From 11c36f42d1471629fd783aaf1db4aaf3d1d01ef6 Mon Sep 17 00:00:00 2001
From: Suvayu Ali <fatkasuvayu+linux@gmail.com>
Date: Tue, 23 Aug 2011 14:25:08 +0200
Subject: [PATCH] Implement history facility for org-occur searches

Changed function:
* org.el (org-occur): Add history functionality and corresponding
  documentation

New functions:
* org.el (org-occur-history-next): Function for history traversal
  (org-occur-history-forward) and (org-occur-history-backward):
  User funtions for moving forward and backward in search history

New variables:
* org.el (org-occur-match-history): Search history variable
  (org-occur-match-history-len): Search history size
---
 lisp/org.el |   65 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 files changed, 63 insertions(+), 2 deletions(-)

diff --git a/lisp/org.el b/lisp/org.el
index bbc6a75..d419a04 100644
--- a/lisp/org.el
+++ b/lisp/org.el
@@ -12294,6 +12294,15 @@ (defvar org-occur-parameters nil
 as well.")
 (make-variable-buffer-local 'org-occur-parameters)
 
+;;;; Org occur history variables
+(defvar org-occur-match-history nil
+  "History list of `org-occur' searches.")
+(make-variable-buffer-local 'org-occur-match-history)
+(defcustom org-occur-match-history-len 10
+  "Length of `org-occur-match-history'."
+  :type 'integer
+  :group 'org)
+
 (defun org-occur (regexp &optional keep-previous callback)
   "Make a compact tree which shows all matches of REGEXP.
 The tree will show the lines where the regexp matches, and all higher
@@ -12303,7 +12312,15 @@ (defun org-occur (regexp &optional keep-previous callback)
 call to `org-occur' will be kept, to allow stacking of calls to this
 command.
 If CALLBACK is non-nil, it is a function which is called to confirm
-that the match should indeed be shown."
+that the match should indeed be shown.
+
+The org-occur search history is stored in the variable
+`org-occur-match-history'. The length of the history is determined by the
+variable `org-occur-match-history-len'. The function
+`org-occur-history-next' can be used to traverse the org-occur history.
+Two user functions `org-occur-history-forward' and
+`org-occur-history-backward' are provided to conveniently traverse the
+org-occur history one step at a time."
   (interactive "sRegexp: \nP")
   (when (equal regexp "")
     (error "Regexp cannot be empty"))
@@ -12322,7 +12339,17 @@ (defun org-occur (regexp &optional keep-previous callback)
 		  (save-match-data (funcall callback)))
 	  (setq cnt (1+ cnt))
 	  (when org-highlight-sparse-tree-matches
-	    (org-highlight-new-match (match-beginning 0) (match-end 0)))
+	    (org-highlight-new-match (match-beginning 0) (match-end 0))
+	    ;; remove duplicate element
+	    (setq org-occur-match-history
+		  (delete regexp org-occur-match-history))
+	    ;; add last search at the front
+	    (add-to-list 'org-occur-match-history regexp)
+	    ;; curtail history to max history length
+	    (if (eq org-occur-match-history-len
+		    (length org-occur-match-history))
+		(setq org-occur-match-history
+		      (butlast org-occur-match-history))))
 	  (org-show-context 'occur-tree))))
     (when org-remove-highlights-with-change
       (org-add-hook 'before-change-functions 'org-remove-occur-highlights
@@ -12360,6 +12387,40 @@ (defun org-occur-next-match (&optional n reset)
       (goto-char p1)
       (error "No more matches"))))
 
+(defun org-occur-history-next (steps)
+    "Traverse org occur history by STEPS steps in the forward direction
+with respect to the current position. The search history is saved after
+removing any duplicate searches. It is reordered to reflect the most
+recent search. Before traversing the history the following transformation
+is applied: STEPS MODULO `org-occur-match-history-len'.
+
+For negative STEPS, history traversal is done in the backward direction
+starting at the end of the history list. When called interactively it
+prompts for the number of steps."
+    (interactive "NSteps: ")
+    (let (match)
+      (if (< steps 0)
+	  (setq match
+		(car (last org-occur-match-history
+			   (mod (- steps) org-occur-match-history-len))))
+	(setq match (nth (mod steps org-occur-match-history-len)
+			 org-occur-match-history)))
+      (org-occur match)
+      (setq org-occur-match-history
+	    (delete match org-occur-match-history))
+      (add-to-list 'org-occur-match-history match t)))
+
+(defun org-occur-history-forward ()
+  "Repeat last org occur search."
+  (interactive)
+  (let ((steps (if org-occur-highlights 1 0)))
+    (org-occur-history-next steps)))
+
+(defun org-occur-history-backward ()
+  "Repeat last org occur search."
+  (interactive)
+  (org-occur-history-next -1))
+
 (defun org-show-context (&optional key)
   "Make sure point and context are visible.
 How much context is shown depends upon the variables
-- 
1.7.4.4