+
+DEFUN ("internal--text-restyle", Finternal__text_restyle,
+ Sinternal__text_restyle, 1, 1, 0,
+ doc: /* Return STRING, possibly substituting quote characters.
+
+In the result, replace each curved single quote (\\=‘ and \\=’) by
+left and right quote characters as specified by ‘text-quoting-style’.
+
+Return the original STRING in the common case where no changes are needed.
+Otherwise, return a new string. */)
+ (Lisp_Object string)
+{
+ bool changed = false;
+
+ CHECK_STRING (string);
+ if (! STRING_MULTIBYTE (string))
+ return string;
+
+ enum text_quoting_style quoting_style = text_quoting_style ();
+ if (quoting_style == CURVE_QUOTING_STYLE)
+ return string;
+
+ ptrdiff_t bsize = SBYTES (string);
+ unsigned char const *strp = SDATA (string);
+ unsigned char const *strlim = strp + bsize;
+ USE_SAFE_ALLOCA;
+ char *buf = SAFE_ALLOCA (bsize);
+ char *bufp = buf;
+ ptrdiff_t nchars = 0;
+
+ while (strp < strlim)
+ {
+ unsigned char const *cp = strp;
+ switch (STRING_CHAR_ADVANCE (strp))
+ {
+ case LEFT_SINGLE_QUOTATION_MARK:
+ *bufp++ = quoting_style == GRAVE_QUOTING_STYLE ? '`': '\'';
+ changed = true;
+ break;
+
+ case RIGHT_SINGLE_QUOTATION_MARK:
+ *bufp++ = '\'';
+ changed = true;
+ break;
+
+ default:
+ do
+ *bufp++ = *cp++;
+ while (cp != strp);
+
+ break;
+ }
+
+ nchars++;
+ }
+
+ Lisp_Object result
+ = changed ? make_string_from_bytes (buf, nchars, bufp - buf) : string;
+ SAFE_FREE ();
+ return result;
+}