namespace.pmc

/*
Copyright (C) 2005-2011, Parrot Foundation.

=head1 NAME

src/pmc/namespace.pmc - NameSpace PMC

=head1 DESCRIPTION

These are the vtable functions for the namespace PMC.

=head2 Functions

=over 4

=cut

*/

#include "pmc/pmc_sub.h"

/* HEADERIZER HFILE: none */
/* HEADERIZER BEGIN: static */
/* Don't modify between HEADERIZER BEGIN / HEADERIZER END.  Your changes will be lost. */

static void add_multi_to_namespace(PARROT_INTERP,
    ARGIN(PMC *SELF),
    ARGIN(STRING *key),
    ARGIN_NULLOK(PMC *value))
        __attribute__nonnull__(1)
        __attribute__nonnull__(2)
        __attribute__nonnull__(3);

static void add_native_to_namespace(PARROT_INTERP,
    ARGIN(PMC *SELF),
    ARGIN(STRING *key),
    ARGIN_NULLOK(PMC *value))
        __attribute__nonnull__(1)
        __attribute__nonnull__(2)
        __attribute__nonnull__(3);

static void add_to_class(PARROT_INTERP,
    ARGMOD(Parrot_NameSpace_attributes *nsinfo),
    ARGMOD_NULLOK(PMC *classobj),
    ARGIN(STRING *key),
    ARGIN(PMC *value))
        __attribute__nonnull__(1)
        __attribute__nonnull__(2)
        __attribute__nonnull__(4)
        __attribute__nonnull__(5)
        FUNC_MODIFIES(*nsinfo)
        FUNC_MODIFIES(*classobj);

PARROT_WARN_UNUSED_RESULT
static int maybe_add_sub_to_namespace(PARROT_INTERP,
    ARGIN(PMC *SELF),
    ARGIN(STRING *key),
    ARGIN(PMC *value))
        __attribute__nonnull__(1)
        __attribute__nonnull__(2)
        __attribute__nonnull__(3)
        __attribute__nonnull__(4);

PARROT_WARN_UNUSED_RESULT
static int ns_insert_sub_keyed_str(PARROT_INTERP,
    ARGIN(PMC *self),
    ARGIN(STRING *key),
    ARGIN(PMC *value))
        __attribute__nonnull__(1)
        __attribute__nonnull__(2)
        __attribute__nonnull__(3)
        __attribute__nonnull__(4);

#define ASSERT_ARGS_add_multi_to_namespace __attribute__unused__ int _ASSERT_ARGS_CHECK = (\
       PARROT_ASSERT_ARG(interp) \
    , PARROT_ASSERT_ARG(SELF) \
    , PARROT_ASSERT_ARG(key))
#define ASSERT_ARGS_add_native_to_namespace __attribute__unused__ int _ASSERT_ARGS_CHECK = (\
       PARROT_ASSERT_ARG(interp) \
    , PARROT_ASSERT_ARG(SELF) \
    , PARROT_ASSERT_ARG(key))
#define ASSERT_ARGS_add_to_class __attribute__unused__ int _ASSERT_ARGS_CHECK = (\
       PARROT_ASSERT_ARG(interp) \
    , PARROT_ASSERT_ARG(nsinfo) \
    , PARROT_ASSERT_ARG(key) \
    , PARROT_ASSERT_ARG(value))
#define ASSERT_ARGS_maybe_add_sub_to_namespace __attribute__unused__ int _ASSERT_ARGS_CHECK = (\
       PARROT_ASSERT_ARG(interp) \
    , PARROT_ASSERT_ARG(SELF) \
    , PARROT_ASSERT_ARG(key) \
    , PARROT_ASSERT_ARG(value))
#define ASSERT_ARGS_ns_insert_sub_keyed_str __attribute__unused__ int _ASSERT_ARGS_CHECK = (\
       PARROT_ASSERT_ARG(interp) \
    , PARROT_ASSERT_ARG(self) \
    , PARROT_ASSERT_ARG(key) \
    , PARROT_ASSERT_ARG(value))
/* Don't modify between HEADERIZER BEGIN / HEADERIZER END.  Your changes will be lost. */
/* HEADERIZER END: static */

/*

=item C<static void add_to_class(PARROT_INTERP, Parrot_NameSpace_attributes
*nsinfo, PMC *classobj, STRING *key, PMC *value)>

=cut

*/

static void
add_to_class(PARROT_INTERP, ARGMOD(Parrot_NameSpace_attributes *nsinfo),
        ARGMOD_NULLOK(PMC *classobj), ARGIN(STRING *key), ARGIN(PMC *value))
{
    ASSERT_ARGS(add_to_class)

    /* Insert it in class, if there is a class */
    if (!PMC_IS_NULL(classobj) && PObj_is_class_TEST(classobj))
        VTABLE_add_method(interp, classobj, key, value);

    /* Otherwise, store it in the namespace for the class to
     * retrieve later */
    else {
        /* If we don't have a place to hang methods, make one. */
        if (PMC_IS_NULL(nsinfo->methods))
            nsinfo->methods = Parrot_pmc_new(interp, enum_class_Hash);

