bug#66614: 29.1.50; Support not capitalizing words inside symbols

[Spencer Baugh]

Patch follows.

>From e11c5096b2e0a3eddec8fac692142ff31c889109 Mon Sep 17 00:00:00 2001
From: Spencer Baugh <sbaugh@janestreet.com>
Date: Wed, 18 Oct 2023 12:51:37 -0400
Subject: [PATCH] Add case-symbols-as-words to configure symbol case behavior

In some programming languages and styles, a symbol (or every symbol in
a sequence of symbols) might be capitalized, but the individual words
making up the symbol should never be capitalized.

For example, in OCaml, type names Look_like_this and variable names
look_like_this, but it is basically never correct for something to
Look_Like_This.  And one might have "aa_bb cc_dd ee_ff" or "Aa_bb
Cc_dd Ee_ff", but never "Aa_Bb Cc_Dd Ee_Ff".

To support this, the new variable case-symbols-as-words causes symbol
constituents to be treated as part of words only for case operations.

* src/casefiddle.c (case_ch_is_word): Add.
(case_character_impl): Use case_ch_is_word.
(case_character): Use case_ch_is_word.
(syms_of_casefiddle): Define case-symbols-as-words. (bug#66614)
* src/search.c (Freplace_match): Use case-symbols-as-words when
calculating case pattern.
* test/src/casefiddle-tests.el (casefiddle-tests--check-syms)
(casefiddle-case-symbols-as-words): Test case-symbols-as-words.
* etc/NEWS: Announce case-symbols-as-words.
* doc/lispref/strings.texi (Case Conversion): Document
case-symbols-as-words.
---
 doc/lispref/strings.texi     |  8 ++++++--
 etc/NEWS                     |  8 ++++++++
 src/casefiddle.c             | 23 +++++++++++++++++++++--
 src/search.c                 | 11 +++++++----
 test/src/casefiddle-tests.el | 12 ++++++++++++
 5 files changed, 54 insertions(+), 8 deletions(-)

diff --git a/doc/lispref/strings.texi b/doc/lispref/strings.texi
index 7d11db49def..417614c9320 100644
--- a/doc/lispref/strings.texi
+++ b/doc/lispref/strings.texi
@@ -1510,7 +1510,9 @@ Case Conversion
 
 The definition of a word is any sequence of consecutive characters that
 are assigned to the word constituent syntax class in the current syntax
-table (@pxref{Syntax Class Table}).
+table (@pxref{Syntax Class Table}), or if @var{case-symbols-as-words} is
+non-nil, also characters assigned to the symbol constituent syntax
+class.
 
 When @var{string-or-char} is a character, this function does the same
 thing as @code{upcase}.
@@ -1542,7 +1544,9 @@ Case Conversion
 
 The definition of a word is any sequence of consecutive characters that
 are assigned to the word constituent syntax class in the current syntax
-table (@pxref{Syntax Class Table}).
+table (@pxref{Syntax Class Table}), or if @var{case-symbols-as-words} is
+non-nil, also characters assigned to the symbol constituent syntax
+class.
 
 When the argument to @code{upcase-initials} is a character,
 @code{upcase-initials} has the same result as @code{upcase}.
diff --git a/etc/NEWS b/etc/NEWS
index 129017f7dbe..23078f18273 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -1100,6 +1100,14 @@ instead of "ctags", "ebrowse", "etags", "hexl", 
"emacsclient", and
 "rcs2log", when starting one of these built in programs in a
 subprocess.
 
++++
+** New variable 'case-symbols-as-words' to change case behavior for symbols.
+If this is set to non-nil, then case operations such as
+'upcase-initials' or 'replace-match' (with nil FIXEDCASE) will treat
+symbol constituents as if they were part of words.  This is useful for
+programming languages and style where words in the middle of symbols
+are never capitalized.
+
 +++
 ** 'x-popup-menu' now understands touch screen events.
 When a 'touchscreen-begin' or 'touchscreen-end' event is passed as the
diff --git a/src/casefiddle.c b/src/casefiddle.c
index d567a5e353a..3f1f5680dd5 100644
--- a/src/casefiddle.c
+++ b/src/casefiddle.c
@@ -92,6 +92,12 @@ prepare_casing_context (struct casing_context *ctx,
     SETUP_BUFFER_SYNTAX_TABLE ();      /* For syntax_prefix_flag_p.  */
 }
 
+static bool
+case_ch_is_word (enum syntaxcode syntax)
+{
+  return syntax == Sword || (case_symbols_as_words && syntax == Ssymbol);
+}
+
 struct casing_str_buf
 {
   unsigned char data[max (6, MAX_MULTIBYTE_LENGTH)];
@@ -115,7 +121,7 @@ case_character_impl (struct casing_str_buf *buf,
 
   /* Update inword state */
   bool was_inword = ctx->inword;
-  ctx->inword = SYNTAX (ch) == Sword &&
+  ctx->inword = case_ch_is_word (SYNTAX (ch)) &&
     (!ctx->inbuffer || was_inword || !syntax_prefix_flag_p (ch));
 
