php-src/Zend/zend_string.h
2014-02-19 01:12:05 +04:00

242 lines
7.5 KiB
C

/*
+----------------------------------------------------------------------+
| Zend Engine |
+----------------------------------------------------------------------+
| Copyright (c) 1998-2014 Zend Technologies Ltd. (http://www.zend.com) |
+----------------------------------------------------------------------+
| This source file is subject to version 2.00 of the Zend license, |
| that is bundled with this package in the file LICENSE, and is |
| available through the world-wide-web at the following url: |
| http://www.zend.com/license/2_00.txt. |
| If you did not receive a copy of the Zend license and are unable to |
| obtain it through the world-wide-web, please send a note to |
| license@zend.com so we can mail you a copy immediately. |
+----------------------------------------------------------------------+
| Authors: Dmitry Stogov <dmitry@zend.com> |
+----------------------------------------------------------------------+
*/
/* $Id: $ */
#ifndef ZEND_STRING_H
#define ZEND_STRING_H
#include "zend.h"
BEGIN_EXTERN_C()
ZEND_API extern zend_string *(*zend_new_interned_string)(zend_string *str TSRMLS_DC);
ZEND_API extern void (*zend_interned_strings_snapshot)(TSRMLS_D);
ZEND_API extern void (*zend_interned_strings_restore)(TSRMLS_D);
ZEND_API zend_ulong zend_hash_func(const char *str, uint len);
void zend_interned_strings_init(TSRMLS_D);
void zend_interned_strings_dtor(TSRMLS_D);
END_EXTERN_C()
#ifndef ZTS
# define IS_INTERNED(s) ((s)->gc.u.v.flags & IS_STR_INTERNED)
#else
# define IS_INTERNED(s) 0
#endif
#define STR_HASH_VAL(s) zend_str_hash_val(s)
#define STR_FORGET_HASH_VAL(s) zend_str_forget_hash_val(s)
#define STR_REFCOUNT(s) zend_str_refcount(s)
#define STR_ADDREF(s) zend_str_addref(s)
#define STR_DELREF(s) zend_str_delref(s)
#define STR_ALLOC(len, persistent) zend_str_alloc(len, persistent)
#define STR_INIT(str, len, persistent) zend_str_init(str, len, persistent)
#define STR_COPY(s) zend_str_copy(s)
#define STR_DUP(s, persistent) zend_str_dup(s, persistent)
#define STR_REALLOC(s, len, persistent) zend_str_realloc(s, len, persistent)
#define STR_FREE(s) zend_str_free(s)
#define STR_RELEASE(s) zend_str_release(s)
#define STR_EMPTY_ALLOC() CG(empty_string)
static zend_always_inline zend_ulong zend_str_hash_val(zend_string *s)
{
if (!s->h) {
s->h = zend_hash_func(s->val, s->len + 1);
}
return s->h;
}
static zend_always_inline void zend_str_forget_hash_val(zend_string *s)
{
s->h = 0;
}
static zend_always_inline zend_uint zend_str_refcount(zend_string *s)
{
if (!IS_INTERNED(s)) {
return s->gc.refcount;
}
return 1;
}
static zend_always_inline zend_uint zend_str_addref(zend_string *s)
{
if (!IS_INTERNED(s)) {
return ++s->gc.refcount;
}
return 1;
}
static zend_always_inline zend_uint zend_str_delref(zend_string *s)
{
if (!IS_INTERNED(s)) {
return --s->gc.refcount;
}
return 1;
}
static zend_always_inline zend_string *zend_str_alloc(int len, int persistent)
{
zend_string *ret = pemalloc(sizeof(zend_string) + len, persistent);
ret->gc.refcount = 1;
ret->gc.u.v.type = IS_STRING;
ret->gc.u.v.flags = (persistent ? IS_STR_PERSISTENT : 0);
ret->gc.u.v.buffer = 0;
ret->h = 0;
ret->len = len;
return ret;
}
static zend_always_inline zend_string *zend_str_init(const char *str, int len, int persistent)
{
zend_string *ret = STR_ALLOC(len, persistent);
memcpy(ret->val, str, len);
ret->val[len] = '\0';
return ret;
}
static zend_always_inline zend_string *zend_str_copy(zend_string *s)
{
if (!IS_INTERNED(s)) {
STR_ADDREF(s);
}
return s;
}
static zend_always_inline zend_string *zend_str_dup(zend_string *s, int persistent)
{
//??? if (IS_INTERNED(s)) {
