Add \o{} escape

This commit adds the new construct \o{} to express a character constant
by its octal ordinal value, along with ancillary tests and
documentation.

A function to handle this is added to util.c, and it is called from the
3 parsing places it could occur.  The function is a candidate for
in-lining, though I doubt that it will ever be used frequently.

1 files changed, 67 insertions, 1 deletions

diff --git a/util.c b/util.c
index b3b385e2cc..6fdc6534a9 100644
--- a/util.c
+++ b/util.c
@@ -3904,7 +3904,7 @@ Perl_report_evil_fh(pTHX_ const GV *gv, const IO *io, I32 op)
 char
 Perl_grok_bslash_c(pTHX_ const char source, const bool output_warning)
 {
-    
+
     U8 result;
 
     if (! isASCII(source)) {
@@ -3935,6 +3935,72 @@ Perl_grok_bslash_c(pTHX_ const char source, const bool output_warning)
     return result;
 }
 
+char *
+Perl_grok_bslash_o(pTHX_ const char *s, UV *uv, STRLEN *len, const bool output_warning)
+{
+
+/*  Documentation to be supplied when interface nailed down finally
+ *  This returns NULL on success, otherwise a pointer to an internal constant
+ *  error message.  On input:
+ *	s   points to a string that begins with o, and the previous character was
+ *	    a backslash.
+ *	uv  points to a UV that will hold the output value
+ *	len will point to the next character in the string past the end of this
+ *	    construct
+ *	output_warning says whether to output any warning messages, or suppress
+ *	    them
+ */
+    char* e;
+    STRLEN numbers_len;
+    I32 flags = PERL_SCAN_ALLOW_UNDERSCORES
+		| PERL_SCAN_DISALLOW_PREFIX
+		/* XXX Until the message is improved in grok_oct, handle errors
+		 * ourselves */
+	        | PERL_SCAN_SILENT_ILLDIGIT;
+
+    PERL_ARGS_ASSERT_GROK_BSLASH_O;
+
+
+    assert(*s == 'o');
+    s++;
+
+    if (*s != '{') {
+	*len = 1;	/* Move past the o */
+	return "Missing braces on \\o{}";
+    }
+
+    e = strchr(s, '}');
+    if (!e) {
+	*len = 2;	/* Move past the o{ */
+	return "Missing right brace on \\o{";
+    }
+
+    /* Return past the '}' no matter what is inside the braces */
+    *len = e - s + 2;	/* 2 = 1 for the o + 1 for the '}' */
+
+    s++;    /* Point to first digit */
+
+    numbers_len = e - s;
+    if (numbers_len == 0) {
+	return "Number with no digits";
+    }
+
+    *uv = NATIVE_TO_UNI(grok_oct(s, &numbers_len, &flags, NULL));
+    /* Note that if has non-octal, will ignore everything starting with that up
+     * to the '}' */
+
+    if (output_warning && numbers_len != (STRLEN) (e - s)) {
+	Perl_ck_warner(aTHX_ packWARN(WARN_DIGIT),
+	/* diag_listed_as: Non-octal character '%c'.  Resolved as "%s" */
+		       "Non-octal character '%c'.  Resolved as \"\\o{%.*s}\"",
+		       *(s + numbers_len),
+		       (int) numbers_len,
+		       s);
+    }
+
+    return NULL;
+}
+
 /* To workaround core dumps from the uninitialised tm_zone we get the
  * system to give us a reasonable struct to copy.  This fix means that
  * strftime uses the tm_zone and tm_gmtoff values returned by