Google Git
Sign in
apache / xalan-site / 0d2033dc971d6434bfdd3e0960f79af3b185abac / . / docs / xalan / old / xalan-j / xsltc / xsl_sort_design.html
blob: d7a6f4bcf0eeb07ddae6dfe69c8bb38e342ec2ff [file] [log] [blame]
<HTML><HEAD><SCRIPT language="JavaScript" src="resources/script.js" type="text/javascript"></SCRIPT><TITLE>&lt;xsl:sort&gt;</TITLE></HEAD><BODY alink="#ff0000" bgcolor="#ffffff" leftmargin="4" link="#0000ff" marginheight="4" marginwidth="4" text="#000000" topmargin="4" vlink="#0000aa"><TABLE border="0" cellpadding="0" cellspacing="0" width="620"><TR><TD align="left" height="60" rowspan="3" valign="top" width="135"><IMG alt="logo" border="0" height="60" hspace="0" src="resources/logo.gif" vspace="0" width="135"></TD><TD align="left" colspan="4" height="5" valign="top" width="456"><IMG alt="line" border="0" height="5" hspace="0" src="resources/line.gif" vspace="0" width="456"></TD><TD align="left" height="60" rowspan="3" valign="top" width="29"><IMG alt="right" border="0" height="60" hspace="0" src="resources/right.gif" vspace="0" width="29"></TD></TR><TR><TD align="left" bgcolor="#0086b2" colspan="4" height="35" valign="top" width="456"><IMG alt="" border="0" height="35" hspace="0" src="graphics/xsl_sort_design-header.jpg" vspace="0" width="456"></TD></TR><TR><TD align="left" height="20" valign="top" width="168"><IMG alt="bottom" border="0" height="20" hspace="0" src="resources/bottom.gif" vspace="0" width="168"></TD><TD align="left" height="20" valign="top" width="96"><A href="http://xml.apache.org/" onMouseOut="rolloverOff('xml');" onMouseOver="rolloverOn('xml');" target="new"><IMG alt="http://xml.apache.org/" border="0" height="20" hspace="0" name="xml" onLoad="rolloverLoad('xml','resources/button-xml-hi.gif','resources/button-xml-lo.gif');" src="resources/button-xml-lo.gif" vspace="0" width="96"></A></TD><TD align="left" height="20" valign="top" width="96"><A href="http://www.apache.org/" onMouseOut="rolloverOff('asf');" onMouseOver="rolloverOn('asf');" target="new"><IMG alt="http://www.apache.org/" border="0" height="20" hspace="0" name="asf" onLoad="rolloverLoad('asf','resources/button-asf-hi.gif','resources/button-asf-lo.gif');" src="resources/button-asf-lo.gif" vspace="0" width="96"></A></TD><TD align="left" height="20" valign="top" width="96"><A href="http://www.w3.org/" onMouseOut="rolloverOff('w3c');" onMouseOver="rolloverOn('w3c');" target="new"><IMG alt="http://www.w3.org/" border="0" height="20" hspace="0" name="w3c" onLoad="rolloverLoad('w3c','resources/button-w3c-hi.gif','resources/button-w3c-lo.gif');" src="resources/button-w3c-lo.gif" vspace="0" width="96"></A></TD></TR></TABLE><TABLE border="0" cellpadding="0" cellspacing="0" width="620"><TR><TD align="left" valign="top" width="120"><IMG alt="join" border="0" height="14" hspace="0" src="resources/join.gif" vspace="0" width="120"><BR>
<A href="index.html" onMouseOut="rolloverOff('side-index');" onMouseOver="rolloverOn('side-index');"><IMG alt="Overview" border="0" height="12" hspace="0" name="side-index" onLoad="rolloverLoad('side-index','graphics/index-label-2.jpg','graphics/index-label-3.jpg');" src="graphics/index-label-3.jpg" vspace="0" width="120"></A><BR>
<IMG alt="separator" border="0" height="6" hspace="0" src="resources/separator.gif" vspace="0" width="120"><BR>
<A href="xsltc_compiler.html" onMouseOut="rolloverOff('side-xsltc_compiler');" onMouseOver="rolloverOn('side-xsltc_compiler');"><IMG alt="Compiler design" border="0" height="12" hspace="0" name="side-xsltc_compiler" onLoad="rolloverLoad('side-xsltc_compiler','graphics/xsltc_compiler-label-2.jpg','graphics/xsltc_compiler-label-3.jpg');" src="graphics/xsltc_compiler-label-3.jpg" vspace="0" width="120"></A><BR>