        /* Insert it. */
        VTABLE_set_pmc_keyed_str(interp, nsinfo->methods, key, value);
    }
}

/*

=item C<static int ns_insert_sub_keyed_str(PARROT_INTERP, PMC *self, STRING
*key, PMC *value)>

=cut

*/

PARROT_WARN_UNUSED_RESULT
static int
ns_insert_sub_keyed_str(PARROT_INTERP, ARGIN(PMC *self), ARGIN(STRING *key),
        ARGIN(PMC *value))
{
    ASSERT_ARGS(ns_insert_sub_keyed_str)

    Parrot_NameSpace_attributes * const nsinfo   = PARROT_NAMESPACE(self);
    PMC              *       vtable   = nsinfo->vtable;
    PMC              * const classobj = VTABLE_get_class(interp, self);
    STRING           * vtable_key     = STRINGNULL;
    Parrot_Sub_attributes *sub;
    INTVAL stored = 0;

    PMC_get_sub(interp, value, sub);

    if (sub->vtable_index != -1) {
        /* Insert it in class, if there is a class */
        if (!PMC_IS_NULL(classobj) && PObj_is_class_TEST(classobj)) {
            const char * const vtable_key_c =
                Parrot_get_vtable_name(interp, sub->vtable_index);
            PARROT_ASSERT(vtable_key_c);
            vtable_key = Parrot_str_new(interp, vtable_key_c,
                strlen(vtable_key_c));
            VTABLE_add_vtable_override(interp, classobj, vtable_key, value);
        }

        /* Otherwise, store it in the namespace for the class to
         * retrieve later */
        else {
            /* If we don't have a place to hang vtables, make one. */
            if (PMC_IS_NULL(vtable))
                nsinfo->vtable = vtable = Parrot_pmc_new(interp, enum_class_Hash);

            /* Insert it. */
            VTABLE_set_pmc_keyed_int(interp, vtable, sub->vtable_index, value);
        }
        if (!(sub->comp_flags & SUB_COMP_FLAG_NSENTRY))
            stored = 1;
    }

    if (sub->comp_flags & SUB_COMP_FLAG_METHOD) {
        STRING *method_name = key;

        if (STRING_equal(interp, sub->method_name, CONST_STRING(interp, ""))) {
            if (sub->vtable_index != -1 && !STRING_IS_NULL(vtable_key)) {
                method_name = vtable_key;
            }
        }
        else {
            method_name = sub->method_name;
        }
        add_to_class(interp, nsinfo, classobj, method_name, value);

        if (!(sub->comp_flags & SUB_COMP_FLAG_NSENTRY))
            stored = 1;
    }

    return stored;
}

/*

=item C<static int maybe_add_sub_to_namespace(PARROT_INTERP, PMC *SELF, STRING
*key, PMC *value)>

=cut

*/

PARROT_WARN_UNUSED_RESULT
static int
maybe_add_sub_to_namespace(PARROT_INTERP, ARGIN(PMC *SELF), ARGIN(STRING *key),
        ARGIN(PMC *value))
{
    ASSERT_ARGS(maybe_add_sub_to_namespace)

    STRING * const sub_str = CONST_STRING(interp, "Sub");

    if (!PMC_IS_NULL(value)
    &&   VTABLE_isa(interp, value, sub_str)
    &&   value->vtable->base_type != enum_class_Object)
        return ns_insert_sub_keyed_str(interp, SELF, key, value);

    return 0;
}

/*

=item C<static void add_native_to_namespace(PARROT_INTERP, PMC *SELF, STRING
*key, PMC *value)>

=cut

*/

static void
add_native_to_namespace(PARROT_INTERP, ARGIN(PMC *SELF), ARGIN(STRING *key),
        ARGIN_NULLOK(PMC *value))
{
    ASSERT_ARGS(add_native_to_namespace)

    if (!PMC_IS_NULL(value)
    && (value->vtable->base_type == enum_class_NativePCCMethod ||
        value->vtable->base_type == enum_class_NCI)) {
        Parrot_NameSpace_attributes * const nsinfo = PARROT_NAMESPACE(SELF);
        PMC * const classobj = VTABLE_get_class(interp, SELF);

        /* Insert it in class, if there is a class */
        add_to_class(interp, nsinfo, classobj, key, value);
    }
}

/*

=item C<static void add_multi_to_namespace(PARROT_INTERP, PMC *SELF, STRING
*key, PMC *value)>

=cut

*/

static void
add_multi_to_namespace(PARROT_INTERP, ARGIN(PMC *SELF), ARGIN(STRING *key),
        ARGIN_NULLOK(PMC *value))
{
    ASSERT_ARGS(add_multi_to_namespace)

    STRING * const multi_str = CONST_STRING(interp, "MultiSub");

    if (!PMC_IS_NULL(value)
    &&   VTABLE_isa(interp, value, multi_str)) {

        /* TT #10; work around that Sub doesn't use PMC ATTRs */
        if (value->vtable->base_type != enum_class_Object
        &&  VTABLE_elements(interp, value) > 0) {
            Parrot_NameSpace_attributes * const nsinfo = PARROT_NAMESPACE(SELF);
            PMC * const classobj = VTABLE_get_class(interp, SELF);

