[vlc-devel] [PATCH 1/9] vlc_list: add a typedef vlc_list_node to clarify which is the list and which is the node

Rémi Denis-Courmont remi at remlab.net
Mon Aug 20 12:05:05 CEST 2018


This is standard terminology for a tree structure. Siblings are on same level. Children are below and parent is above.

Le 20 août 2018 10:24:51 GMT+03:00, Steve Lhomme <robux4 at ycbcr.xyz> a écrit :
>An example of the confusion we want to avoid and what led me to dig
>into 
>this code:
>
>vlc_list siblings
>
>Is is a list or a list item/node ? The plural led me to think it it's a
>
>list of siblings but I was wrong. Having "vlc_list_node siblings" would
>
>clear that confusion.
>
>
>On 20/08/2018 09:21, Steve Lhomme wrote:
>> On 17/08/2018 19:06, Rémi Denis-Courmont wrote:
>>> You cannot have a different typedef here. This is by design. And we 
>>> already use different member names for heads and nodes.
>>
>> It's possible, it's even desirable. "vlc_list node" is the part that 
>> doesn't make sense here. A node is not a list, the fact it shares the
>
>> same internals is because of the current design. It may change in the
>
>> future, but what is 100% is that a node must not be used as a
>vlc_list 
>> despite its type. And so it should not imply it can be from its type 
>> (maybe the mnemonic is wrong, who knows).
>>
>>>
>>> Le 17 août 2018 16:04:33 GMT+03:00, Steve Lhomme <robux4 at ycbcr.xyz>
>a 
>>> écrit :
>>>
>>>     ---
>>>       include/vlc_list.h | 23 +++++++++++++----------
>>>       1 file changed, 13 insertions(+), 10 deletions(-)
>>>
>>>     diff --git a/include/vlc_list.h b/include/vlc_list.h
>>>     index 45263cc789..002119db6b 100644
>>>     --- a/include/vlc_list.h
>>>     +++ b/include/vlc_list.h
>>>     @@ -45,6 +45,9 @@ struct vlc_list
>>>           struct vlc_list *next;
>>>       };
>>>           +/* type to use in list items to differentiate with the 
>>> list itself */
>>>     +typedef struct vlc_list   vlc_list_node;
>>>     +
>>>       /**
>>>        * Static initializer for a list head.
>>>        */
>>>     @@ -66,7 +69,7 @@ static inline void vlc_list_init(struct 
>>> vlc_list *restrict head)
>>>        * \param prev Node pointer of the previous element.
>>>        * \param next Node pointer of the next element.
>>>        */
>>>     -static inline void vlc_list_add_between(struct vlc_list 
>>> *restrict node,
>>>     +static inline void vlc_list_add_between(vlc_list_node *restrict
>
>>> node,
>>>                                               struct vlc_list *prev,
>>>                                               struct vlc_list *next)
>>>       {
>>>     @@ -82,7 +85,7 @@ static inline void vlc_list_add_between(struct
>
>>> vlc_list *restrict node,
>>>        * \param node Node pointer of the element to insert [OUT].
>>>        * \param prev Node pointer of the previous element.
>>>        */
>>>     -static inline void vlc_list_add_after(struct vlc_list *restrict
>
>>> node,
>>>     +static inline void vlc_list_add_after(vlc_list_node *restrict
>node,
>>>                                             struct vlc_list *prev)
>>>       {
>>>           vlc_list_add_between(node, prev, prev->next);
>>>     @@ -94,7 +97,7 @@ static inline void vlc_list_add_after(struct 
>>> vlc_list *restrict node,
>>>        * \param node Node pointer of the element to insert [OUT].
>>>        * \param prev Node pointer of the next element.
>>>        */
>>>     -static inline void vlc_list_add_before(struct vlc_list
>*restrict 
>>> node,
>>>     +static inline void vlc_list_add_before(vlc_list_node *restrict 
>>> node,
>>>                                              struct vlc_list *next)
>>>       {
>>>           vlc_list_add_between(node, next->prev, next);
>>>     @@ -106,7 +109,7 @@ static inline void
>vlc_list_add_before(struct 
>>> vlc_list *restrict node,
