staticperl/perl/hv.h

/*    hv.h
 *
 *    Copyright (C) 1991, 1992, 1993, 1996, 1997, 1998, 1999,
 *    2000, 2001, 2002, 2005, by Larry Wall and others
 *
 *    You may distribute under the terms of either the GNU General Public
 *    License or the Artistic License, as specified in the README file.
 *
 */

/* typedefs to eliminate some typing */
typedef struct he HE;
typedef struct hek HEK;

/* entry in hash value chain */
struct he {
    HE          *hent_next;     /* next entry in chain */
    HEK         *hent_hek;      /* hash key */
    SV          *hent_val;      /* scalar value that was hashed */
};

/* hash key -- defined separately for use as shared pointer */
struct hek {
    U32         hek_hash;       /* hash of key */
    I32         hek_len;        /* length of hash key */
    char        hek_key[1];     /* variable-length hash key */
    /* the hash-key is \0-terminated */
    /* after the \0 there is a byte for flags, such as whether the key
       is UTF-8 */
};

/* hash structure: */
/* This structure must match the beginning of struct xpvmg in sv.h. */
struct xpvhv {
    char *      xhv_array;      /* pointer to malloced string */
    STRLEN      xhv_fill;       /* how full xhv_array currently is */
    STRLEN      xhv_max;        /* subscript of last element of xhv_array */
    IV          xhv_keys;       /* how many elements in the array */
    NV          xnv_nv;         /* numeric value, if any */
#define xhv_placeholders xnv_nv
    MAGIC*      xmg_magic;      /* magic for scalar array */
    HV*         xmg_stash;      /* class package */

    I32         xhv_riter;      /* current root of iterator */
    HE          *xhv_eiter;     /* current entry of iterator */
    PMOP        *xhv_pmroot;    /* list of pm's for this package */
    char        *xhv_name;      /* name, if a symbol table */
};

/* hash a key */
/* FYI: This is the "One-at-a-Time" algorithm by Bob Jenkins
 * from requirements by Colin Plumb.
 * (http://burtleburtle.net/bob/hash/doobs.html) */
/* The use of a temporary pointer and the casting games
 * is needed to serve the dual purposes of
 * (a) the hashed data being interpreted as "unsigned char" (new since 5.8,
 *     a "char" can be either signed or signed, depending on the compiler)
 * (b) catering for old code that uses a "char"
 *
 * The "hash seed" feature was added in Perl 5.8.1 to perturb the results
 * to avoid "algorithmic complexity attacks".
 *
 * If USE_HASH_SEED is defined, hash randomisation is done by default
 * If USE_HASH_SEED_EXPLICIT is defined, hash randomisation is done
 * only if the environment variable PERL_HASH_SEED is set.
 * For maximal control, one can define PERL_HASH_SEED.
 * (see also perl.c:perl_parse()).
 */
#ifndef PERL_HASH_SEED
#   if defined(USE_HASH_SEED) || defined(USE_HASH_SEED_EXPLICIT)
#       define PERL_HASH_SEED   PL_hash_seed
#   else
#       define PERL_HASH_SEED   0
#   endif
#endif
#define PERL_HASH(hash,str,len) \
     STMT_START { \
        register const char *s_PeRlHaSh_tmp = str; \
        register const unsigned char *s_PeRlHaSh = (const unsigned char *)s_PeRlHaSh_tmp; \
        register I32 i_PeRlHaSh = len; \
        register U32 hash_PeRlHaSh = PERL_HASH_SEED; \
        while (i_PeRlHaSh--) { \
            hash_PeRlHaSh += *s_PeRlHaSh++; \
            hash_PeRlHaSh += (hash_PeRlHaSh << 10); \
            hash_PeRlHaSh ^= (hash_PeRlHaSh >> 6); \
        } \
        hash_PeRlHaSh += (hash_PeRlHaSh << 3); \
        hash_PeRlHaSh ^= (hash_PeRlHaSh >> 11); \
        (hash) = (hash_PeRlHaSh + (hash_PeRlHaSh << 15)); \
    } STMT_END

/* Only hv.c and mod_perl should be doing this.  */
#ifdef PERL_HASH_INTERNAL_ACCESS
#define PERL_HASH_INTERNAL(hash,str,len) \
     STMT_START { \
        register const char *s_PeRlHaSh_tmp = str; \
        register const unsigned char *s_PeRlHaSh = (const unsigned char *)s_PeRlHaSh_tmp; \
        register I32 i_PeRlHaSh = len; \
        register U32 hash_PeRlHaSh = PL_rehash_seed; \
        while (i_PeRlHaSh--) { \
            hash_PeRlHaSh += *s_PeRlHaSh++; \
            hash_PeRlHaSh += (hash_PeRlHaSh << 10); \
            hash_PeRlHaSh ^= (hash_PeRlHaSh >> 6); \
        } \
        hash_PeRlHaSh += (hash_PeRlHaSh << 3); \
        hash_PeRlHaSh ^= (hash_PeRlHaSh >> 11); \
        (hash) = (hash_PeRlHaSh + (hash_PeRlHaSh << 15)); \
    } STMT_END
#endif

