Add mc/insert-letters function and test cases

* README.md: Add to readme, under special section.
 * features/insert-letters.feature: Add scenarios.
 * features/step-definitions/multiple-cursors-steps.el: Add call.
 * features/support/env.el: Add keybinding for insert-letters to H-3.
 * mc-separate-operations.el: Add function and helper functions.
 * multiple-cursors-core.el: Add insert-letters to functions that run once.
 * multiple-cursors.el: Add to readme.

README.md

@@ -85,6 +85,7 @@ You can [watch an intro to multiple-cursors at Emacs Rocks](http://emacsrocks.co
  - `set-rectangular-region-anchor`: Think of this one as `set-mark` except you're marking a rectangular region.
  - `mc/mark-sgml-tag-pair`: Mark the current opening and closing tag.
  - `mc/insert-numbers`: Insert increasing numbers for each cursor, top to bottom.
+ - `mc/insert-letters`: Insert increasing letters for each cursor, top to bottom.
  - `mc/sort-regions`: Sort the marked regions alphabetically.
  - `mc/reverse-regions`: Reverse the order of the marked regions.
 

features/insert-letters.feature

@@ -0,0 +1,19 @@
+Feature: Insert increasing letters
+
+  Scenario: Three cursors, a-b-c
+    Given I have cursors at "text" in "This text contains the word text thrice (text)"
+    When I press "H-3"
+    And I press "SPC"
+    Then I should see "This a text contains the word b text thrice (c text)"
+
+  Scenario: Three cursors, j-k-l
+    Given I have cursors at "text" in "This text contains the word text thrice (text)"
+    When I press "C-9 H-3"
+    And I press "SPC"
+    Then I should see "This j text contains the word k text thrice (l text)"
+
+  Scenario: Three cursors, z-aa-ab
+    Given I have cursors at "text" in "This text contains the word text thrice (text)"
+    When I press "C-u 2 5 H-3"
+    And I press "SPC"
+    Then I should see "This z text contains the word aa text thrice (ab text)"

features/step-definitions/multiple-cursors-steps.el

@@ -16,6 +16,9 @@
 (When "^I insert numbers$"
       (lambda () (call-interactively 'mc/insert-numbers)))
 
+(When "^I insert letters$"
+      (lambda () (call-interactively 'mc/insert-letters)))
+
 (When "^I reverse regions$"
       (lambda () (call-interactively 'mc/reverse-regions)))
 

features/support/env.el

@@ -27,6 +27,7 @@
  (global-set-key (kbd "C-$") 'mc/mark-all-dwim)
  (global-set-key (kbd "M-#") 'mc/mark-all-in-region)
  (global-set-key (kbd "H-0") 'mc/insert-numbers)
+ (global-set-key (kbd "H-3") 'mc/insert-letters)
  (global-set-key (kbd "H-1") 'mc/reverse-regions)
  (global-set-key (kbd "H-2") 'mc/sort-regions)
  (global-set-key (kbd "C-S-c C-S-c") 'mc/edit-lines)

mc-separate-operations.el

@@ -53,6 +53,31 @@
                             (mc/cursor-end cursor)) strings))))
     (nreverse strings)))
 
+;;;###autoload
+(defun mc/insert-letters (arg)
+  "Insert increasing letters for each cursor, starting at 0 or ARG.
+     Where letter[0]=a letter[2]=c letter[26]=aa"
+  (interactive "P")
+  (setq mc--insert-letters-number (or arg 0))
+  (mc/for-each-cursor-ordered
+   (mc/execute-command-for-fake-cursor 'mc--insert-letter-and-increase cursor)))
+
+(defun mc--number-to-letters (number)
+  (let ((letter
+	 (char-to-string
+	  (nth (mod number 26) '(?a ?b ?c ?d ?e ?f ?g ?h ?i ?j ?k ?l ?m ?n ?o ?p ?q ?r ?s ?t ?u ?v ?w ?x ?y ?z))))
+	(number2 (/ number 26)))
+    (if (> number2 0)
+	(concat (mc--number-to-letters (- number2 1)) letter)
+      letter)))
+
+(defvar mc--insert-letters-number 0)
+
+(defun mc--insert-letter-and-increase ()
+  (interactive)
+  (insert (mc--number-to-letters mc--insert-letters-number))
+  (setq mc--insert-letters-number (1+ mc--insert-letters-number)))
+
 (defvar mc--strings-to-replace nil)
 
 (defun mc--replace-region-strings-1 ()

multiple-cursors-core.el

@@ -612,6 +612,7 @@ for running commands with multiple cursors.")
                                      mc/mark-all-dwim
                                      mc/mark-sgml-tag-pair
                                      mc/insert-numbers
+				     mc/insert-letters
                                      mc/sort-regions
                                      mc/reverse-regions
                                      mc/cycle-forward

multiple-cursors.el

@@ -85,6 +85,7 @@
 ;;  - `set-rectangular-region-anchor`: Think of this one as `set-mark` except you're marking a rectangular region.
 ;;  - `mc/mark-sgml-tag-pair`: Mark the current opening and closing tag.
 ;;  - `mc/insert-numbers`: Insert increasing numbers for each cursor, top to bottom.
+;;  - `mc/insert-letters`: Insert increasing letters for each cursor, top to bottom.
 ;;  - `mc/sort-regions`: Sort the marked regions alphabetically.
 ;;  - `mc/reverse-regions`: Reverse the order of the marked regions.