<IMG alt="separator" border="0" height="6" hspace="0" src="resources/separator.gif" vspace="0" width="120"><BR>
<A href="xsl_whitespace_design.html" onMouseOut="rolloverOff('side-xsl_whitespace_design');" onMouseOver="rolloverOn('side-xsl_whitespace_design');"><IMG alt="Whitespace" border="0" height="12" hspace="0" name="side-xsl_whitespace_design" onLoad="rolloverLoad('side-xsl_whitespace_design','graphics/xsl_whitespace_design-label-2.jpg','graphics/xsl_whitespace_design-label-3.jpg');" src="graphics/xsl_whitespace_design-label-3.jpg" vspace="0" width="120"></A><BR>
<IMG alt="xsl:sort" border="0" height="12" hspace="0" src="graphics/xsl_sort_design-label-1.jpg" vspace="0" width="120"><BR>
<A href="xsl_key_design.html" onMouseOut="rolloverOff('side-xsl_key_design');" onMouseOver="rolloverOn('side-xsl_key_design');"><IMG alt="Keys" border="0" height="12" hspace="0" name="side-xsl_key_design" onLoad="rolloverLoad('side-xsl_key_design','graphics/xsl_key_design-label-2.jpg','graphics/xsl_key_design-label-3.jpg');" src="graphics/xsl_key_design-label-3.jpg" vspace="0" width="120"></A><BR>
<A href="xsl_comment_design.html" onMouseOut="rolloverOff('side-xsl_comment_design');" onMouseOver="rolloverOn('side-xsl_comment_design');"><IMG alt="Comment design" border="0" height="12" hspace="0" name="side-xsl_comment_design" onLoad="rolloverLoad('side-xsl_comment_design','graphics/xsl_comment_design-label-2.jpg','graphics/xsl_comment_design-label-3.jpg');" src="graphics/xsl_comment_design-label-3.jpg" vspace="0" width="120"></A><BR>
<IMG alt="separator" border="0" height="6" hspace="0" src="resources/separator.gif" vspace="0" width="120"><BR>
<A href="xsl_lang_design.html" onMouseOut="rolloverOff('side-xsl_lang_design');" onMouseOver="rolloverOn('side-xsl_lang_design');"><IMG alt="lang()" border="0" height="12" hspace="0" name="side-xsl_lang_design" onLoad="rolloverLoad('side-xsl_lang_design','graphics/xsl_lang_design-label-2.jpg','graphics/xsl_lang_design-label-3.jpg');" src="graphics/xsl_lang_design-label-3.jpg" vspace="0" width="120"></A><BR>
<A href="xsl_unparsed_design.html" onMouseOut="rolloverOff('side-xsl_unparsed_design');" onMouseOver="rolloverOn('side-xsl_unparsed_design');"><IMG alt="Unparsed entities" border="0" height="12" hspace="0" name="side-xsl_unparsed_design" onLoad="rolloverLoad('side-xsl_unparsed_design','graphics/xsl_unparsed_design-label-2.jpg','graphics/xsl_unparsed_design-label-3.jpg');" src="graphics/xsl_unparsed_design-label-3.jpg" vspace="0" width="120"></A><BR>
<IMG alt="separator" border="0" height="6" hspace="0" src="resources/separator.gif" vspace="0" width="120"><BR>
<A href="xsl_if_design.html" onMouseOut="rolloverOff('side-xsl_if_design');" onMouseOver="rolloverOn('side-xsl_if_design');"><IMG alt="If design" border="0" height="12" hspace="0" name="side-xsl_if_design" onLoad="rolloverLoad('side-xsl_if_design','graphics/xsl_if_design-label-2.jpg','graphics/xsl_if_design-label-3.jpg');" src="graphics/xsl_if_design-label-3.jpg" vspace="0" width="120"></A><BR>
<A href="xsl_choose_design.html" onMouseOut="rolloverOff('side-xsl_choose_design');" onMouseOver="rolloverOn('side-xsl_choose_design');"><IMG alt="Choose|When|Otherwise design" border="0" height="12" hspace="0" name="side-xsl_choose_design" onLoad="rolloverLoad('side-xsl_choose_design','graphics/xsl_choose_design-label-2.jpg','graphics/xsl_choose_design-label-3.jpg');" src="graphics/xsl_choose_design-label-3.jpg" vspace="0" width="120"></A><BR>
