hash.c

/*
Copyright (C) 2001-2010, Parrot Foundation.

=head1 NAME

src/hash.c - Hash table

=head1 DESCRIPTION

A hashtable contains an array of bucket indexes. Buckets are nodes in a
linked list, each containing a C<void *> key and value. During hash
creation, the types of key and value as well as appropriate compare and
hashing functions can be set.

This hash implementation uses just one piece of malloced memory. The
C<< hash->buckets >> bucket store points to this region.

=head2 Functions

=over 4

=cut

*/

#include "parrot/parrot.h"

/* hash first allocation size */
#define INITIAL_SIZE  2

/* below this hash size we use fixed_size_allocator
 * else we use system allocator */
#define SPLIT_POINT  16

/* HEADERIZER HFILE: include/parrot/hash.h */

/* HEADERIZER BEGIN: static */
/* Don't modify between HEADERIZER BEGIN / HEADERIZER END.  Your changes will be lost. */

static void allocate_buckets(PARROT_INTERP,
    ARGMOD(Hash *hash),
    ARGIN_NULLOK(const UINTVAL size))
        __attribute__nonnull__(1)
        __attribute__nonnull__(2)
        FUNC_MODIFIES(*hash);

static void expand_hash(PARROT_INTERP, ARGMOD(Hash *hash))
        __attribute__nonnull__(1)
        __attribute__nonnull__(2)
        FUNC_MODIFIES(*hash);

PARROT_WARN_UNUSED_RESULT
PARROT_PURE_FUNCTION
PARROT_INLINE
static int hash_compare(PARROT_INTERP,
    ARGIN(const Hash *hash),
    ARGIN_NULLOK(void *a),
    ARGIN_NULLOK(void *b))
        __attribute__nonnull__(1)
        __attribute__nonnull__(2);

PARROT_WARN_UNUSED_RESULT
PARROT_PURE_FUNCTION
PARROT_INLINE
static int hash_compare_cstring(SHIM_INTERP,
    ARGIN(const char *a),
    ARGIN(const char *b))
        __attribute__nonnull__(2)
        __attribute__nonnull__(3);

PARROT_WARN_UNUSED_RESULT
PARROT_PURE_FUNCTION
PARROT_INLINE
static int hash_compare_int(SHIM_INTERP,
    ARGIN_NULLOK(const void *a),
    ARGIN_NULLOK(const void *b));

PARROT_WARN_UNUSED_RESULT
PARROT_PURE_FUNCTION
PARROT_INLINE
static int hash_compare_pmc(PARROT_INTERP, ARGIN(PMC *a), ARGIN(PMC *b))
        __attribute__nonnull__(1)
        __attribute__nonnull__(2)
        __attribute__nonnull__(3);

PARROT_WARN_UNUSED_RESULT
PARROT_PURE_FUNCTION
PARROT_INLINE
static int hash_compare_pointer(SHIM_INTERP,
    ARGIN_NULLOK(const void *a),
    ARGIN_NULLOK(const void *b));

PARROT_WARN_UNUSED_RESULT
PARROT_PURE_FUNCTION
PARROT_INLINE
static int hash_compare_string(PARROT_INTERP,
    ARGIN(const void *search_key),
    ARGIN_NULLOK(const void *bucket_key))
        __attribute__nonnull__(1)
        __attribute__nonnull__(2);

PARROT_WARN_UNUSED_RESULT
static int hash_compare_string_enc(PARROT_INTERP,
    ARGIN(const void *search_key),
    ARGIN(const void *bucket_key))
        __attribute__nonnull__(1)
        __attribute__nonnull__(2)
        __attribute__nonnull__(3);

PARROT_WARN_UNUSED_RESULT
PARROT_PURE_FUNCTION
PARROT_INLINE
static size_t key_hash(PARROT_INTERP,
    ARGIN(const Hash *hash),
    ARGIN_NULLOK(void *key))
        __attribute__nonnull__(1)
        __attribute__nonnull__(2);

PARROT_WARN_UNUSED_RESULT
PARROT_PURE_FUNCTION
PARROT_INLINE
static size_t key_hash_cstring(SHIM_INTERP,
    ARGIN(const void *value),
    size_t seed)
        __attribute__nonnull__(2);

PARROT_WARN_UNUSED_RESULT
PARROT_PURE_FUNCTION
PARROT_INLINE
static size_t key_hash_STRING(PARROT_INTERP,
    ARGIN(const STRING *s),
    size_t seed)
        __attribute__nonnull__(1)
        __attribute__nonnull__(2);

PARROT_CAN_RETURN_NULL
static HashBucket * parrot_hash_get_bucket_string(PARROT_INTERP,
    ARGIN(const Hash *hash),
    ARGIN(const STRING *s),
    UINTVAL hashval)
        __attribute__nonnull__(1)
        __attribute__nonnull__(2)
        __attribute__nonnull__(3);

static void parrot_hash_store_value_in_bucket(PARROT_INTERP,
    ARGMOD(Hash *hash),
    ARGMOD_NULLOK(HashBucket *bucket),
    INTVAL hashval,
    ARGIN_NULLOK(void *key),
    ARGIN_NULLOK(void *value))
        __attribute__nonnull__(1)
        __attribute__nonnull__(2)
        FUNC_MODIFIES(*hash)
        FUNC_MODIFIES(*bucket);

static void parrot_mark_hash_both(PARROT_INTERP, ARGIN(Hash *hash))
        __attribute__nonnull__(1)
        __attribute__nonnull__(2);

static void parrot_mark_hash_keys(PARROT_INTERP, ARGIN(Hash *hash))
        __attribute__nonnull__(1)
        __attribute__nonnull__(2);

static void parrot_mark_hash_values(PARROT_INTERP, ARGIN(Hash *hash))
        __attribute__nonnull__(1)
        __attribute__nonnull__(2);

#define ASSERT_ARGS_allocate_buckets __attribute__unused__ int _ASSERT_ARGS_CHECK = (\
       PARROT_ASSERT_ARG(interp) \
    , PARROT_ASSERT_ARG(hash))
#define ASSERT_ARGS_expand_hash __attribute__unused__ int _ASSERT_ARGS_CHECK = (\
       PARROT_ASSERT_ARG(interp) \
    , PARROT_ASSERT_ARG(hash))
#define ASSERT_ARGS_hash_compare __attribute__unused__ int _ASSERT_ARGS_CHECK = (\
       PARROT_ASSERT_ARG(interp) \
    , PARROT_ASSERT_ARG(hash))
#define ASSERT_ARGS_hash_compare_cstring __attribute__unused__ int _ASSERT_ARGS_CHECK = (\
       PARROT_ASSERT_ARG(a) \
    , PARROT_ASSERT_ARG(b))
#define ASSERT_ARGS_hash_compare_int __attribute__unused__ int _ASSERT_ARGS_CHECK = (0)
#define ASSERT_ARGS_hash_compare_pmc __attribute__unused__ int _ASSERT_ARGS_CHECK = (\
       PARROT_ASSERT_ARG(interp) \
    , PARROT_ASSERT_ARG(a) \
    , PARROT_ASSERT_ARG(b))
#define ASSERT_ARGS_hash_compare_pointer __attribute__unused__ int _ASSERT_ARGS_CHECK = (0)
#define ASSERT_ARGS_hash_compare_string __attribute__unused__ int _ASSERT_ARGS_CHECK = (\
       PARROT_ASSERT_ARG(interp) \
    , PARROT_ASSERT_ARG(search_key))
#define ASSERT_ARGS_hash_compare_string_enc __attribute__unused__ int _ASSERT_ARGS_CHECK = (\
       PARROT_ASSERT_ARG(interp) \
    , PARROT_ASSERT_ARG(search_key) \
    , PARROT_ASSERT_ARG(bucket_key))
#define ASSERT_ARGS_key_hash __attribute__unused__ int _ASSERT_ARGS_CHECK = (\
       PARROT_ASSERT_ARG(interp) \
    , PARROT_ASSERT_ARG(hash))
#define ASSERT_ARGS_key_hash_cstring __attribute__unused__ int _ASSERT_ARGS_CHECK = (\
       PARROT_ASSERT_ARG(value))
#define ASSERT_ARGS_key_hash_STRING __attribute__unused__ int _ASSERT_ARGS_CHECK = (\
       PARROT_ASSERT_ARG(interp) \
    , PARROT_ASSERT_ARG(s))
#define ASSERT_ARGS_parrot_hash_get_bucket_string __attribute__unused__ int _ASSERT_ARGS_CHECK = (\
       PARROT_ASSERT_ARG(interp) \
    , PARROT_ASSERT_ARG(hash) \
    , PARROT_ASSERT_ARG(s))
#define ASSERT_ARGS_parrot_hash_store_value_in_bucket \
     __attribute__unused__ int _ASSERT_ARGS_CHECK = (\
       PARROT_ASSERT_ARG(interp) \
    , PARROT_ASSERT_ARG(hash))
#define ASSERT_ARGS_parrot_mark_hash_both __attribute__unused__ int _ASSERT_ARGS_CHECK = (\
       PARROT_ASSERT_ARG(interp) \
    , PARROT_ASSERT_ARG(hash))
#define ASSERT_ARGS_parrot_mark_hash_keys __attribute__unused__ int _ASSERT_ARGS_CHECK = (\
       PARROT_ASSERT_ARG(interp) \
    , PARROT_ASSERT_ARG(hash))
#define ASSERT_ARGS_parrot_mark_hash_values __attribute__unused__ int _ASSERT_ARGS_CHECK = (\
       PARROT_ASSERT_ARG(interp) \
    , PARROT_ASSERT_ARG(hash))
/* Don't modify between HEADERIZER BEGIN / HEADERIZER END.  Your changes will be lost. */
/* HEADERIZER END: static */