/*
=head1 Hash Manipulation Functions

=for apidoc AmU||HEf_SVKEY
This flag, used in the length slot of hash entries and magic structures,
specifies the structure contains an C<SV*> pointer where a C<char*> pointer
is to be expected. (For information only--not to be used).

=head1 Handy Values

=for apidoc AmU||Nullhv
Null HV pointer.

=head1 Hash Manipulation Functions

=for apidoc Am|char*|HvNAME|HV* stash
Returns the package name of a stash.  See C<SvSTASH>, C<CvSTASH>.

=for apidoc Am|void*|HeKEY|HE* he
Returns the actual pointer stored in the key slot of the hash entry. The
pointer may be either C<char*> or C<SV*>, depending on the value of
C<HeKLEN()>.  Can be assigned to.  The C<HePV()> or C<HeSVKEY()> macros are
usually preferable for finding the value of a key.

=for apidoc Am|STRLEN|HeKLEN|HE* he
If this is negative, and amounts to C<HEf_SVKEY>, it indicates the entry
holds an C<SV*> key.  Otherwise, holds the actual length of the key.  Can
be assigned to. The C<HePV()> macro is usually preferable for finding key
lengths.

=for apidoc Am|SV*|HeVAL|HE* he
Returns the value slot (type C<SV*>) stored in the hash entry.

=for apidoc Am|U32|HeHASH|HE* he
Returns the computed hash stored in the hash entry.

=for apidoc Am|char*|HePV|HE* he|STRLEN len
Returns the key slot of the hash entry as a C<char*> value, doing any
necessary dereferencing of possibly C<SV*> keys.  The length of the string
is placed in C<len> (this is a macro, so do I<not> use C<&len>).  If you do
not care about what the length of the key is, you may use the global
variable C<PL_na>, though this is rather less efficient than using a local
variable.  Remember though, that hash keys in perl are free to contain
embedded nulls, so using C<strlen()> or similar is not a good way to find
the length of hash keys. This is very similar to the C<SvPV()> macro
described elsewhere in this document.

=for apidoc Am|SV*|HeSVKEY|HE* he
Returns the key as an C<SV*>, or C<Nullsv> if the hash entry does not
contain an C<SV*> key.

=for apidoc Am|SV*|HeSVKEY_force|HE* he
Returns the key as an C<SV*>.  Will create and return a temporary mortal
C<SV*> if the hash entry contains only a C<char*> key.

=for apidoc Am|SV*|HeSVKEY_set|HE* he|SV* sv
Sets the key to a given C<SV*>, taking care to set the appropriate flags to
indicate the presence of an C<SV*> key, and returns the same
C<SV*>.

=cut
*/

/* these hash entry flags ride on hent_klen (for use only in magic/tied HVs) */
#define HEf_SVKEY       -2      /* hent_key is an SV* */


#define Nullhv Null(HV*)
#define HvARRAY(hv)     (*(HE***)&((XPVHV*)  SvANY(hv))->xhv_array)
#define HvFILL(hv)      ((XPVHV*)  SvANY(hv))->xhv_fill
#define HvMAX(hv)       ((XPVHV*)  SvANY(hv))->xhv_max
#define HvRITER(hv)     ((XPVHV*)  SvANY(hv))->xhv_riter
#define HvEITER(hv)     ((XPVHV*)  SvANY(hv))->xhv_eiter
#define HvPMROOT(hv)    ((XPVHV*)  SvANY(hv))->xhv_pmroot
#define HvNAME(hv)      ((XPVHV*)  SvANY(hv))->xhv_name

/* the number of keys (including any placeholers) */
#define XHvTOTALKEYS(xhv)       ((xhv)->xhv_keys)

/* The number of placeholders in the enumerated-keys hash */
#define XHvPLACEHOLDERS(xhv)    ((xhv)->xhv_placeholders)

/* the number of keys that exist() (i.e. excluding placeholders) */
#define XHvUSEDKEYS(xhv)      (XHvTOTALKEYS(xhv) - (IV)XHvPLACEHOLDERS(xhv))