<A href="xsl_include_design.html" onMouseOut="rolloverOff('side-xsl_include_design');" onMouseOver="rolloverOn('side-xsl_include_design');"><IMG alt="Include|Import design" border="0" height="12" hspace="0" name="side-xsl_include_design" onLoad="rolloverLoad('side-xsl_include_design','graphics/xsl_include_design-label-2.jpg','graphics/xsl_include_design-label-3.jpg');" src="graphics/xsl_include_design-label-3.jpg" vspace="0" width="120"></A><BR>
<A href="xsl_variable_design.html" onMouseOut="rolloverOff('side-xsl_variable_design');" onMouseOver="rolloverOn('side-xsl_variable_design');"><IMG alt="Variable|Param design" border="0" height="12" hspace="0" name="side-xsl_variable_design" onLoad="rolloverLoad('side-xsl_variable_design','graphics/xsl_variable_design-label-2.jpg','graphics/xsl_variable_design-label-3.jpg');" src="graphics/xsl_variable_design-label-3.jpg" vspace="0" width="120"></A><BR>
<IMG alt="separator" border="0" height="6" hspace="0" src="resources/separator.gif" vspace="0" width="120"><BR>
<A href="xsltc_runtime.html" onMouseOut="rolloverOff('side-xsltc_runtime');" onMouseOver="rolloverOn('side-xsltc_runtime');"><IMG alt="Runtime" border="0" height="12" hspace="0" name="side-xsltc_runtime" onLoad="rolloverLoad('side-xsltc_runtime','graphics/xsltc_runtime-label-2.jpg','graphics/xsltc_runtime-label-3.jpg');" src="graphics/xsltc_runtime-label-3.jpg" vspace="0" width="120"></A><BR>
<IMG alt="separator" border="0" height="6" hspace="0" src="resources/separator.gif" vspace="0" width="120"><BR>
<A href="xsltc_dom.html" onMouseOut="rolloverOff('side-xsltc_dom');" onMouseOver="rolloverOn('side-xsltc_dom');"><IMG alt="Internal DOM" border="0" height="12" hspace="0" name="side-xsltc_dom" onLoad="rolloverLoad('side-xsltc_dom','graphics/xsltc_dom-label-2.jpg','graphics/xsltc_dom-label-3.jpg');" src="graphics/xsltc_dom-label-3.jpg" vspace="0" width="120"></A><BR>
<A href="xsltc_namespace.html" onMouseOut="rolloverOff('side-xsltc_namespace');" onMouseOver="rolloverOn('side-xsltc_namespace');"><IMG alt="Namespaces" border="0" height="12" hspace="0" name="side-xsltc_namespace" onLoad="rolloverLoad('side-xsltc_namespace','graphics/xsltc_namespace-label-2.jpg','graphics/xsltc_namespace-label-3.jpg');" src="graphics/xsltc_namespace-label-3.jpg" vspace="0" width="120"></A><BR>
<IMG alt="separator" border="0" height="6" hspace="0" src="resources/separator.gif" vspace="0" width="120"><BR>
<A href="xsltc_trax.html" onMouseOut="rolloverOff('side-xsltc_trax');" onMouseOver="rolloverOn('side-xsltc_trax');"><IMG alt="Translet & TrAX" border="0" height="12" hspace="0" name="side-xsltc_trax" onLoad="rolloverLoad('side-xsltc_trax','graphics/xsltc_trax-label-2.jpg','graphics/xsltc_trax-label-3.jpg');" src="graphics/xsltc_trax-label-3.jpg" vspace="0" width="120"></A><BR>
<A href="xsltc_predicates.html" onMouseOut="rolloverOff('side-xsltc_predicates');" onMouseOver="rolloverOn('side-xsltc_predicates');"><IMG alt="XPath Predicates" border="0" height="12" hspace="0" name="side-xsltc_predicates" onLoad="rolloverLoad('side-xsltc_predicates','graphics/xsltc_predicates-label-2.jpg','graphics/xsltc_predicates-label-3.jpg');" src="graphics/xsltc_predicates-label-3.jpg" vspace="0" width="120"></A><BR>
<A href="xsltc_iterators.html" onMouseOut="rolloverOff('side-xsltc_iterators');" onMouseOver="rolloverOn('side-xsltc_iterators');"><IMG alt="Xsltc Iterators" border="0" height="12" hspace="0" name="side-xsltc_iterators" onLoad="rolloverLoad('side-xsltc_iterators','graphics/xsltc_iterators-label-2.jpg','graphics/xsltc_iterators-label-3.jpg');" src="graphics/xsltc_iterators-label-3.jpg" vspace="0" width="120"></A><BR>
<A href="xsltc_native_api.html" onMouseOut="rolloverOff('side-xsltc_native_api');" onMouseOver="rolloverOn('side-xsltc_native_api');"><IMG alt="Xsltc Native API" border="0" height="12" hspace="0" name="side-xsltc_native_api" onLoad="rolloverLoad('side-xsltc_native_api','graphics/xsltc_native_api-label-2.jpg','graphics/xsltc_native_api-label-3.jpg');" src="graphics/xsltc_native_api-label-3.jpg" vspace="0" width="120"></A><BR>