            /* Extract the first alternate and check if it is a method */
            PMC * const pmc_sub = VTABLE_get_pmc_keyed_int(interp, value, 0);
            Parrot_Sub_attributes *sub;
            PMC_get_sub(interp, pmc_sub, sub);

            if (sub->comp_flags & SUB_COMP_FLAG_METHOD) {
                STRING * const empty_str   = CONST_STRING(interp, "");
                STRING *method_name = key;
                Hash   *hash;

                if (!STRING_equal(interp, sub->method_name, empty_str))
                    method_name = sub->method_name;

                add_to_class(interp, nsinfo, classobj, method_name, value);

                GETATTR_NameSpace_hash(interp, SELF, hash);
                PARROT_GC_WRITE_BARRIER(interp, SELF);

                Parrot_hash_put(interp, hash,
                    Parrot_hash_key_from_string(interp, hash, key),
                    Parrot_hash_value_from_pmc(interp, hash, value));
            }
        }
    }
}


/*
 * Typically a named slot contains either another namespace or a
 * var/sub (not both).
 * In case that the bucket->value is occupied, a FixedPMCArray is
 * created, and the items are moved over to that extra storage.
 * The array is flagged with FPA_is_ns_ext to distinguish it from a
 * plain array variable.
 *
 * This could easily expand to a full-fledged typed namespace if needed.
 */

typedef enum {
    NS_slot_ns,
    NS_slot_var_sub,         /* unspecified ~half-raw slot */
    NS_max_slots
} NS_slot_enum;

#define FPA_is_ns_ext PObj_private0_FLAG

pmclass NameSpace extends Hash provides hash no_ro auto_attrs {

    ATTR STRING *name;     /* Name of this namespace part. */
    ATTR PMC    *_class;   /* The class or role attached to this namespace. */
    ATTR PMC    *methods;  /* A Hash of methods, keyed on the method name. This
                            * goes away when the methods are sucked in by a
                            * class. */
    ATTR PMC    *vtable;   /* A Hash of vtable subs, keyed on the vtable index */
    ATTR PMC    *parent;   /* This NameSpace's parent NameSpace */

/*

=item C<void init()>

Initialize a C<NameSpace> PMC.

=cut

*/

    VTABLE void init() {
        SUPER();
        PARROT_NAMESPACE(SELF)->vtable  = PMCNULL;
        PARROT_NAMESPACE(SELF)->methods = PMCNULL;
        PARROT_NAMESPACE(SELF)->_class  = PMCNULL;
        PObj_custom_mark_SET(SELF);
    }

/*

=item C<void mark()>

Marks the namespace as live.

=cut

*/
    VTABLE void mark() {
        Parrot_NameSpace_attributes * const nsinfo = PARROT_NAMESPACE(SELF);

        SUPER();
        Parrot_gc_mark_PMC_alive(INTERP, nsinfo->parent);
        Parrot_gc_mark_PMC_alive(INTERP, nsinfo->_class);
        Parrot_gc_mark_PMC_alive(INTERP, nsinfo->vtable);
        Parrot_gc_mark_PMC_alive(INTERP, nsinfo->methods);
        Parrot_gc_mark_STRING_alive(INTERP, nsinfo->name);
    }

/*

=item C<PMC *get_class()>

Returns the class or role PMC that is associated with this namespace.

=cut

*/

    PMC *get_class() {
        UNUSED(INTERP);
        return PARROT_NAMESPACE(SELF)->_class;
    }

/*

=item C<void set_pmc_keyed_str(STRING *key, PMC *value)>

Sets C<*value> as the namespace item for C<*key>. This is part of the
raw interface. If the PMC C<value> is exactly a NameSpace, C<SELF>
will be set as the parent of that namespace and the name C<key> of
C<value> is stored too.

=item C<void set_pmc_keyed(PMC *key, PMC *value)>

If C<key> is a simple key, it works like above. If C<key> is an array
of strings or a chained key, add all components to the namespace.

=item C<PMC *get_pmc_keyed(PMC *key)>

Return the given namespace or PMCNULL. C<key> is either an array of
strings, or a possibly nested key.

=item C<PMC *get_pmc_keyed_str(STRING *key)>

Return the given namespace item or PMCNULL. If the named item is either
a NameSpace or a var, the NameSpace is returned.

=item C<PMC *get_pmc_keyed_int(INTVAL key)>

Return a Sub representing an overridden vtable entry or PMCNULL.  This is not
really a public API.

