2 styles of string literals, using cc-mode

[yary <not.com@gmail.com>]

Hi all,

I'm using csharp-mode by Moonfire games ( http://mfgames.com/linux/csharp-mode
), which is derived from cc-mode.

C# has a "feature", two styles of strings. Regular strings are very
much like C strings, starting and ending with double quotes, backslash
escapes allowed inside.

@"Verbatim literal strings look like this"- they have an at-sign just
before the double-quote. Verbatim literal strings can have embedded
newlines, regular strings can't. Backslashes have no special meaning
inside verbatim literals, so:

@"\x00" == "\\x00"
@"foo\" == "foo\\"

I haven't hacked much cc-mode or elisp in general, still it was pretty
simple to get multiline verbatim literals working:

;; Can't escape a newline in a regular string
(c-lang-defconst c-string-escaped-newlines
  csharp nil)

;; Literal strings can be multiline without escaping
(c-lang-defconst c-multiline-string-start-char
  csharp ?@)

I had expected the @ to fontify the same as the " in @" after adding
the following, but these seem to have made no difference:

;; Start of a comment or any string literal- copied from cc-lang,
added @? before \"
(c-lang-defconst c-literal-start-regexp
  csharp (concat (c-lang-const c-comment-start-regexp)
	    "\\|"
	    (if (memq 'gen-string-delim c-emacs-features)
		"@?\"|"
	      "@?\"")))

;; add verbatim string literal to primary regexp
(c-lang-defconst c-primary-expr-regexp
  csharp (concat (c-lang-const c-primary-expr-regexp)
		 "\\|@\""))

... and I have no clue how to tell emacs to change the syntax of \
inside a verbatim literal in csharp mode, so it won't be an escape
anymore. I took a look at cc-engine.el to get a clue as to how it
works, but its elisp is too advanced for me. Any pointers?