (abbreviate-file-name afile)))
+	    infile-p (equal file (abbreviate-file-name (or afile ""))))
       (unless afile
 	(error "Invalid `org-archive-location'"))

@@ -230,6 +231,12 @@ this heading."
 	(setq buffer (current-buffer)))
       (unless buffer
 	(error "Cannot access file \"%s\"" afile))
+      (when (string-match "\\`datetree/" heading)
+	;; Replace with ***, to represent the 3 levels of headings the
+	;; datetree has.
+	(setq heading (string-replace-match "\\`datetree/" heading "***"))
+	(setq datetree-date (org-date-to-gregorian
+			     (or (org-entry-get nil "CLOSED" t) time))))
       (if (and (> (length heading) 0)
 	       (string-match "^\\*+" heading))
 	  (setq level (match-end 0))
@@ -262,6 +269,9 @@ this heading."
 	  (goto-char (point-max))
 	  (insert (format "\nArchived entries from file %s\n\n"
 			  (buffer-file-name this-buffer))))
+	(when datetree-date
+	  (org-datetree-find-date-create datetree-date)
+	  (org-narrow-to-subtree))
 	;; Force the TODO keywords of the original buffer
 	(let ((org-todo-line-regexp tr-org-todo-line-regexp)
 	      (org-todo-keywords-1 tr-org-todo-keywords-1)
@@ -285,7 +295,8 @@ this heading."
 		  ;; Heading not found, just insert it at the end
 		  (goto-char (point-max))
 		  (or (bolp) (insert "\n"))
-		  (insert "\n" heading "\n")
+		  ;; datetrees don't need too much spacing
+		  (if datetree-date (insert heading) (insert "\n" heading "\n"))
 		  (end-of-line 0))
 		;; Make the subtree visible
 		(show-subtree)
@@ -296,7 +307,8 @@ this heading."
 		  (org-end-of-subtree t))
 		(skip-chars-backward " \t\r\n")
 		(and (looking-at "[ \t\r\n]*")
-		     (replace-match "\n\n")))
+		     ;; datetree archives don't need so much spacing.
+		     (replace-match (if datetree-date "\n" "\n\n"))))
 	    ;; No specific heading, just go to end of file.
 	    (goto-char (point-max)) (insert "\n"))
 	  ;; Paste
@@ -326,6 +338,7 @@ this heading."
 		  (setq n (concat "ARCHIVE_" (upcase (symbol-name e))))
 		  (org-entry-put (point) n v)))))

+	  (widen)
 	  ;; Save and kill the buffer, if it is not the same buffer.
 	  (when (not (eq this-buffer buffer))
 	    (save-buffer))))
diff --git a/lisp/org.el b/lisp/org.el
index 6ee3b4e..e19894a 100644
--- a/lisp/org.el
+++ b/lisp/org.el
@@ -4046,6 +4046,13 @@ Here are a few examples:
 	Archive in file ./basement (relative path), as level 3 trees
 	below the level 2 heading \"** Finished Tasks\".

+\"~/org/datetree.org::datetree/* Finished Tasks\"
+        The \"datetree/\" string is special, signifying to
+        archive items to the datetree.  Items are placed in
+        either the CLOSED date of the item, or the current date
+        if there is no CLOSED date.  The heading will be a
+        subentry to the current date.
+
 You may set this option on a per-file basis by adding to the buffer a
 line like

-- 
1.7.3.1