Reusing a {SAX,DOM,IDOM}Parser

["Jason E. Stewart" <ja...@openinformatics.com>]

Hey All,

I'd like to create a single parser instance, and then reuse it to
parse a few thousand small XML files over and over (the xmlconf test
suite). 

The problem happens when I parse a file that causes an error. When I
try to parse the next file, it seems that the previous parse left the
parser in a bad state:

   Received XMLException without handler
   Exception thrown in file: 'SAXParser.cpp'
   At line: '385'
   Exception message is:  
   Parse may not be called while parsing

DOM seems to have a reset() method, but not SAX. When I try calling
DOM::reset(), or IDOM, I get an abort because it calls a pure virtual
method.

Any suggestions appreciated.
jas.

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Re: Reusing a {SAX,DOM,IDOM}Parser

["Jason E. Stewart" <ja...@openinformatics.com>]

"Jason E. Stewart" <ja...@openinformatics.com> writes:

> I'd like to create a single parser instance, and then reuse it to
> parse a few thousand small XML files over and over (the xmlconf test
> suite).
> 
> The problem happens when I parse a file that causes an error. When I
> try to parse the next file, it seems that the previous parse left the
> parser in a bad state:
> 
>    Received XMLException without handler
>    Exception thrown in file: 'SAXParser.cpp'
>    At line: '385'
>    Exception message is:  
>    Parse may not be called while parsing
> 
> DOM seems to have a reset() method, but not SAX. When I try calling
> DOM::reset(), or IDOM, I get an abort because it calls a pure virtual
> method.

Hey,

I also tried using the SAXParser progressive parsing interface:
parseFirst(), parseNext(), and parseReset(). 

This works for a while, but eventually parseReset() throws an
undocumented XMLException from XMLScanner.cpp:818:

   parseReset caused exception: XMLException:
   FILE:    XMLScanner.cpp
   LINE:    818
   CODE:    _p_XMLExcepts__Codes=SCALAR(0x129590e0)
   MESSAGE: The call to scanNext() is illegal at this time

Not exactly what I would call a useful error msg... What is
scanNext()? The exception is because of an invalid scan token, but I
don't know why a SAXParseException would cause the parse token to
become invalid.

I'm getting the sense that when Xerces' Parsers throw exceptions,
they are left in a fundamentally unstable state that cannot be
restored, and so one should *never* attempt to reuse a parser
instance. 

I hope that I'm wrong, but I can't seem to get this working. Help is
appreciated. 

jas.

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