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<refentry xml:id="php-user-filter.filter" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink">
 <refnamediv>
  <refname>php_user_filter::filter</refname>
  <refpurpose>Called when applying the filter</refpurpose>
 </refnamediv>

 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis role="php_user_filter">
   <modifier>public</modifier> <type>int</type><methodname>php_user_filter::filter</methodname>
   <methodparam><type>resource</type><parameter>in</parameter></methodparam>
   <methodparam><type>resource</type><parameter>out</parameter></methodparam>
   <methodparam><type>int</type><parameter role="reference">consumed</parameter></methodparam>
   <methodparam><type>bool</type><parameter>closing</parameter></methodparam>
  </methodsynopsis>
  <para>
   This method is called whenever data is read from or written to
   the attached stream (such as with <function>fread</function> or <function>fwrite</function>).
  </para>

 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  <variablelist>
   <varlistentry>
    <term><parameter>in</parameter></term>
    <listitem>
     <para>
      <parameter>in</parameter> is a resource pointing to a <literal>bucket brigade</literal>
      which contains one or more <literal>bucket</literal> objects containing data to be filtered.
     </para>
    </listitem>
   </varlistentry>
   <varlistentry>
    <term><parameter>out</parameter></term>
    <listitem>
     <para>
      <parameter>out</parameter> is a resource pointing to a second <literal>bucket brigade</literal>
      into which your modified buckets should be placed.
     </para>
    </listitem>
   </varlistentry>
   <varlistentry>
    <term><parameter>consumed</parameter></term>
    <listitem>
     <para>
      <parameter>consumed</parameter>, which must <emphasis>always</emphasis>
      be declared by reference, should be incremented by the length of the data
      which your filter reads in and alters.  In most cases this means you will
      increment <parameter>consumed</parameter> by <literal>$bucket-&gt;datalen</literal>
      for each <literal>$bucket</literal>.
     </para>
    </listitem>
   </varlistentry>
   <varlistentry>
    <term><parameter>closing</parameter></term>
    <listitem>
     <para>
      If the stream is in the process of closing
      (and therefore this is the last pass through the filterchain),
      the <parameter>closing</parameter> parameter will be set to &true;.
     </para>
    </listitem>
   </varlistentry>
  </variablelist>
 </refsect1>

 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   The <methodname>filter</methodname> method must return one of
   three values upon completion.
   <informaltable>
    <tgroup cols="2">
     <thead>
      <row>
       <entry>Return Value</entry>
       <entry>Meaning</entry>
      </row>
     </thead>
     <tbody>
      <row>
       <entry><constant>PSFS_PASS_ON</constant></entry>
       <entry>
        Filter processed successfully with data available in the
        <parameter>out</parameter> <literal>bucket brigade</literal>.
       </entry>
      </row>
      <row>
       <entry><constant>PSFS_FEED_ME</constant></entry>
       <entry>
        Filter processed successfully, however no data was available to
        return. More data is required from the stream or prior filter.
       </entry>
      </row>
      <row>
       <entry><constant>PSFS_ERR_FATAL</constant> (default)</entry>
       <entry>
        The filter experienced an unrecoverable error and cannot continue.
       </entry>
      </row>
     </tbody>
    </tgroup>
   </informaltable>
  </para>
 </refsect1>


</refentry>
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