Stub out capture snapshots in signatures. Note we can't do them as re…

…al snapshots until we get CaptureCursor style stuff in place, but we should be able to quickly get equivalent semantics in place, and when we do get CaptureCursor the infrastructure is there to use.

src/binder/bind.c

@@ -509,8 +509,26 @@ Rakudo_binding_bind_signature(PARROT_INTERP, PMC *lexpad, PMC *signature,
 
     /* Now we'll walk through the signature and go about binding things. */
     for (i = 0; i < num_elements; i++) {
+        /* Is it looking for us to bind a capture here? */
+        if (elements[i]->flags & SIG_ELEM_IS_CAPTURE) {
+            /* XXX In the long run, we need to snapshot any current CaptureCursor.
+             * For now, we don't have that, so we just build off the current
+             * capture. */
+            PMC *ns       = Parrot_get_ctx_HLL_namespace(interp);
+            PMC *snapper  = Parrot_get_global(interp, ns, string_from_literal(interp, "!snapshot_capture"));
+            PMC *snapshot = PMCNULL;
+            Parrot_ext_call(interp, snapper, "PiIP->P", capture, cur_pos_arg, named_args_copy, &snapshot);
+            bind_fail = Rakudo_binding_bind_one_param(interp, lexpad, elements[i], snapshot,
+                    no_nom_type_check, error);
+            if (bind_fail) {
+                if (pos_from_named)
+                    mem_sys_free(pos_from_named);
+                return bind_fail;
+            }
+        }
+
         /* Is it a positional sourced from a named? */
-        if (pos_from_named && pos_from_named[i]) {
+        else if (pos_from_named && pos_from_named[i]) {
             /* We have the value - try bind this parameter. */
             bind_fail = Rakudo_binding_bind_one_param(interp, lexpad, elements[i],
                     pos_from_named[i], no_nom_type_check, error);

src/builtins/Capture.pir

@@ -92,6 +92,29 @@ XXX Returns Parrot Hash, not Perl 6 Hash.
 
 =back
 
+=head2 Functions
+
+=over 4
+
+=item !snapshot_capture
+
+Snapshots the current capture cursor.
+
+Well, akshually...until we implement Capture Cursor it just kinda pretends
+to. :-) Hands back a Capture containing the snapshot.
+
+=cut
+
+.namespace []
+.sub '!snapshot_capture'
+    .param pmc capture
+    .param int pos_position
+    .param pmc nameds_unbound
+    die "Capture snapshots in signatures not yet implemented."
+.end
+
+=back
+
 =cut
 
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