/*

=item C<static size_t key_hash_STRING(PARROT_INTERP, const STRING *s, size_t
seed)>

Returns the hashed value of the key C<value>.  See also string.c.

=cut

*/


PARROT_WARN_UNUSED_RESULT
PARROT_PURE_FUNCTION
PARROT_INLINE
static size_t
key_hash_STRING(PARROT_INTERP, ARGIN(const STRING *s), size_t seed)
{
    ASSERT_ARGS(key_hash_STRING)

    if (s->hashval)
        return s->hashval;

    return STRING_hash(interp, s, seed);
}


/*

=item C<static int hash_compare_string(PARROT_INTERP, const void *search_key,
const void *bucket_key)>

Compares the two strings, returning 0 if they are identical.

=cut

*/

PARROT_WARN_UNUSED_RESULT
PARROT_PURE_FUNCTION
PARROT_INLINE
static int
hash_compare_string(PARROT_INTERP, ARGIN(const void *search_key),
        ARGIN_NULLOK(const void *bucket_key))
{
    ASSERT_ARGS(hash_compare_string)
    STRING const *s1 = (STRING const *)search_key;
    STRING const *s2 = (STRING const *)bucket_key;

    return !STRING_equal(interp, s1, s2);
}


/*

=item C<static int hash_compare_string_enc(PARROT_INTERP, const void
*search_key, const void *bucket_key)>

Compare two strings. Returns 0 if they are identical. Considers differing
encodings to be distinct.

*/

PARROT_WARN_UNUSED_RESULT
static int
hash_compare_string_enc(PARROT_INTERP, ARGIN(const void *search_key),
                                       ARGIN(const void *bucket_key))
{
    ASSERT_ARGS(hash_compare_string_enc)
    STRING const *s1 = (STRING const *)search_key;
    STRING const *s2 = (STRING const *)bucket_key;

    if (s1->hashval != s2->hashval)
        return 1;
    if (s1 && s2 && s1->encoding != s2->encoding)
        return 1;
    else
        return memcmp(s1->strstart, s2->strstart, s1->bufused);
}


/*

=item C<static int hash_compare_pointer(PARROT_INTERP, const void *a, const void
*b)>

Compares the two pointers, returning 0 if they are identical

=cut

*/

PARROT_WARN_UNUSED_RESULT
PARROT_PURE_FUNCTION
PARROT_INLINE
static int
hash_compare_pointer(SHIM_INTERP, ARGIN_NULLOK(const void *a), ARGIN_NULLOK(const void *b))
{
    ASSERT_ARGS(hash_compare_pointer)
    return a != b;
}


/*

=item C<static size_t key_hash_cstring(PARROT_INTERP, const void *value, size_t
seed)>

Creates and returns a hash value from a string.

Takes an interpreter, a pointer to a string, and a seed value.
Returns the hash value.

Used by Parrot_hash_new_cstring_hash.

=cut

*/

PARROT_WARN_UNUSED_RESULT
PARROT_PURE_FUNCTION
PARROT_INLINE
static size_t
key_hash_cstring(SHIM_INTERP, ARGIN(const void *value), size_t seed)
{
    ASSERT_ARGS(key_hash_cstring)
    const unsigned char *p = (const unsigned char *) value;
    size_t h = seed;
    while (*p) {
        h += h << 5;
        h += *p++;
    }
    return h;
}


/*

=item C<static int hash_compare_cstring(PARROT_INTERP, const char *a, const char
*b)>

Compares two C strings for equality, returning -1, 0, and 1 if the first string
is less than, equal to, or greater than the second, respectively.

=cut

*/

PARROT_WARN_UNUSED_RESULT
PARROT_PURE_FUNCTION
PARROT_INLINE
static int
hash_compare_cstring(SHIM_INTERP, ARGIN(const char *a), ARGIN(const char *b))
{
    ASSERT_ARGS(hash_compare_cstring)
    return strcmp(a, b);
}


/*

=item C<static int hash_compare_pmc(PARROT_INTERP, PMC *a, PMC *b)>

Compares two PMC for equality, returning 0 if the first is equal to second.
Uses void pointers to store the PMC, sadly.

=cut

*/

PARROT_WARN_UNUSED_RESULT
PARROT_PURE_FUNCTION
PARROT_INLINE
static int
hash_compare_pmc(PARROT_INTERP, ARGIN(PMC *a), ARGIN(PMC *b))
{
    ASSERT_ARGS(hash_compare_pmc)

    /* If pointers are same - PMCs are same */
    if (a == b)
        return 0;

    /* PMCs of different types are different */
    if (a->vtable->base_type != b->vtable->base_type)
        return 1;

    return !VTABLE_is_equal(interp, a, b);
}

/*

=item C<static int hash_compare_int(PARROT_INTERP, const void *a, const void
*b)>

Compares two integers for equality, returning -1, 0, and 1 if the first is less
than, equal to, or greater than the second, respectively.  Uses void pointers
to store the integers, sadly.

=cut

*/

PARROT_WARN_UNUSED_RESULT
PARROT_PURE_FUNCTION
PARROT_INLINE
static int
hash_compare_int(SHIM_INTERP, ARGIN_NULLOK(const void *a), ARGIN_NULLOK(const void *b))
{
    ASSERT_ARGS(hash_compare_int)
    return a != b;
}

/*

=item C<static size_t key_hash(PARROT_INTERP, const Hash *hash, void *key)>

Generic function to get the hashvalue of a given key. It may dispatches to
key_hash_STRING, key_hash_cstring, etc. depending on hash->key_type.

=cut

*/


PARROT_WARN_UNUSED_RESULT
PARROT_PURE_FUNCTION
PARROT_INLINE
static size_t
key_hash(PARROT_INTERP, ARGIN(const Hash *hash), ARGIN_NULLOK(void *key))
{
    ASSERT_ARGS(key_hash)

    if (hash->key_type == Hash_key_type_STRING
    ||  hash->key_type == Hash_key_type_STRING_enc)
        return key_hash_STRING(interp, (STRING *)key, hash->seed);

    if (hash->key_type == Hash_key_type_cstring)
        return key_hash_cstring(interp, (char *)key, hash->seed);

    if (hash->key_type == Hash_key_type_PMC)
        return VTABLE_hashvalue(interp, (PMC *)key);

    return ((size_t) key) ^ hash->seed;

}

/*

=item C<static int hash_compare(PARROT_INTERP, const Hash *hash, void *a, void
*b)>

Generic function to compare values. It may dispatches to
hash_compare_string, hash_compare_cstring, etc. depending on hash->key_type.