=cut

*/

    VTABLE void set_pmc_keyed_str(STRING *key, PMC *value) {
        PMC        *new_tuple = NULL;
        const int   val_is_NS = PMC_IS_NULL(value)
                              ? 0
                              :value->vtable->base_type == enum_class_NameSpace;

        /* don't need this everywhere yet */
        PMC *old;

        /* If it's a sub... */
        if (maybe_add_sub_to_namespace(INTERP, SELF, key, value))
            return;

        /* If it's an native method */
        add_native_to_namespace(INTERP, SELF, key, value);

        /* If it's a multi-sub and the first in this NS... */
        add_multi_to_namespace(INTERP, SELF, key, value);

        old = (PMC *)Parrot_hash_get(INTERP, (Hash *)SELF.get_pointer(), key);

        if (!old)
            SUPER(key, value);
        else {
            if ((old->vtable->base_type == enum_class_NameSpace) == val_is_NS) {
                /* simple ns or simple var/sub changed */
                SUPER(key, value);
            }
            else if ((PObj_get_FLAGS(old) & FPA_is_ns_ext) &&
                    old->vtable->base_type == enum_class_FixedPMCArray) {
                /* we have a tuple extension already */
                VTABLE_set_pmc_keyed_int(INTERP, old,
                        val_is_NS ? NS_slot_ns : NS_slot_var_sub,
                        value);
            }
            else {
                /* create new tuple */
                /* for a fully typed namespace, we'd need 3 or 4 */
                new_tuple = Parrot_pmc_new_init_int(INTERP,
                        enum_class_FixedPMCArray, NS_max_slots);

                /* flag it as special */
                PObj_get_FLAGS(new_tuple) |= FPA_is_ns_ext;
            }
        }

        if (val_is_NS) {
            /* TODO - this hack needs to go */
            Parrot_NameSpace_attributes * const nsinfo = PARROT_NAMESPACE(value);
            nsinfo->parent = SELF;  /* set parent */
            nsinfo->name   = key;   /* and name */

            if (new_tuple) {
                VTABLE_set_pmc_keyed_int(INTERP, new_tuple, NS_slot_ns, value);
                VTABLE_set_pmc_keyed_int(INTERP, new_tuple, NS_slot_var_sub,
                                         old);

                Parrot_hash_put(INTERP, (Hash *)SELF.get_pointer(), key, new_tuple);
                /* distinction from a plain FPA, which doesn't extend the
                 * namespace storage */
            }
        }
        else if (new_tuple) {
            VTABLE_set_pmc_keyed_int(INTERP, new_tuple, NS_slot_ns, old);
            VTABLE_set_pmc_keyed_int(INTERP, new_tuple, NS_slot_var_sub, value);
            Parrot_hash_put(INTERP, (Hash *)SELF.get_pointer(), key, new_tuple);
        }
    }

    VTABLE void set_pmc_keyed(PMC *key, PMC *value) {
        PMC *ns = SELF;

        if (key->vtable->base_type == enum_class_String) {
            SELF.set_pmc_keyed_str(VTABLE_get_string(INTERP, key), value);
            return;
        }

        if (key->vtable->base_type == enum_class_Key) {
            while (1) {
                STRING * const part = VTABLE_get_string(INTERP, key);
                key                 = VTABLE_shift_pmc(INTERP, key);

                if (!key) {
                    Parrot_ns_set_global(INTERP, ns, part, value);
                    return;
                }

                ns = Parrot_ns_make_namespace_keyed_str(INTERP, ns, part);
            }
        }

        if (key->vtable->base_type == enum_class_ResizableStringArray) {
            const INTVAL elements = VTABLE_elements(INTERP, key);
            INTVAL i;
            for (i = 0; i < elements; ++i)  {
                STRING * const part = VTABLE_get_string_keyed_int(INTERP, key, i);

                if ((i + 1) >= elements) { /* Last entry in the array */
                    Parrot_ns_set_global(INTERP, ns, part, value);
                    return;
                }

                ns = Parrot_ns_make_namespace_keyed_str(INTERP, ns, part);
            }
        }

        Parrot_ex_throw_from_c_args(INTERP, NULL, EXCEPTION_GLOBAL_NOT_FOUND,
            "Invalid namespace key in set_pmc_keyed");
    }

    VTABLE PMC *get_pmc_keyed_str(STRING *key) {
        Hash * const hash = (Hash *)SELF.get_pointer();
        PMC *ns = (PMC *)Parrot_hash_get(INTERP, hash, key);

        if (!ns)
            return PMCNULL;

        if ((PObj_get_FLAGS(ns) & FPA_is_ns_ext) &&
                ns->vtable->base_type == enum_class_FixedPMCArray)
            ns = VTABLE_get_pmc_keyed_int(INTERP, ns, NS_slot_ns);

        return ns;
    }

    VTABLE PMC *get_pmc_keyed(PMC *key) {
        PMC *ns = SUPER(key);
        /* Is this equivalent?
        PMC    *ns = INTERP->vtables[enum_class_Hash]->get_pmc_keyed(INTERP, SELF, key);
        */

        if (!PMC_IS_NULL(ns))
            return ns;

        ns = SELF;

        if (key->vtable->base_type == enum_class_Key) {
            STRING * const part = VTABLE_get_string(INTERP, key);
            key                 = VTABLE_shift_pmc(INTERP, key);

            if (!key)
                return VTABLE_get_pmc_keyed_str(INTERP, ns, part);

            ns = Parrot_ns_get_namespace_keyed_str(INTERP, ns, part);

