pathspec: create parse_element_magic helper

Factor out the logic responsible for the magic in a pathspec element
into its own function.

Also avoid calling into the parsing functions when
`PATHSPEC_LITERAL_PATH` is specified since it causes magic to be
ignored and all paths to be treated as literals.

Signed-off-by: Brandon Williams <bmwill@google.com>
Reviewed-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

pathspec.c

@@ -245,6 +245,19 @@ static const char *parse_short_magic(unsigned *magic, const char *elem)
 	return pos;
 }
 
+static const char *parse_element_magic(unsigned *magic, int *prefix_len,
+				       const char *elem)
+{
+	if (elem[0] != ':' || get_literal_global())
+		return elem; /* nothing to do */
+	else if (elem[1] == '(')
+		/* longhand */
+		return parse_long_magic(magic, prefix_len, elem);
+	else
+		/* shorthand */
+		return parse_short_magic(magic, elem);
+}
+
 /*
  * Take an element of a pathspec and check for magic signatures.
  * Append the result to the prefix. Return the magic bitmap.
@@ -267,26 +280,16 @@ static unsigned prefix_pathspec(struct pathspec_item *item, unsigned flags,
 	char *match;
 	int i, pathspec_prefix = -1;
 
-	if (elt[0] != ':' || get_literal_global() ||
-	    (flags & PATHSPEC_LITERAL_PATH)) {
-		; /* nothing to do */
-	} else if (elt[1] == '(') {
-		/* longhand */
-		copyfrom = parse_long_magic(&element_magic,
-					    &pathspec_prefix,
-					    elt);
-	} else {
-		/* shorthand */
-		copyfrom = parse_short_magic(&element_magic, elt);
-	}
-
-	magic |= element_magic;
-
 	/* PATHSPEC_LITERAL_PATH ignores magic */
-	if (flags & PATHSPEC_LITERAL_PATH)
+	if (flags & PATHSPEC_LITERAL_PATH) {
 		magic = PATHSPEC_LITERAL;
-	else
+	} else {
+		copyfrom = parse_element_magic(&element_magic,
+					       &pathspec_prefix,
+					       elt);
+		magic |= element_magic;
 		magic |= get_global_magic(element_magic);
+	}
 
 	if (pathspec_prefix >= 0 &&
 	    (prefixlen || (prefix && *prefix)))