=cut

*/


PARROT_WARN_UNUSED_RESULT
PARROT_PURE_FUNCTION
PARROT_INLINE
static int
hash_compare(PARROT_INTERP, ARGIN(const Hash *hash), ARGIN_NULLOK(void *a),
    ARGIN_NULLOK(void *b))
{
    ASSERT_ARGS(hash_compare)

    if (a == b)
        return 0;

    if (hash->key_type == Hash_key_type_STRING)
        return hash_compare_string(interp, (STRING *)a, (STRING *)b);

    if (hash->key_type == Hash_key_type_STRING_enc)
        return hash_compare_string_enc(interp, (STRING *)a, (STRING *)b);

    if (hash->key_type == Hash_key_type_cstring)
        return strcmp((char *)a, (char *)b);

    if (hash->key_type == Hash_key_type_PMC)
        return hash_compare_pmc(interp, (PMC *)a, (PMC *) b);

    return 1;
}

/*

=item C<void Parrot_hash_dump(PARROT_INTERP, const Hash *hash)>

Prints out the hash in human-readable form, at least once someone implements
this.

=cut

*/

PARROT_EXPORT
void
Parrot_hash_dump(SHIM_INTERP, SHIM(const Hash *hash))
{
    ASSERT_ARGS(Parrot_hash_dump)
}


/*

=item C<void Parrot_hash_mark(PARROT_INTERP, Hash *hash)>

Marks the hash and its contents as live.  Assumes that key and value are
non-null in all buckets.

=cut

*/

PARROT_EXPORT
void
Parrot_hash_mark(PARROT_INTERP, ARGMOD(Hash *hash))
{
    ASSERT_ARGS(Parrot_hash_mark)
    int mark_key   = 0;
    int mark_value = 0;

    if (!hash->buckets)
        return;

    if (hash->entry_type == (PARROT_DATA_TYPE) enum_hash_string
    ||  hash->entry_type == (PARROT_DATA_TYPE) enum_hash_pmc)
        mark_value = 1;

    if (hash->key_type == Hash_key_type_STRING
    ||  hash->key_type == Hash_key_type_STRING_enc
    ||  hash->key_type == Hash_key_type_PMC
    ||  hash->key_type == Hash_key_type_PMC_ptr)
        mark_key = 1;

    if (mark_key) {
        if (mark_value)
            parrot_mark_hash_both(interp, hash);
        else
            parrot_mark_hash_keys(interp, hash);
    }
    else {
        if (mark_value)
            parrot_mark_hash_values(interp, hash);
    }
}


/*

=item C<static void parrot_mark_hash_keys(PARROT_INTERP, Hash *hash)>

Marks the hash and only its keys as live.

=cut

*/

static void
parrot_mark_hash_keys(PARROT_INTERP, ARGIN(Hash *hash))
{
    ASSERT_ARGS(parrot_mark_hash_keys)

    if (hash->key_type == Hash_key_type_STRING
     || hash->key_type == Hash_key_type_STRING_enc) {
        parrot_hash_iterate(hash,
            PARROT_ASSERT(_bucket->key);
            Parrot_gc_mark_STRING_alive(interp, (STRING *)_bucket->key););
    }
    else {
        parrot_hash_iterate(hash,
            PARROT_ASSERT(_bucket->key);
            Parrot_gc_mark_PMC_alive(interp, (PMC *)_bucket->key););
    }
}


/*

=item C<static void parrot_mark_hash_values(PARROT_INTERP, Hash *hash)>

Marks the hash and only its values as live.

=cut

*/

static void
parrot_mark_hash_values(PARROT_INTERP, ARGIN(Hash *hash))
{
    ASSERT_ARGS(parrot_mark_hash_values)

    if (hash->entry_type == (PARROT_DATA_TYPE) enum_hash_string) {
        parrot_hash_iterate(hash,
            PARROT_ASSERT(_bucket->value);
            Parrot_gc_mark_STRING_alive(interp, (STRING *)_bucket->value););
    }
    else if (hash->entry_type == (PARROT_DATA_TYPE) enum_hash_pmc) {
        parrot_hash_iterate(hash,
            PARROT_ASSERT(_bucket->value);
            Parrot_gc_mark_PMC_alive(interp, (PMC *)_bucket->value););
    }
}


/*

=item C<static void parrot_mark_hash_both(PARROT_INTERP, Hash *hash)>

Marks the hash and both its keys and values as live.

=cut

*/

static void
parrot_mark_hash_both(PARROT_INTERP, ARGIN(Hash *hash))
{
    ASSERT_ARGS(parrot_mark_hash_both)

    if ((hash->key_type == Hash_key_type_STRING
    ||   hash->key_type == Hash_key_type_STRING_enc)
    &&  hash->entry_type == (PARROT_DATA_TYPE) enum_hash_pmc) {
        parrot_hash_iterate(hash,
            PARROT_ASSERT(_bucket->key);
            Parrot_gc_mark_STRING_alive(interp, (STRING *)_bucket->key);
            PARROT_ASSERT(_bucket->value);
            Parrot_gc_mark_PMC_alive(interp, (PMC *)_bucket->value););
    }
    else {
        parrot_hash_iterate(hash,
            PARROT_ASSERT(_bucket->key);
            Parrot_gc_mark_PObj_alive(interp, (PObj *)_bucket->key);
            PARROT_ASSERT(_bucket->value);
            Parrot_gc_mark_PObj_alive(interp, (PObj *)_bucket->value););
    }
}

/*

=item C<Hash * Parrot_hash_thaw(PARROT_INTERP, PMC *info)>

Visits the contents of a hash during freeze/thaw.

C<pinfo> is the visit info, (see include/parrot/pmc_freeze.h>).

=cut

*/

PARROT_CANNOT_RETURN_NULL
PARROT_WARN_UNUSED_RESULT
Hash *
Parrot_hash_thaw(PARROT_INTERP, ARGMOD(PMC *info))
{
    ASSERT_ARGS(Parrot_hash_thaw)

    const size_t            num_entries = VTABLE_shift_integer(interp, info);
    const Hash_key_type     key_type    = (Hash_key_type)VTABLE_shift_integer(interp, info);
    const PARROT_DATA_TYPE  entry_type  = (PARROT_DATA_TYPE)VTABLE_shift_integer(interp, info);
    size_t                  entry_index;
    Hash *hash = Parrot_hash_create_sized(interp, entry_type, key_type, num_entries);

    /* special case for great speed */
    if (key_type   == Hash_key_type_STRING
    &&  entry_type == (PARROT_DATA_TYPE)enum_hash_int) {
        for (entry_index = 0; entry_index < num_entries; ++entry_index) {
            STRING * const key     = VTABLE_shift_string(interp, info);
            const INTVAL   i       = VTABLE_shift_integer(interp, info);
            const INTVAL   hashval = key_hash_STRING(interp, key, hash->seed);
            /* serialized hashes assumed not to contain duplicates */
            parrot_hash_store_value_in_bucket(interp, hash, NULL, hashval,
                                         (void *)key, (void *)i);
        }

        return hash;
    }

    for (entry_index = 0; entry_index < num_entries; ++entry_index) {
        void       *key;

        switch (key_type) {
          case Hash_key_type_int:
            {
                const INTVAL i_key = VTABLE_shift_integer(interp, info);
                key                = (void *)i_key;
            }
            break;
          case Hash_key_type_STRING:
          case Hash_key_type_STRING_enc:
            {
                STRING * const s_key = VTABLE_shift_string(interp, info);
                key                  = (void *)s_key;
            }
            break;
          case Hash_key_type_PMC:
          case Hash_key_type_PMC_ptr:
            {
                PMC * const p_key = VTABLE_shift_pmc(interp, info);
                key               = (void *)p_key;
                break;
            }
          default:
            Parrot_ex_throw_from_c_args(interp, NULL, 1,
                    "unimplemented key type");
            break;
        }

        switch (entry_type) {
          case enum_hash_int:
            {
                const INTVAL i = VTABLE_shift_integer(interp, info);
                Parrot_hash_put(interp, hash, key, (void *)i);
                break;
            }
          case enum_hash_string:
            {
                STRING * const s = VTABLE_shift_string(interp, info);
                Parrot_hash_put(interp, hash, key, (void *)s);
                break;
            }
          case enum_hash_pmc:
            {
                PMC * const p = VTABLE_shift_pmc(interp, info);
                Parrot_hash_put(interp, hash, key, (void *)p);
                break;
            }
          default:
            Parrot_ex_throw_from_c_args(interp, NULL, 1,
                    "unimplemented value type");
            break;
        }
    }

    return hash;
}


/*

=item C<void Parrot_hash_freeze(PARROT_INTERP, const Hash *hash, PMC *info)>

Freezes hash into a string.