//??? return s;
//??? } else {
return STR_INIT(s->val, s->len, persistent);
//??? }
}
static zend_always_inline zend_string *zend_str_realloc(zend_string *s, int len, int persistent)
{
zend_string *ret;
if (IS_INTERNED(s)) {
ret = STR_ALLOC(len, persistent);
memcpy(ret->val, s->val, (len > s->len ? s->len : len) + 1);
} else if (STR_REFCOUNT(s) == 1) {
ret = perealloc(s, sizeof(zend_string) + len, persistent);
ret->len = len;
STR_FORGET_HASH_VAL(ret);
} else {
ret = STR_ALLOC(len, persistent);
memcpy(ret->val, s->val, (len > s->len ? s->len : len) + 1);
STR_DELREF(s);
}
return ret;
}
static zend_always_inline void zend_str_free(zend_string *s)
{
if (!IS_INTERNED(s)) {
ZEND_ASSERT(STR_REFCOUNT(s) <= 1);
pefree(s, s->gc.u.v.flags & IS_STR_PERSISTENT);
}
}
static zend_always_inline void zend_str_release(zend_string *s)
{
if (!IS_INTERNED(s)) {
if (STR_DELREF(s) == 0) {
pefree(s, s->gc.u.v.flags & IS_STR_PERSISTENT);
}
}
}
/*
* DJBX33A (Daniel J. Bernstein, Times 33 with Addition)
*
* This is Daniel J. Bernstein's popular `times 33' hash function as
* posted by him years ago on comp.lang.c. It basically uses a function
* like ``hash(i) = hash(i-1) * 33 + str[i]''. This is one of the best
* known hash functions for strings. Because it is both computed very
* fast and distributes very well.
*
* The magic of number 33, i.e. why it works better than many other
* constants, prime or not, has never been adequately explained by
* anyone. So I try an explanation: if one experimentally tests all
* multipliers between 1 and 256 (as RSE did now) one detects that even
* numbers are not useable at all. The remaining 128 odd numbers
* (except for the number 1) work more or less all equally well. They
* all distribute in an acceptable way and this way fill a hash table
* with an average percent of approx. 86%.
*
* If one compares the Chi^2 values of the variants, the number 33 not
* even has the best value. But the number 33 and a few other equally
* good numbers like 17, 31, 63, 127 and 129 have nevertheless a great
* advantage to the remaining numbers in the large set of possible
* multipliers: their multiply operation can be replaced by a faster
* operation based on just one shift plus either a single addition
* or subtraction operation. And because a hash function has to both
* distribute good _and_ has to be very fast to compute, those few
* numbers should be preferred and seems to be the reason why Daniel J.
* Bernstein also preferred it.
*
*
* -- Ralf S. Engelschall <rse@engelschall.com>
*/
static inline ulong zend_inline_hash_func(const char *str, uint len)
{
register ulong hash = 5381;
/* variant with the hash unrolled eight times */
for (; len >= 8; len -= 8) {
hash = ((hash << 5) + hash) + *str++;
hash = ((hash << 5) + hash) + *str++;
hash = ((hash << 5) + hash) + *str++;
hash = ((hash << 5) + hash) + *str++;
hash = ((hash << 5) + hash) + *str++;
hash = ((hash << 5) + hash) + *str++;
hash = ((hash << 5) + hash) + *str++;
hash = ((hash << 5) + hash) + *str++;
}
switch (len) {
case 7: hash = ((hash << 5) + hash) + *str++; /* fallthrough... */
case 6: hash = ((hash << 5) + hash) + *str++; /* fallthrough... */
case 5: hash = ((hash << 5) + hash) + *str++; /* fallthrough... */
case 4: hash = ((hash << 5) + hash) + *str++; /* fallthrough... */
case 3: hash = ((hash << 5) + hash) + *str++; /* fallthrough... */
case 2: hash = ((hash << 5) + hash) + *str++; /* fallthrough... */
case 1: hash = ((hash << 5) + hash) + *str++; break;
case 0: break;
EMPTY_SWITCH_DEFAULT_CASE()
}
return hash;
}
#endif /* ZEND_STRING_H */
/*
* Local variables:
* tab-width: 4
* c-basic-offset: 4
* indent-tabs-mode: t
* End:
*/