原:PHP内核研究 函数的定义
声明：本文为斯人原创，全部为作者一一分析得之，有不对的地方望赐教。博客地址:PHP技术博客在CSDN也会同步更新的哦.
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PHP中,函数的定义 是用关键字 function来定义的.
function hello($str){
echo $str;
}
在/zend/zend_language_parse.y中找到 关键字 T_FUNCTION
function:
T_FUNCTION { $$.u.opline_num = CG(zend_lineno); }
;
发现这个只是用来保存当前函数设置的位置的..
而真正parse的地方在哪里?我找了很久没找到,不得已 Google了一下,才知道是在这里
http://imsiren.com/wp-includes/js/tinymce/plugins/wordpress/img/trans.gif
unticked_function_declaration_statement: //译为 "函数声明语句"
function is_reference T_STRING { zend_do_begin_function_declaration(&$1, &$3, 0, $2.op_type, NULL TSRMLS_CC); }
'(' parameter_list ')' '{' inner_statement_list '}' { zend_do_end_function_declaration(&$1 TSRMLS_CC); }
;
is_reference :是引用吗?
T_STRING :我们定义的函数名 ,等于hello
zend_do_begin_function_declaration:开始声明函数.
parameter_list :是参数表
inner_statement_list :函数体语句
zend_do_end_function_declaration:结束声明
一个一个来 先进 zend_do_begin_function_declaration看看,
比较长 一点点来看
void zend_do_begin_function_declaration(znode *function_token, znode *function_name, int is_method, int return_reference, znode *fn_flags_znode TSRMLS_DC) /* {{{ */
{
zend_op_array op_array;
char *name = function_name->u.constant.value.str.val; //函数名
int name_len = function_name->u.constant.value.str.len;//函数名长度
int function_begin_line = function_token->u.opline_num;//函数定义的位置
zend_uint fn_flags;
char *lcname;
zend_bool orig_interactive;
if (is_method) { //是类的方法? 这里不涉及到类的方法的内容 所以暂时跳过
if (CG(active_class_entry)->ce_flags & ZEND_ACC_INTERFACE) {
if ((Z_LVAL(fn_flags_znode->u.constant) & ~(ZEND_ACC_STATIC|ZEND_ACC_PUBLIC))) {
}
Z_LVAL(fn_flags_znode->u.constant) |= ZEND_ACC_ABSTRACT; /* propagates to the rest of the parser */
}
fn_flags = Z_LVAL(fn_flags_znode->u.constant); /* must be done *after* the above check */
} else {
fn_flags = 0;
}
//类相关 跳过
if ((fn_flags & ZEND_ACC_STATIC) && (fn_flags & ZEND_ACC_ABSTRACT) && !(CG(active_class_entry)->ce_flags & ZEND_ACC_INTERFACE)) {
zend_error(E_STRICT, "Static function %s%s%s() should not be abstract", is_method ? CG(active_class_entry)->name : "", is_method ? "::" : "", Z_STRVAL(function_name->u.constant));
}
//转换为小写
lcname = zend_str_tolower_dup(name, name_len);
orig_interactive = CG(interactive);
CG(interactive) = 0;
//初始化zend_op_array
/*要特别说明一下 在PHP里面 函数有两种一种是自定义函数:ZEND_USER_FUNCTION,
*一种是内置函数ZEND_INTERNAL_FUNCTION,这里我们是自定义函数所以 类型为ZEND_USER_FUNCTION
*/
init_op_array(&op_array, ZEND_USER_FUNCTION, INITIAL_OP_ARRAY_SIZE TSRMLS_CC);
CG(interactive) = orig_interactive;
op_array.function_name = name; //函数名称
op_array.return_reference = return_reference; //是否是引用函数
op_array.fn_flags |= fn_flags; //可能是标示声明为类的方法
op_array.pass_rest_by_reference = 0; //所有参数都强制为引用?