/*
 * HvKEYS gets the number of keys that actually exist(), and is provided
 * for backwards compatibility with old XS code. The core uses HvUSEDKEYS
 * (keys, excluding placeholdes) and HvTOTALKEYS (including placeholders)
 */
#define HvKEYS(hv)              XHvUSEDKEYS((XPVHV*)  SvANY(hv))
#define HvUSEDKEYS(hv)          XHvUSEDKEYS((XPVHV*)  SvANY(hv))
#define HvTOTALKEYS(hv)         XHvTOTALKEYS((XPVHV*)  SvANY(hv))
#define HvPLACEHOLDERS(hv)      XHvPLACEHOLDERS((XPVHV*)  SvANY(hv))

#define HvSHAREKEYS(hv)         (SvFLAGS(hv) & SVphv_SHAREKEYS)
#define HvSHAREKEYS_on(hv)      (SvFLAGS(hv) |= SVphv_SHAREKEYS)
#define HvSHAREKEYS_off(hv)     (SvFLAGS(hv) &= ~SVphv_SHAREKEYS)

/* This is an optimisation flag. It won't be set if all hash keys have a 0
 * flag. Currently the only flags relate to utf8.
 * Hence it won't be set if all keys are 8 bit only. It will be set if any key
 * is utf8 (including 8 bit keys that were entered as utf8, and need upgrading
 * when retrieved during iteration. It may still be set when there are no longer
 * any utf8 keys.
 * See HVhek_ENABLEHVKFLAGS for the trigger.
 */
#define HvHASKFLAGS(hv)         (SvFLAGS(hv) & SVphv_HASKFLAGS)
#define HvHASKFLAGS_on(hv)      (SvFLAGS(hv) |= SVphv_HASKFLAGS)
#define HvHASKFLAGS_off(hv)     (SvFLAGS(hv) &= ~SVphv_HASKFLAGS)

#define HvLAZYDEL(hv)           (SvFLAGS(hv) & SVphv_LAZYDEL)
#define HvLAZYDEL_on(hv)        (SvFLAGS(hv) |= SVphv_LAZYDEL)
#define HvLAZYDEL_off(hv)       (SvFLAGS(hv) &= ~SVphv_LAZYDEL)

#define HvREHASH(hv)            (SvFLAGS(hv) & SVphv_REHASH)
#define HvREHASH_on(hv)         (SvFLAGS(hv) |= SVphv_REHASH)
#define HvREHASH_off(hv)        (SvFLAGS(hv) &= ~SVphv_REHASH)

/* Maybe amagical: */
/* #define HV_AMAGICmb(hv)      (SvFLAGS(hv) & (SVpgv_badAM | SVpgv_AM)) */

#define HV_AMAGIC(hv)        (SvFLAGS(hv) &   SVpgv_AM)
#define HV_AMAGIC_on(hv)     (SvFLAGS(hv) |=  SVpgv_AM)
#define HV_AMAGIC_off(hv)    (SvFLAGS(hv) &= ~SVpgv_AM)

/*
#define HV_AMAGICbad(hv)     (SvFLAGS(hv) & SVpgv_badAM)
#define HV_badAMAGIC_on(hv)  (SvFLAGS(hv) |= SVpgv_badAM)
#define HV_badAMAGIC_off(hv) (SvFLAGS(hv) &= ~SVpgv_badAM)
*/

#define Nullhe Null(HE*)
#define HeNEXT(he)              (he)->hent_next
#define HeKEY_hek(he)           (he)->hent_hek
#define HeKEY(he)               HEK_KEY(HeKEY_hek(he))
#define HeKEY_sv(he)            (*(SV**)HeKEY(he))
#define HeKLEN(he)              HEK_LEN(HeKEY_hek(he))
#define HeKUTF8(he)  HEK_UTF8(HeKEY_hek(he))
#define HeKWASUTF8(he)  HEK_WASUTF8(HeKEY_hek(he))
#define HeKREHASH(he)  HEK_REHASH(HeKEY_hek(he))
#define HeKLEN_UTF8(he)  (HeKUTF8(he) ? -HeKLEN(he) : HeKLEN(he))
#define HeKFLAGS(he)  HEK_FLAGS(HeKEY_hek(he))
#define HeVAL(he)               (he)->hent_val
#define HeHASH(he)              HEK_HASH(HeKEY_hek(he))
#define HePV(he,lp)             ((HeKLEN(he) == HEf_SVKEY) ?            \
                                 SvPV(HeKEY_sv(he),lp) :                \
                                 (((lp = HeKLEN(he)) >= 0) ?            \
                                  HeKEY(he) : Nullch))

