xml - 如何根据节点属性动态更改 xslt 页面序列？

Question

我遇到的问题的简化版本是这样的。对于像这样的 XML 文件:

<?xml version="1.0" encoding="UTF-8"?>
<items>
    <item cols="1">Item 1</item>
    <item cols="1">Item 2</item>
    <item cols="1">Item 3</item>
    <item cols="1">Item 4</item>
    <item cols="1">Item 5</item>
    <item cols="1">Item 6</item>
    <item cols="1">Item 7</item>
    <item cols="1">Item 8</item>
    <item cols="1">Item 9</item>
    <item cols="2">Item 10</item>
    <item cols="1">Item 11</item>
    <item cols="1">Item 12</item>
    <item cols="1">Item 13</item>
    <item cols="1">Item 14</item>
    <item cols="1">Item 15</item>
    <item cols="1">Item 16</item>
    <item cols="1">Item 17</item>
    <item cols="1">Item 18</item>
</items>

我需要能够在单列页面布局中打印具有“cols=1”的“项目”，以及在双列页面布局中打印具有“cols=2”的“项目”。必须保留项目的顺序。所有具有相同 @cols 值的连续“项目”都需要显示为连续流。每当 @cols 值发生变化时，我都需要跳转到一个新页面并根据需要更改布局。

我正在做这样的事情:

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
    xmlns:fo="http://www.w3.org/1999/XSL/Format">

    <xsl:strip-space elements="*"/>

    <xsl:template match="/">
        <fo:root xmlns:fo="http://www.w3.org/1999/XSL/Format">
            <fo:layout-master-set>

                <fo:simple-page-master master-name="one-column-page-master">
                    <fo:region-body margin-top="3cm" region-name="body" column-count="1"/>
                </fo:simple-page-master>

                <fo:simple-page-master master-name="two-column-page-master">
                    <fo:region-body margin-top="3cm" region-name="body" column-count="2"/>
                    <fo:region-before region-name="header" extent="2cm"/>
                </fo:simple-page-master>

                <fo:page-sequence-master master-name="one-column-page">
                    <fo:repeatable-page-master-reference master-reference="one-column-page-master"/>
                </fo:page-sequence-master>

                <fo:page-sequence-master master-name="two-column-page">
                    <fo:repeatable-page-master-reference master-reference="two-column-page-master"/>
                </fo:page-sequence-master>

            </fo:layout-master-set>

            <xsl:for-each select="//item">
                <xsl:choose>
                    <xsl:when test="@cols = preceding-sibling::item[1]/@cols">
                        <!--cols value hasn't changed, don't create a new page-sequence-->
                        <!--But we cannot directly add fo:flow as the child of fo:root! -->
                        <xsl:call-template name="itemtemplate"/>
                    </xsl:when>
                    <xsl:otherwise>
                        <xsl:choose>
                            <xsl:when test="@cols = 1">
                                <fo:page-sequence master-reference="one-column-page">
                                    <xsl:call-template name="itemtemplate"/>
                                </fo:page-sequence>
                            </xsl:when>
                            <xsl:otherwise>
                                <fo:page-sequence master-reference="two-column-page">
                                    <xsl:call-template name="itemtemplate"/>
                                </fo:page-sequence>
                            </xsl:otherwise>
                        </xsl:choose>
                    </xsl:otherwise>
                </xsl:choose>
            </xsl:for-each>
        </fo:root>

    </xsl:template>

    <xsl:template name="itemtemplate">
            <fo:flow flow-name="body">
                <fo:block margin-bottom="5cm">
                    <xsl:apply-templates/>
                </fo:block>
            </fo:flow>

    </xsl:template>

</xsl:stylesheet>

当然，问题是我要么必须在我的样式表中包含 ，要么不，我不能“动态地”决定根据注释属性放入一个。 (除非我有一个首先动态创建样式表的元程序，但我希望仅使用普通静态样式表来完成此操作)。

Answer 1

这是一个使用 xsl:for-each-group 的 XSLT 2.0 解决方案与 group-adjacent:

<xsl:stylesheet version="2.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
                xmlns:fo="http://www.w3.org/1999/XSL/Format">

    <xsl:strip-space elements="*"/>
    <xsl:output indent="yes"/>

    <xsl:template match="/">
      <fo:root xmlns:fo="http://www.w3.org/1999/XSL/Format">
        <fo:layout-master-set>

          <fo:simple-page-master master-name="one-column-page-master">
            <fo:region-body margin-top="3cm" region-name="body" 
                            column-count="1"/>
          </fo:simple-page-master>

