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Date: Fri, 02 Oct 2009 16:46:28 +0200
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To: Mathieu Suen <mathieu.suen@easyflirt.com>
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Subject: Re: [PHP-DEV] Doc on the VM
From: scope@planetavent.de (Nicolai Scheer)

Hi!

Mathieu Suen schrieb:
> Hi,
>
> I would like to know if there is some documentation on the different
> layout of the array, object varaible ... in php.
> Or were in the source can we read how the php VM reprensent those entites?

At first, you should have a look at Zend/zend.h in the php source tree.
There you'll find the definition of a "php variable", the zval struct:

struct _zval_struct {
	/* Variable information */
	zvalue_value value;		/* value */
	zend_uint refcount__gc;
	zend_uchar type;	/* active type */
	zend_uchar is_ref__gc;
};

The content of the variable is:

typedef union _zvalue_value {
	long lval;					/* long value */
	double dval;				/* double value */
	struct {
		char *val;
		int len;
	} str;
	HashTable *ht;				/* hash table value */
	zend_object_value obj;
} zvalue_value;

Since a php variable can contain any type php has to offer, this
representation was choosen in order to simplify access on the internal side.

There's a bunch of macros for creating zvals, getting/setting
types/values, etc. so you don't need to do this by hand (of course, in
complex cases you have to).

Does this help?

greetings,

Nico