#define HeSVKEY(he)             ((HeKEY(he) &&                          \
                                  HeKLEN(he) == HEf_SVKEY) ?            \
                                 HeKEY_sv(he) : Nullsv)

#define HeSVKEY_force(he)       (HeKEY(he) ?                            \
                                 ((HeKLEN(he) == HEf_SVKEY) ?           \
                                  HeKEY_sv(he) :                        \
                                  sv_2mortal(newSVpvn(HeKEY(he),        \
                                                     HeKLEN(he)))) :    \
                                 &PL_sv_undef)
#define HeSVKEY_set(he,sv)      ((HeKLEN(he) = HEf_SVKEY), (HeKEY_sv(he) = sv))

#define Nullhek Null(HEK*)
#define HEK_BASESIZE            STRUCT_OFFSET(HEK, hek_key[0])
#define HEK_HASH(hek)           (hek)->hek_hash
#define HEK_LEN(hek)            (hek)->hek_len
#define HEK_KEY(hek)            (hek)->hek_key
#define HEK_FLAGS(hek)  (*((unsigned char *)(HEK_KEY(hek))+HEK_LEN(hek)+1))

#define HVhek_UTF8      0x01 /* Key is utf8 encoded. */
#define HVhek_WASUTF8   0x02 /* Key is bytes here, but was supplied as utf8. */
#define HVhek_REHASH    0x04 /* This key is in an hv using a custom HASH . */
#define HVhek_FREEKEY   0x100 /* Internal flag to say key is malloc()ed.  */
#define HVhek_PLACEHOLD 0x200 /* Internal flag to create placeholder.
                               * (may change, but Storable is a core module) */
#define HVhek_MASK      0xFF

/* Which flags enable HvHASKFLAGS? Somewhat a hack on a hack, as
   HVhek_REHASH is only needed because the rehash flag has to be duplicated
   into all keys as hv_iternext has no access to the hash flags. At this
   point Storable's tests get upset, because sometimes hashes are "keyed"
   and sometimes not, depending on the order of data insertion, and whether
   it triggered rehashing. So currently HVhek_REHAS is exempt.
*/
   
#define HVhek_ENABLEHVKFLAGS    (HVhek_MASK - HVhek_REHASH)

#define HEK_UTF8(hek)           (HEK_FLAGS(hek) & HVhek_UTF8)
#define HEK_UTF8_on(hek)        (HEK_FLAGS(hek) |= HVhek_UTF8)
#define HEK_UTF8_off(hek)       (HEK_FLAGS(hek) &= ~HVhek_UTF8)
#define HEK_WASUTF8(hek)        (HEK_FLAGS(hek) & HVhek_WASUTF8)
#define HEK_WASUTF8_on(hek)     (HEK_FLAGS(hek) |= HVhek_WASUTF8)
#define HEK_WASUTF8_off(hek)    (HEK_FLAGS(hek) &= ~HVhek_WASUTF8)
#define HEK_REHASH(hek)         (HEK_FLAGS(hek) & HVhek_REHASH)
#define HEK_REHASH_on(hek)      (HEK_FLAGS(hek) |= HVhek_REHASH)

/* calculate HV array allocation */
#if defined(STRANGE_MALLOC) || defined(MYMALLOC)
#  define PERL_HV_ARRAY_ALLOC_BYTES(size) ((size) * sizeof(HE*))
#else
#  define MALLOC_OVERHEAD 16
#  define PERL_HV_ARRAY_ALLOC_BYTES(size) \
                        (((size) < 64)                                  \
                         ? (size) * sizeof(HE*)                         \
                         : (size) * sizeof(HE*) * 2 - MALLOC_OVERHEAD)
#endif

/* Flags for hv_iternext_flags.  */
#define HV_ITERNEXT_WANTPLACEHOLDERS    0x01    /* Don't skip placeholders.  */

