XML::SAX::ByRecord(3pm) User Contributed Perl Documentation XML::SAX::ByRecord(3pm)
NAME
XML::SAX::ByRecord - Record oriented processing of (data) documents
SYNOPSIS
use XML::SAX::Machines qw( ByRecord ) ;
my $m = ByRecord(
"My::RecordFilter1",
"My::RecordFilter2",
...
{
Handler => $h, ## optional
}
);
$m->parse_uri( "foo.xml" );
DESCRIPTION
XML::SAX::ByRecord is a SAX machine that treats a document as a series of records. Everything before and after the records is emitted as-
is while the records are excerpted in to little mini-documents and run one at a time through the filter pipeline contained in ByRecord.
The output is a document that has the same exact things before, after, and between the records that the input document did, but which has
run each record through a filter. So if a document has 10 records in it, the per-record filter pipeline will see 10 sets of (
start_document, body of record, end_document ) events. An example is below.
This has several use cases:
o Big, record oriented documents
Big documents can be treated a record at a time with various DOM oriented processors like XML::Filter::XSLT.
o Streaming XML
Small sections of an XML stream can be run through a document processor without holding up the stream.
o Record oriented style sheets / processors
Sometimes it's just plain easier to write a style sheet or SAX filter that applies to a single record at at time, rather than having to
run through a series of records.
Topology
Here's how the innards look:
+-----------------------------------------------------------+
| An XML:SAX::ByRecord |
| Intake |
| +----------+ +---------+ +--------+ Exhaust |
--+-->| Splitter |--->| Stage_1 |-->...-->| Merger |----------+----->
| +----------+ +---------+ +--------+ |
| ^ |
| | |
| +---------->---------------+ |
| Events not in any records |
| |
+-----------------------------------------------------------+
The "Splitter" is an XML::Filter::DocSplitter by default, and the "Merger" is an XML::Filter::Merger by default. The line that bypasses
the "Stage_1 ..." filter pipeline is used for all events that do not occur in a record. All events that occur in a record pass through the
filter pipeline.
Example
Here's a quick little filter to uppercase text content:
package My::Filter::Uc;
use vars qw( @ISA );
@ISA = qw( XML::SAX::Base );
use XML::SAX::Base;
sub characters {
my $self = shift;
my ( $data ) = @_;
$data->{Data} = uc $data->{Data};
$self->SUPER::characters( @_ );
}
And here's a little machine that uses it:
$m = Pipeline(
ByRecord( "My::Filter::Uc" ),
$out,
);
When fed a document like:
<root> a
<rec>b</rec> c
<rec>d</rec> e
<rec>f</rec> g
</root>
the output looks like:
<root> a
<rec>B</rec> c
<rec>C</rec> e
<rec>D</rec> g
</root>
and the My::Filter::Uc got three sets of events like:
start_document
start_element: <rec>
characters: 'b'
end_element: </rec>
end_document
start_document
start_element: <rec>
characters: 'd'
end_element: </rec>
end_document
start_document
start_element: <rec>
characters: 'f'
end_element: </rec>
end_document
METHODS
new
my $d = XML::SAX::ByRecord->new( @channels, \%options );
Longhand for calling the ByRecord function exported by XML::SAX::Machines.
CREDIT
Proposed by Matt Sergeant, with advise by Kip Hampton and Robin Berjon.
Writing an aggregator.
To be written. Pretty much just that "start_manifold_processing" and "end_manifold_processing" need to be provided. See
XML::Filter::Merger and it's source code for a starter.
perl v5.10.0 2009-06-11 XML::SAX::ByRecord(3pm)