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Subject: Re: [PHP-DEV] Re: Question on XMLReader
From: jstokes@heartofthefyre.us (John Stokes)

Well, fine then.

I'm trying to understand the mechanics behind XMLReader::next() and 
XMLReader::read()

Given an XML file like this:
$library = '
<?xml version="1.0"?>
<library>
     <book>
         <title>Of Mice and Men</title>
     </book>
     <book>
         <title>A Tale of Two Cities</title>
     </book>
</library>';
$XMLdoc = XMLReader::XML($library);

It seems to me that the XMLReader object essentially functions as a pointer.

QUESTION 1
I'm guessing that calling $XMLdoc->next(); moves the pointer like this.

POINTER--> <library>
                 <book>
                 ...

However, a call to readOuterXML(), readInnerXML(), etc. results in 
nothing being printed.

Another $XMLdoc->next(); call results in
                 ...
                 </book>
POINTER--></library>

And again, a call to read...XML() results in nothing being printed. The 
second case makes sense, because you're at the end of the document. I 
don't understand why the first call returns nothing.


QUESTION 2
A similar scenario using XMLReader::read(). If I were to do successive 
calls to $XMLdoc->read(); and $XMLdoc->readOuterXML() I get:

1. POINTER--><library>
                 <book>
                     ...
Prints the whole document.

2. <library>POINTER-->(empty text node)
                 <book>
                     ...
Prints nothing, as expected.

3. <library>
     POINTER--><book>
                     <title>Of Mice and Men</title>
                     ...
SHOULD print the whole book node. It doesn't.

3. <library>
         <book>POINTER-->(empty text node)
             <title>Of Mice and Men</title>
             ...
Prints nothing, as expected.

4. <library>
         <book>
             POINTER--><title>Of Mice and Men</title>
             ...
Prints <title>Of Mice and Men</title>

5. <library>
         <book>
             <title>POINTER-->Of Mice and Men</title>
             ...
Prints Of Mice and Men

Why doesn't iteration 3 print the entire book node?

QUESTION 2a
Using the same scenario as above, does the read() actually read in the 
entire document on iteration 1, or does it wait for a call to 
readOuterXML(),readInnerXML(), etc? If it actually reads the entire 
document, doesn't that defeat the purpose of a pull parser?


QUESTION 3
Starting with iteration 3 above, if I assume that it DID print the whole 
book node, a call to $XMLdoc->next() should do this:
<library>
     <book>
         <title>Of Mice and Men</title>
     </book>
     POINTER--><book>
         <title>A Tale of Two Cities</title>
     ...

Now a call to readOuterXML() SHOULD print the entire 2nd book node. 
Instead it prints nothing. Why?

Thanks in advance for the help.

-John


On 9/21/2013 6:37 AM, David Soria Parra wrote:
> John Stokes <jstokes@heartofthefyre.us> schrieb:
>> I'm working on documenting the XMLReader and XMLWriter classes. Is there
>> someone on the list that can answer some questions about the details of
>> how XMLReader works?
> Please don't ask to ask. Sent a mail to this list or to the php.doc
> mailinglist and just ask your question.
>
> Thank you
>
> ps.: yes there will be people that can answer questions regarding those
> two classes
>