Takes an interpreter, a pointer to the hash, and a pointer to the structure
containing the string start location.

=cut

*/

void
Parrot_hash_freeze(PARROT_INTERP, ARGIN(const Hash *hash), ARGMOD(PMC *info))
{
    ASSERT_ARGS(Parrot_hash_freeze)
    const Hash_key_type    key_type   = hash->key_type;
    const PARROT_DATA_TYPE entry_type = hash->entry_type;
    const size_t           entries    = hash->entries;

    VTABLE_push_integer(interp, info, entries);
    VTABLE_push_integer(interp, info, key_type);
    VTABLE_push_integer(interp, info, entry_type);

    parrot_hash_iterate(hash,
        switch (key_type) {
          case Hash_key_type_int:
            VTABLE_push_integer(interp, info, (INTVAL)_bucket->key);
            break;
          case Hash_key_type_STRING:
          case Hash_key_type_STRING_enc:
            VTABLE_push_string(interp, info, (STRING *)_bucket->key);
            break;
          case Hash_key_type_PMC:
          case Hash_key_type_PMC_ptr:
            VTABLE_push_pmc(interp, info, (PMC *)_bucket->key);
            break;
          default:
            Parrot_ex_throw_from_c_args(interp, NULL, 1,
                    "unimplemented key type");
            break;
        }
        switch (entry_type) {
          case enum_hash_int:
            VTABLE_push_integer(interp, info, (INTVAL)_bucket->value);
            break;
          case enum_hash_string:
            VTABLE_push_string(interp, info, (STRING *)_bucket->value);
            break;
          case enum_hash_pmc:
            VTABLE_push_pmc(interp, info, (PMC *)_bucket->value);
            break;
          default:
            Parrot_ex_throw_from_c_args(interp, NULL, 1,
                    "unimplemented value type");
            break;
        });
}

/*

=item C<static void allocate_buckets(PARROT_INTERP, Hash *hash, const UINTVAL
size)>

Allocate sized buckets and index storage for a hash

=cut

*/

static void
allocate_buckets(PARROT_INTERP, ARGMOD(Hash *hash), ARGIN_NULLOK(const UINTVAL size))
{
    ASSERT_ARGS(allocate_buckets)

    UINTVAL new_size = INITIAL_SIZE;
    HashBucket *new_buckets, *bucket;
    size_t i;

    while (size > new_size)
        new_size <<= 1;

    if (new_size > SPLIT_POINT)
        new_buckets  = (HashBucket *) Parrot_gc_allocate_memory_chunk(
                        interp, HASH_ALLOC_SIZE(new_size));
    else
        new_buckets  = (HashBucket *) Parrot_gc_allocate_fixed_size_storage(
                        interp, HASH_ALLOC_SIZE(new_size));

    memset(new_buckets, 0, HASH_ALLOC_SIZE(new_size));

    hash->mask      = new_size - 1;
    hash->buckets   = new_buckets;
    hash->index     = (HashBucket **)(new_buckets + N_BUCKETS(new_size));

    /* add new buckets to free_list
     * lowest bucket is top on free list and will be used first */

    bucket = hash->buckets + N_BUCKETS(new_size) - 1;
    for (i = 0; i < N_BUCKETS(new_size); ++i, --bucket) {
        bucket->next    = hash->free_list;
        hash->free_list = bucket;
    }
}

/*

=item C<static void expand_hash(PARROT_INTERP, Hash *hash)>

Expands a hash when necessary.

For a hashtable of size N, we use C<MAXFULL_PERCENT> % of N as the
number of buckets. This way, as soon as we run out of buckets on the
free list, we know that it's time to resize the hashtable.

Algorithm for expansion: We exactly double the size of the hashtable.
Keys are assigned to buckets with the formula

    bucket_index = hash(key) % Parrot_hash_size

When doubling the size of the hashtable, we know that every key is either
already in the correct bucket, or belongs in the current bucket plus
C<Parrot_hash_size> (the old C<Parrot_hash_size>). In fact, because the
hashtable is always a power of two in size, it depends only on the next bit
in the hash value, after the ones previously used.

We scan through all the buckets in order, moving the buckets that need to be
moved. No bucket will be scanned twice, and the cache should be reasonably
happy because the hashtable accesses will be two parallel sequential scans.
(Of course, this also mucks with the C<< ->next >> pointers, and they'll be
all over memory.)

=cut

*/

static void
expand_hash(PARROT_INTERP, ARGMOD(Hash *hash))
{
    ASSERT_ARGS(expand_hash)
    HashBucket  **new_index,  **index;
    HashBucket   *new_buckets, *bucket;

    void *        new_mem;
    void * const  old_mem    = hash->buckets;
    const UINTVAL old_size   = hash->mask + 1;
    const UINTVAL new_size   = old_size  << 1; /* Double. Right-shift is 2x */
    const UINTVAL new_mask   = new_size   - 1;
    size_t        offset, i;

    /*
       allocate some less buckets
       e.g. 3 buckets, 4 pointers:

         +---+---+---+-+-+-+-+
         | --> buckets |     |
         +---+---+---+-+-+-+-+
         ^             ^
         | old_mem     | hash->index
    */

    /* resize mem */
    if (new_size > SPLIT_POINT)
        new_mem  = Parrot_gc_allocate_memory_chunk(
                        interp, HASH_ALLOC_SIZE(new_size));
    else
        new_mem  = Parrot_gc_allocate_fixed_size_storage(
                        interp, HASH_ALLOC_SIZE(new_size));

    offset = (char *)new_mem - (char *)old_mem;

    new_buckets = (HashBucket *)  new_mem;
    new_index   = (HashBucket **)(new_buckets + N_BUCKETS(new_size));

    /* copy buckets and index */
    mem_sys_memcopy(new_buckets, hash->buckets,
            N_BUCKETS(old_size) * sizeof (HashBucket));
    mem_sys_memcopy(new_index, hash->index, old_size * sizeof (HashBucket *));

    /* free */
    if (old_size > SPLIT_POINT)
        Parrot_gc_free_memory_chunk(interp, old_mem);
    else
        Parrot_gc_free_fixed_size_storage(interp, HASH_ALLOC_SIZE(old_size), old_mem);


    /* clear second half of the buckets, freed by old the index */
    memset(new_buckets + N_BUCKETS(old_size), 0,
            sizeof (HashBucket) * old_size);

    /* clear second half of the index */
    memset(new_index + (old_size), 0, sizeof (HashBucket *) * old_size);



    /*
         +---+---+---+---+---+---+-+-+-+-+-+-+-+-+
         |  buckets  | old_index |  new_index    |
         +---+---+---+---+---+---+-+-+-+-+-+-+-+-+
         ^                       ^
         | new_mem               | hash->index
    */

    /* update hash data */
    hash->index     = new_index;
    hash->buckets   = new_buckets;
    hash->mask      = new_mask;

    /* reloc pointers and recalc bucket indices */
    for (i = 0; i < old_size; ++i) {
        index = new_index + i;

        while (*index != NULL) {
            size_t new_loc;
            size_t hashval;

            bucket = (HashBucket *)((char *)*index + offset);

            /* rehash the bucket */
            if (hash->key_type == Hash_key_type_STRING
            ||  hash->key_type == Hash_key_type_STRING_enc) {
                STRING *s = (STRING *)bucket->key;
                hashval   = s->hashval;
            }
            else {
                hashval = key_hash(interp, hash, bucket->key);
            }

            new_loc = hashval & new_mask;

            if (i != new_loc) {
                *index              = bucket->next;
                bucket->next        = new_index[new_loc];
                new_index[new_loc]  = bucket;
            }
            else {
                *index = bucket;
                index  = &bucket->next;
            }
        }
    }

    /* add new buckets to free_list
     * lowest bucket is top on free list and will be used first */
    bucket = new_buckets + N_BUCKETS(old_size);
    for (i = N_BUCKETS(old_size)-1 ; i > 0; --i, ++bucket) {
        bucket->next = bucket + 1;
    }

    bucket->next = NULL;
    hash->free_list = new_buckets + N_BUCKETS(old_size);
}


/*

=item C<Hash* Parrot_hash_new(PARROT_INTERP)>

Creates a new Parrot STRING hash.

