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<?xml version='1.0'?> <!-- -*- xml -*- -->
<!DOCTYPE refentry PUBLIC
"-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<refentry id='xmlif'>
<refentryinfo>
<title>xmlif</title>
<date>April 2009</date>
<productname>Linux</productname>
<author>
<firstname>Eric</firstname>
<othername role="initial">S.</othername>
<surname>Raymond</surname>
<affiliation>
<address><email>esr@snark.thyrsus.com</email></address>
</affiliation>
<contrib>Author of xmlif program</contrib>
</author>
</refentryinfo>
<refmeta>
<refentrytitle>xmlif</refentrytitle>
<manvolnum>1</manvolnum>
<refmiscinfo class='date'>Sept 26 2002</refmiscinfo>
</refmeta>
<refnamediv id='name'>
<refname>xmlif</refname>
<refpurpose>conditional processing instructions for XML</refpurpose>
</refnamediv>
<refsynopsisdiv id='synopsis'>
<cmdsynopsis>
<command>xmlif</command> <arg rep='repeat'>attrib=value</arg>
</cmdsynopsis>
</refsynopsisdiv>
<refsect1 id='description'><title>DESCRIPTION</title>
<para><application>xmlif</application> filters XML according to
conditionalizing markup. This can be useful for formatting one
of several versions of an XML document depending on conditions
passed to the command.</para>
<para>Attribute/value pairs from the command line are matched
against the attributes associated with certain processing
instructions in the document. The instructions are
<sgmltag><?xmlif if?></sgmltag> and its inverse <sgmltag><?xmlif if
not?></sgmltag>, <sgmltag><?xmlif elif?></sgmltag> and its
inverse <sgmltag><?xmlif elif not?></sgmltag>,
<sgmltag><?xmlif else?></sgmltag>, and
<sgmltag><?xmlif fi?></sgmltag>.</para>
<para>Argument/value pairs given on the command line are checked
against the value of corresponding attributes in the conditional
processing instructions. An `attribute match' happens if an
attribute occurs in both the command-line arguments and the tag,
and the values match. An `attribute mismatch' happens if an
attribute occurs in both the command-line arguments and the tag,
but the values do not match.</para>
<para>Spans between <sgmltag><?xmlif if?></sgmltag> or
<sgmltag><?xmlif elif?></sgmltag> and the next conditional
processing instruction at the same nesting level are passed
through unaltered if there is at least one attribute match and
no attribute mismatch; spans between <sgmltag><?xmlif if
not?></sgmltag> and <sgmltag><?xmlif elif not?></sgmltag> and
the next conditional processing instruction are passed
otherwise. Spans between <sgmltag><?xmlif else?></sgmltag> and
the next conditional-processing tag are passed through only if
no previous span at the same level has been passed
through. <sgmltag><?xmlif if?></sgmltag> and
<sgmltag><?xmlif fi?></sgmltag> (and their `not' variants) change
the current nesting level; <sgmltag><?xmlif else?></sgmltag> and
<sgmltag><?xmlif elif?></sgmltag> do not.</para>
<para>All these processing instructions will be removed from the
output produced. Aside from the conditionalization, all other
input is passed through untouched; in particular, entity
references are not resolved.</para>
<para>Value matching is by string equality, except that "|" in an
attribute value is interpreted as an alternation character.
Thus, saying foo='red|blue' on the command line enables
conditions red and blue. Saying color='black|white' in a tag
matches command-line conditions color='black' and
color='white'.</para>
<para>Here is an example:
<programlisting>
Always issue this text.
<?xmlif if condition='html'?>
Issue this text if 'condition=html' is given on the command line.
<?xmlif elif condition='pdf|ps'?>
Issue this text if 'condition=pdf' or 'condition=ps'
is given on the command line.
<?xmlif else?>
Otherwise issue this text.
<?xmlif fi?>
Always issue this text.
</programlisting></para>
</refsect1>
</refentry>
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