<A href="xsltc_trax_api.html" onMouseOut="rolloverOff('side-xsltc_trax_api');" onMouseOver="rolloverOn('side-xsltc_trax_api');"><IMG alt="Xsltc TrAX API" border="0" height="12" hspace="0" name="side-xsltc_trax_api" onLoad="rolloverLoad('side-xsltc_trax_api','graphics/xsltc_trax_api-label-2.jpg','graphics/xsltc_trax_api-label-3.jpg');" src="graphics/xsltc_trax_api-label-3.jpg" vspace="0" width="120"></A><BR>
<A href="xsltc_performance.html" onMouseOut="rolloverOff('side-xsltc_performance');" onMouseOver="rolloverOn('side-xsltc_performance');"><IMG alt="Performance Hints" border="0" height="12" hspace="0" name="side-xsltc_performance" onLoad="rolloverLoad('side-xsltc_performance','graphics/xsltc_performance-label-2.jpg','graphics/xsltc_performance-label-3.jpg');" src="graphics/xsltc_performance-label-3.jpg" vspace="0" width="120"></A><BR>
<IMG alt="close" border="0" height="14" hspace="0" src="resources/close.gif" vspace="0" width="120"><BR></TD><TD align="left" valign="top" width="500"><TABLE border="0" cellpadding="3" cellspacing="0"><TR><TD>
<UL>
<LI><A href="#functionality">Functionality</A></LI>
<LI><A href="#sort-class">The Sort class</A></LI>
<LI><A href="#iterator">The SortingIterator class</A></LI>
<LI><A href="#sortrecord">The NodeSortRecord class</A></LI>
<LI><A href="#recordfactory">The NodeSortRecordFactory class</A></LI>
</UL>
<A name="functionality"><!--anchor--></A>
<TABLE border="0" cellpadding="0" cellspacing="0" width="494"><TR><TD bgcolor="666699" colspan="2" width="494"><TABLE border="0" cellpadding="0" cellspacing="0" width="494"><TR><TD bgcolor="#039acc" height="1" width="1"><IMG alt="" border="0" height="1" hspace="0" src="resources/void.gif" vspace="0" width="1"></TD><TD bgcolor="#039acc" height="1" width="492"><IMG alt="" border="0" height="1" hspace="0" src="resources/void.gif" vspace="0" width="492"></TD><TD bgcolor="#0086b2" height="1" width="1"><IMG alt="" border="0" height="1" hspace="0" src="resources/void.gif" vspace="0" width="1"></TD></TR><TR><TD bgcolor="#039acc" width="1"><IMG alt="" border="0" height="1" hspace="0" src="resources/void.gif" vspace="0" width="1"></TD><TD bgcolor="#0086b2" width="492"><FONT color="#ffffff" face="arial,helvetica,sanserif" size="+1"><IMG alt="" border="0" height="2" hspace="0" src="resources/void.gif" vspace="0" width="2"><B>Functionality</B></FONT></TD><TD bgcolor="#017299" width="1"><IMG alt="" border="0" height="1" hspace="0" src="resources/void.gif" vspace="0" width="1"></TD></TR><TR><TD bgcolor="#0086b2" height="1" width="1"><IMG alt="" border="0" height="1" hspace="0" src="resources/void.gif" vspace="0" width="1"></TD><TD bgcolor="#017299" height="1" width="492"><IMG alt="" border="0" height="1" hspace="0" src="resources/void.gif" vspace="0" width="492"></TD><TD bgcolor="#017299" height="1" width="1"><IMG alt="" border="0" height="1" hspace="0" src="resources/void.gif" vspace="0" width="1"></TD></TR></TABLE></TD></TR><TR><TD width="10">&nbsp;</TD><TD width="484"><FONT color="#000000" face="arial,helvetica,sanserif">
<P>The <CODE><FONT face="courier, monospaced">&lt;xsl:sort&gt;</FONT></CODE> element is used to define a sort key
which specifies the order in which nodes selected by either
<CODE><FONT face="courier, monospaced">&lt;xsl:apply-templates&gt;</FONT></CODE> or <CODE><FONT face="courier, monospaced">&lt;xsl:for-each&gt;</FONT></CODE>
are processed. The nodes can be sorted either in numerical or alphabetic
order, and the alphabetic order may vary depeinding on the language in use.
