原创:PHP内核研究之类的成员属性和方法
作者 斯人 | 发布于 2012 年 3 月 10 日
PHP PHP内核

上一章讲到类的实现
这一篇要详细讲讲PHP类的成员属性及方法.
上一篇中曾经介绍到zend_do_begin_class_declaration这个函数,它用来创建并初始化一个zend_class_entry
类的所有信息都保存在这个结构中,那么 属性和方法是怎么保存的呢?

class Person{
      public $name;
}

还记得上一篇说过的zend_initialize_class_data函数吗?不记得也没关系.我们仔细来瞧瞧这个函数
zend_initialize_class_data(new_class_entry, 1 TSRMLS_CC);

ZEND_API void zend_initialize_class_data(zend_class_entry *ce, zend_bool nullify_handlers TSRMLS_DC) /* {{{ */
{
        zend_bool persistent_hashes = (ce->type == ZEND_INTERNAL_CLASS) ? 1 : 0; 
        dtor_func_t zval_ptr_dtor_func = ((persistent_hashes) ? ZVAL_INTERNAL_PTR_DTOR : ZVAL_PTR_DTOR);

        ce->refcount = 1;
        ce->constants_updated = 0;
        ce->ce_flags = 0;

        ce->doc_comment = NULL;
        ce->doc_comment_len = 0;

        zend_hash_init_ex(&ce->default_properties, 0, NULL, zval_ptr_dtor_func, persistent_hashes, 0);
        zend_hash_init_ex(&ce->properties_info, 0, NULL, (dtor_func_t) (persistent_hashes ? zend_destroy_property_info_internal : zend_destroy_property_info), persistent_hashes, 0);
        zend_hash_init_ex(&ce->default_static_members, 0, NULL, zval_ptr_dtor_func, persistent_hashes, 0);        zend_hash_init_ex(&ce->constants_table, 0, NULL, zval_ptr_dtor_func, persistent_hashes, 0);
        zend_hash_init_ex(&ce->function_table, 0, NULL, ZEND_FUNCTION_DTOR, persistent_hashes, 0);

        if (ce->type == ZEND_INTERNAL_CLASS) {
#ifdef ZTS
                int n = zend_hash_num_elements(CG(class_table));

                if (CG(static_members) && n >= CG(last_static_member)) {
                        /* Support for run-time declaration: dl() */
                        CG(last_static_member) = n+1;
                        CG(static_members) = realloc(CG(static_members), (n+1)*sizeof(HashTable*));
                        CG(static_members)[n] = NULL;
                }
                ce->static_members = (HashTable*)(zend_intptr_t)n;
#else
                ce->static_members = NULL;
#endif
       } else {
                ce->static_members = &ce->default_static_members;
        }

        if (nullify_handlers) {
                ce->constructor = NULL;
                ce->destructor = NULL;
                ce->clone = NULL;
                ce->__get = NULL;
                ce->__set = NULL;
                ce->__unset = NULL;
                ce->__isset = NULL;
                ce->__call = NULL;
                ce->__callstatic = NULL;
                ce->__tostring = NULL;
                ce->create_object = NULL;
                ce->get_iterator = NULL;
                ce->iterator_funcs.funcs = NULL;
                ce->interface_gets_implemented = NULL;
                ce->get_static_method = NULL;
                ce->parent = NULL;
                ce->num_interfaces = 0;
                ce->interfaces = NULL;
                ce->module = NULL;
                ce->serialize = NULL;
                ce->unserialize = NULL;
                ce->serialize_func = NULL;
                ce->unserialize_func = NULL;
                ce->builtin_functions = NULL;
        }
}

zend_bool persistent_hashes = (ce->type == ZEND_INTERNAL_CLASS) ? 1 : 0;
普通用户类与内部类 分配内存的方式不同….为什么会有区别呢???我还没来得及研究哦..^.^
注意看13-16行.
zend_hash_init_ex(&ce->default_properties, 0, NULL, zval_ptr_dtor_func, persistent_hashes, 0);
zend_hash_init_ex(&ce->default_static_members, 0, NULL, zval_ptr_dtor_func, persistent_hashes, 0);
zend_hash_init_ex(&ce->constants_table, 0, NULL, zval_ptr_dtor_func, persistent_hashes, 0);
zend_hash_init_ex(&ce->function_table, 0, NULL, ZEND_FUNCTION_DTOR, persistent_hashes, 0);
如果你看过之前的文章,那么你肯定知道这是在初始化HashTable.
是的..确实是这样,
default_properties,default_static_members等都是HashTable类型的指针.所以初始化当然要zend_hash_init了.
第36-61行初始化魔术方法
不过这里只是初始化哦..好像并没有设置属性.$name属性是如何添加到属性表里的呢???

unticked_class_declaration_statement:
                class_entry_type T_STRING extends_from
                        { zend_do_begin_class_declaration(&$1, &$2, &$3 TSRMLS_CC); }
                        implements_list
                        '{'  
                                class_statement_list
                        '}' { zend_do_end_class_declaration(&$1, &$2 TSRMLS_CC); }
        |       interface_entry T_STRING
                        { zend_do_begin_class_declaration(&$1, &$2, NULL TSRMLS_CC); }
                        interface_extends_list
                        '{'  
                                class_statement_list
                        '}' { zend_do_end_class_declaration(&$1, &$2 TSRMLS_CC); }
;
class_statement:
                variable_modifiers { CG(access_type) = Z_LVAL($1.u.constant); } class_variable_declaration ';'
        |       class_constant_declaration ';'
        |       method_modifiers function is_reference T_STRING { zend_do_begin_function_declaration(&$2, &$4, 1, $3.op_type, &$1 TSRMLS_CC); } '('
                        parameter_list ')' method_body { zend_do_abstract_method(&$4, &$1, &$9 TSRMLS_CC); zend_do_end_function_declaration(&$2 TSRMLS_CC); }
;
class_variable_declaration:
                class_variable_declaration ',' T_VARIABLE                                       { zend_do_declare_property(&$3, NULL, CG(access_type) TSRMLS_CC); }
        |       class_variable_declaration ',' T_VARIABLE '=' static_scalar     { zend_do_declare_property(&$3, &$5, CG(access_type) TSRMLS_CC); }
        |       T_VARIABLE                                              { zend_do_declare_property(&$1, NULL, CG(access_type) TSRMLS_CC); }
        |       T_VARIABLE '=' static_scalar    { zend_do_declare_property(&$1, &$3, CG(access_type) TSRMLS_CC); }
;