/* available as a function in hv.c */
#define Perl_sharepvn(sv, len, hash) HEK_KEY(share_hek(sv, len, hash))
#define sharepvn(sv, len, hash)      Perl_sharepvn(sv, len, hash)
Revision:	1.1
Committed:	Thu Jun 30 14:26:41 2005 UTC (21 years, 4 months ago) by root
Content type:	text/plain
Branch:	MAIN
CVS Tags:	PERL-5-8-7, HEAD
Branch point for:	PERL
Log Message:	* empty log message *
#	User	Rev	Content
1	root	1.1	/* hv.h
2			*
3			* Copyright (C) 1991, 1992, 1993, 1996, 1997, 1998, 1999,
4			* 2000, 2001, 2002, 2005, by Larry Wall and others
5			*
6			* You may distribute under the terms of either the GNU General Public
7			* License or the Artistic License, as specified in the README file.
8			*
9			*/
10
11			/* typedefs to eliminate some typing */
12			typedef struct he HE;
13			typedef struct hek HEK;
14
15			/* entry in hash value chain */
16			struct he {
17			HE hent_next; / next entry in chain */
18			HEK hent_hek; / hash key */
19			SV hent_val; / scalar value that was hashed */
20			};
21
22			/* hash key -- defined separately for use as shared pointer */
23			struct hek {
24			U32 hek_hash; /* hash of key */
25			I32 hek_len; /* length of hash key */
26			char hek_key[1]; /* variable-length hash key */
27			/* the hash-key is \0-terminated */
28			/* after the \0 there is a byte for flags, such as whether the key
29			is UTF-8 */
30			};
31
32			/* hash structure: */
33			/* This structure must match the beginning of struct xpvmg in sv.h. */
34			struct xpvhv {
35			char * xhv_array; /* pointer to malloced string */
36			STRLEN xhv_fill; /* how full xhv_array currently is */
37			STRLEN xhv_max; /* subscript of last element of xhv_array */
38			IV xhv_keys; /* how many elements in the array */
39			NV xnv_nv; /* numeric value, if any */
40			#define xhv_placeholders xnv_nv
41			MAGIC* xmg_magic; /* magic for scalar array */
42			HV* xmg_stash; /* class package */
43
44			I32 xhv_riter; /* current root of iterator */
45			HE xhv_eiter; / current entry of iterator */
46			PMOP xhv_pmroot; / list of pm's for this package */
47			char xhv_name; / name, if a symbol table */
48			};
49
50			/* hash a key */
51			/* FYI: This is the "One-at-a-Time" algorithm by Bob Jenkins
52			* from requirements by Colin Plumb.
53			* (http://burtleburtle.net/bob/hash/doobs.html) */
54			/* The use of a temporary pointer and the casting games
55			* is needed to serve the dual purposes of
56			* (a) the hashed data being interpreted as "unsigned char" (new since 5.8,
57			* a "char" can be either signed or signed, depending on the compiler)
58			* (b) catering for old code that uses a "char"
59			*
60			* The "hash seed" feature was added in Perl 5.8.1 to perturb the results
61			* to avoid "algorithmic complexity attacks".
62			*
63			* If USE_HASH_SEED is defined, hash randomisation is done by default
64			* If USE_HASH_SEED_EXPLICIT is defined, hash randomisation is done
65			* only if the environment variable PERL_HASH_SEED is set.
66			* For maximal control, one can define PERL_HASH_SEED.
67			* (see also perl.c:perl_parse()).
68			*/
69			#ifndef PERL_HASH_SEED
70			# if defined(USE_HASH_SEED) \|\| defined(USE_HASH_SEED_EXPLICIT)
71			# define PERL_HASH_SEED PL_hash_seed
72			# else
73			# define PERL_HASH_SEED 0
74			# endif
75			#endif
76			#define PERL_HASH(hash,str,len) \
77			STMT_START { \
78			register const char *s_PeRlHaSh_tmp = str; \
79			register const unsigned char s_PeRlHaSh = (const unsigned char )s_PeRlHaSh_tmp; \
80			register I32 i_PeRlHaSh = len; \
81			register U32 hash_PeRlHaSh = PERL_HASH_SEED; \
