Setup the very basic KnowHOWAttribute in 6model core rather than leav…

…ing every HLL the problem of setting up an initial one. It's especially a pain if you're going to have a compile time meta-model and need the attribute meta-object available to the compiler. (FWIW, nqpclr ended up with this in core too, though with a different initial motivation.)

src/6model/knowhow_bootstrapper.c

@@ -220,3 +220,80 @@ PMC * SixModelObject_bootstrap_knowhow(PARROT_INTERP, PMC *sc) {
 
     return knowhow_pmc;
 }
+
+/* Attribute new method. */
+static void attr_new(PARROT_INTERP, PMC *nci) {
+    PMC    *capture = Parrot_pcc_get_signature(interp, CURRENT_CONTEXT(interp));
+    PMC    *type    = VTABLE_get_pmc_keyed_int(interp, capture, 0);
+    STRING *name    = VTABLE_get_string_keyed_str(interp, capture, name_str);
+    PMC    *self    = REPR(type)->instance_of(interp, REPR_PMC(type), type);
+    REPR(self)->set_str(interp, REPR_PMC(self), self, name);
+    Parrot_pcc_build_call_from_c_args(interp, capture, "P", self);
+}
+
+/* Attribute name introspection. */
+static void attr_name(PARROT_INTERP, PMC *nci) {
+    PMC    *capture = Parrot_pcc_get_signature(interp, CURRENT_CONTEXT(interp));
+    PMC    *self    = VTABLE_get_pmc_keyed_int(interp, capture, 0);
+    STRING *name    = REPR(self)->get_str(interp, REPR_PMC(self), self);
+    Parrot_pcc_build_call_from_c_args(interp, capture, "S", name);
+}
+
+/* Sets up a very simple attribute meta-object. Just supports having a
+ * name, and even uses the P6str representation to store it, so that's
+ * really all that it supports. */
+PMC * SixModelObject_setup_knowhow_attribute(PARROT_INTERP, PMC *sc, PMC *knowhow) {
+    PMC *old_ctx, *cappy, *meth, *knowhow_attr, *how;
+
+    /* Create a new KnowHOWAttribute type using P6str repr.. */
+    meth = STABLE(knowhow)->find_method(interp, knowhow,
+        Parrot_str_new_constant(interp, "new_type"), NO_HINT);
+    old_ctx = Parrot_pcc_get_signature(interp, CURRENT_CONTEXT(interp));
+    cappy   = Parrot_pmc_new(interp, enum_class_CallContext);
+    VTABLE_push_pmc(interp, cappy, knowhow);
+    VTABLE_set_string_keyed_str(interp, cappy, name_str,
+        Parrot_str_new_constant(interp, "KnowHOWAttribute"));
+    VTABLE_set_string_keyed_str(interp, cappy, repr_str,
+        Parrot_str_new_constant(interp, "P6str"));
+    Parrot_pcc_invoke_from_sig_object(interp, meth, cappy);
+    cappy = Parrot_pcc_get_signature(interp, CURRENT_CONTEXT(interp));
+    Parrot_pcc_set_signature(interp, CURRENT_CONTEXT(interp), old_ctx);
+    knowhow_attr = VTABLE_get_pmc_keyed_int(interp, cappy, 0);
+    how = STABLE(knowhow_attr)->HOW;
+
+    /* Add new method. */
+    meth = STABLE(how)->find_method(interp, how,
+        Parrot_str_new_constant(interp, "add_method"), NO_HINT);
+    cappy   = Parrot_pmc_new(interp, enum_class_CallContext);
+    VTABLE_push_pmc(interp, cappy, how);
+    VTABLE_push_pmc(interp, cappy, knowhow_attr);
+    VTABLE_push_string(interp, cappy, Parrot_str_new_constant(interp, "new"));
+    VTABLE_push_pmc(interp, cappy, wrap_c(interp, F2DPTR(attr_new)));
+    Parrot_pcc_invoke_from_sig_object(interp, meth, cappy);
+    Parrot_pcc_set_signature(interp, CURRENT_CONTEXT(interp), old_ctx);
+
+    /* Add name method. */
+    cappy   = Parrot_pmc_new(interp, enum_class_CallContext);
+    VTABLE_push_pmc(interp, cappy, how);
+    VTABLE_push_pmc(interp, cappy, knowhow_attr);
+    VTABLE_push_string(interp, cappy, name_str);
+    VTABLE_push_pmc(interp, cappy, wrap_c(interp, F2DPTR(attr_name)));
+    Parrot_pcc_invoke_from_sig_object(interp, meth, cappy);
+    Parrot_pcc_set_signature(interp, CURRENT_CONTEXT(interp), old_ctx);
+
+    /* Compose. */
+    meth = STABLE(knowhow)->find_method(interp, how,
+        Parrot_str_new_constant(interp, "compose"), NO_HINT);
+    cappy   = Parrot_pmc_new(interp, enum_class_CallContext);
+    VTABLE_push_pmc(interp, cappy, how);
+    VTABLE_push_pmc(interp, cappy, knowhow_attr);
+    Parrot_pcc_invoke_from_sig_object(interp, meth, cappy);
+    Parrot_pcc_set_signature(interp, CURRENT_CONTEXT(interp), old_ctx);
+
+    /* Associate the created object with the intial core serialization
+     * context. */
+    VTABLE_set_pmc_keyed_int(interp, sc, 2, knowhow_attr);
+    SC_PMC(knowhow_attr) = sc;
+
+    return knowhow_attr;
+}

