Emacs: Change to Title Case 🚀

Here's emacs command to change letter case by title convention.

For example, “A Tale of Two Cities”, not “A Tale Of Two Cities”.

put this in your Emacs Init File:

(defun xah-title-case-region-or-line (&optional Begin End)
  "Title case text between nearest brackets, or current line or selection.
Capitalize first letter of each word, except words like {to, of, the, a, in, or, and}. If a word already contains cap letters such as HTTP, URL, they are left as is.

When called in a elisp program, Begin End are region boundaries.

URL `http://xahlee.info/emacs/emacs/elisp_title_case_text.html'
Version: 2017-01-11 2021-03-30 2021-09-19"
  (interactive)
  (let* ((xskipChars "^\"<>(){}[]“”‘’‹›«»「」『』【】〖〗《》〈〉〔〕")
         (xp0 (point))
         (xp1 (if Begin
                  Begin
                (if (region-active-p)
                    (region-beginning)
                  (progn
                    (skip-chars-backward xskipChars (line-beginning-position)) (point)))))
         (xp2 (if End
                  End
                (if (region-active-p)
                    (region-end)
                  (progn (goto-char xp0)
                         (skip-chars-forward xskipChars (line-end-position)) (point)))))
         (xstrPairs [
                     [" A " " a "]
                     [" An " " an "]
                     [" And " " and "]
                     [" At " " at "]
                     [" As " " as "]
                     [" By " " by "]
                     [" Be " " be "]
                     [" Into " " into "]
                     [" In " " in "]
                     [" Is " " is "]
                     [" It " " it "]
                     [" For " " for "]
                     [" Of " " of "]
                     [" Or " " or "]
                     [" On " " on "]
                     [" Via " " via "]
                     [" The " " the "]
                     [" That " " that "]
                     [" To " " to "]
                     [" Vs " " vs "]
                     [" With " " with "]
                     [" From " " from "]
                     ["'S " "'s "]
                     ["'T " "'t "]
                     ]))
    (save-excursion
      (save-restriction
        (narrow-to-region xp1 xp2)
        (upcase-initials-region (point-min) (point-max))
        (let ((case-fold-search nil))
          (mapc
           (lambda (xx)
             (goto-char (point-min))
             (while
                 (search-forward (aref xx 0) nil t)
               (replace-match (aref xx 1) t t)))
           xstrPairs))))))