Provide functions to narrow around current-line

It's nice to be able to run Iedit on only the current line or lines
near the current line. Provide functions to narrow the Iedit search
region to the current line and to expand the search region near the
current line ad-hoc.

README.org

@@ -35,6 +35,14 @@ Renaming refactoring is convinient in Iedit mode
  - Last renaming refactoring is remembered and can be applied to other buffers
    later
 
+ - Restricting the search area to just the current line can be done by
+   pressing M-I.
+
+ - Restricting the search area to the lines near the current line can
+   be done by pressing M-{ and M-}. These will expand the search
+   region one line at a time from the top and bottom. Add a prefix
+   argument to go the opposite direction.
+
 Iedit-rectangle-mode provides rectangle support with *visible rectangle*
 highlighting, which is similar with cua mode rectangle support.  But it's
 lighter weight and uses iedit mechanisms.

iedit-lib.el

@@ -848,6 +848,25 @@ STRING is already `regexp-quote'ed"
           (concat (substring string 0 50) "...")
         string))))
 
+(defun iedit-char-at-bol (&optional N)
+  "Get char position of the beginning of the current line. If `N'
+is given, move forward (or backward) that many lines (using
+`forward-line') and get the char position at the beginning of
+that line."
+  (save-excursion
+    (forward-line (if N N 0))
+    (point)))
+
+(defun iedit-char-at-eol (&optional N)
+  "Get char position of the end of the current line. If `N' is
+given, move forward (or backward) that many lines (using
+`forward-line') and get the char position at the end of that
+line."
+  (save-excursion
+    (forward-line (if N N 0))
+    (end-of-line)
+    (point)))
+
 (defun iedit-region-active ()
   "Return t if region is active and not empty.
 If variable `iedit-transient-mark-sensitive' is t, active region

iedit.el

@@ -132,6 +132,13 @@ Iedit mode is turned off last time.")
   "This is buffer local variable which is the initial region
 where Iedit mode is started from.")
 
+(defvar iedit-num-lines-to-expand-up 0
+  "This is a global variable indicating how many lines up from
+point should be included in the replacement region.")
+
+(defvar iedit-num-lines-to-expand-down 0
+  "This is a global variable indicating how many lines down from
+point should be included in the replacement region.")
 
 (make-variable-buffer-local 'iedit-mode)
 (make-variable-buffer-local 'iedit-only-complete-symbol-local)
@@ -223,6 +230,9 @@ This is like `describe-bindings', but displays only Iedit keys."
   (let ((map (make-sparse-keymap)))
     (set-keymap-parent map iedit-occurrence-keymap-default)
     (define-key map (kbd "M-H") 'iedit-restrict-function)
+    (define-key map (kbd "M-I") 'iedit-restrict-current-line)
+    (define-key map (kbd "M-{") 'iedit-expand-up-a-line)
+    (define-key map (kbd "M-}") 'iedit-expand-down-a-line)
     (define-key map (kbd "M-G") 'iedit-apply-global-modification)
     (define-key map (kbd "M-C") 'iedit-toggle-case-sensitive)
     map)
@@ -414,6 +424,8 @@ the initial string globally."
   (setq iedit-last-occurrence-local (iedit-current-occurrence-string))
   (setq iedit-last-occurrence-global iedit-last-occurrence-local)
   (setq iedit-last-initial-string-global iedit-initial-string-local)
+  (setq iedit-num-lines-to-expand-up 0)
+  (setq iedit-num-lines-to-expand-down 0)
 
   (iedit-cleanup)
 
@@ -502,6 +514,64 @@ the initial string globally."
   (message "Restricted in current function, %d matches."
            (length iedit-occurrences-overlays)))
 
+(defun iedit-restrict-current-line ()
+  "Restrict Iedit mode to current line."
+  (interactive)
+  (iedit-restrict-region (iedit-char-at-bol) (iedit-char-at-eol))
+  (message "Restricted to current line, %d match%s."
+           (length iedit-occurrences-overlays)
+           (if (= 1 (length iedit-occurrences-overlays)) "" "es")))
+
+(defun iedit-expand-by-a-line (where amount)
+  "After restricting iedit to the current line with
+`iedit-restrict-current-line', this function expands the top or
+bottom of the search region upwards or downwards by `amount'
+lines. The region being acted upon is controlled with
+`where' ('top to act on the top, anything else for the
+bottom). With a prefix, collapses the top or bottom of the search
+region by `amount' lines."
+  (interactive "P")
+  ;; Since iedit-done resets iedit-num-lines-to-expand-{down,up}, we
+  ;; have to hang on to them in tmp variables
+  (let ((tmp-up iedit-num-lines-to-expand-up)
+        (tmp-down iedit-num-lines-to-expand-down)
+        ;; we want to call iedit-mode with a universal prefix arg
+        (current-prefix-arg '(4)))
+    (iedit-done)
+    (call-interactively 'iedit-mode)
+    (setq iedit-num-lines-to-expand-up tmp-up)
+    (setq iedit-num-lines-to-expand-down tmp-down)
+    (if (eq where 'top)
+        (setq iedit-num-lines-to-expand-up (max 0
+                                                (+ amount iedit-num-lines-to-expand-up)))
+      (setq iedit-num-lines-to-expand-down (max 0
+                                                (+ amount iedit-num-lines-to-expand-down))))
+    (iedit-restrict-region (iedit-char-at-bol (- iedit-num-lines-to-expand-up))
+                           (iedit-char-at-eol iedit-num-lines-to-expand-down))
+    (message "Now looking -%d/+%d lines around current line, %d match%s."
+             iedit-num-lines-to-expand-up
+             iedit-num-lines-to-expand-down
+             (length iedit-occurrences-overlays)
+             (if (= 1 (length iedit-occurrences-overlays)) "" "es"))))
+
+(defun iedit-expand-up-a-line (&optional arg)
+  "After restricting iedit to the current line with
+`iedit-restrict-current-line', this function expands the search
+region upwards by one line. With a prefix, bring the top of the
+region back down one line."
+  (interactive "P")
+  (iedit-expand-by-a-line 'top
+                          (if arg -1 1)))
+
+(defun iedit-expand-down-a-line (&optional arg)
+  "After restricting iedit to the current line with
+`iedit-restrict-current-line', this function expands the search
+region downwards by one line. With a prefix, bring the bottom of
+the region back up one line."
+  (interactive "P")
+  (iedit-expand-by-a-line 'bottom
+                          (if arg -1 1)))
+
 (defun iedit-restrict-region (beg end &optional inclusive)
   "Restricting Iedit mode in a region."
   (when iedit-buffering