=cut

*/

PARROT_EXPORT
PARROT_CANNOT_RETURN_NULL
Hash*
Parrot_hash_new(PARROT_INTERP)
{
    ASSERT_ARGS(Parrot_hash_new)
    return Parrot_hash_create(interp,
            enum_type_PMC,
            Hash_key_type_STRING);
}


/*

=item C<Hash* Parrot_hash_new_cstring_hash(PARROT_INTERP)>

Creates a new C string hash in C<hptr>.

=cut

*/

PARROT_EXPORT
PARROT_CANNOT_RETURN_NULL
Hash*
Parrot_hash_new_cstring_hash(PARROT_INTERP)
{
    ASSERT_ARGS(Parrot_hash_new_cstring_hash)
    return Parrot_hash_create(interp,
            enum_type_PMC,
            Hash_key_type_cstring);
}


/*

=item C<Hash * Parrot_hash_new_pointer_hash(PARROT_INTERP)>

Create and return a new hash with void * keys and values.

=cut

*/

PARROT_EXPORT
PARROT_CANNOT_RETURN_NULL
Hash *
Parrot_hash_new_pointer_hash(PARROT_INTERP)
{
    ASSERT_ARGS(Parrot_hash_new_pointer_hash)
    return Parrot_hash_create(interp,
            enum_type_ptr,
            Hash_key_type_ptr);
}


/*

=item C<Hash* Parrot_hash_new_intval_hash(PARROT_INTERP)>

Creates and returns new Hash PMC with INTVAL keys and values. C<flags> can be
C<PObj_constant_FLAG> or 0.

=cut

*/


PARROT_EXPORT
PARROT_WARN_UNUSED_RESULT
PARROT_CANNOT_RETURN_NULL
Hash*
Parrot_hash_new_intval_hash(PARROT_INTERP)
{
    ASSERT_ARGS(Parrot_hash_new_intval_hash)
    return Parrot_hash_create(interp,
            enum_type_INTVAL,
            Hash_key_type_int);
}

/*

=item C<Hash * Parrot_hash_create(PARROT_INTERP, PARROT_DATA_TYPE val_type,
Hash_key_type hkey_type)>

Creates and initializes a hash.  Function pointers determine its behaviors.

Memory from this function must be freed.

=cut

*/

PARROT_CANNOT_RETURN_NULL
PARROT_WARN_UNUSED_RESULT
Hash *
Parrot_hash_create(PARROT_INTERP, PARROT_DATA_TYPE val_type, Hash_key_type hkey_type)
{
    ASSERT_ARGS(Parrot_hash_create)
    Hash * const hash = (Hash*) Parrot_gc_allocate_fixed_size_storage(interp, sizeof (Hash));

    hash->entry_type = val_type;
    hash->key_type   = hkey_type;
    hash->seed       = interp->hash_seed;
    hash->mask       = 0;
    hash->entries    = 0;
    hash->index      = NULL;
    hash->buckets    = NULL;
    hash->free_list  = NULL;

    return hash;
}


/*

=item C<Hash * Parrot_hash_create_sized(PARROT_INTERP, PARROT_DATA_TYPE
val_type, Hash_key_type hkey_type, UINTVAL size)>

Creates and initializes a hash, similar to C<Parrot_hash_create>.

Preallocates at least C<size> buckets.

=cut

*/

PARROT_CANNOT_RETURN_NULL
PARROT_WARN_UNUSED_RESULT
Hash *
Parrot_hash_create_sized(PARROT_INTERP, PARROT_DATA_TYPE val_type, Hash_key_type hkey_type,
        UINTVAL size)
{
    ASSERT_ARGS(Parrot_hash_create_sized)

    Hash *hash = Parrot_hash_create(interp, val_type, hkey_type);
    allocate_buckets(interp, hash, size);
    return hash;
}

/*

=item C<void Parrot_hash_destroy(PARROT_INTERP, Hash *hash)>

Frees the memory allocated to the specified hash and its bucket store.  Used by
Parrot_hash_chash_destroy.

Unlike the C library function free(), the hash function must not be NULL.

=cut

*/

PARROT_EXPORT
void
Parrot_hash_destroy(PARROT_INTERP, ARGFREE_NOTNULL(Hash *hash))
{
    ASSERT_ARGS(Parrot_hash_destroy)
    if (hash->buckets){
        if (hash->mask > SPLIT_POINT)
            Parrot_gc_free_memory_chunk(interp, hash->buckets);
        else
            Parrot_gc_free_fixed_size_storage(interp,
                HASH_ALLOC_SIZE(hash->mask+1), hash->buckets);
    }
    Parrot_gc_free_fixed_size_storage(interp, sizeof (Hash), hash);
}


/*

=item C<void Parrot_hash_chash_destroy(PARROT_INTERP, Hash *hash)>

Deletes the specified hash by freeing the memory allocated to all the key-value
pairs, and finally the hash itself.

=cut

*/

void
Parrot_hash_chash_destroy(PARROT_INTERP, ARGMOD(Hash *hash))
{
    ASSERT_ARGS(Parrot_hash_chash_destroy)
    parrot_hash_iterate(hash,
        mem_gc_free(interp, _bucket->key);
        mem_gc_free(interp, _bucket->value););
    Parrot_hash_destroy(interp, hash);
}


/*

=item C<void Parrot_hash_chash_destroy_values(PARROT_INTERP, Hash *hash,
value_free func)>

Deletes the specified hash by freeing the memory allocated to all the key-value
pairs, calling the provided callback to free the values, and finally the hash
itself.

The callback returns C<void> and takes a C<void *>.

=cut

*/

void
Parrot_hash_chash_destroy_values(PARROT_INTERP, ARGMOD(Hash *hash), NOTNULL(value_free func))
{
    ASSERT_ARGS(Parrot_hash_chash_destroy_values)
    UINTVAL i;

    parrot_hash_iterate(hash,
        mem_gc_free(interp, _bucket->key);
        func(_bucket->value););

    Parrot_hash_destroy(interp, hash);
}


/*

=item C<INTVAL Parrot_hash_size(PARROT_INTERP, const Hash *hash)>

Returns the number of used entries in the hash.

=cut

*/

PARROT_EXPORT
PARROT_WARN_UNUSED_RESULT
PARROT_PURE_FUNCTION
INTVAL
Parrot_hash_size(SHIM_INTERP, ARGIN(const Hash *hash))
{
    ASSERT_ARGS(Parrot_hash_size)

    return hash->entries;
}


/*

=item C<HashBucket * Parrot_hash_get_bucket(PARROT_INTERP, const Hash *hash,
const void *key)>

Returns the bucket for C<key>, if found, and NULL otherwise.

=cut

*/

PARROT_EXPORT
PARROT_WARN_UNUSED_RESULT
PARROT_CAN_RETURN_NULL
HashBucket *
Parrot_hash_get_bucket(PARROT_INTERP, ARGIN(const Hash *hash), ARGIN_NULLOK(const void *key))
{
    ASSERT_ARGS(Parrot_hash_get_bucket)
    DECL_CONST_CAST;

    if (hash->entries <= 0)
        return NULL;

    if (hash->key_type == Hash_key_type_STRING) {
        const STRING * const str = (const STRING *)key;
        const size_t hashval = key_hash_STRING(interp, str, hash->seed);

        return parrot_hash_get_bucket_string(interp, hash, str, hashval);
    }
    else {
        /* The const casts are needed for PMC keys */
        const size_t hashval = key_hash(interp, hash,
                                    PARROT_const_cast(void *, key));
        HashBucket  *bucket  = hash->index[hashval & hash->mask];

        while (bucket) {
            if (hash_compare(interp, hash,
                    PARROT_const_cast(void *, key),
                    bucket->key) == 0)
                break;
            bucket = bucket->next;
        }

        return bucket;
    }
}

/*

=item C<void * Parrot_hash_get(PARROT_INTERP, const Hash *hash, const void
*key)>

Returns the value keyed by C<key>, or C<NULL> if no bucket is found.

=cut

*/

PARROT_EXPORT
PARROT_WARN_UNUSED_RESULT
PARROT_CAN_RETURN_NULL
void *
Parrot_hash_get(PARROT_INTERP, ARGIN(const Hash *hash), ARGIN(const void *key))
{
    ASSERT_ARGS(Parrot_hash_get)
    const HashBucket * const bucket = Parrot_hash_get_bucket(interp, hash, key);
    return bucket ? bucket->value : NULL;
}


/*

=item C<INTVAL Parrot_hash_exists(PARROT_INTERP, const Hash *hash, const void
*key)>

Returns whether the key exists in the hash.