            if (PMC_IS_NULL(ns))
                return PMCNULL;

            return VTABLE_get_pmc_keyed(INTERP, ns, key);
        }
        else if (VTABLE_does(INTERP, key, CONST_STRING(INTERP, "array"))) {
            const INTVAL elements = VTABLE_elements(INTERP, key);
            INTVAL i;
            for (i = 0; i < elements && !PMC_IS_NULL(ns); ++i) {
                STRING * const name = VTABLE_get_string_keyed_int(INTERP, key, i);
                if (STRING_IS_NULL(name)) {
                    ns = PMCNULL;
                    /* What to do here? Throw an exception or something? */
                    break;
                }
                ns = Parrot_ns_get_namespace_keyed_str(INTERP, ns, name);
            }
            return ns;
        }
        else {
            STRING * const name = VTABLE_get_string(INTERP, key);
            ns = Parrot_ns_get_namespace_keyed_str(INTERP, ns, name);
            return ns;
        }
        /* If we get the wrong type, should we throw an exception?
        Parrot_ex_throw_from_c_args(INTERP, NULL, EXCEPTION_GLOBAL_NOT_FOUND,
            "Invalid namespace key in get_pmc_keyed_str");
        */
    }

    VTABLE PMC *get_pmc_keyed_int(INTVAL key) {
        Parrot_NameSpace_attributes * const nsinfo = PARROT_NAMESPACE(SELF);
        PMC              * const vtable = nsinfo->vtable;

        if (PMC_IS_NULL(vtable))
            return PMCNULL;

        return VTABLE_get_pmc_keyed_int(INTERP, vtable, key);
    }

/*

=item C<void *get_pointer_keyed_str(STRING *key)>

=item C<void *get_pointer_keyed(PMC *key)>

Return the given namespace item or PMCNULL. If the named item is either
a NameSpace or a var, the var is returned.

TT #1472
TOTAL KLUDGE.  ON THE CHOPPING BLOCK.

=cut

*/

    VTABLE void *get_pointer_keyed_str(STRING *key) {
        PMC  *ns;
        Hash *hash;
        GETATTR_NameSpace_hash(INTERP, SELF, hash);

        ns = (PMC *)Parrot_hash_get(INTERP, hash, key);

        if (ns && (PObj_get_FLAGS(ns) & FPA_is_ns_ext)
        &&   ns->vtable->base_type == enum_class_FixedPMCArray)
            ns = VTABLE_get_pmc_keyed_int(INTERP, ns, NS_slot_var_sub);

        /* Be extra careful about returning PMCNULL */
        return ns ? ns : PMCNULL;
    }

    VTABLE void *get_pointer_keyed(PMC *key) {
        PMC    *ns = SELF;

        if (PMC_IS_NULL(key))
            return PMCNULL;

        switch (key->vtable->base_type) {
            case enum_class_String:
                return SELF.get_pointer_keyed_str(VTABLE_get_string(INTERP, key));
            case enum_class_Key: {
                /* this loop (and function) could use a rewrite for clarity */
                while (1) {
                    STRING * const part = VTABLE_get_string(INTERP, key);
                    key                 = VTABLE_shift_pmc(INTERP, key);

                    if (!key)
                        return VTABLE_get_pointer_keyed_str(INTERP, ns, part);

                    ns = Parrot_ns_get_namespace_keyed_str(INTERP, ns, part);

                    if (PMC_IS_NULL(ns))
                        return PMCNULL;
                }
            }
            case enum_class_ResizableStringArray: {
                const INTVAL elements = VTABLE_elements(INTERP, key);
                INTVAL i;
                for (i = 0; i < elements; ++i)  {
                    STRING * const part = VTABLE_get_string_keyed_int(INTERP, key, i);

                    /* Last entry in the array */
                    if ((i + 1) >= elements)
                        return VTABLE_get_pointer_keyed_str(INTERP, ns, part);

                    ns = Parrot_ns_get_namespace_keyed_str(INTERP, ns, part);

                    if (PMC_IS_NULL(ns))
                        return PMCNULL;
                }
                return ns;
            }
            default:
                Parrot_ex_throw_from_c_args(INTERP, NULL, EXCEPTION_GLOBAL_NOT_FOUND,
                    "Invalid namespace key of type '%S' in get_pointer_keyed",
                    key->vtable->whoami);
        }
    }

/*

=item C<STRING *get_string()>

Return the name of this namespace part.

=cut

*/

    VTABLE STRING *get_string() {
        const Parrot_NameSpace_attributes * const nsinfo = PARROT_NAMESPACE(SELF);
        UNUSED(INTERP);
        return nsinfo->name;
    }

/*

=item C<PMC *inspect_str(STRING *what)>

Provides introspection of a specific piece of information about the
namespace. The available information is:

=over 8

=item class

The class object associated with the namespace, if any.

=item methods

A temporary cache of methods (destroyed when class object is created).
Hash keyed on method name, value is an invokable PMC. Includes methods
composed in from roles.

=item vtable_overrides

A temporary cache of vtable overrides (destroyed when class object is
created). Hash keyed on vtable name, value is an invokable PMC.
Includes vtable overrides composed in from roles.

