php 变量的结构和实现

php版本 7.2.3

文件地址：Zend/zend_types.h

typedef struct _zval_struct     zval;

变量的存储结构

struct _zval_struct {
    zend_value        value;            /* value */
    union {
        struct {
            ZEND_ENDIAN_LOHI_4(
                zend_uchar    type,            /* active type */
                zend_uchar    type_flags,
                zend_uchar    const_flags,
                zend_uchar    reserved)        /* call info for EX(This) */
        } v;
        uint32_t type_info;
    } u1;
    union {
        uint32_t     next;                 /* hash collision chain */
        uint32_t     cache_slot;           /* literal cache slot */
        uint32_t     lineno;               /* line number (for ast nodes) */
        uint32_t     num_args;             /* arguments number for EX(This) */
        uint32_t     fe_pos;               /* foreach position */
        uint32_t     fe_iter_idx;          /* foreach iterator index */
        uint32_t     access_flags;         /* class constant access flags */
        uint32_t     property_guard;       /* single property guard */
        uint32_t     extra;                /* not further specified */
    } u2;
};
value：存放变量值
u1:变量的属性
u2:变量被使用时使用

变量值的实际存储结构，一个联合体（节省空间）

 1 typedef union _zend_value {
 2     zend_long         lval;                /* long value */
 3     double            dval;                /* double value */
 4     zend_refcounted  *counted;
 5     zend_string      *str;
 6     zend_array       *arr;
 7     zend_object      *obj;
 8     zend_resource    *res;
 9     zend_reference   *ref;
10     zend_ast_ref     *ast;
11     zval             *zv;
12     void             *ptr;
13     zend_class_entry *ce;
14     zend_function    *func;
15     struct {
16         uint32_t w1;
17         uint32_t w2;
18     } ww;
19 } zend_value;
posted @ 2018-03-15 17:36  DearMrLi  阅读(417)  评论(0)  编辑  收藏  举报