src/6model/knowhow_bootstrapper.h

@@ -1 +1,2 @@
 PMC * SixModelObject_bootstrap_knowhow(PARROT_INTERP, PMC *sc);
+PMC * SixModelObject_setup_knowhow_attribute(PARROT_INTERP, PMC *sc, PMC *knowhow);

src/6model/sixmodelobject.c

@@ -17,7 +17,7 @@ static STRING *find_method_str = NULL;
 static STRING *type_check_str = NULL;
 
 /* Initializes 6model and produces the KnowHOW core meta-object. */
-PMC * SixModelObject_initialize(PARROT_INTERP) {
+void SixModelObject_initialize(PARROT_INTERP, PMC **knowhow, PMC **knowhow_attribute) {
     PMC    *initial_sc;
     STRING *initial_sc_name;
 
@@ -38,8 +38,11 @@ PMC * SixModelObject_initialize(PARROT_INTERP) {
     /* Build representations and initializes the representation registry. */
     REPR_initialize_registry(interp);
 
-    /* Bootstrap the KnowHOW and return it. */
-    return SixModelObject_bootstrap_knowhow(interp, initial_sc);
+    /* Bootstrap the KnowHOW. */
+    *knowhow = SixModelObject_bootstrap_knowhow(interp, initial_sc);
+
+    /* Set up the simple KnowHOWAttribute. */
+    *knowhow_attribute = SixModelObject_setup_knowhow_attribute(interp, initial_sc, *knowhow);
 }
 
 /* Takes a representation and wraps it up in a REPR PMC. */

src/6model/sixmodelobject.h

@@ -166,7 +166,7 @@ typedef struct {
 #define REPR_STRUCT(p)   ((REPRCommonalities *)PMC_data(p))
 
 /* Object model initialization. */
-PMC * SixModelObject_initialize(PARROT_INTERP);
+void SixModelObject_initialize(PARROT_INTERP, PMC **knowhow, PMC **knowhow_attribute);
 
 /* Some utility functions. */
 PMC * wrap_repr(PARROT_INTERP, void *REPR);

src/ops/nqp.ops

@@ -25,8 +25,9 @@ static INTVAL smo_id    = 0;
 static INTVAL disp_id   = 0;
 static INTVAL ms_id     = 0;
 
-/* Built-in HOWs (meta-objects). */
+/* Built-in meta-objects. */
 static PMC *KnowHOW = NULL;
+static PMC *KnowHOWAttribute = NULL;
 
 END_OPS_PREAMBLE
 
@@ -51,7 +52,7 @@ inline op nqp_dynop_setup() :base_core {
         ms_id     = pmc_type(interp, Parrot_str_new(interp, "NQPMultiSig", 0));
 
         /* Initialize the object model. */
-        KnowHOW = SixModelObject_initialize(interp);
+        SixModelObject_initialize(interp, &KnowHOW, &KnowHOWAttribute);
     }
 }
 
@@ -74,6 +75,24 @@ inline op get_knowhow(out PMC) :base_core {
 }
 
 
+/*
+
+=item get_knowhow_attribute()
+
+Returns the 6model core meta-attribute, KnowHOWAttribute.
+
+=cut
+
+*/
+inline op get_knowhow_attribute(out PMC) :base_core {
+    if (KnowHOWAttribute)
+        $1 = KnowHOWAttribute;
+    else
+        Parrot_ex_throw_from_c_args(interp, NULL, EXCEPTION_INVALID_OPERATION,
+            "6model not yet initialized; cannot use get_knowhow_attribute");
+}
+
+
 /*
 
 =item get_how(obj)