The nodes can be sorted either in ascending or descending order.</P>
</FONT></TD></TR></TABLE><BR><A name="sort-class"><!--anchor--></A>
<TABLE border="0" cellpadding="0" cellspacing="0" width="494"><TR><TD bgcolor="666699" colspan="2" width="494"><TABLE border="0" cellpadding="0" cellspacing="0" width="494"><TR><TD bgcolor="#039acc" height="1" width="1"><IMG alt="" border="0" height="1" hspace="0" src="resources/void.gif" vspace="0" width="1"></TD><TD bgcolor="#039acc" height="1" width="492"><IMG alt="" border="0" height="1" hspace="0" src="resources/void.gif" vspace="0" width="492"></TD><TD bgcolor="#0086b2" height="1" width="1"><IMG alt="" border="0" height="1" hspace="0" src="resources/void.gif" vspace="0" width="1"></TD></TR><TR><TD bgcolor="#039acc" width="1"><IMG alt="" border="0" height="1" hspace="0" src="resources/void.gif" vspace="0" width="1"></TD><TD bgcolor="#0086b2" width="492"><FONT color="#ffffff" face="arial,helvetica,sanserif" size="+1"><IMG alt="" border="0" height="2" hspace="0" src="resources/void.gif" vspace="0" width="2"><B>The Sort class</B></FONT></TD><TD bgcolor="#017299" width="1"><IMG alt="" border="0" height="1" hspace="0" src="resources/void.gif" vspace="0" width="1"></TD></TR><TR><TD bgcolor="#0086b2" height="1" width="1"><IMG alt="" border="0" height="1" hspace="0" src="resources/void.gif" vspace="0" width="1"></TD><TD bgcolor="#017299" height="1" width="492"><IMG alt="" border="0" height="1" hspace="0" src="resources/void.gif" vspace="0" width="492"></TD><TD bgcolor="#017299" height="1" width="1"><IMG alt="" border="0" height="1" hspace="0" src="resources/void.gif" vspace="0" width="1"></TD></TR></TABLE></TD></TR><TR><TD width="10">&nbsp;</TD><TD width="484"><FONT color="#000000" face="arial,helvetica,sanserif">
<P>Static methods of the Sort class is responsible for generating the
necessary code for invoking SortingIterators under
<CODE><FONT face="courier, monospaced">&lt;xsl:apply-templates&gt;</FONT></CODE> and <CODE><FONT face="courier, monospaced">&lt;xsl:for-each&gt;</FONT></CODE>
elements. Both these elements can have several <CODE><FONT face="courier, monospaced">&lt;xsl:sort&gt;</FONT></CODE>
child nodes defining primary, secondary, teriary, etc. keys. The code for
<CODE><FONT face="courier, monospaced">&lt;xsl:apply-templates&gt;</FONT></CODE> and <CODE><FONT face="courier, monospaced">&lt;xsl:for-each&gt;</FONT></CODE>
create vectors containg a Sort object for each sort key. The object methods
of the Sort object encapsulate a container for key-specific data (such as the
sort key itself, sort order, sort type, and such) while the static methods
take a vector of Sort objects and generate the actual code.</P>
<P>The <CODE><FONT face="courier, monospaced">translate()</FONT></CODE> method of the Sort object is never called. The
vectors containing the Sort objects for a <CODE><FONT face="courier, monospaced">&lt;xsl:apply-templates&gt;</FONT></CODE>
or <CODE><FONT face="courier, monospaced">&lt;xsl:for-each&gt;</FONT></CODE> element are instead passed to the static
<CODE><FONT face="courier, monospaced">translateSortIterator()</FONT></CODE> method. This method compiles code that
instanciates a SortingIterator object that will pass on a node-set in a
specific order to the code handling the <CODE><FONT face="courier, monospaced">&lt;xsl:apply-templates&gt;</FONT></CODE>
or <CODE><FONT face="courier, monospaced">&lt;xsl:for-each&gt;</FONT></CODE> element.</P>
</FONT></TD></TR></TABLE><BR><A name="iterator"><!--anchor--></A>