=back

=cut

*/

    VTABLE PMC *inspect_str(STRING *what) {
        const Parrot_NameSpace_attributes * const nsinfo = PARROT_NAMESPACE(SELF);
        PMC *found;

        if (STRING_equal(INTERP, what, CONST_STRING(INTERP, "methods"))) {
            found = nsinfo->methods;
        }
        else if (STRING_equal(INTERP, what, CONST_STRING(INTERP, "vtable_overrides"))) {
            found = nsinfo->vtable;
        }
        else if (STRING_equal(INTERP, what, CONST_STRING(INTERP, "class"))) {
            found = nsinfo->_class;
        }
        else
            Parrot_ex_throw_from_c_args(INTERP, NULL, EXCEPTION_INVALID_OPERATION,
                "Unknown introspection value '%S'", what);

        /* return found value */
        if (PMC_IS_NULL(found))
            return PMCNULL;

        return found;
    }

/*

=back

=head2 Methods

=over 4

=cut

*/

/*

=item C<METHOD make_namespace(PMC* key)>

Create and retrieve the namespace given by C<key>.  If the namespace
already exists, only retrieve it.

=cut

*/

    METHOD make_namespace(PMC *key) {
        PMC *ns = Parrot_ns_get_namespace_keyed(INTERP, SELF, key);
        if (PMC_IS_NULL(ns)) {
            ns = Parrot_ns_make_namespace_keyed(INTERP, SELF, key);
        }
        RETURN(PMC *ns);
    }

/*

=item C<METHOD add_namespace(STRING *name, PMC *namespace)>

Stores the given namespace under this namespace, with the given name.  Throws
an invalid type exception if C<namespace> is not a NameSpace PMC or subclass.

=cut

*/

    METHOD add_namespace(STRING *name, PMC *_namespace) {
        STRING * const s_ns = CONST_STRING(INTERP, "NameSpace");

        if (!VTABLE_isa(INTERP, _namespace, s_ns))
            Parrot_ex_throw_from_c_args(INTERP, NULL, EXCEPTION_INVALID_OPERATION,
                "Invalid type %d in add_namespace()",
                _namespace->vtable->base_type);

        VTABLE_set_pmc_keyed_str(INTERP, SELF, name, _namespace);
    }

/*

=item C<METHOD add_sub(STRING *name, PMC *sub)>

Stores the given sub under this namespace, with the given name.  Throws an
invalid type exception if C<sub> is not a Sub PMC or subclass.

=cut

*/

    METHOD add_sub(STRING *name, PMC *sub) {
        STRING * const s_sub      = CONST_STRING(INTERP, "Sub");
        STRING * const s_multisub = CONST_STRING(INTERP, "MultiSub");

        if (!VTABLE_isa(INTERP, sub, s_sub)
        &&  !VTABLE_isa(INTERP, sub, s_multisub))
            Parrot_ex_throw_from_c_args(INTERP, NULL,
                EXCEPTION_INVALID_OPERATION,
                "Invalid type %d in add_sub()", sub->vtable->base_type);

        VTABLE_set_pmc_keyed_str(INTERP, SELF, name, sub);
    }

/*

=item C<METHOD add_var(STRING *name, PMC *var)>

Stores the given variable under this namespace, with the given name.

=cut

*/

    METHOD add_var(STRING *name, PMC *var) {
        VTABLE_set_pmc_keyed_str(INTERP, SELF, name, var);
    }

/*

=item C<METHOD get_name()>

Returns the name of the namespace as an array of strings.

  $P2 = $P3.'get_name'()
  $S0 = join '::', $P2            # '::Foo::Bar'

=cut

*/

    METHOD get_name() {
        PMC * const ar = Parrot_pmc_new(INTERP, enum_class_ResizableStringArray);
        INTVAL elements = 0;
        PMC *ns        = SELF;

        while (ns) {
            Parrot_NameSpace_attributes *nsinfo = PARROT_NAMESPACE(ns);
            VTABLE_unshift_string(INTERP, ar, nsinfo->name);
            ns = nsinfo->parent;
            ++elements;
        }

        /* remove the NULL string of the namespace root */
        if (elements > 0)
            VTABLE_shift_string(INTERP, ar);

        RETURN(PMC *ar);
    }
/*

=item C<METHOD find_namespace(STRING *name)>

Return the namespace with the given name.

=cut

*/

    METHOD find_namespace(STRING *key) {
        STRING * const s_ns = CONST_STRING(INTERP, "NameSpace");
        PMC    * const ns   = (PMC *)Parrot_hash_get(INTERP, (Hash *)SELF.get_pointer(),
                                                     key);

        if (!ns)
            RETURN(PMC *PMCNULL);

        /* it's a NameSpace */
        if (VTABLE_isa(INTERP, ns, s_ns))
            RETURN(PMC *ns);

        RETURN(PMC *PMCNULL);
    }

/*

=item C<METHOD find_sub(STRING *name)>

Return the Sub PMC with the given name.