   /* Normalize flag so its one of CASE_UP, CASE_DOWN or CASE_CAPITALIZE.  */
@@ -222,7 +228,7 @@ case_character (struct casing_str_buf *buf, struct 
casing_context *ctx,
      has a word syntax (i.e. current character is end of word), use final
      sigma.  */
   if (was_inword && ch == GREEK_CAPITAL_LETTER_SIGMA && changed
-      && (!next || SYNTAX (STRING_CHAR (next)) != Sword))
+      && (!next || !case_ch_is_word (SYNTAX (STRING_CHAR (next)))))
     {
       buf->len_bytes = CHAR_STRING (GREEK_SMALL_LETTER_FINAL_SIGMA, buf->data);
       buf->len_chars = 1;
@@ -720,6 +726,19 @@ syms_of_casefiddle (void)
   3rd argument.  */);
   Vregion_extract_function = Qnil; /* simple.el sets this.  */
 
+  DEFVAR_BOOL ("case-symbols-as-words", case_symbols_as_words,
+              doc: /* If non-nil, case functions treat symbol syntax as part 
of words.
+
+Functions such as `upcase-initials' and `replace-match' check or modify
+the case pattern of sequences of characters.  Normally, these operate on
+sequences of characters whose syntax is word constituent.  If this
+variable is non-nil, then they operate on sequences of characters who
+syntax is either word constituent or symbol constituent.
+
+This is useful for programming styles which wish to capitalize the
+beginning of symbols, but not capitalize individual words in a symbol.*/);
+  case_symbols_as_words = 0;
+
   defsubr (&Supcase);
   defsubr (&Sdowncase);
   defsubr (&Scapitalize);
diff --git a/src/search.c b/src/search.c
index e9b29bb7179..b15ec52fa46 100644
--- a/src/search.c
+++ b/src/search.c
@@ -2365,7 +2365,7 @@ DEFUN ("replace-match", Freplace_match, Sreplace_match, 
1, 5, 0,
 convert NEWTEXT to all caps.  Otherwise if all words are capitalized
 in the replaced text, capitalize each word in NEWTEXT.  Note that
 what exactly is a word is determined by the syntax tables in effect
-in the current buffer.
+in the current buffer, and the variable `case-symbols-as-words'.
 
 If optional third arg LITERAL is non-nil, insert NEWTEXT literally.
 Otherwise treat `\\' as special:
@@ -2479,7 +2479,8 @@ DEFUN ("replace-match", Freplace_match, Sreplace_match, 
1, 5, 0,
              /* Cannot be all caps if any original char is lower case */
 
              some_lowercase = 1;
-             if (SYNTAX (prevc) != Sword)
+             if (SYNTAX (prevc) != Sword
+                 && (!case_symbols_as_words || SYNTAX (prevc) != Ssymbol))
                some_nonuppercase_initial = 1;
              else
                some_multiletter_word = 1;
@@ -2487,7 +2488,8 @@ DEFUN ("replace-match", Freplace_match, Sreplace_match, 
1, 5, 0,
          else if (uppercasep (c))
            {
              some_uppercase = 1;
-             if (SYNTAX (prevc) != Sword)
+             if (SYNTAX (prevc) != Sword
+                 && (!case_symbols_as_words || SYNTAX (prevc) != Ssymbol))
                ;
              else
                some_multiletter_word = 1;
@@ -2496,7 +2498,8 @@ DEFUN ("replace-match", Freplace_match, Sreplace_match, 
1, 5, 0,
            {
              /* If the initial is a caseless word constituent,
                 treat that like a lowercase initial.  */
-             if (SYNTAX (prevc) != Sword)
+             if (SYNTAX (prevc) != Sword
+                 && (!case_symbols_as_words || SYNTAX (prevc) != Ssymbol))
                some_nonuppercase_initial = 1;
            }
 
diff --git a/test/src/casefiddle-tests.el b/test/src/casefiddle-tests.el
index e7f4348b0c6..12984d898b9 100644
--- a/test/src/casefiddle-tests.el
+++ b/test/src/casefiddle-tests.el
@@ -294,4 +294,16 @@ casefiddle-turkish
     ;;(should (string-equal (capitalize "indIá") "İndıa"))
     ))
 
+(defun casefiddle-tests--check-syms (init with-words with-symbols)
+  (let ((case-symbols-as-words nil))
+    (should (string-equal (upcase-initials init) with-words)))
+  (let ((case-symbols-as-words t))
+    (should (string-equal (upcase-initials init) with-symbols))))
+
+(ert-deftest casefiddle-case-symbols-as-words ()
+  (casefiddle-tests--check-syms "Aa_bb Cc_dd" "Aa_Bb Cc_Dd" "Aa_bb Cc_dd")
+  (casefiddle-tests--check-syms "Aa_bb cc_DD" "Aa_Bb Cc_DD" "Aa_bb Cc_DD")
+  (casefiddle-tests--check-syms "aa_bb cc_dd" "Aa_Bb Cc_Dd" "Aa_bb Cc_dd")
+  (casefiddle-tests--check-syms "Aa_Bb Cc_Dd" "Aa_Bb Cc_Dd" "Aa_Bb Cc_Dd"))
+
 ;;; casefiddle-tests.el ends here
-- 
2.39.3