82			while (i_PeRlHaSh--) { \
83			hash_PeRlHaSh += *s_PeRlHaSh++; \
84			hash_PeRlHaSh += (hash_PeRlHaSh << 10); \
85			hash_PeRlHaSh ^= (hash_PeRlHaSh >> 6); \
86			} \
87			hash_PeRlHaSh += (hash_PeRlHaSh << 3); \
88			hash_PeRlHaSh ^= (hash_PeRlHaSh >> 11); \
89			(hash) = (hash_PeRlHaSh + (hash_PeRlHaSh << 15)); \
90			} STMT_END
91
92			/* Only hv.c and mod_perl should be doing this. */
93			#ifdef PERL_HASH_INTERNAL_ACCESS
94			#define PERL_HASH_INTERNAL(hash,str,len) \
95			STMT_START { \
96			register const char *s_PeRlHaSh_tmp = str; \
97			register const unsigned char s_PeRlHaSh = (const unsigned char )s_PeRlHaSh_tmp; \
98			register I32 i_PeRlHaSh = len; \
99			register U32 hash_PeRlHaSh = PL_rehash_seed; \
100			while (i_PeRlHaSh--) { \
101			hash_PeRlHaSh += *s_PeRlHaSh++; \
102			hash_PeRlHaSh += (hash_PeRlHaSh << 10); \
103			hash_PeRlHaSh ^= (hash_PeRlHaSh >> 6); \
104			} \
105			hash_PeRlHaSh += (hash_PeRlHaSh << 3); \
106			hash_PeRlHaSh ^= (hash_PeRlHaSh >> 11); \
107			(hash) = (hash_PeRlHaSh + (hash_PeRlHaSh << 15)); \
108			} STMT_END
109			#endif
110
111			/*
112			=head1 Hash Manipulation Functions
113
114			=for apidoc AmU\|\|HEf_SVKEY
115			This flag, used in the length slot of hash entries and magic structures,
116			specifies the structure contains an C<SV> pointer where a C<char> pointer
117			is to be expected. (For information only--not to be used).
118
119			=head1 Handy Values
120
121			=for apidoc AmU\|\|Nullhv
122			Null HV pointer.
123
124			=head1 Hash Manipulation Functions
125
126			=for apidoc Am\|char\|HvNAME\|HV stash
127			Returns the package name of a stash. See C<SvSTASH>, C<CvSTASH>.
128
129			=for apidoc Am\|void\|HeKEY\|HE he
130			Returns the actual pointer stored in the key slot of the hash entry. The
131			pointer may be either C<char> or C<SV>, depending on the value of
132			C<HeKLEN()>. Can be assigned to. The C<HePV()> or C<HeSVKEY()> macros are
133			usually preferable for finding the value of a key.
134
135			=for apidoc Am\|STRLEN\|HeKLEN\|HE* he
136			If this is negative, and amounts to C<HEf_SVKEY>, it indicates the entry
137			holds an C<SV*> key. Otherwise, holds the actual length of the key. Can
138			be assigned to. The C<HePV()> macro is usually preferable for finding key
139			lengths.
140
141			=for apidoc Am\|SV\|HeVAL\|HE he
142			Returns the value slot (type C<SV*>) stored in the hash entry.
143
144			=for apidoc Am\|U32\|HeHASH\|HE* he
145			Returns the computed hash stored in the hash entry.
146
147			=for apidoc Am\|char\|HePV\|HE he\|STRLEN len
148			Returns the key slot of the hash entry as a C<char*> value, doing any
149			necessary dereferencing of possibly C<SV*> keys. The length of the string
150			is placed in C<len> (this is a macro, so do I<not> use C<&len>). If you do
151			not care about what the length of the key is, you may use the global
152			variable C<PL_na>, though this is rather less efficient than using a local
153			variable. Remember though, that hash keys in perl are free to contain
154			embedded nulls, so using C<strlen()> or similar is not a good way to find
155			the length of hash keys. This is very similar to the C<SvPV()> macro
156			described elsewhere in this document.
157
158			=for apidoc Am\|SV\|HeSVKEY\|HE he
159			Returns the key as an C<SV*>, or C<Nullsv> if the hash entry does not
160			contain an C<SV*> key.
161
162			=for apidoc Am\|SV\|HeSVKEY_force\|HE he
163			Returns the key as an C<SV*>. Will create and return a temporary mortal
164			C<SV> if the hash entry contains only a C<char> key.
165
