Thanks for the info. I think I assumed Lex was more of a linked list based
on MysQL's use of pointers for a lot of things and lack using the C++
features that I am used to. I also wanted to make sure as push_back I have
only seen in a vector for use. I am now reading up more on lists as I have
only really used vectors in basic reading I see why they are used. I also
had to make sure as I got confused as I knew I read somewhere to stay away
from STL features in c++ and the likes for MySQL code in one of the
tutorials.
Joe
On 7/5/09 4:44 AM, "Sergei Golubchik" <serg@stripped> wrote:
> Hi, Joseph!
>
>> As implementation I figured since the Lex is essentially a linked list
>> I would traverse the Lex until the Select statements are reached and
>> break the linked list. I would then make a List(Set Linked List) and
>> call the set functions like it is doen normally. I would then find
>> the Select functions and send to them. I figure during while
>> traversing the Set statement I could copy the chain of variables that
>> are to be Set this way before I send to the SET function I could
>> retrieve the variables for GET to reset the values after I perform the
>> SELECT. Does this sound logical or am I off in how the Lex is setup?
>
> I'm confused. Where did you see that Lex is a linked list ?
> SET stores variables in the Lex->var_list, that is in a list inside one
> Lex, not in a list of Lex'es.
>
>> I will finally start on the traversing the Lex today after I take care
>> of a few chores. If you could point me into how to start the at the
>> first item and pointer type would be helpful and save time. Is there
>> are pointer *start -> item or no in the YYTHD
>
> Traversing the Lex->var_list ? If yes - see below.
>
>> Just a quick question is Lex->var_list a vector? As I see it uses
>> .empty() and push_back . If that is the case I can go through it
>> pretty quickly I think. Although given everything is pretty much
>> linked lists used in mysql I would have thought it was a bunch of
>> pointers in a linked list style. (even though a vector is likely a
>> specialized linked list anyways being dynamic in size)
>
> It's not an std::vector, if that's what you mean. MySQL doesn't use STL.
> Lex->var_list is defined as
>
> List<set_var_base> var_list;
>
> and to iterate the list you use the following:
>
> List_iterator_fast<set_var_base> it(*Lex->var_list);
> set_var_base *var;
> while ((var=it++))
> {
> ... do something with 'var' ...
> }
>
> see sql_set_variables() for an example.
>
> Regards / Mit vielen Grüßen,
> Sergei