=cut

*/

    METHOD find_sub(STRING *key) {
        STRING * const s_sub = CONST_STRING(INTERP, "Sub");
        PMC    * const sub   = (PMC *)Parrot_hash_get(INTERP, (Hash *)SELF.get_pointer(),
                                                      key);

        if (!sub)
            RETURN(PMC *PMCNULL);

        /* it's a Sub */
        if (VTABLE_isa(INTERP, sub, s_sub))
            RETURN(PMC *sub);

        RETURN(PMC *PMCNULL);
    }

/*

=item C<METHOD find_var(STRING *name)>

Return the PMC with the given name.

=cut

*/

    METHOD find_var(STRING *key) {
        PMC * const val = (PMC *)Parrot_hash_get(INTERP, (Hash *)SELF.get_pointer(), key);

        if (!val)
            RETURN(PMC *PMCNULL);

        RETURN(PMC *val);
    }

/*

=item C<METHOD del_namespace(STRING *name)>

Deletes the contained NameSpace PMC with the given name.  Throws an invalid
type exception if the item to delete is not a NameSpace PMC or subclass, and
does not delete the PMC.

=cut

*/

    METHOD del_namespace(STRING *name) {
        Hash   * const hash = (Hash *)SELF.get_pointer();
        PMC    * const ns   = (PMC *)Parrot_hash_get(INTERP, hash, name);
        STRING * const s_ns = CONST_STRING(INTERP, "NameSpace");

        if (PMC_IS_NULL(ns))
            RETURN(void);

        if (!VTABLE_isa(INTERP, ns, s_ns))
            Parrot_ex_throw_from_c_args(INTERP, NULL, EXCEPTION_INVALID_OPERATION,
                "Invalid type %d for '%Ss' in del_namespace()",
                ns->vtable->base_type, name);

        Parrot_hash_delete(INTERP, hash, name);
    }

/*

=item C<METHOD del_sub(STRING *name)>

Deletes the contained Sub PMC with the given name.  Throws an invalid type
exception if the item to delete is not a Sub PMC or subclass, and does not
delete the PMC.

=cut

*/

    METHOD del_sub(STRING *name) {
        Hash   * const hash  = (Hash *)SELF.get_pointer();
        PMC    * const sub   = (PMC *)Parrot_hash_get(INTERP, hash, name);
        STRING * const s_sub = CONST_STRING(INTERP, "Sub");

        if (PMC_IS_NULL(sub))
            RETURN(void);

        if (!VTABLE_isa(INTERP, sub, s_sub))
            Parrot_ex_throw_from_c_args(INTERP, NULL, EXCEPTION_INVALID_OPERATION,
                "Invalid type %d for '%Ss' in del_sub()",
                sub->vtable->base_type, name);

        Parrot_hash_delete(INTERP, hash, name);
    }

/*

=item C<METHOD del_var(STRING *name)>

Deletes the contained variable-like PMC with the given name.

=cut

*/

    METHOD del_var(STRING *name) {
        Parrot_hash_delete(INTERP, (Hash *)SELF.get_pointer(), name);
    }

/*

=item C<METHOD get_sym(STRING *name)>

Return the symbol (var or sub) with the given name. This can be used
to retrieve symbols, if a NameSpace with the same name exists.

=cut

*/

    METHOD get_sym(STRING *key) {
        PMC *ns = (PMC *)Parrot_hash_get(INTERP, (Hash *)SELF.get_pointer(), key);

        if (!ns)
            RETURN(PMC *PMCNULL);

        /* it's a NameSpace */
        if (ns->vtable == SELF->vtable)
            RETURN(PMC *PMCNULL);

        if ((PObj_get_FLAGS(ns) & FPA_is_ns_ext)
        &&  ns->vtable->base_type == enum_class_FixedPMCArray)
            ns = VTABLE_get_pmc_keyed_int(INTERP, ns, NS_slot_var_sub);

        RETURN(PMC *ns);
    }

/*

=item C<METHOD export_to(PMC *dest, PMC *what)>

Export items from this NameSpace into the C<dest> NameSpace. The items to
export are named in C<what>, which may be an array of strings, a hash, or null.
If C<what> is an array of strings, interpretation of items in an array follows
the conventions of the source (exporting) namespace.
If C<what> is a hash, the keys correspond to the names in the source namespace,
and the values correspond to the names in the destination namespace.
if a hash value is null or an empty string, the name in the hash key is used.
A null C<what> requests the 'default' set of items.
Any other type passed in C<what> throws an exception.

NOTE: exporting 'default' set of items is not yet implemented.

