2 files changed, 62 insertions(+), 12 deletions(-)

M README.org
M substitute.el

@@ 99,6 99,22 @@ scope are as follows:
 4. ~substitute-target-above-point~: Substitute the target from point
    to the beginning of the buffer (alias ~substitute-target-to-beginning-of-buffer~).
 
+[ The ~substitute-fixed-letter-case~ and the =FIXED-CASE= prefix
+  argument for all commands is part of {{{development-version}}}. ]
+
+#+vindex: substitute-fixed-letter-case
+All of the aforementioned commands accept an optional prefix argument
+(=C-u= with the default key bindings).  This passes the =FIXED-CASE=
+argument, which means that the substitution will not try to preserve
+the letter casing of the target text.  Concretely, targeting =test=
+and =TEST= with a substitute of =test-new= will make both of those
+lower case.  Whereas without the prefix argument the result would be
+=test-new= and =TEST-NEW=.  In many cases this is the desired effect.
+To always have fixed letter casing, set the user option
+~substitute-fixed-letter-case~ to a non-nil value.  Doing so is the
+same as always calling the aforementioned commands with a prefix
+argument.
+
 #+vindex: substitute-post-replace-functions
 #+findex: substitute-report-operation
 Every substitution triggers the ~substitute-post-replace-functions~.


@@ 172,9 188,14 @@ Everything is in place to set up the package.
 #+begin_src emacs-lisp
 (require 'substitute)
 
-;; If you do not like visual feedback on the matching target.  Default is t.
+;; Set this to nil if you do not like visual feedback on the matching
+;; target.  Default is t.
 (setq substitute-highlight nil)
 
+;; Set this to t if you want to always treat the letter casing
+;; literally.
+(setq substitute-fixed-letter-case t)
+
 ;; If you want a message reporting the matches that changed in the
 ;; given context.  We don't do it by default.
 (add-hook 'substitute-post-replace-functions #'substitute-report-operation)


@@ 202,7 223,7 @@ matters.
 + Contributions to code or the manual :: Ed Tavinor, Kostas Andreadis,
   Wang Chunye.
 
-+ Ideas and/or user feedback :: Tomasz Hołubowicz.
++ Ideas and/or user feedback :: Tomasz Hołubowicz, revrari.
 
 * COPYING
 :PROPERTIES:

@@ 51,6 51,18 @@ of the substitution."
   :group 'substitute
   :type 'boolean)
 
+(defcustom substitute-fixed-letter-case nil
+  "If non-nil, do not alter the letter case of the substituted text.
+Otherwise try to perform capitalization or upcasing based on the
+target text (per `replace-match').
+
+Instead of setting this user option, users can invoke the
+substitution commands, such as `substitute-target-in-buffer',
+with a universal prefix argument."
+  :package-version '(substitute . "0.2.0")
+  :group 'substitute
+  :type 'boolean)
+
 (define-obsolete-variable-alias
   'substitute-post-replace-hook
   'substitute-post-replace-functions


@@ 215,10 227,15 @@ Each entry is a list of the symbol and its buffer positions.")
                                              (nth 2 target)))
                 targets)))))
 
-(defun substitute--replace-targets (sub &optional scope)
+(defun substitute--replace-targets (sub &optional scope fixed)
   "Replace `substitute--last-matches' target with SUB.
 If optional SCOPE is equal to `above', then adjust for a reverse
-motion."
+motion.
+
+With optional FIXED as a non-nil value, do not alter the case of
+the substituted text.  Otherwise perform capitalization or
+upcasing based on the target text.  See the documenation of
+`replace-match' for how this works."
   (when-let ((targets substitute--last-matches))
     (save-excursion
       (when (listp buffer-undo-list)


@@ 233,15 250,17 @@ motion."
                     (funcall
                      (if reverse 're-search-backward 're-search-forward)
                      (car target))
-                    (replace-match sub)))
+                    (replace-match sub (or fixed substitute-fixed-letter-case))))
                 targets)))))
 
-(defun substitute--operate (target sub &optional scope)
-  "Operate on TARGET with SUB in SCOPE."
+(defun substitute--operate (target sub &optional scope fixed)
+  "Operate on TARGET with SUB in SCOPE.
+Optional FIXED does not alter the letter casing of substituted
+text (also see `substitute-fixed-letter-case')."
   (let* ((targets (or substitute--last-matches
                       (substitute--collect-targets target scope)))
          (count (length targets)))
-    (substitute--replace-targets sub scope)
+    (substitute--replace-targets sub scope fixed)
     (setq-local substitute--last-matches nil)
     (run-hook-with-args 'substitute-post-replace-hook
                         target sub count


@@ 264,7 283,7 @@ Report a `user-error' if no target is found."
 
 (defmacro substitute-define-substitute-command (fn doc &optional scope)
   "Produce substitute command using FN, DOC, and SCOPE."
-  `(defun ,fn (target sub)
+  `(defun ,fn (target sub &optional fixed-case)
      ,(format
        "Substitute TARGET with SUB %s.
 


@@ 272,12 291,22 @@ When called interactively, TARGET is the symbol at point and SUB
 is a string that is provided at the minibuffer prompt.
 
 If the region is active, TARGET is the text within the region's
-boundaries." doc)
+boundaries.
+
+With optional FIXED-CASE as a prefix argument, do not try to
+preserve the letter casing of the target text: the substitution
+is literal.  Otherwise try to preserve the case (per
+`replace-match').
+
+Instead of the optional FIXED-CASE argument, the user can set the
+option `substitute-fixed-letter-case' to non-nil.  That is the
+same as always calling this command with FIXED-CASE." doc)
      (interactive
       (let ((target (substitute--determine-target)))
         (list target
-              (substitute--prompt target ,scope))))
-     (substitute--operate target sub ,scope)))
+              (substitute--prompt target ,scope)
+              current-prefix-arg)))
+     (substitute--operate target sub ,scope fixed-case)))
 
 ;;;###autoload (autoload 'substitute-target-in-buffer "substitute")
 (substitute-define-substitute-command