=cut

*/

PARROT_EXPORT
PARROT_WARN_UNUSED_RESULT
INTVAL
Parrot_hash_exists(PARROT_INTERP, ARGIN(const Hash *hash), ARGIN(const void *key))
{
    ASSERT_ARGS(Parrot_hash_exists)
    const HashBucket * const bucket = Parrot_hash_get_bucket(interp, hash, key);
    return bucket ? 1 : 0;
}


/*

=item C<static HashBucket * parrot_hash_get_bucket_string(PARROT_INTERP, const
Hash *hash, const STRING *s, UINTVAL hashval)>

Given a hash, a STRING key, and the hashval of the key, returns the appropriate
bucket of the hash for the key.  This assumes buckets are already available, so
ensure the hash has storage before calling this function.

=cut

*/

PARROT_CAN_RETURN_NULL
static HashBucket *
parrot_hash_get_bucket_string(PARROT_INTERP, ARGIN(const Hash *hash),
        ARGIN(const STRING *s), UINTVAL hashval)
{
    ASSERT_ARGS(parrot_hash_get_bucket_string)
    HashBucket *bucket = hash->index[hashval & hash->mask];

    while (bucket) {
        const STRING *s2 = (const STRING *)bucket->key;
        if (s == s2)
            break;

        /* manually inline part of string_equal  */
        if (hashval == s2->hashval) {
            if (s->encoding == s2->encoding) {
                if ((STRING_byte_length(s) == STRING_byte_length(s2))
                && (memcmp(s->strstart, s2->strstart, STRING_byte_length(s)) == 0))
                    break;
            } else if (STRING_equal(interp, s, s2))
                    break;
        }
        bucket = bucket->next;
    }

    return bucket;
}


/*

=item C<static void parrot_hash_store_value_in_bucket(PARROT_INTERP, Hash *hash,
HashBucket *bucket, INTVAL hashval, void *key, void *value)>

Given a hash, a bucket, the hashval of the key, the key, and its value, stores
the value in the bucket.  The bucket can be NULL, in which case this function
will allocate more storage as appropriate.

Note that C<key> is B<not> copied.

=cut

*/

static void
parrot_hash_store_value_in_bucket(PARROT_INTERP, ARGMOD(Hash *hash),
    ARGMOD_NULLOK(HashBucket *bucket), INTVAL hashval,
    ARGIN_NULLOK(void *key), ARGIN_NULLOK(void *value))
{
    ASSERT_ARGS(parrot_hash_store_value_in_bucket)

    /* If we have a bucket already, put the value in it. Otherwise, we need
       to get a new bucket */
    if (bucket)
        bucket->value = value;
    else {
        /* Get a new bucket off the free list. If the free list is empty, we
           expand the hash so we get more items on the free list */
        if (!hash->free_list)
            expand_hash(interp, hash);

        bucket = hash->free_list;

        /* Add the value to the new bucket, increasing the count of elements */
        ++hash->entries;
        hash->free_list                   = bucket->next;
        bucket->key                       = key;
        bucket->value                     = value;
        bucket->next                      = hash->index[hashval & hash->mask];
        hash->index[hashval & hash->mask] = bucket;
    }
}


/*

=item C<HashBucket* Parrot_hash_put(PARROT_INTERP, Hash *hash, void *key, void
*value)>

Puts the key and value into the hash. Note that C<key> is B<not> copied.

=cut

*/

PARROT_EXPORT
PARROT_IGNORABLE_RESULT
PARROT_CANNOT_RETURN_NULL
HashBucket*
Parrot_hash_put(PARROT_INTERP, ARGMOD(Hash *hash),
        ARGIN_NULLOK(void *key), ARGIN_NULLOK(void *value))
{
    ASSERT_ARGS(Parrot_hash_put)
    HashBucket *bucket = NULL;
    size_t      hashval;

    if (!hash->buckets){
        allocate_buckets(interp, hash, INITIAL_SIZE);
        hashval = key_hash(interp, hash, key);
    }
    else {
        if (hash->key_type == Hash_key_type_STRING) {
            STRING *s = (STRING *)key;
            hashval = key_hash_STRING(interp, s, hash->seed);
            bucket  = parrot_hash_get_bucket_string(interp, hash, s, hashval);
        }
        else {
            hashval = key_hash(interp, hash, key);
            bucket  = hash->index[hashval & hash->mask];

            while (bucket) {
                if (hash_compare(interp, hash, key, bucket->key) == 0)
                    break;
                bucket = bucket->next;
            }
        }
    }

    parrot_hash_store_value_in_bucket(interp, hash, bucket, hashval,
        key, value);

    return bucket;
}


/*

=item C<void Parrot_hash_delete(PARROT_INTERP, Hash *hash, void *key)>

Deletes the key from the hash.

=cut

*/

PARROT_EXPORT
void
Parrot_hash_delete(PARROT_INTERP, ARGMOD(Hash *hash), ARGIN_NULLOK(void *key))
{
    ASSERT_ARGS(Parrot_hash_delete)
    const UINTVAL hashval = key_hash(interp, hash, key) & hash->mask;
    if (hash->buckets){
        HashBucket   **prev   = &hash->index[hashval];
        if (*prev) {
            for (; *prev; prev = &(*prev)->next) {
                HashBucket *current = *prev;
                if (hash_compare(interp, hash, key, current->key) == 0) {
                    *prev = current->next;
                    --hash->entries;
                    current->next    = hash->free_list;
                    current->key     = NULL;
                    hash->free_list = current;
                    return;
                }
            }
        }
    }
}


/*

=item C<void Parrot_hash_clone(PARROT_INTERP, const Hash *hash, Hash *dest)>

Clones C<hash> to C<dest>.

=cut

*/

PARROT_EXPORT
void
Parrot_hash_clone(PARROT_INTERP, ARGIN(const Hash *hash), ARGOUT(Hash *dest))
{
    ASSERT_ARGS(Parrot_hash_clone)
    Parrot_hash_clone_prunable(interp, hash, dest, 1);
}

/*

=item C<void Parrot_hash_clone_prunable(PARROT_INTERP, const Hash *hash, Hash
*dest, int deep)>

helper function to Clone C<hash> to C<dest>

allows deep cloning of PMC types if deep set

=cut

*/

void
Parrot_hash_clone_prunable(PARROT_INTERP, ARGIN(const Hash *hash),
    ARGOUT(Hash *dest), int deep)
{
    ASSERT_ARGS(Parrot_hash_clone_prunable)

    /* dest hash has the same size as source hash */
    if (dest->buckets){
        if (dest->mask+1 > SPLIT_POINT)
            Parrot_gc_free_memory_chunk(interp, dest->buckets);
        else
            Parrot_gc_free_fixed_size_storage(interp, HASH_ALLOC_SIZE(dest->mask+1), dest->buckets);
    }
    allocate_buckets(interp, dest, hash->mask);

    parrot_hash_iterate(hash,
        void         *valtmp;
        void * const  key = _bucket->key;

        switch (hash->entry_type) {
          case enum_type_STRING:
            valtmp = _bucket->value;
            break;

          case enum_type_PMC:
            if (PMC_IS_NULL((PMC *)_bucket->value))
                valtmp = (void *)PMCNULL;
            else
                if (deep)
                    valtmp = (void *)VTABLE_clone(interp, (PMC*)_bucket->value);
                else
                    valtmp = _bucket->value;
            break;

          case enum_type_undef:
          case enum_type_ptr:
          case enum_type_INTVAL:
            valtmp = (void *)_bucket->value;
            break;

          default:
            valtmp = NULL; /* avoid warning */
            Parrot_ex_throw_from_c_args(interp, NULL, -1,
                    "hash corruption: type = %d\n", hash->entry_type);
        };
        if (key) {
            const size_t hashval = key_hash(interp, dest, key);
            /* hash tables has no duplicate keys */
            parrot_hash_store_value_in_bucket(interp, dest, NULL, hashval, key, valtmp);
        });
}

/*

Poor-man polymorphic functions to convert something to something.

There is bunch of functions to convert from passed value to stored keys type and to/from
stored values type.

void *hash_key_from_TYPE convert to keys type.
TYPE hash_key_to_TYPE convert from keys type.
void *hash_value_from_TYPE convert to values type.
TYPE hash_value_to_TYPE convert from values type.