166			=for apidoc Am\|SV\|HeSVKEY_set\|HE he\|SV* sv
167			Sets the key to a given C<SV*>, taking care to set the appropriate flags to
168			indicate the presence of an C<SV*> key, and returns the same
169			C<SV*>.
170
171			=cut
172			*/
173
174			/* these hash entry flags ride on hent_klen (for use only in magic/tied HVs) */
175			#define HEf_SVKEY -2 /* hent_key is an SV* */
176
177
178			#define Nullhv Null(HV*)
179			#define HvARRAY(hv) ((HE*)&((XPVHV) SvANY(hv))->xhv_array)
180			#define HvFILL(hv) ((XPVHV*) SvANY(hv))->xhv_fill
181			#define HvMAX(hv) ((XPVHV*) SvANY(hv))->xhv_max
182			#define HvRITER(hv) ((XPVHV*) SvANY(hv))->xhv_riter
183			#define HvEITER(hv) ((XPVHV*) SvANY(hv))->xhv_eiter
184			#define HvPMROOT(hv) ((XPVHV*) SvANY(hv))->xhv_pmroot
185			#define HvNAME(hv) ((XPVHV*) SvANY(hv))->xhv_name
186
187			/* the number of keys (including any placeholers) */
188			#define XHvTOTALKEYS(xhv) ((xhv)->xhv_keys)
189
190			/* The number of placeholders in the enumerated-keys hash */
191			#define XHvPLACEHOLDERS(xhv) ((xhv)->xhv_placeholders)
192
193			/* the number of keys that exist() (i.e. excluding placeholders) */
194			#define XHvUSEDKEYS(xhv) (XHvTOTALKEYS(xhv) - (IV)XHvPLACEHOLDERS(xhv))
195
196			/*
197			* HvKEYS gets the number of keys that actually exist(), and is provided
198			* for backwards compatibility with old XS code. The core uses HvUSEDKEYS
199			* (keys, excluding placeholdes) and HvTOTALKEYS (including placeholders)
200			*/
201			#define HvKEYS(hv) XHvUSEDKEYS((XPVHV*) SvANY(hv))
202			#define HvUSEDKEYS(hv) XHvUSEDKEYS((XPVHV*) SvANY(hv))
203			#define HvTOTALKEYS(hv) XHvTOTALKEYS((XPVHV*) SvANY(hv))
204			#define HvPLACEHOLDERS(hv) XHvPLACEHOLDERS((XPVHV*) SvANY(hv))
205
206			#define HvSHAREKEYS(hv) (SvFLAGS(hv) & SVphv_SHAREKEYS)
207			#define HvSHAREKEYS_on(hv) (SvFLAGS(hv) \|= SVphv_SHAREKEYS)
208			#define HvSHAREKEYS_off(hv) (SvFLAGS(hv) &= ~SVphv_SHAREKEYS)
209
210			/* This is an optimisation flag. It won't be set if all hash keys have a 0
211			* flag. Currently the only flags relate to utf8.
212			* Hence it won't be set if all keys are 8 bit only. It will be set if any key
213			* is utf8 (including 8 bit keys that were entered as utf8, and need upgrading
214			* when retrieved during iteration. It may still be set when there are no longer
215			* any utf8 keys.
216			* See HVhek_ENABLEHVKFLAGS for the trigger.
217			*/
218			#define HvHASKFLAGS(hv) (SvFLAGS(hv) & SVphv_HASKFLAGS)
219			#define HvHASKFLAGS_on(hv) (SvFLAGS(hv) \|= SVphv_HASKFLAGS)
220			#define HvHASKFLAGS_off(hv) (SvFLAGS(hv) &= ~SVphv_HASKFLAGS)
221
222			#define HvLAZYDEL(hv) (SvFLAGS(hv) & SVphv_LAZYDEL)
223			#define HvLAZYDEL_on(hv) (SvFLAGS(hv) \|= SVphv_LAZYDEL)
224			#define HvLAZYDEL_off(hv) (SvFLAGS(hv) &= ~SVphv_LAZYDEL)
225
226			#define HvREHASH(hv) (SvFLAGS(hv) & SVphv_REHASH)
227			#define HvREHASH_on(hv) (SvFLAGS(hv) \|= SVphv_REHASH)
228			#define HvREHASH_off(hv) (SvFLAGS(hv) &= ~SVphv_REHASH)
229
230			/* Maybe amagical: */
231			/* #define HV_AMAGICmb(hv) (SvFLAGS(hv) & (SVpgv_badAM \| SVpgv_AM)) */
232
233			#define HV_AMAGIC(hv) (SvFLAGS(hv) & SVpgv_AM)
234			#define HV_AMAGIC_on(hv) (SvFLAGS(hv) \|= SVpgv_AM)
235			#define HV_AMAGIC_off(hv) (SvFLAGS(hv) &= ~SVpgv_AM)
236
237			/*
238			#define HV_AMAGICbad(hv) (SvFLAGS(hv) & SVpgv_badAM)
239			#define HV_badAMAGIC_on(hv) (SvFLAGS(hv) \|= SVpgv_badAM)
240			#define HV_badAMAGIC_off(hv) (SvFLAGS(hv) &= ~SVpgv_badAM)
241			*/
242
243			#define Nullhe Null(HE*)
244			#define HeNEXT(he) (he)->hent_next
245			#define HeKEY_hek(he) (he)->hent_hek