<TABLE border="0" cellpadding="0" cellspacing="0" width="494"><TR><TD bgcolor="666699" colspan="2" width="494"><TABLE border="0" cellpadding="0" cellspacing="0" width="494"><TR><TD bgcolor="#039acc" height="1" width="1"><IMG alt="" border="0" height="1" hspace="0" src="resources/void.gif" vspace="0" width="1"></TD><TD bgcolor="#039acc" height="1" width="492"><IMG alt="" border="0" height="1" hspace="0" src="resources/void.gif" vspace="0" width="492"></TD><TD bgcolor="#0086b2" height="1" width="1"><IMG alt="" border="0" height="1" hspace="0" src="resources/void.gif" vspace="0" width="1"></TD></TR><TR><TD bgcolor="#039acc" width="1"><IMG alt="" border="0" height="1" hspace="0" src="resources/void.gif" vspace="0" width="1"></TD><TD bgcolor="#0086b2" width="492"><FONT color="#ffffff" face="arial,helvetica,sanserif" size="+1"><IMG alt="" border="0" height="2" hspace="0" src="resources/void.gif" vspace="0" width="2"><B>The SortingIterator class</B></FONT></TD><TD bgcolor="#017299" width="1"><IMG alt="" border="0" height="1" hspace="0" src="resources/void.gif" vspace="0" width="1"></TD></TR><TR><TD bgcolor="#0086b2" height="1" width="1"><IMG alt="" border="0" height="1" hspace="0" src="resources/void.gif" vspace="0" width="1"></TD><TD bgcolor="#017299" height="1" width="492"><IMG alt="" border="0" height="1" hspace="0" src="resources/void.gif" vspace="0" width="492"></TD><TD bgcolor="#017299" height="1" width="1"><IMG alt="" border="0" height="1" hspace="0" src="resources/void.gif" vspace="0" width="1"></TD></TR></TABLE></TD></TR><TR><TD width="10">&nbsp;</TD><TD width="484"><FONT color="#000000" face="arial,helvetica,sanserif">
<P>The SortingIterator class is responsible for sorting nodes encapsulated in
sort obects. These sort objects must be of a class inheriting from
NodeSortRecord, a the SortingIterator object needs a factory object providing
it with the correct type of objects:</P>
<P><IMG align="right" alt="sort_objects.gif" border="0" hspace="4" src="images/sort_objects.gif" vspace="4"><BR clear="all"></P>
<P><I>Figure 1: SortingIterator</I></P>
<P>The SortingIterator class is fairly dumb and leaves much of the work to the
NodeSortRecord class. The iterator gets the NodeSortRecords from the factory
object and sorts them using quicksort and calling <CODE><FONT face="courier, monospaced">compareTo()</FONT></CODE> on
pairs of NodeSortRecord objects.</P>
</FONT></TD></TR></TABLE><BR><A name="sortrecord"><!--anchor--></A>
<TABLE border="0" cellpadding="0" cellspacing="0" width="494"><TR><TD bgcolor="666699" colspan="2" width="494"><TABLE border="0" cellpadding="0" cellspacing="0" width="494"><TR><TD bgcolor="#039acc" height="1" width="1"><IMG alt="" border="0" height="1" hspace="0" src="resources/void.gif" vspace="0" width="1"></TD><TD bgcolor="#039acc" height="1" width="492"><IMG alt="" border="0" height="1" hspace="0" src="resources/void.gif" vspace="0" width="492"></TD><TD bgcolor="#0086b2" height="1" width="1"><IMG alt="" border="0" height="1" hspace="0" src="resources/void.gif" vspace="0" width="1"></TD></TR><TR><TD bgcolor="#039acc" width="1"><IMG alt="" border="0" height="1" hspace="0" src="resources/void.gif" vspace="0" width="1"></TD><TD bgcolor="#0086b2" width="492"><FONT color="#ffffff" face="arial,helvetica,sanserif" size="+1"><IMG alt="" border="0" height="2" hspace="0" src="resources/void.gif" vspace="0" width="2"><B>The NodeSortRecord class</B></FONT></TD><TD bgcolor="#017299" width="1"><IMG alt="" border="0" height="1" hspace="0" src="resources/void.gif" vspace="0" width="1"></TD></TR><TR><TD bgcolor="#0086b2" height="1" width="1"><IMG alt="" border="0" height="1" hspace="0" src="resources/void.gif" vspace="0" width="1"></TD><TD bgcolor="#017299" height="1" width="492"><IMG alt="" border="0" height="1" hspace="0" src="resources/void.gif" vspace="0" width="492"></TD><TD bgcolor="#017299" height="1" width="1"><IMG alt="" border="0" height="1" hspace="0" src="resources/void.gif" vspace="0" width="1"></TD></TR></TABLE></TD></TR><TR><TD width="10">&nbsp;</TD><TD width="484"><FONT color="#000000" face="arial,helvetica,sanserif">