*/

/*

=item C<void* Parrot_hash_key_from_int(PARROT_INTERP, const Hash *hash, INTVAL
key)>

Cast INTVAL to hash key.

=cut

*/

PARROT_CAN_RETURN_NULL
void*
Parrot_hash_key_from_int(PARROT_INTERP, ARGIN(const Hash *hash), INTVAL key)
{
    ASSERT_ARGS(Parrot_hash_key_from_int)
    void *ret;
    switch (hash->key_type) {
      case Hash_key_type_int:
        ret = (void *)key;
        break;
        /* Currently PMCs are stringified */
      case Hash_key_type_PMC:
      case Hash_key_type_PMC_ptr:
        ret = (void *)Parrot_pmc_box_integer(interp, key);
        break;
      case Hash_key_type_STRING:
      case Hash_key_type_STRING_enc:
        ret = (void *)Parrot_str_from_int(interp, key);
        break;
      default:
        Parrot_ex_throw_from_c_args(interp, NULL, EXCEPTION_UNIMPLEMENTED,
                    "Hash: unsupported key_type");
    }
    return ret;
}

/*

=item C<void* Parrot_hash_key_from_string(PARROT_INTERP, const Hash *hash,
STRING *key)>

Cast STRING to hash key.

=cut

*/

PARROT_CAN_RETURN_NULL
void*
Parrot_hash_key_from_string(PARROT_INTERP, ARGIN(const Hash *hash), ARGIN(STRING *key))
{
    ASSERT_ARGS(Parrot_hash_key_from_string)
    void *ret;
    switch (hash->key_type) {
      case Hash_key_type_int:
      {
        /* Pacify compiler about casting INVTAL to void */
        const INTVAL int_key = Parrot_str_to_int(interp, key);
        ret                  = INTVAL2PTR(void *, int_key);
        break;
      }

      case Hash_key_type_PMC:
      case Hash_key_type_PMC_ptr:
        ret = Parrot_pmc_box_string(interp, key);
        break;

      case Hash_key_type_STRING:
      case Hash_key_type_STRING_enc:
        ret = key;
        break;

      default:
        Parrot_ex_throw_from_c_args(interp, NULL, EXCEPTION_UNIMPLEMENTED,
                    "Hash: unsupported key_type");
    }
    return ret;
}

/*

=item C<void* Parrot_hash_key_from_pmc(PARROT_INTERP, const Hash *hash, PMC
*key)>

Cast PMC* to hash key.

=cut

*/

PARROT_CAN_RETURN_NULL
void*
Parrot_hash_key_from_pmc(PARROT_INTERP, ARGIN(const Hash *hash), ARGIN(PMC *key))
{
    ASSERT_ARGS(Parrot_hash_key_from_pmc)
    void *ret;
    switch (hash->key_type) {
      case Hash_key_type_int:
        {
            const INTVAL int_key = VTABLE_get_integer(interp, key);
            ret                  = INTVAL2PTR(void *, int_key);
            break;
        }
      case Hash_key_type_PMC:
      case Hash_key_type_PMC_ptr:
        {
            /* Extract real value from Key (and box it if nessary) */
            if (key->vtable->base_type == enum_class_Key)
                switch (Parrot_key_type(interp, key)) {
                  case KEY_integer_FLAG:
                    key = Parrot_pmc_box_integer(interp, Parrot_key_integer(interp, key));
                    break;
                  case KEY_string_FLAG:
                    key = Parrot_pmc_box_string(interp, Parrot_key_string(interp, key));
                    break;
                  case KEY_pmc_FLAG:
                    key = Parrot_key_pmc(interp, key);
                    break;
                  default:
                    /* It's impossible if Keys are same (and they are not) */
                    /* So throw exception */
                    Parrot_ex_throw_from_c_args(interp, NULL, EXCEPTION_INVALID_OPERATION,
                                "hash: unexpected type of Key");
                    break;
                }

            ret = key;
            break;
        }
      case Hash_key_type_STRING:
      case Hash_key_type_STRING_enc:
        {
            STRING * const tmp = VTABLE_get_string(interp, key);
            if (STRING_IS_NULL(tmp))
                Parrot_ex_throw_from_c_args(interp, NULL, EXCEPTION_UNEXPECTED_NULL,
                            "hash: can't use null as key");
            ret = (void *)tmp;
        }
        break;
      default:
        Parrot_ex_throw_from_c_args(interp, NULL, EXCEPTION_UNIMPLEMENTED,
                    "Hash: unsupported key_type");
    }
    return ret;
}

/*

=item C<INTVAL Parrot_hash_key_to_int(PARROT_INTERP, const Hash *hash, void
*key)>

Cast hash key to INTVAL.

=cut

*/

INTVAL
Parrot_hash_key_to_int(PARROT_INTERP, ARGIN(const Hash *hash), ARGIN_NULLOK(void *key))
{
    ASSERT_ARGS(Parrot_hash_key_to_int)
    INTVAL ret;
    switch (hash->key_type) {
      case Hash_key_type_int:
        ret = (INTVAL)key;
        break;
      case Hash_key_type_PMC:
      case Hash_key_type_PMC_ptr:
        ret = VTABLE_get_integer(interp, (PMC *)key);
        break;
      case Hash_key_type_STRING:
      case Hash_key_type_STRING_enc:
        ret = Parrot_str_to_int(interp, (STRING *)key);
        break;
      default:
        Parrot_ex_throw_from_c_args(interp, NULL, EXCEPTION_UNIMPLEMENTED,
                    "Hash: unsupported key_type");
    }
    return ret;
}

/*

=item C<STRING* Parrot_hash_key_to_string(PARROT_INTERP, const Hash *hash, void
*key)>

Cast hash key to STRING.

=cut

*/

PARROT_CANNOT_RETURN_NULL
STRING*
Parrot_hash_key_to_string(PARROT_INTERP, ARGIN(const Hash *hash), ARGIN_NULLOK(void *key))
{
    ASSERT_ARGS(Parrot_hash_key_to_string)
    STRING *ret;
    switch (hash->key_type) {
      case Hash_key_type_int:
        ret = Parrot_str_from_int(interp, (INTVAL)key);
        break;

      case Hash_key_type_PMC:
      case Hash_key_type_PMC_ptr:
        ret = VTABLE_get_string(interp, (PMC *)key);
        break;

      case Hash_key_type_STRING:
      case Hash_key_type_STRING_enc:
        ret = (STRING *)key;
        break;

      default:
        Parrot_ex_throw_from_c_args(interp, NULL, EXCEPTION_UNIMPLEMENTED,
                    "Hash: unsupported key_type");
    }
    return ret;
}

/*

=item C<PMC* Parrot_hash_key_to_pmc(PARROT_INTERP, const Hash * const hash, void
*key)>

Cast hash key to PMC*.

=cut

*/

PARROT_CANNOT_RETURN_NULL
PMC*
Parrot_hash_key_to_pmc(PARROT_INTERP, ARGIN(const Hash * const hash), ARGIN(void *key))
{
    ASSERT_ARGS(Parrot_hash_key_to_pmc)
    PMC *ret;
    switch (hash->key_type) {
      case Hash_key_type_int:
        ret = Parrot_pmc_box_integer(interp, (INTVAL)key);
        break;
      case Hash_key_type_PMC:
      case Hash_key_type_PMC_ptr:
        ret = (PMC*)key;
        break;
      case Hash_key_type_STRING:
      case Hash_key_type_STRING_enc:
        ret = Parrot_pmc_box_string(interp, (STRING*)key);
        break;
      default:
        Parrot_ex_throw_from_c_args(interp, NULL, EXCEPTION_UNIMPLEMENTED,
                    "Hash: unsupported key_type");
    }
    return ret;
}

/* Second part - convert from stored void* to real type */
/* TODO: FLOATVALs converted into Float PMC for now */

/*

=item C<void* Parrot_hash_value_from_int(PARROT_INTERP, const Hash *hash, INTVAL
value)>

Cast INTVAL to hash value.