>>>        * \param node Node pointer of the element to append to the 
>>> list [OUT].
>>>        * \param head Head pointer of the list to append the element
>to.
>>>        */
>>>     -static inline void vlc_list_append(struct vlc_list *restrict
>node,
>>>     +static inline void vlc_list_append(vlc_list_node *restrict
>node,
>>>                                          struct vlc_list *head)
>>>       {
>>>           vlc_list_add_before(node, head);
>>>     @@ -118,7 +121,7 @@ static inline void vlc_list_append(struct 
>>> vlc_list *restrict node,
>>>        * \param node Node pointer of the element to prepend to the 
>>> list [OUT].
>>>        * \param head Head pointer of the list to prepend the element
>to.
>>>        */
>>>     -static inline void vlc_list_prepend(struct vlc_list *restrict
>node,
>>>     +static inline void vlc_list_prepend(vlc_list_node *restrict
>node,
>>>                                           struct vlc_list *head)
>>>       {
>>>           vlc_list_add_after(node, head);
>>>     @@ -131,7 +134,7 @@ static inline void vlc_list_prepend(struct 
>>> vlc_list *restrict node,
>>>        * \warning The element must be inside a list.
>>>        * Otherwise the behaviour is undefined.
>>>        */
>>>     -static inline void vlc_list_remove(struct vlc_list *restrict
>node)
>>>     +static inline void vlc_list_remove(vlc_list_node *restrict
>node)
>>>       {
>>>           struct vlc_list *prev = node->prev;
>>>           struct vlc_list *next = node->next;
>>>     @@ -177,7 +180,7 @@ static inline bool vlc_list_is_empty(const 
>>> struct vlc_list *head)
>>>        * \retval false The element is not first (or is in another
>list).
>>>        * \retval true The element is first.
>>>        */
>>>     -static inline bool vlc_list_is_first(const struct vlc_list
>*node,
>>>     +static inline bool vlc_list_is_first(const vlc_list_node *node,
>>>                                            const struct vlc_list
>*head)
>>>       {
>>>           return node->prev == head;
>>>     @@ -192,7 +195,7 @@ static inline bool vlc_list_is_first(const 
>>> struct vlc_list *node,
>>>        * \retval false The element is not last (or is in another
>list).
>>>        * \retval true The element is last.
>>>        */
>>>     -static inline bool vlc_list_is_last(const struct vlc_list
>*node,
>>>     +static inline bool vlc_list_is_last(const vlc_list_node *node,
>>>                                           const struct vlc_list
>*head)
>>>       {
>>>           return node->next == head;
>>>     @@ -289,7 +292,7 @@ static inline void 
>>> *vlc_list_last_or_null(const struct vlc_list *head,
>>>       }
>>>             static inline void *vlc_list_prev_or_null(const struct 
>>> vlc_list *head,
>>>     -                                          struct vlc_list
>*node,
>>>     +                                          vlc_list_node *node,
>>>                                                 size_t offset)
>>>       {
>>>           if (vlc_list_is_first(node, head))
>>>     @@ -298,7 +301,7 @@ static inline void 
>>> *vlc_list_prev_or_null(const struct vlc_list *head,
>>>       }
>>>             static inline void *vlc_list_next_or_null(const struct 
>>> vlc_list *head,
>>>     -                                          struct vlc_list
>*node,
>>>     +                                          vlc_list_node *node,
>>>                                                 size_t offset)
>>>       {
>>>           if (vlc_list_is_last(node, head))
>>>
>>>
>>> -- 
>>> Envoyé de mon appareil Android avec Courriel K-9 Mail. Veuillez 
>>> excuser ma brièveté.
>>>
>>>
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>>
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-- 
Envoyé de mon appareil Android avec Courriel K-9 Mail. Veuillez excuser ma brièveté.
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