Move all the signature param parsing logic out of perly.y into a help…

…er API

Provide a subsignature_*() API

Added:
 * subsignature_start()
 * subsignature_append_slurpy()
 * subsignature_append_positional()
 * subsignature_finish()

Call these from code blocks in perly.y

Make the actual parser signature struct opaque, hidden in toke.c. This
gives it much more robustness against future modifications.

embed.fnc

@@ -3090,6 +3090,19 @@ ATdmp	|bool	|strict_utf8_to_uv					\
 CRp	|NV	|str_to_version |NN SV *sv
 : Used in pp_ctl.c
 p	|void	|sub_crush_depth|NN CV *cv
+: Used in perly.y
+p	|void	|subsignature_append_positional 			\
+				|NULLOK OP *varop			\
+				|OPCODE defmode 			\
+				|NULLOK OP *defexpr
+p	|void	|subsignature_append_slurpy				\
+				|I32 sigil				\
+				|NULLOK OP *varop
+p	|OP *	|subsignature_finish
+p	|yy_parser_signature *|subsignature_parser_dup				\
+				|NULLOK const yy_parser_signature * const proto \
+				|NN CLONE_PARAMS * const param
+p	|void	|subsignature_start
 Adp	|void	|suspend_compcv |NN struct suspended_compcv *buffer
 ATdip	|void	|SvAMAGIC_off	|NN SV *sv
 ATdip	|void	|SvAMAGIC_on	|NN SV *sv

embed.h

@@ -1211,6 +1211,11 @@
 #   define sighandler1                          Perl_sighandler1
 #   define sighandler3                          Perl_sighandler3
 #   define sub_crush_depth(a)                   Perl_sub_crush_depth(aTHX_ a)
+#   define subsignature_append_positional(a,b,c) Perl_subsignature_append_positional(aTHX_ a,b,c)
+#   define subsignature_append_slurpy(a,b)      Perl_subsignature_append_slurpy(aTHX_ a,b)
+#   define subsignature_finish()                Perl_subsignature_finish(aTHX)
+#   define subsignature_parser_dup(a,b)         Perl_subsignature_parser_dup(aTHX_ a,b)
+#   define subsignature_start()                 Perl_subsignature_start(aTHX)
 #   define sv_2num(a)                           Perl_sv_2num(aTHX_ a)
 #   define sv_clean_all()                       Perl_sv_clean_all(aTHX)
 #   define sv_clean_objs()                      Perl_sv_clean_objs(aTHX)

parser.h

@@ -31,6 +31,10 @@ typedef struct yy_lexshared {
     SV			*re_eval_str;	/* "(?{...})" text */
 } LEXSHARED;
 
+/* Opaque struct of data relevant during parsing and construction of a
+ * subroutine signature. Defined and used exclusively by toke.c */
+typedef struct yy_parser_signature yy_parser_signature;
+
 typedef struct yy_parser {
 
     /* parser state */
@@ -112,10 +116,7 @@ typedef struct yy_parser {
     line_t	herelines;	/* number of lines in here-doc */
     line_t	preambling;	/* line # when processing $ENV{PERL5DB} */
 
-    /* these are valid while parsing a subroutine signature */
-    UV          sig_elems;      /* number of signature elements seen so far */
-    UV          sig_optelems;   /* number of optional signature elems seen */
-    char        sig_slurpy;     /* the sigil of the slurpy var (or null) */
+    yy_parser_signature *signature; /* parser state of a subroutine signature */
     bool        sig_seen;       /* the currently parsing sub has a signature */
 
     bool        recheck_charset_validity;