=cut

*/

PARROT_CAN_RETURN_NULL
void*
Parrot_hash_value_from_int(PARROT_INTERP, ARGIN(const Hash *hash), INTVAL value)
{
    ASSERT_ARGS(Parrot_hash_value_from_int)
    void *ret;
    switch (hash->entry_type) {
      case enum_type_INTVAL:
        ret = INTVAL2PTR(void *, value);
        break;
      case enum_type_PMC:
        {
            PMC * const tmp = Parrot_pmc_box_integer(interp, value);
            ret = (void *)tmp;
        }
        break;
      case enum_type_STRING:
        ret = (void *)Parrot_str_from_int(interp, value);
        break;
      default:
        Parrot_ex_throw_from_c_args(interp, NULL, EXCEPTION_UNIMPLEMENTED,
                    "Hash: unsupported entry_type");
    }
    return ret;
}

/*

=item C<void* Parrot_hash_value_from_string(PARROT_INTERP, const Hash *hash,
STRING *value)>

Cast STRING to hash value.

=cut

*/

PARROT_CAN_RETURN_NULL
void*
Parrot_hash_value_from_string(PARROT_INTERP, ARGIN(const Hash *hash),
        ARGIN_NULLOK(STRING *value))
{
    ASSERT_ARGS(Parrot_hash_value_from_string)
    void *ret;
    switch (hash->entry_type) {
      case enum_type_INTVAL:
        {
            const INTVAL int_val = STRING_IS_NULL(value) ?
                    (INTVAL) 0 : Parrot_str_to_int(interp, value);
            ret = INTVAL2PTR(void *, int_val);
        }
        break;
      case enum_type_STRING:
        ret = (void *)value;
        break;
      case enum_type_PMC:
        {
            PMC * const s = STRING_IS_NULL(value)
                            ? PMCNULL
                            : Parrot_pmc_box_string(interp, value);
            ret = (void *)s;
        }
        break;
      default:
        Parrot_ex_throw_from_c_args(interp, NULL, EXCEPTION_UNIMPLEMENTED,
                    "Hash: unsupported entry_type");
    }
    return ret;
}

/*

=item C<void* Parrot_hash_value_from_pmc(PARROT_INTERP, const Hash *hash, PMC
*value)>

Cast PMC to hash value.

=cut

*/

PARROT_CAN_RETURN_NULL
void*
Parrot_hash_value_from_pmc(PARROT_INTERP, ARGIN(const Hash *hash),
    ARGIN_NULLOK(PMC *value))
{
    ASSERT_ARGS(Parrot_hash_value_from_pmc)
    void *ret;
    switch (hash->entry_type) {
      case enum_type_INTVAL:
        {
            const INTVAL int_val = PMC_IS_NULL(value) ?
                    (INTVAL) 0 : VTABLE_get_integer(interp, value);
            ret                  = INTVAL2PTR(void *, int_val);
        }
        break;
      case enum_type_STRING:
        ret = PMC_IS_NULL(value) ?
                PMCNULL : (void *)VTABLE_get_string(interp, value);
        break;
      case enum_type_PMC:
        ret = (void *)value;
        break;
      default:
        Parrot_ex_throw_from_c_args(interp, NULL, EXCEPTION_UNIMPLEMENTED,
                    "Hash: unsupported entry_type");
    }
    return ret;
}

/*

=item C<void* Parrot_hash_value_from_number(PARROT_INTERP, const Hash *hash,
FLOATVAL value)>

Cast FLOATVAL to hash value.

=cut

*/

PARROT_CAN_RETURN_NULL
void*
Parrot_hash_value_from_number(PARROT_INTERP, ARGIN(const Hash *hash), FLOATVAL value)
{
    ASSERT_ARGS(Parrot_hash_value_from_number)
    void *ret;
    switch (hash->entry_type) {
      case enum_type_INTVAL:
        {
            const INTVAL tmp = value;
            ret = (void*)tmp;
        }
        break;
      case enum_type_STRING:
        ret = (void *)Parrot_str_from_num(interp, value);
        break;
      case enum_type_PMC:
        {
            PMC * const tmp = Parrot_pmc_box_number(interp, value);
            ret = (void *)tmp;
        }
        break;
      default:
        Parrot_ex_throw_from_c_args(interp, NULL, EXCEPTION_UNIMPLEMENTED,
                    "Hash: unsupported entry_type");
    }
    return ret;
}

/*

=item C<INTVAL Parrot_hash_value_to_int(PARROT_INTERP, const Hash *hash, void
*value)>

Cast hash value to INTVAL.

=cut

*/

INTVAL
Parrot_hash_value_to_int(PARROT_INTERP, ARGIN(const Hash *hash), ARGIN_NULLOK(void *value))
{
    ASSERT_ARGS(Parrot_hash_value_to_int)
    INTVAL ret;
    switch (hash->entry_type) {
      case enum_type_ptr:
      case enum_type_INTVAL:
        ret = (INTVAL)value;
        break;
      case enum_type_STRING:
        ret = Parrot_str_to_int(interp, (STRING*)value);
        break;
      case enum_type_PMC:
        ret = VTABLE_get_integer(interp, (PMC*)value);
        break;
      default:
        Parrot_ex_throw_from_c_args(interp, NULL, EXCEPTION_UNIMPLEMENTED,
                    "Hash: unsupported entry_type");
    }
    return ret;
}

/*

=item C<STRING* Parrot_hash_value_to_string(PARROT_INTERP, const Hash *hash,
void *value)>

Cast hash value to STRING.

=cut

*/

PARROT_CANNOT_RETURN_NULL
STRING*
Parrot_hash_value_to_string(PARROT_INTERP, ARGIN(const Hash *hash), ARGIN_NULLOK(void *value))
{
    ASSERT_ARGS(Parrot_hash_value_to_string)
    STRING *ret;
    switch (hash->entry_type) {
      case enum_type_INTVAL:
        ret = Parrot_str_from_int(interp, (INTVAL)value);
        break;
      case enum_type_STRING:
        ret = (STRING *)value;
        break;
      case enum_type_PMC:
        ret = VTABLE_get_string(interp, (PMC *)value);
        break;
      default:
        Parrot_ex_throw_from_c_args(interp, NULL, EXCEPTION_UNIMPLEMENTED,
                    "Hash: unsupported entry_type");
    }
    return ret;
}

/*

=item C<PMC* Parrot_hash_value_to_pmc(PARROT_INTERP, const Hash *hash, void
*value)>

Cast hash value to PMC.

=cut

*/

PARROT_CANNOT_RETURN_NULL
PMC*
Parrot_hash_value_to_pmc(PARROT_INTERP, ARGIN(const Hash *hash), ARGIN_NULLOK(void *value))
{
    ASSERT_ARGS(Parrot_hash_value_to_pmc)
    PMC *ret;
    switch (hash->entry_type) {
      case enum_type_INTVAL:
        ret = Parrot_pmc_box_integer(interp, (INTVAL)value);
        break;
      case enum_type_STRING:
        ret = Parrot_pmc_box_string(interp, (STRING*)value);
        break;
      case enum_type_PMC:
        ret = (PMC *)value;
        break;
      default:
        Parrot_ex_throw_from_c_args(interp, NULL, EXCEPTION_UNIMPLEMENTED,
                    "Hash: unsupported entry_type");
    }
    return ret;
}

/*

=item C<FLOATVAL Parrot_hash_value_to_number(PARROT_INTERP, const Hash *hash,
void *value)>

Cast hash value to FLOATVAL.

=cut

*/

FLOATVAL
Parrot_hash_value_to_number(PARROT_INTERP, ARGIN(const Hash *hash), ARGIN_NULLOK(void *value))
{
    ASSERT_ARGS(Parrot_hash_value_to_number)
    FLOATVAL ret;
    switch (hash->entry_type) {
      case enum_type_INTVAL:
        {
            /* Pacify compiler about casting */
            const INTVAL tmp = (INTVAL)value;
            ret = tmp;
        }
        break;
      case enum_type_STRING:
        ret = Parrot_str_to_num(interp, (STRING*)value);
        break;
      case enum_type_PMC:
        ret = VTABLE_get_number(interp, (PMC*)value);
        break;
      default:
        Parrot_ex_throw_from_c_args(interp, NULL, EXCEPTION_UNIMPLEMENTED,
                    "Hash: unsupported entry_type");
    }
    return ret;
}

/*

=back

=head1 SEE ALSO

F<docs/pdds/pdd08_keys.pod>.

=head1 TODO

Future optimizations:

=over 4

=item * Stop reallocating the bucket pool, and instead add chunks on.
(Saves pointer fixups and copying during C<realloc>.)

=item * Hash contraction (don't if it's worth it)

=back

=cut

*/


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