<P>The static methods in the Sort class generates a class inheriting from
NodeSortRecord, with the following overloaded methods:</P>
<UL>
<LI><B>Class Constructor</B></LI>
<UL><LI>The class constructor is overloaded to create sort-key global
tables, such as an array containing the sort order for all the sort keys
and another array containg all the sort types. Different sort order/types
can be specified for the different levels of sort keys, but we assume that
the same language is used for all levels.</LI></UL>
<LI><CODE><FONT face="courier, monospaced">extractValueFromDOM(int level)</FONT></CODE></LI>
<UL><LI>This method is called by the SortingIterator object to extract the
value for a specific sort key for a node. The SortingIterator will only
use this method once and will cache the returned value for later use. The
method will only be called if absultely necessary.</LI></UL>
<LI><CODE><FONT face="courier, monospaced">compareType(int level)</FONT></CODE></LI>
<UL><LI>This method returns the sort type for one sort key level. Returns
either <CODE><FONT face="courier, monospaced">COMPARE_STRING</FONT></CODE> or <CODE><FONT face="courier, monospaced">COMPARE_NUMERIC</FONT></CODE>.</LI></UL>
<LI><CODE><FONT face="courier, monospaced">sortOrder(int level)</FONT></CODE></LI>
<UL><LI>This method returns the sort order for one sort key level. Returns
either <CODE><FONT face="courier, monospaced">COMPARE_ASCENDING</FONT></CODE> or <CODE><FONT face="courier, monospaced">COMPARE_DESCENDING</FONT></CODE></LI></UL>
<LI><CODE><FONT face="courier, monospaced">getCollator(int level)</FONT></CODE></LI>
<UL><LI>This method returns a Collator object for language-specific
string comparisons. The same Collator is used for all levels of the key.
</LI></UL>
</UL>
<P>The <CODE><FONT face="courier, monospaced">compareTo()</FONT></CODE> method of the NodeSortRecord base class deserves
a bit of attention. It takes its own node (from the this pointer) and another
node and compares, if necessary, the values for all sort keys:</P>
<DIV align="right"><TABLE border="0" cellpadding="0" cellspacing="4" width="464"><TR><TD bgcolor="#0086b2" height="1" width="1"><IMG alt="" border="0" height="1" hspace="0" src="resources/void.gif" vspace="0" width="1"></TD><TD bgcolor="#0086b2" height="1" width="462"><IMG alt="" border="0" height="1" hspace="0" src="resources/void.gif" vspace="0" width="462"></TD><TD bgcolor="#0086b2" height="1" width="1"><IMG alt="" border="0" height="1" hspace="0" src="resources/void.gif" vspace="0" width="1"></TD></TR><TR><TD bgcolor="#0086b2" width="1"><IMG alt="" border="0" height="1" hspace="0" src="resources/void.gif" vspace="0" width="1"></TD><TD bgcolor="#ffffff" width="462"><FONT size="-1"><PRE>
/**
* Compare this sort element to another. The first level is checked first,
* and we proceed to the next level only if the first level keys are
* identical (and so the key values may not even be extracted from the DOM)
*/
public int compareTo(NodeSortRecord other) {
int cmp;
for (int level=0; level&lt;_levels; level++) {
// Compare the two nodes either as numeric or text values
if (compareType(level) == COMPARE_NUMERIC) {
final Double our = numericValue(level);
final Double their = other.numericValue(level);
if (our == null) return(-1);
if (their == null) return(1);
cmp = our.compareTo(their);
}
else {
String our = stringValue(level);
String their = other.stringValue(level);
if (our == null) return(-1);
if (their == null) return(1);
cmp = getCollator().compare(our,their);
}
// Return inverse compare value if inverse sort order
if (cmp != 0) {
if (sortOrder(level) == COMPARE_DESCENDING)
