function test(){
static $a=1;
$a++;
}
test(); //$a=2
test();//$a=3
test();//$a=4
最后 $a=4了..
下面我们从内核里面分析它
static不是一个函数 ,它是一个关键字 ,所以只能从LEX语法分析中来查找
打开 zend/zend_language_scanner.l 查找 static
找到代码
"static" {
return T_STATIC;
}
是一个宏
再打开 zend/zend_language_pareser.l
搜 T_STATIC
找到代码
T_STATIC static_var_list ';'
跟进 static_var_list
找到代码
static_var_list:
static_var_list ',' T_VARIABLE { zend_do_fetch_static_variable(&$3, NULL, ZEND_FETCH_STATIC TSRMLS_CC); }
| static_var_list ',' T_VARIABLE '=' static_scalar { zend_do_fetch_static_variable(&$3, &$5, ZEND_FETCH_STATIC TSRMLS_CC); }
| T_VARIABLE { zend_do_fetch_static_variable(&$1, NULL, ZEND_FETCH_STATIC TSRMLS_CC); }
| T_VARIABLE '=' static_scalar { zend_do_fetch_static_variable(&$1, &$3, ZEND_FETCH_STATIC TSRMLS_CC); }
;
就是这里了..它由PHP的语法分析程序 解析成上面的代码
zend_do_fetch_static_variable 这个函数就是了
它在zend/zend_compile.c里定义
代码如下
void zend_do_fetch_static_variable(znode *varname, const znode *static_assignment, int fetch_type TSRMLS_DC)
{
zval *tmp; //一个临时变量
zend_op *opline;
znode lval;
znode result;
ALLOC_ZVAL(tmp); //申请一块内存
if (static_assignment) {
*tmp = static_assignment->u.constant;
} else {
INIT_ZVAL(*tmp);
}
if (!CG(active_op_array)->static_variables) {//初始化静态变量的HASH 键值
ALLOC_HASHTABLE(CG(active_op_array)->static_variables);
//初始化HASH值
zend_hash_init(CG(active_op_array)->static_variables, 2, NULL, ZVAL_PTR_DTOR, 0);
}
zend_hash_update(CG(active_op_array)->static_variables, varname->u.constant.value.str.val, varname->u.constant.value.str.len+1, &tmp, sizeof(zval *), NULL);
if (varname->op_type == IS_CONST) {
if (Z_TYPE(varname->u.constant) != IS_STRING) {
convert_to_string(&varname->u.constant);
}
}
opline = get_next_op(CG(active_op_array) TSRMLS_CC);
opline->result.op_type = IS_VAR;
opline->result.u.EA.type = 0;
opline->result.u.var = get_temporary_variable(CG(active_op_array));
opline->op1 = *varname;
SET_UNUSED(opline->op2);
opline->op2.u.EA.type = ZEND_FETCH_STATIC;
result = opline->result;
if (varname->op_type == IS_CONST) {
zval_copy_ctor(&varname->u.constant);
}
fetch_simple_variable(&lval, varname, 0 TSRMLS_CC); /* Relies on the fact that the default fetch is BP_VAR_W */ www.2cto.com
if (fetch_type == ZEND_FETCH_LEXICAL) {
znode dummy;
zend_do_begin_variable_parse(TSRMLS_C);
zend_do_assign(&dummy, &lval, &result TSRMLS_CC);
zend_do_free(&dummy TSRMLS_CC);
} else {
zend_do_assign_ref(NULL, &lval, &result TSRMLS_CC);
}
CG(active_op_array)->opcodes[CG(active_op_array)->last-1].result.u.EA.type |= EXT_TYPE_UNUSED;
/* zval_dtor(&varname->u.constant); */
}
http://www.bkjia.com/PHPjc/477784.htmlwww.bkjia.comtruehttp://www.bkjia.com/PHPjc/477784.htmlTechArticle静态变量 它可以是 静态全局变量,如果不调用unset,那么这个静态变量会一直存在,直到程序退出时才由Zend内存管理来释放 它可以是 静态局部...