=cut

*/

    METHOD export_to(PMC *dest, PMC *what) {
        STRING * const s_hash  = CONST_STRING(INTERP, "hash");
        STRING * const s_array = CONST_STRING(INTERP, "array");

        if (PMC_IS_NULL(dest))
            Parrot_ex_throw_from_c_args(INTERP, NULL, EXCEPTION_INVALID_OPERATION,
                "destination namespace not specified");

        if (PMC_IS_NULL(what) || !VTABLE_elements(INTERP, what))
            Parrot_ex_throw_from_c_args(INTERP, NULL, EXCEPTION_UNIMPLEMENTED,
                "exporting default object set not yet implemented");

        /* if "what" does "hash", we extract string key/value pairs,
         * lookup the object with the name specified in the key,
         * and export it with the name specified as value. */
        if (VTABLE_does(INTERP, what, s_hash)) {
            PMC * const  iter = VTABLE_get_iter(INTERP, what);
            const INTVAL n    = VTABLE_elements(INTERP, what);
            INTVAL       i;

            for (i = 0; i < n; ++i) {
                STRING *dest_name;
                PMC    *object;
                STRING * const src_name = VTABLE_shift_string(INTERP, iter);

                if (STRING_IS_NULL(src_name) || STRING_IS_EMPTY(src_name))
                    Parrot_ex_throw_from_c_args(INTERP, NULL, EXCEPTION_INVALID_OPERATION,
                        "source object name not specified");

                if (PMC_IS_NULL(VTABLE_get_pmc_keyed_str(INTERP, what, src_name))) {
                    dest_name = src_name;
                }
                else {
                    dest_name = VTABLE_get_string_keyed_str(INTERP, what, src_name);
                    if (STRING_IS_NULL(dest_name) || STRING_IS_EMPTY(dest_name))
                        dest_name = src_name;
                }

                object = VTABLE_get_pmc_keyed_str(INTERP, SELF, src_name);

                if (PMC_IS_NULL(object))
                    Parrot_ex_throw_from_c_args(INTERP, NULL, EXCEPTION_GLOBAL_NOT_FOUND,
                        "object '%Ss' not found in current namespace", src_name);

                VTABLE_set_pmc_keyed_str(INTERP, dest, dest_name, object);
            }
        }
        else if (VTABLE_does(INTERP, what, s_array)) {
            const INTVAL n = VTABLE_elements(INTERP, what);
            INTVAL       i;

            for (i = 0; i < n; ++i) {
                PMC    *object;
                STRING * const name = VTABLE_get_string_keyed_int(INTERP, what, i);

                if (STRING_IS_NULL(name) || STRING_IS_EMPTY(name))
                    Parrot_ex_throw_from_c_args(INTERP, NULL, EXCEPTION_INVALID_OPERATION,
                        "object name not specified");

                object = VTABLE_get_pmc_keyed_str(INTERP, SELF, name);

                if (PMC_IS_NULL(object))
                    Parrot_ex_throw_from_c_args(INTERP, NULL, EXCEPTION_GLOBAL_NOT_FOUND,
                        "object '%Ss' not found in current namespace", name);

                VTABLE_set_pmc_keyed_str(INTERP, dest, name, object);
            }
        }
        else
            Parrot_ex_throw_from_c_args(INTERP, NULL, EXCEPTION_INVALID_OPERATION,
                "can't handle argument of type %Ss", what->vtable->whoami);
    }

/*

=item C<METHOD get_parent()>

Return the parent NameSpace or PMCNULL, if none.

=cut

*/

    METHOD get_parent() {
        PMC * const parent = PARROT_NAMESPACE(SELF)->parent ?
                                 PARROT_NAMESPACE(SELF)->parent : PMCNULL;
        RETURN(PMC *parent);
    }

/*

=item C<METHOD get_class()>

Returns the class or role PMC that is associated with this namespace.

=cut

*/

    METHOD get_class() {
        Parrot_NameSpace_attributes * const nsinfo = PARROT_NAMESPACE(SELF);
        PMC              *ret_class     = nsinfo->_class;

        if (PMC_IS_NULL(ret_class))
            ret_class = PMCNULL;

        RETURN(PMC *ret_class);
    }

/*

=item C<METHOD set_class(PMC *class_or_role)>

Sets the class or role PMC that is associated with this namespace.

=cut

*/

    METHOD set_class(PMC *class_or_role) {
        PARROT_NAMESPACE(SELF)->_class = class_or_role;
    }

/*

=item C<METHOD get_associated_methods()>

Gets the Hash of methods associated with this namespace and removes it from
the namespace.

=cut

*/

    METHOD get_associated_methods() {
        Parrot_NameSpace_attributes * const nsinfo      = PARROT_NAMESPACE(SELF);
        PMC              * const ret_methods = nsinfo->methods;

        nsinfo->methods = PMCNULL;

        RETURN(PMC *ret_methods);
    }

/*

=item C<METHOD get_associated_vtable_methods()>

Gets the Hash of vtables associated with this namespace and removes it
from the namespace.

=cut

*/

    METHOD get_associated_vtable_methods() {
        Parrot_NameSpace_attributes * const nsinfo      = PARROT_NAMESPACE(SELF);
        PMC              * const ret_methods = nsinfo->vtable;

        nsinfo->vtable = PMCNULL;

        RETURN(PMC *ret_methods);
    }

}

/*

=back

=head1 SEE ALSO

F<docs/pdds/pdd21_namespaces.pod>

=cut

*/

/*
 * Local variables:
 *   c-file-style: "parrot"
 * End:
 * vim: expandtab shiftwidth=4 cinoptions='\:2=2' :
 */