Re: [xml] libxml2 API crazy?

[Nikolay Sivov <bunglehead gmail com>]

On 4/29/2013 08:18, Nikita Churaev wrote:
> Is this allowed by the C standard? And where is this documented?
It doesn't have anything to do with C standard. Not sure if it's 
documented anywhere,
you have headers with all that info, personally I just read lib code if 
in doubt.
> On Mon, 2013-04-29 at 08:14 +0400, Nikolay Sivov wrote:
> > On 4/29/2013 07:59, Nikita Churaev wrote:
> > > No it's not.
> > >
> > > http://xmlsoft.org/html/libxml-tree.html#xmlDoc
> > >
> > > http://xmlsoft.org/html/libxml-tree.html#xmlNode
> > >
> > > xmlDoc has int compression instead of xmlNode's xmlNs
> > I see what you mean. All node types are using same layout containing basic
> > stuff to link node in a tree - up to 'doc' field. That's what a comment
> > in tree.h means:
> >
> > ---
> > struct _xmlNode {
> >       void           *_private;    /* application data */
> >       xmlElementType   type;    /* type number, must be second ! */
> >       const xmlChar   *name;      /* the name of the node, or the entity */
> >       struct _xmlNode *children;    /* parent->childs link */
> >       struct _xmlNode *last;    /* last child link */
> >       struct _xmlNode *parent;    /* child->parent link */
> >       struct _xmlNode *next;    /* next sibling link  */
> >       struct _xmlNode *prev;    /* previous sibling link  */
> >       struct _xmlDoc  *doc;    /* the containing document */
> >
> >       /* End of common part */
> > ---
> >
> > So to be clean with casting it should have some sort of header struct
> > containing these fields only,
> > and have every node type start with this header, it's just not done this
> > way. To be safe you always
> > need to check type and cast appropriately.
> > > On Mon, 2013-04-29 at 07:48 +0400, Nikolay Sivov wrote:
> > > > On 4/29/2013 07:30, Nikita Churaev wrote:
> > > > > #include <libxml/parser.h>
> > > > > #include <libxml/tree.h>
> > > > > #include <stdio.h>
> > > > >
> > > > > int
> > > > > main (int argc, char** argv)
> > > > > {
> > > > >      xmlDocPtr doc = xmlReadMemory("<doc/>", 6, "egg.xml", NULL, 0);
> > > > >
> > > > >                      /* XmlNode */            /* XmlDoc */
> > > > >      printf("%s\n", (doc->children->parent == doc) ? "true" : "false");
> > > > >      return 0;
> > > > > }
> > > > >
> > > > > This gives out "true"... Why? xmlNode.parent is xmlNodePtr... So I can't
> > > > > just rely on xmlNode pointers to actually point to xmlNode?
> > > > Just take a look what xmlDocPtr actually is - document is also a node.
> > > > >     I looked all
> > > > > around the API reference and tutorials and found nothing on this topic.
> > > > >
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