Implement (representation-polymorphic) type creation by KnowHOWs. Als…

…o implement add_method and find_method in the KnowHOW meta-object. This means we can create KnowHOWs, add methods do them and dispatch to them.

src/metamodel/knowhow_bootstrapper.c

@@ -9,6 +9,72 @@
 #include "repr_registry.h"
 #include "reprs/KnowHOWREPR.h"
 
+/* Cached string constants. */
+static STRING *repr_str     = NULL;
+static STRING *p6opaque_str = NULL;
+
+/* Creates a new type with this HOW as its meta-object. */
+static void new_type(PARROT_INTERP, PMC *nci) {
+    /* We first create a new HOW instance. */
+    PMC *capture = Parrot_pcc_get_signature(interp, CURRENT_CONTEXT(interp));
+    PMC *self    = VTABLE_get_pmc_keyed_int(interp, capture, 0);
+    PMC *HOW     = REPR(self)->instance_of(interp, REPR_PMC(self), STABLE(self)->WHAT);
+
+    /* See if we have a representation name; if not default to P6opaque. */
+    STRING *repr_name = VTABLE_exists_keyed_str(interp, capture, repr_str) ?
+        VTABLE_get_string_keyed_str(interp, capture, repr_str) :
+        p6opaque_str;
+
+    /* Create a new type object of the desired REPR. (Note that we can't
+     * default to KnowHOWREPR here, since it doesn't know how to actually
+     * store attributes, it's just for bootstrapping knowhow's. */
+    PMC *repr_to_use = REPR_get_by_name(interp, repr_name);
+    PMC *type_object = REPR_STRUCT(repr_to_use)->type_object_for(interp, repr_to_use, HOW);
+
+    /* Put it into capture to act as return value. */
+    Parrot_pcc_build_call_from_c_args(interp, capture, "P", type_object);
+}
+
+/* Adds a method. */
+static void add_method(PARROT_INTERP, PMC *nci) {
+    /* Get methods table out of meta-object. */
+    PMC    *capture = Parrot_pcc_get_signature(interp, CURRENT_CONTEXT(interp));
+    PMC    *self    = VTABLE_get_pmc_keyed_int(interp, capture, 0);
+    PMC    *methods = ((KnowHOWREPRInstance *)PMC_data(self))->methods;
+
+    /* Get name and method to add. */
+    STRING *name   = VTABLE_get_string_keyed_int(interp, capture, 2);
+    PMC    *method = VTABLE_get_pmc_keyed_int(interp, capture, 3);
+
+    /* Add it, and return added method as result. */
+    VTABLE_set_pmc_keyed_str(interp, methods, name, method);
+    Parrot_pcc_build_call_from_c_args(interp, capture, "P", method);
+}
+
+/* Finds a method. */
+static void find_method(PARROT_INTERP, PMC *nci) {
+    /* Get methods table out of meta-object and look up method. */
+    PMC    *capture = Parrot_pcc_get_signature(interp, CURRENT_CONTEXT(interp));
+    PMC    *self    = VTABLE_get_pmc_keyed_int(interp, capture, 0);
+    PMC    *methods = ((KnowHOWREPRInstance *)PMC_data(self))->methods;
+    STRING *name    = VTABLE_get_string_keyed_int(interp, capture, 2);
+    PMC    *method  = VTABLE_get_pmc_keyed_str(interp, methods, name);
+    if (PMC_IS_NULL(method))
+        /* XXX Awesomeize. */
+        Parrot_ex_throw_from_c_args(interp, NULL, EXCEPTION_INVALID_OPERATION,
+                "Could not find method '%Ss'", name);
+
+    /* Put into capture to act as return value. */
+    Parrot_pcc_build_call_from_c_args(interp, capture, "P", method);
+}
+
+/* Wraps up a C function as a raw NCI method. */
+static PMC * wrap_c(PARROT_INTERP, void *func) {
+    PMC * const wrapped = Parrot_pmc_new(interp, enum_class_NCI);
+    VTABLE_set_pointer(interp, wrapped, func);
+    return wrapped;
+}
+
 /* This is the find_method where things eventually bottom out. */
 static PMC * bottom_find_method(PARROT_INTERP, PMC *obj, STRING *name, INTVAL hint) {
     PMC *methods = ((KnowHOWREPRInstance *)PMC_data(obj))->methods;
@@ -43,11 +109,23 @@ void RakudoObject_bootstrap_knowhow(PARROT_INTERP) {
     knowhow_how->common.stable = st_copy;
 
     /* Add various methods to the KnowHOW's HOW. */
-    /* XXX TODO */
+    VTABLE_set_pmc_keyed_str(interp, knowhow_how->methods,
+        Parrot_str_new_constant(interp, "new_type"),
+        wrap_c(interp, F2DPTR(new_type)));
+    VTABLE_set_pmc_keyed_str(interp, knowhow_how->methods,
+        Parrot_str_new_constant(interp, "find_method"),
+        wrap_c(interp, F2DPTR(find_method)));
+    VTABLE_set_pmc_keyed_str(interp, knowhow_how->methods,
+        Parrot_str_new_constant(interp, "add_method"),
+        wrap_c(interp, F2DPTR(add_method)));
 
     /* Set this built up HOW as the KnowHOW's HOW. */
     STABLE(knowhow_pmc)->HOW = knowhow_how_pmc;
 
+    /* Set up some string constants that the methods here use. */
+    repr_str     = Parrot_str_new_constant(interp, "repr");
+    p6opaque_str = Parrot_str_new_constant(interp, "P6opaque");
+
     /* Install KnowHOW into the root Parrot namespace, since that's where NQP
      * lives.
      * XXX We'll likely want to change this in the future. */