bug#8415: 23.3.50; Extensible Emacs Registers

[Leo]

Hello Stefan,

Is this patch OK?

=== modified file 'lisp/ChangeLog'
--- lisp/ChangeLog      2011-06-23 03:35:05 +0000
+++ lisp/ChangeLog      2011-06-23 07:46:05 +0000
@@ -1,3 +1,11 @@
+2011-06-23  Leo Liu  <sdl.web@gmail.com>
+
+       * register.el (registerv): New struct.
+       (registerv-make): New function.
+       (jump-to-register, describe-register-1, insert-register): Support
+       the jump-func, print-func and insert-func slot of a registerv
+       struct.
+
 2011-06-22  Leo Liu  <sdl.web@gmail.com>
 
        * minibuffer.el (completing-read-function)

=== modified file 'lisp/register.el'
--- lisp/register.el    2011-04-19 13:44:55 +0000
+++ lisp/register.el    2011-06-23 05:07:49 +0000
@@ -28,6 +28,8 @@
 ;; pieces of buffer state to named variables.  The entry points are
 ;; documented in the Emacs user's manual.
 
+(eval-when-compile (require 'cl))
+
 (declare-function semantic-insert-foreign-tag "semantic/tag" (foreign-tag))
 (declare-function semantic-tag-buffer "semantic/tag" (tag))
 (declare-function semantic-tag-start "semantic/tag" (tag))
@@ -50,9 +52,36 @@
 
 ;;; Code:
 
+(defstruct
+  (registerv (:constructor nil)
+            (:constructor registerv--make (&optional data print-func
+                                                     jump-func insert-func))
+            (:copier nil)
+            (:type list)
+            :named)
+  (data        nil :read-only t)
+  (print-func  nil :read-only t)
+  (jump-func   nil :read-only t)
+  (insert-func nil :read-only t))
+
+(defun* registerv-make (data &key print-func jump-func insert-func)
+  "Create a register value object.
+
+DATA can be any value.
+PRINT-FUNC if provided controls how `list-registers' and
+`view-register' print the register.  It should be a function
+recieving one argument DATA and print text that completes
+this sentence:
+  Register X contains [TEXT PRINTED BY PRINT-FUNC]
+JUMP-FUNC if provided, controls how `jump-to-register' jumps to the register.
+INSERT-FUNC if provided, controls how `insert-register' insert the register.
+They both receive DATA as argument."
+  (registerv--make data print-func jump-func insert-func))
+
 (defvar register-alist nil
   "Alist of elements (NAME . CONTENTS), one for each Emacs register.
-NAME is a character (a number).  CONTENTS is a string, number, marker or list.
+NAME is a character (a number).  CONTENTS is a string, number, marker, list
+or a struct returned by `registerv-make'.
 A list of strings represents a rectangle.
 A list of the form (file . FILE-NAME) represents the file named FILE-NAME.
 A list of the form (file-query FILE-NAME POSITION) represents
@@ -118,8 +147,10 @@
 delete any existing frames that the frame configuration doesn't mention.
 \(Otherwise, these frames are iconified.)"
   (interactive "cJump to register: \nP")
-  (let ((val (get-register register)))
+  (let* ((val (get-register register))
+        (jump-func (and (registerv-p val) (registerv-jump-func val))))
     (cond
+     (jump-func (funcall jump-func (registerv-data val)))
      ((and (consp val) (frame-configuration-p (car val)))
       (set-frame-configuration (car val) (not delete))
       (goto-char (cadr val)))
@@ -207,8 +238,11 @@
   (princ "Register ")
   (princ (single-key-description register))
   (princ " contains ")
-  (let ((val (get-register register)))
+  (let* ((val (get-register register))
+        (print-func (and (registerv-p val) (registerv-print-func val))))
     (cond
+     (print-func (funcall print-func (registerv-data val)))
+
      ((numberp val)
       (princ val))
 
@@ -283,8 +317,10 @@
 Interactively, second arg is non-nil if prefix arg is supplied."
   (interactive "*cInsert register: \nP")
   (push-mark)
-  (let ((val (get-register register)))
+  (let* ((val (get-register register))
+        (insert-func (and (registerv-p val) (registerv-insert-func val))))
     (cond
+     (insert-func (funcall insert-func (registerv-data val)))
      ((consp val)
       (insert-rectangle val))
      ((stringp val)

Leo