靜態變量 它可以是 靜態全局變量,如果不調用unset,那麼這個靜態變量會一直存在,直到程序退出時才由Zend內存管理來釋放 它可以是 靜態局部變量:在函數裡定義,函數執行完後,該靜態變量不會消失 它可以是 靜態成員變量:在類裡定義,它可以在所有類的對象中共享 例如 <?php function test(){ static $a=1; $a++; } test(); //$a=2 test();//$a=3 test();//$a=4 最後 $a=4了.. 下面我們從內核裡面分析它 static不是一個函數 ,它是一個關鍵字 ,所以只能從LEX語法分析中來查找 打開 zend/zend_language_scanner.l 查找 static 找到代碼 <ST_IN_SCRIPTING>"static" { return T_STATIC; } 是一個宏 再打開 zend/zend_language_pareser.l 搜 T_STATIC 找到代碼 T_STATIC static_var_list ';' 跟進 static_var_list 找到代碼 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); } ; 就是這裡了..它由PHP的語法分析程序 解析成上面的代碼 zend_do_fetch_static_variable 這個函數就是了 它在zend/zend_compile.c裡定義 代碼如下 void zend_do_fetch_static_variable(znode *varname, const znode *static_assignment, int fetch_type TSRMLS_DC) { zval *tmp; //一個臨時變量 zend_op *opline; znode lval; znode result; ALLOC_ZVAL(tmp); //申請一塊內存 if (static_assignment) { *tmp = static_assignment->u.constant; } else { INIT_ZVAL(*tmp); } if (!CG(active_op_array)->static_variables) {//初始化靜態變量的HASH 鍵值 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); */ }
