Allow a CC Mode derived mode to have strings delimited by single quotes.

Also fix the bug where the delimiters of '\033', etc. got the error face.

* lisp/progmodes/cc-langs.el (c-single-quotes-quote-strings): Enhance the docr
string.
(c-string-delims): Change doc string to doc comment.

* listp/progmodes/cc-mode.el (c-before-change-check-unbalanced-strings): In
searches and comparisons, take account of the string delimiters possibly
being '.  Fix argument in call of c-before-change-check-unbalanced-strings.
(c-parse-quotes-before-change, c-parse-quotes-after-change): Bind
case-fold-search to nil.  Analyze escape constructs inside character constants
more accurately, in particular accepting as valid more than one character
after /[0-7], /x, /u, and /U.  Amend calculations to account for this extra
length.

2 files changed, 43 insertions, 21 deletions

diff --git a/lisp/progmodes/cc-langs.el b/lisp/progmodes/cc-langs.el
index 22b7b602f1e..2dff5cf83c8 100644
--- a/lisp/progmodes/cc-langs.el
+++ b/lisp/progmodes/cc-langs.el
@@ -599,13 +599,21 @@ EOL terminated statements."
 (c-lang-defvar c-has-bitfields (c-lang-const c-has-bitfields))
 
 (c-lang-defconst c-single-quotes-quote-strings
-  "Whether the language uses single quotes for multi-char strings."
+  "Whether the language uses single quotes for multi-char strings.
+
+Note that to set up a language to use this, additionally:
+\(i) the syntax of \"'\" must be \"string quote\" (7);
+\(ii) the language's value of `c-has-quoted-numbers' must be nil;
+\(iii) the language's value of `c-get-state-before-change-functions' may not
+  contain `c-parse-quotes-before-change';
+\(iv) the language's value of `c-before-font-lock-functions' may not contain
+  `c-parse-quotes-after-change'."
   t nil)
 (c-lang-defvar c-single-quotes-quote-strings
                (c-lang-const c-single-quotes-quote-strings))
 
 (c-lang-defconst c-string-delims
-  "A list of characters which can delimit arbitrary length strings"
+;; A list of characters which can delimit arbitrary length strings.
   t (if (c-lang-const c-single-quotes-quote-strings)
         '(?\" ?\')
       '(?\")))
diff --git a/lisp/progmodes/cc-mode.el b/lisp/progmodes/cc-mode.el
index b7812fa8f3d..49268c4482e 100644
--- a/lisp/progmodes/cc-mode.el
+++ b/lisp/progmodes/cc-mode.el
@@ -1212,12 +1212,15 @@ Note that the style variables are always made local to the buffer."
                (while
                    (and
                     (c-syntactic-re-search-forward
-                     "\"\\|\\s|" (point-max) t t)
+                     (if c-single-quotes-quote-strings
+                         "[\"']\\|\\s|"
+                       "\"\\|\\s|")
+                     (point-max) t t)
                     (progn
                       (c-clear-char-property (1- (point)) 'syntax-table)
                       (c-truncate-semi-nonlit-pos-cache (1- (point)))
-                      (not (eq (char-before) ?\")))))
-               (eq (char-before) ?\"))
+                      (not (memq (char-before) c-string-delims)))))
+               (memq (char-before) c-string-delims))
              (progn
                (c-pps-to-string-delim (point-max))
                (< (point) (point-max))))))
@@ -1229,7 +1232,9 @@ Note that the style variables are always made local to the buffer."
                      (eq beg-literal-type 'string))))
       ;; Deal with deletion of backslashes before "s.
       (goto-char end)
-      (if (and (looking-at "\\\\*\"")
+      (if (and (looking-at (if c-single-quotes-quote-strings
+                               "\\\\*[\"']"
+                             "\\\\*\""))
                (eq (logand (skip-chars-backward "\\\\" beg) 1) 1))
           (setq c-bc-changed-stringiness (not c-bc-changed-stringiness)))
       (if (eq beg-literal-type 'string)
@@ -1250,12 +1255,12 @@ Note that the style variables are always made local to the buffer."
                 (forward-char)
                 (backward-sexp)
                 (c-clear-char-property eoll-1 'syntax-table)
-                (c-truncate-semi-nonlit-pos-cache eoll-1)
-                (c-clear-char-property (point) 'syntax-table))
+                (c-clear-char-property (point) 'syntax-table)
+                (c-truncate-semi-nonlit-pos-cache (point)))
             ;; Opening " at EOB.
             (c-clear-char-property (1- (point)) 'syntax-table))
         (when (and (c-search-backward-char-property 'syntax-table '(15) c-new-BEG)
-                   (eq (char-after) ?\")) ; Ignore an unterminated raw string's (.
+                   (memq (char-after) c-string-delims)) ; Ignore an unterminated raw string's (.
           ;; Opening " on last line of text (without EOL).
           (c-clear-char-property (point) 'syntax-table)
           (c-truncate-semi-nonlit-pos-cache (point)))))
@@ -1264,7 +1269,7 @@ Note that the style variables are always made local to the buffer."
         (when
             (and
              (c-search-backward-char-property 'syntax-table '(15) c-new-BEG)
-             (eq (char-after) ?\"))
+             (memq (char-after) c-string-delims))
           (c-clear-char-property (point) 'syntax-table)
           (c-truncate-semi-nonlit-pos-cache (point)))))
 