return(0 - cmp);
else
return(cmp);
}
}
return(0);
}
</PRE></FONT></TD><TD bgcolor="#0086b2" width="1"><IMG alt="" border="0" height="1" hspace="0" src="resources/void.gif" vspace="0" width="1"></TD></TR><TR><TD bgcolor="#0086b2" height="1" width="1"><IMG alt="" border="0" height="1" hspace="0" src="resources/void.gif" vspace="0" width="1"></TD><TD bgcolor="#0086b2" height="1" width="462"><IMG alt="" border="0" height="1" hspace="0" src="resources/void.gif" vspace="0" width="462"></TD><TD bgcolor="#0086b2" height="1" width="1"><IMG alt="" border="0" height="1" hspace="0" src="resources/void.gif" vspace="0" width="1"></TD></TR></TABLE></DIV>
<P>The two methods <CODE><FONT face="courier, monospaced">stringValue(int level)</FONT></CODE> and
<CODE><FONT face="courier, monospaced">numericValue(int level)</FONT></CODE> return values for one level of the sort key
of a node. These methods cache these values after they are first read so that
the <CODE><FONT face="courier, monospaced">DOM.getNodeValue()</FONT></CODE> is only called once. Also, the algorithm
used for these two methods assure that <CODE><FONT face="courier, monospaced">DOM.getNodeValue()</FONT></CODE> is only
called when needed. The value for a node's secondary sort key is never
retrieved if the node can be uniquely identified by its primary key.</P>
</FONT></TD></TR></TABLE><BR><A name="recordfactory"><!--anchor--></A>
<TABLE border="0" cellpadding="0" cellspacing="0" width="494"><TR><TD bgcolor="666699" colspan="2" width="494"><TABLE border="0" cellpadding="0" cellspacing="0" width="494"><TR><TD bgcolor="#039acc" height="1" width="1"><IMG alt="" border="0" height="1" hspace="0" src="resources/void.gif" vspace="0" width="1"></TD><TD bgcolor="#039acc" height="1" width="492"><IMG alt="" border="0" height="1" hspace="0" src="resources/void.gif" vspace="0" width="492"></TD><TD bgcolor="#0086b2" height="1" width="1"><IMG alt="" border="0" height="1" hspace="0" src="resources/void.gif" vspace="0" width="1"></TD></TR><TR><TD bgcolor="#039acc" width="1"><IMG alt="" border="0" height="1" hspace="0" src="resources/void.gif" vspace="0" width="1"></TD><TD bgcolor="#0086b2" width="492"><FONT color="#ffffff" face="arial,helvetica,sanserif" size="+1"><IMG alt="" border="0" height="2" hspace="0" src="resources/void.gif" vspace="0" width="2"><B>The NodeSortRecordFactory class</B></FONT></TD><TD bgcolor="#017299" width="1"><IMG alt="" border="0" height="1" hspace="0" src="resources/void.gif" vspace="0" width="1"></TD></TR><TR><TD bgcolor="#0086b2" height="1" width="1"><IMG alt="" border="0" height="1" hspace="0" src="resources/void.gif" vspace="0" width="1"></TD><TD bgcolor="#017299" height="1" width="492"><IMG alt="" border="0" height="1" hspace="0" src="resources/void.gif" vspace="0" width="492"></TD><TD bgcolor="#017299" height="1" width="1"><IMG alt="" border="0" height="1" hspace="0" src="resources/void.gif" vspace="0" width="1"></TD></TR></TABLE></TD></TR><TR><TD width="10">&nbsp;</TD><TD width="484"><FONT color="#000000" face="arial,helvetica,sanserif">
<P>After the static methods of the Sort class has generated the new class for
sort objects it generates code that instanciates a new NodeSortRecordFactory
object. This object is passed as a parameter to SortingIterators constructor
and is used by the iterator to generate the necessary sort objects.</P>
</FONT></TD></TR></TABLE><BR>
</TD></TR></TABLE></TD></TR></TABLE><BR><TABLE border="0" cellpadding="0" cellspacing="0" width="620"><TR><TD bgcolor="#0086b2"><IMG alt="dot" height="1" src="resources/dot.gif" width="1"></TD></TR><TR><TD align="center"><FONT color="#0086b2" size="-1"><I>
Copyright &copy; 2004 The Apache Software Foundation.
All Rights Reserved.
</I></FONT></TD></TR></TABLE></BODY></HTML>