PHP静态变量的实现

[php]代码库

static int ZEND_FASTCALL  ZEND_FETCH_W_SPEC_CV_HANDLER(ZEND_OPCODE_HANDLER_ARGS)
{
    return zend_fetch_var_address_helper_SPEC_CV(BP_VAR_W, ZEND_OPCODE_HANDLER_ARGS_PASSTHRU);
}
 
static int ZEND_FASTCALL zend_fetch_var_address_helper_SPEC_CV(int type, ZEND_OPCODE_HANDLER_ARGS)
{
    ...//省略
 
    if (opline->op2.u.EA.type == ZEND_FETCH_STATIC_MEMBER) {
        retval = zend_std_get_static_property(EX_T(opline->op2.u.var).class_entry, Z_STRVAL_P(varname), Z_STRLEN_P(varname), 0 TSRMLS_CC);
    } else {
        // 取符号表，这里我们取的是EG(active_op_array)->static_variables
        target_symbol_table = zend_get_target_symbol_table(opline, EX(Ts), type, varname TSRMLS_CC);    
        ...//   省略
        if (zend_hash_find(target_symbol_table, varname->value.str.val, varname->value.str.len+1, (void **) &retval) == FAILURE) {
            switch (type) {
                ...//省略
                //  在前面的调用中我们知道type = case BP_VAR_W，于是程序会走按case BP_VAR_W的流程走。
                case BP_VAR_W: {
                        zval *new_zval = &EG(uninitialized_zval);
 
                        Z_ADDREF_P(new_zval);
                        zend_hash_update(target_symbol_table, varname->value.str.val, varname->value.str.len+1, &new_zval, sizeof(zval *), (void **) &retval);
                        // 更新符号表，执行赋值操作
                    }
                    break;
                EMPTY_SWITCH_DEFAULT_CASE()
            }
        }
        switch (opline->op2.u.EA.type) {
            ...//省略
            case ZEND_FETCH_STATIC:
                zval_update_constant(retval, (void*) 1 TSRMLS_CC);
                break;
            case ZEND_FETCH_GLOBAL_LOCK:
                if (IS_CV == IS_VAR && !free_op1.var) {
                    PZVAL_LOCK(*EX_T(opline->op1.u.var).var.ptr_ptr);
                }
                break;
        }
    }
 
    ...//省略
}