@@ -1276,7 +1281,7 @@ Note that the style variables are always made local to the buffer."
         (c-truncate-semi-nonlit-pos-cache (1- (cdr end-limits))))
 
       (when (and (eq beg-literal-type 'string)
-                 (eq (char-after (car beg-limits)) ?\"))
+                 (memq (char-after (car beg-limits)) c-string-delims))
         (setq c-new-BEG (min c-new-BEG (car beg-limits)))
         (c-clear-char-property (car beg-limits) 'syntax-table)
         (c-truncate-semi-nonlit-pos-cache (car beg-limits))))))
@@ -1492,7 +1497,7 @@ Note that this is a strict tail, so won't match, e.g. \"0x....\".")
   ;;
   ;; This function is called exclusively as a before-change function via the
   ;; variable `c-get-state-before-change-functions'.
-  (c-save-buffer-state ()
+  (c-save-buffer-state (case-fold-search)
     (goto-char c-new-BEG)
     ;; We need to scan for 's from the BO (logical) line.
     (beginning-of-line)
@@ -1508,13 +1513,13 @@ Note that this is a strict tail, so won't match, e.g. \"0x....\".")
        ((c-quoted-number-head-before-point)
         (if (>= (point) c-new-BEG)
             (setq c-new-BEG (match-beginning 0))))
-       ((looking-at "\\([^'\\]\\|\\\\.\\)'")
+       ((looking-at
+         "\\([^'\\]\\|\\\\\\([0-7]\\{1,3\\}\\|[xuU][0-9a-fA-F]+\\|.\\)\\)'")
         (goto-char (match-end 0))
         (if (> (match-end 0) c-new-BEG)
             (setq c-new-BEG (1- (match-beginning 0)))))
-       ((or (>= (point) (1- c-new-BEG))
-            (and (eq (point) (- c-new-BEG 2))
-                 (eq (char-after) ?\\)))
+       ((save-excursion
+          (not (search-forward "'" c-new-BEG t)))
         (setq c-new-BEG (1- (point))))
        (t nil)))
 
@@ -1534,19 +1539,26 @@ Note that this is a strict tail, so won't match, e.g. \"0x....\".")
         (goto-char (match-end 0))
         (if (> (match-end 0) c-new-END)
             (setq c-new-END (match-end 0))))
-       ((looking-at "\\([^'\\]\\|\\\\.\\)'")
+       ((looking-at
+         "\\([^'\\]\\|\\\\\\([0-7]\\{1,3\\}\\|[xuU][0-9a-fA-F]+\\|.\\)\\)'")
         (goto-char (match-end 0))
         (if (> (match-end 0) c-new-END)
             (setq c-new-END (match-end 0))))
+       ((equal (c-get-char-property (1- (point)) 'syntax-table) '(1))
+        (when (c-search-forward-char-property-with-value-on-char
+               'syntax-table '(1) ?\' (c-point 'eoll))
+          (setq c-new-END (max (point) c-new-END))))
        (t nil)))
     ;; Having reached c-new-END, handle any 's after it whose context may be
-    ;; changed by the current buffer change.
+    ;; changed by the current buffer change.  The idea is to catch
+    ;; monstrosities like ',',',',',' changing "polarity".
     (goto-char c-new-END)
     (cond
      ((c-quoted-number-tail-after-point)
       (setq c-new-END (match-end 0)))
      ((looking-at
-       "\\(\\\\.\\|.\\)?\\('\\([^'\\]\\|\\\\.\\)\\)*'")
+       "\\(\\\\\\([0-7]\\{1,3\\}\\|[xuU][0-9a-fA-F]+\\|.\\)\\|.\\)?\
+\\('\\([^'\\]\\|\\\\\\([0-7]\\{1,3\\}\\|[xuU][0-9a-fA-F]+\\|.\\)\\)\\)*'")
       (setq c-new-END (match-end 0))))
 
     ;; Remove the '(1) syntax-table property from any "'"s within (c-new-BEG
@@ -1575,7 +1587,7 @@ Note that this is a strict tail, so won't match, e.g. \"0x....\".")
   ;;
   ;; This function is called exclusively as an after-change function via the
   ;; variable `c-before-font-lock-functions'.
-  (c-save-buffer-state (num-beg num-end)
+  (c-save-buffer-state (num-beg num-end case-fold-search)
     ;; Apply the needed syntax-table and c-digit-separator text properties to
     ;; quotes.
     (save-restriction
@@ -1597,7 +1609,9 @@ Note that this is a strict tail, so won't match, e.g. \"0x....\".")
                (c-put-char-properties-on-char num-beg num-end
                                               'c-digit-separator t ?')
                (goto-char num-end))
-              ((looking-at "\\([^\\']\\|\\\\.\\)'") ; balanced quoted expression.
+              ((looking-at
+                "\\([^\\']\\|\\\\\\([0-7]\\{1,3\\}\\|[xuU][0-9a-fA-F]+\\|.\\)\
+\\)'") ; balanced quoted expression.
                (goto-char (match-end 0)))
               (t
                (c-invalidate-state-cache (1- (point)))