op_array.prototype = NULL;//
op_array.line_start = zend_get_compiled_lineno(TSRMLS_C);//开始行
if (is_method) {//类的方法 以下....省略
} else {//到这里 ,用户函数
//生成一个 zend_op
zend_op *opline = get_next_op(CG(active_op_array) TSRMLS_CC);
if (CG(current_namespace)) { //5.3新特性 支持命名空间
/* Prefix function name with current namespcae name */
znode tmp;
tmp.u.constant = *CG(current_namespace);
zval_copy_ctor(&tmp.u.constant);
zend_do_build_namespace_name(&tmp, &tmp, function_name TSRMLS_CC);
op_array.function_name = Z_STRVAL(tmp.u.constant);
efree(lcname);
name_len = Z_STRLEN(tmp.u.constant);
lcname = zend_str_tolower_dup(Z_STRVAL(tmp.u.constant), name_len);
}
//生成的中间代码
opline->opcode = ZEND_DECLARE_FUNCTION;
//类型
opline->op1.op_type = IS_CONST;
build_runtime_defined_function_key(&opline->op1.u.constant, lcname, name_len TSRMLS_CC);
opline->op2.op_type = IS_CONST;
opline->op2.u.constant.type = IS_STRING;
opline->op2.u.constant.value.str.val = lcname;
opline->op2.u.constant.value.str.len = name_len;
Z_SET_REFCOUNT(opline->op2.u.constant, 1);
opline->extended_value = ZEND_DECLARE_FUNCTION;
//更新函数表的HashTable
zend_hash_update(CG(function_table), opline->op1.u.constant.value.str.val, opline->op1.u.constant.value.str.len, &op_array, sizeof(zend_op_array), (void **) &CG(active_op_array));
}
if (CG(compiler_options) & ZEND_COMPILE_EXTENDED_INFO) {
zend_op *opline = get_next_op(CG(active_op_array) TSRMLS_CC);
opline->opcode = ZEND_EXT_NOP;
opline->lineno = function_begin_line;
SET_UNUSED(opline->op1);
SET_UNUSED(opline->op2);
}
{
/* Push a seperator to the switch and foreach stacks */
zend_switch_entry switch_entry;
switch_entry.cond.op_type = IS_UNUSED;
switch_entry.default_case = 0;
switch_entry.control_var = 0;
zend_stack_push(&CG(switch_cond_stack), (void *) &switch_entry, sizeof(switch_entry));
{
/* Foreach stack separator */
zend_op dummy_opline;
dummy_opline.result.op_type = IS_UNUSED;
dummy_opline.op1.op_type = IS_UNUSED;
zend_stack_push(&CG(foreach_copy_stack), (void *) &dummy_opline, sizeof(zend_op));
}
}
if (CG(doc_comment)) {
CG(active_op_array)->doc_comment = CG(doc_comment);
CG(active_op_array)->doc_comment_len = CG(doc_comment_len);
CG(doc_comment) = NULL;
CG(doc_comment_len) = 0;
}
zend_stack_push(&CG(labels_stack), (void *) &CG(labels), sizeof(HashTable*));
CG(labels) = NULL;
}
保存自定义函数的结构如下
typedef union _zend_function {
zend_uchar type; /* MUST be the first element of this struct! */
struct {
zend_uchar type;/* never used */
char *function_name; //函数名称
zend_class_entry *scope;
zend_uint fn_flags;
union _zend_function *prototype;
zend_uint num_args; //参数个数
zend_uint required_num_args;
zend_arg_info *arg_info;
zend_bool pass_rest_by_reference;
unsigned char return_reference;
} common;
zend_op_array op_array;
zend_internal_function internal_function;
} zend_function;
初始化op_array
生成 zend_op
生成的中间码 ZEND_DECLARE_FUNCTION
更新函数表function_table
这样 函数的定义就完了..
下一节详细介绍 函数的参数.
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