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.\" ========================================================================
.\"
.IX Title "XML::SAX::Tap 3pm"
.TH XML::SAX::Tap 3pm "2022-06-28" "perl v5.34.0" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
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.SH "NAME"
XML::SAX::Tap \- Tap a pipeline of SAX processors
.SH "VERSION"
.IX Header "VERSION"
version 0.46
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\&    use XML::SAX::Machines qw( Pipeline Tap ) ;
\&
\&    my $m = Pipeline(
\&        "UpstreamFilter",
\&        Tap( "My::Reformatter", \e*STDERR ),
\&        "DownstreamFilter",
\&    );
\&
\&    my $m = Pipeline(
\&        "UpstreamFilter",
\&        Tap( "| xmllint \-\-format \-" ),
\&        "DownstreamFilter",
\&    );
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
XML::SAX::Tap is a \s-1SAX\s0 machine that passes each event it receives on to
a brach handler and then on down to it's main handler.  This allows
debugging output, logging output, validators, and other processors (and
machines, of course) to be placed in a pipeline.  This differs from
XML::Filter::Tee, XML::Filter::SAXT and XML::SAX::Distributer
in that a tap is also a pipeline; it contains the processoring that
handles the tap.
.PP
It's like XML::Filter::Tee in that the events are not buffered; each
event is sent first to the tap, and then to the branch (this is
different from XML::SAX::Dispatcher, which buffers the events).
.PP
It's like XML::SAX::Pipeline in that it contains a series of processors
in a pipeline; these comprise the \*(L"tapping\*(R" processors:
.PP
.Vb 12
\&            +\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-+
\&            |                  Tap instance                |
\&            |                                              |
\&            |  Intake                                      |
\&            |  +\-\-\-\-\-+    +\-\-\-\-\-\-\-\-\-+        +\-\-\-\-\-\-\-\-\-+   |
\& upstream \-\-+\->| Tee |\-\-\->| Stage_0 |\-\-...\-\->| Stage_N |   |
\&            |  +\-\-\-\-\-+    +\-\-\-\-\-\-\-\-\-+        +\-\-\-\-\-\-\-\-\-+   |
\&            |         \e                                    |
\&            |          \e                          Exhaust  |
\&            |           +\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-+\-\-> downstream
\&            |                                              |
\&            +\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-+
.Ve
.PP
The events are not copied, since they may be data structures that are
difficult or impossibly to copy properly, like parts of a C\-based \s-1DOM\s0
implementation.
.PP
Events go to the tap first so that you can validate events using a tap
that throws exceptions and they will be acted on before the tap's
handler sees them.
.PP
This machine has no \f(CW\*(C`Exhaust\*(C'\fR port (see XML::SAX::Machine for
details about \f(CW\*(C`Intake\*(C'\fR and \f(CW\*(C`Exhaust\*(C'\fR ports).
.SH "NAME"
XML::SAX::Tap \- Tap a pipeline of SAX processors
.SH "METHODS"
.IX Header "METHODS"
.IP "new" 4
.IX Item "new"
.Vb 1
\&    my $tap = XML::SAX::Tap\->new( @tap_processors, \e%options );
.Ve
.SH "AUTHOR"
.IX Header "AUTHOR"
.Vb 1
\&    Barrie Slaymaker <barries@slaysys.com>
.Ve
.SH "COPYRIGHT"
.IX Header "COPYRIGHT"
.Vb 1
\&    Copyright 2002, Barrie Slaymaker, All Rights Reserved
.Ve
.PP
You may use this module under the terms of the Artistic, \s-1GNU\s0 Public, or
\&\s-1BSD\s0 licenses, as you choose.
.SH "AUTHORS"
.IX Header "AUTHORS"
.IP "\(bu" 4
Barry Slaymaker
.IP "\(bu" 4
Chris Prather <chris@prather.org>
.SH "COPYRIGHT AND LICENSE"
.IX Header "COPYRIGHT AND LICENSE"
This software is copyright (c) 2013 by Barry Slaymaker.
.PP
This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.