246			#define HeKEY(he) HEK_KEY(HeKEY_hek(he))
247			#define HeKEY_sv(he) ((SV*)HeKEY(he))
248			#define HeKLEN(he) HEK_LEN(HeKEY_hek(he))
249			#define HeKUTF8(he) HEK_UTF8(HeKEY_hek(he))
250			#define HeKWASUTF8(he) HEK_WASUTF8(HeKEY_hek(he))
251			#define HeKREHASH(he) HEK_REHASH(HeKEY_hek(he))
252			#define HeKLEN_UTF8(he) (HeKUTF8(he) ? -HeKLEN(he) : HeKLEN(he))
253			#define HeKFLAGS(he) HEK_FLAGS(HeKEY_hek(he))
254			#define HeVAL(he) (he)->hent_val
255			#define HeHASH(he) HEK_HASH(HeKEY_hek(he))
256			#define HePV(he,lp) ((HeKLEN(he) == HEf_SVKEY) ? \
257			SvPV(HeKEY_sv(he),lp) : \
258			(((lp = HeKLEN(he)) >= 0) ? \
259			HeKEY(he) : Nullch))
260
261			#define HeSVKEY(he) ((HeKEY(he) && \
262			HeKLEN(he) == HEf_SVKEY) ? \
263			HeKEY_sv(he) : Nullsv)
264
265			#define HeSVKEY_force(he) (HeKEY(he) ? \
266			((HeKLEN(he) == HEf_SVKEY) ? \
267			HeKEY_sv(he) : \
268			sv_2mortal(newSVpvn(HeKEY(he), \
269			HeKLEN(he)))) : \
270			&PL_sv_undef)
271			#define HeSVKEY_set(he,sv) ((HeKLEN(he) = HEf_SVKEY), (HeKEY_sv(he) = sv))
272
273			#define Nullhek Null(HEK*)
274			#define HEK_BASESIZE STRUCT_OFFSET(HEK, hek_key[0])
275			#define HEK_HASH(hek) (hek)->hek_hash
276			#define HEK_LEN(hek) (hek)->hek_len
277			#define HEK_KEY(hek) (hek)->hek_key
278			#define HEK_FLAGS(hek) (((unsigned char )(HEK_KEY(hek))+HEK_LEN(hek)+1))
279
280			#define HVhek_UTF8 0x01 /* Key is utf8 encoded. */
281			#define HVhek_WASUTF8 0x02 /* Key is bytes here, but was supplied as utf8. */
282			#define HVhek_REHASH 0x04 /* This key is in an hv using a custom HASH . */
283			#define HVhek_FREEKEY 0x100 /* Internal flag to say key is malloc()ed. */
284			#define HVhek_PLACEHOLD 0x200 /* Internal flag to create placeholder.
285			* (may change, but Storable is a core module) */
286			#define HVhek_MASK 0xFF
287
288			/* Which flags enable HvHASKFLAGS? Somewhat a hack on a hack, as
289			HVhek_REHASH is only needed because the rehash flag has to be duplicated
290			into all keys as hv_iternext has no access to the hash flags. At this
291			point Storable's tests get upset, because sometimes hashes are "keyed"
292			and sometimes not, depending on the order of data insertion, and whether
293			it triggered rehashing. So currently HVhek_REHAS is exempt.
294			*/
295
296			#define HVhek_ENABLEHVKFLAGS (HVhek_MASK - HVhek_REHASH)
297
298			#define HEK_UTF8(hek) (HEK_FLAGS(hek) & HVhek_UTF8)
299			#define HEK_UTF8_on(hek) (HEK_FLAGS(hek) \|= HVhek_UTF8)
300			#define HEK_UTF8_off(hek) (HEK_FLAGS(hek) &= ~HVhek_UTF8)
301			#define HEK_WASUTF8(hek) (HEK_FLAGS(hek) & HVhek_WASUTF8)
302			#define HEK_WASUTF8_on(hek) (HEK_FLAGS(hek) \|= HVhek_WASUTF8)
303			#define HEK_WASUTF8_off(hek) (HEK_FLAGS(hek) &= ~HVhek_WASUTF8)
304			#define HEK_REHASH(hek) (HEK_FLAGS(hek) & HVhek_REHASH)
305			#define HEK_REHASH_on(hek) (HEK_FLAGS(hek) \|= HVhek_REHASH)
306
307			/* calculate HV array allocation */
308			#if defined(STRANGE_MALLOC) \|\| defined(MYMALLOC)
309			# define PERL_HV_ARRAY_ALLOC_BYTES(size) ((size) * sizeof(HE*))
310			#else
311			# define MALLOC_OVERHEAD 16
312			# define PERL_HV_ARRAY_ALLOC_BYTES(size) \
313			(((size) < 64) \
314			? (size) * sizeof(HE*) \
315			: (size) * sizeof(HE) 2 - MALLOC_OVERHEAD)
316			#endif
317
318			/* Flags for hv_iternext_flags. */
319			#define HV_ITERNEXT_WANTPLACEHOLDERS 0x01 /* Don't skip placeholders. */
320
321			/* available as a function in hv.c */
322			#define Perl_sharepvn(sv, len, hash) HEK_KEY(share_hek(sv, len, hash))
323			#define sharepvn(sv, len, hash) Perl_sharepvn(sv, len, hash)