          <fo:simple-page-master master-name="two-column-page-master">
            <fo:region-body margin-top="3cm" region-name="body" 
                            column-count="2"/>
            <fo:region-before region-name="header" extent="2cm"/>
          </fo:simple-page-master>

          <fo:page-sequence-master master-name="one-column-page">
            <fo:repeatable-page-master-reference 
                master-reference="one-column-page-master"/>
          </fo:page-sequence-master>

          <fo:page-sequence-master master-name="two-column-page">
            <fo:repeatable-page-master-reference 
                master-reference="two-column-page-master"/>
          </fo:page-sequence-master>

        </fo:layout-master-set>
        <xsl:apply-templates/>
      </fo:root>
    </xsl:template>

    <xsl:template match="items">
      <xsl:for-each-group select="item" 
                          group-adjacent="@cols">

        <xsl:choose>
          <xsl:when test="@cols = 1">
            <fo:page-sequence master-reference="one-column-page">
              <fo:flow flow-name="body">
                <xsl:for-each select="current-group()">
                  <xsl:apply-templates select="."/>
                </xsl:for-each>
              </fo:flow>
            </fo:page-sequence>
          </xsl:when>

          <xsl:otherwise>
            <fo:page-sequence master-reference="two-column-page">
              <fo:flow flow-name="body">
                <xsl:for-each select="current-group()">
                  <xsl:apply-templates select="."/>
                </xsl:for-each>
              </fo:flow>
            </fo:page-sequence>
          </xsl:otherwise>

        </xsl:choose>
      </xsl:for-each-group>
    </xsl:template>

    <xsl:template match="item">
      <fo:block margin-bottom="5cm">
        <xsl:apply-templates/>
      </fo:block>
    </xsl:template>

</xsl:stylesheet>

输出:

<?xml version="1.0" encoding="UTF-8"?>
<fo:root xmlns:fo="http://www.w3.org/1999/XSL/Format">
   <fo:layout-master-set>
      <fo:simple-page-master master-name="one-column-page-master">
         <fo:region-body margin-top="3cm" region-name="body" column-count="1"/>
      </fo:simple-page-master>
      <fo:simple-page-master master-name="two-column-page-master">
         <fo:region-body margin-top="3cm" region-name="body" column-count="2"/>
         <fo:region-before region-name="header" extent="2cm"/>
      </fo:simple-page-master>
      <fo:page-sequence-master master-name="one-column-page">
         <fo:repeatable-page-master-reference master-reference="one-column-page-master"/>
      </fo:page-sequence-master>
      <fo:page-sequence-master master-name="two-column-page">
         <fo:repeatable-page-master-reference master-reference="two-column-page-master"/>
      </fo:page-sequence-master>
   </fo:layout-master-set>
   <fo:page-sequence master-reference="one-column-page">
      <fo:flow flow-name="body">
         <fo:block margin-bottom="5cm">Item 1</fo:block>
         <fo:block margin-bottom="5cm">Item 2</fo:block>
         <fo:block margin-bottom="5cm">Item 3</fo:block>
         <fo:block margin-bottom="5cm">Item 4</fo:block>
         <fo:block margin-bottom="5cm">Item 5</fo:block>
         <fo:block margin-bottom="5cm">Item 6</fo:block>
         <fo:block margin-bottom="5cm">Item 7</fo:block>
         <fo:block margin-bottom="5cm">Item 8</fo:block>
         <fo:block margin-bottom="5cm">Item 9</fo:block>
      </fo:flow>
   </fo:page-sequence>
   <fo:page-sequence master-reference="two-column-page">
      <fo:flow flow-name="body">
         <fo:block margin-bottom="5cm">Item 10</fo:block>
      </fo:flow>
   </fo:page-sequence>
   <fo:page-sequence master-reference="one-column-page">
      <fo:flow flow-name="body">
         <fo:block margin-bottom="5cm">Item 11</fo:block>
         <fo:block margin-bottom="5cm">Item 12</fo:block>
         <fo:block margin-bottom="5cm">Item 13</fo:block>
         <fo:block margin-bottom="5cm">Item 14</fo:block>
         <fo:block margin-bottom="5cm">Item 15</fo:block>
         <fo:block margin-bottom="5cm">Item 16</fo:block>
         <fo:block margin-bottom="5cm">Item 17</fo:block>
         <fo:block margin-bottom="5cm">Item 18</fo:block>
      </fo:flow>
   </fo:page-sequence>
</fo:root>