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| |
| <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"> </TD><TD width="484"><FONT color="#000000" face="arial,helvetica,sanserif"> |
| |
| <P>The <CODE><FONT face="courier, monospaced"><xsl:sort></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"><xsl:apply-templates></FONT></CODE> or <CODE><FONT face="courier, monospaced"><xsl:for-each></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"> </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"><xsl:apply-templates></FONT></CODE> and <CODE><FONT face="courier, monospaced"><xsl:for-each></FONT></CODE> |
| elements. Both these elements can have several <CODE><FONT face="courier, monospaced"><xsl:sort></FONT></CODE> |
| child nodes defining primary, secondary, teriary, etc. keys. The code for |
| <CODE><FONT face="courier, monospaced"><xsl:apply-templates></FONT></CODE> and <CODE><FONT face="courier, monospaced"><xsl:for-each></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"><xsl:apply-templates></FONT></CODE> |
| or <CODE><FONT face="courier, monospaced"><xsl:for-each></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"><xsl:apply-templates></FONT></CODE> |
| or <CODE><FONT face="courier, monospaced"><xsl:for-each></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"> </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"> </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<_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"> </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 © 2004 The Apache Software Foundation. |
| All Rights Reserved. |
| </I></FONT></TD></TR></TABLE></BODY></HTML> |