1<?xml version="1.0" encoding="iso-8859-1" ?> 2<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0"> 3<xsl:output method="xml"/> 4 5 <!-- FileName: sort36 --> 6 <!-- Document: http://www.w3.org/TR/xslt --> 7 <!-- DocVersion: 19991116 --> 8 <!-- Section: 10 --> 9 <!-- Creator: David Marston --> 10 <!-- Purpose: Test the famous technique for sorting with conditionals. 11 In this case, we want to sort strings with and without "Re: " prefix by 12 the rest of the string. Technique from Oliver Becker (obecker@informatik.hu-berlin.de). --> 13 14<xsl:template match="/"> 15 <out><xsl:text>Memos by thread: 16</xsl:text> 17 <xsl:for-each select="doc/memo"> 18 <xsl:sort select="concat( 19 substring(subj,1,number(not(starts-with(.,'Re: ')))*string-length(subj)), 20 substring(substring-after(subj,'Re: '),1, 21 number(starts-with(.,'Re: '))*string-length(substring-after(subj,'Re: '))))" 22 data-type="text" /> 23 <!-- First substring in concat is null string when 'Re: ' is at start, all of subj otherwise. 24 Second substring in concat is null at opposite times from first, when non-null it's all of subj beyond 'Re: '. 25 Thus, concat "chooses" which string (all of subj or trimmed subj) based on the boolean starts-with(.,'Re: '), 26 because one of the two substring functions returns a null string while other doesn't. 27 The substring(x,1,0) returns null and substring(x,1,string-length(x)) returns the whole x. 28 The zero comes from converting the boolean false to a number, where multiplying by string-length stays zero. 29 The other branch gets boolean true converted to 1, then multiplied by string-length. --> 30 <xsl:sort select="time" data-type="text" /><!-- Tie breaker, for demonstration only. --> 31 <xsl:value-of select="body"/><xsl:text>: </xsl:text><xsl:value-of select="subj"/><xsl:text>; 32</xsl:text> 33 </xsl:for-each> 34 </out> 35</xsl:template> 36 37 38 <!-- 39 * Licensed to the Apache Software Foundation (ASF) under one 40 * or more contributor license agreements. See the NOTICE file 41 * distributed with this work for additional information 42 * regarding copyright ownership. The ASF licenses this file 43 * to you under the Apache License, Version 2.0 (the "License"); 44 * you may not use this file except in compliance with the License. 45 * You may obtain a copy of the License at 46 * 47 * http://www.apache.org/licenses/LICENSE-2.0 48 * 49 * Unless required by applicable law or agreed to in writing, software 50 * distributed under the License is distributed on an "AS IS" BASIS, 51 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 52 * See the License for the specific language governing permissions and 53 * limitations under the License. 54 --> 55 56</xsl:stylesheet> 57