这个还记得吧?
类初始化成功后类里面的东西当然要执行class_statement_list这个啦..^.^
类体里会调用 zend_do_declare_property处理.

void zend_do_declare_property(const znode *var_name, const znode *value, zend_uint access_type TSRMLS_DC) /* {{{ */
{
        zval *property;
        zend_property_info *existing_property_info;
        char *comment = NULL;
        int comment_len = 0;

        if (CG(active_class_entry)->ce_flags & ZEND_ACC_INTERFACE) {
                zend_error(E_COMPILE_ERROR, "Interfaces may not include member variables");
        }

        if (access_type & ZEND_ACC_ABSTRACT) {
                zend_error(E_COMPILE_ERROR, "Properties cannot be declared abstract");
        }

        if (access_type & ZEND_ACC_FINAL) {
                zend_error(E_COMPILE_ERROR, "Cannot declare property %s::$%s final, the final modifier is allowed only for methods and classes",
                                        CG(active_class_entry)->name, var_name->u.constant.value.str.val);
        }

        if (zend_hash_find(&CG(active_class_entry)->properties_info, var_name->u.constant.value.str.val, var_name->u.constant.value.str.len+1, (void **) &existing_property_info)==SUCCESS) {
                if (!(existing_property_info->flags & ZEND_ACC_IMPLICIT_PUBLIC)) {
                        zend_error(E_COMPILE_ERROR, "Cannot redeclare %s::$%s", CG(active_class_entry)->name, var_name->u.constant.value.str.val);
                }
        }
        ALLOC_ZVAL(property);

        if (value) {
                *property = value->u.constant;
        } else {
                INIT_PZVAL(property);
                Z_TYPE_P(property) = IS_NULL;
        }

        if (CG(doc_comment)) {
                comment = CG(doc_comment);
                comment_len = CG(doc_comment_len);
                CG(doc_comment) = NULL;
                CG(doc_comment_len) = 0;
        }

        zend_declare_property_ex(CG(active_class_entry), var_name->u.constant.value.str.val, var_name->u.constant.value.str.len, property, access_type, comment, comment_len TSRMLS_CC);
        efree(var_name->u.constant.value.str.val);
}

第8-25行:
如果你的类声明的是接口.那么该接口是不能有属性的 会抛出Interfaces may not include member variables
如果类的属性被设置为abstract,那么会抛出Properties cannot be declared abstract
如果类的属性被设置为final,那么会抛出Cannot declare property %s::$%s final, the final modifier is allowed only for methods and classes
一切没有问题,会分配一个zval的数据,
如果属性有初始值,那么该数据会分配给zval,如果没有,则调用INIT_PZVAL初始化zval,并设置类型为IS_NULL;
最后会调用zend_declare_property_ex将该zval添加到指定的active_class_entry中
类的方法

class Person{
      public function test(){
             echo 1;
      }
}

如果是方法呢??是怎么处理的?
先看规则

class_statement:
                variable_modifiers { CG(access_type) = Z_LVAL($1.u.constant); } class_variable_declaration ';'
        |       class_constant_declaration ';'
        |       method_modifiers function is_reference T_STRING { zend_do_begin_function_declaration(&$2, &$4, 1, $3.op_type, &$1 TSRMLS_CC); } '('
                        parameter_list ')' method_body { zend_do_abstract_method(&$4, &$1, &$9 TSRMLS_CC); zend_do_end_function_declaration(&$2 TSRMLS_CC); }

第一个是属性,那么第三个就是就是方法啦..
zend_do_begin_function_declaration眼熟吗?
如果看过之前的文章,肯定眼熟
如果没有看过.先去看看这篇文章. 函数的定义
这里就不详细讲了.
只说说在那篇没提到的内容
在这个函数中 有一个判断

if (is_method) {
                if (CG(active_class_entry)->ce_flags & ZEND_ACC_INTERFACE) {
                        if ((Z_LVAL(fn_flags_znode->u.constant) & ~(ZEND_ACC_STATIC|ZEND_ACC_PUBLIC))) {
                                zend_error(E_COMPILE_ERROR, "Access type for interface method %s::%s() must be omitted", CG(active_class_entry)->name, function_name->u.constant.value.str.val);                                    
                        }
                        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;
        }

很明显,如果是方法 ,那么才会进去处理
3-5行 :
如果你把接口类的属性设置为private私有或受保护的.那么就会抛出Access type for interface method %s::%s() must be omitted
然后会调用
if (zend_hash_add(&CG(active_class_entry)->function_table, lcname, name_len+1, &op_array, sizeof(zend_op_array), (void **) &CG(active_op_array)) == FAILURE) {
zend_error(E_COMPILE_ERROR, “Cannot redeclare %s::%s()”, CG(active_class_entry)->name, name);
}
直接把方法添加到function_table里.
下面会根据不同的类声明做不同的判断.

原文出处:http://www.imsiren.com/archives/380