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”.

(defun xah-title-case-region-or-line (@begin @end)
  "Title case text between nearest brackets, or current line, or text selection.
Capitalize first letter of each word, except words like {to, of, the, a, in, or, and, etc}. 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"
  (interactive
   (if (use-region-p)
       (list (region-beginning) (region-end))
     (let (
           $p1
           $p2
           ($skipChars "^\"<>(){}[]“”‘’‹›«»「」『』【】〖〗《》〈〉〔〕"))
       (progn
         (skip-chars-backward $skipChars (line-beginning-position))
         (setq $p1 (point))
         (skip-chars-forward $skipChars (line-end-position))
         (setq $p2 (point)))
       (list $p1 $p2))))
  (let* (
         ($strPairs [
                     [" A " " a "]
                     [" 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 @begin @end)
        (upcase-initials-region (point-min) (point-max))
        (let ((case-fold-search nil))
          (mapc
           (lambda ($x)
             (goto-char (point-min))
             (while
                 (search-forward (aref $x 0) nil t)
               (replace-match (aref $x 1) "FIXEDCASE" "LITERAL")))
           $strPairs))))))

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