Indenting dynamic table of contents

Question

I have my xml in the following format:

<?xml>
  <chapter>
   <long-name>Chapter 1</long-name> <!-- 1-->
    <chapter>
  <long-name>Chapter A</long-name> <!-- 1.1 -->
   <chapter>
     <long-name>Chapter B</long-name> <!-- 1.1.1 -->
   </chapter>
</chapter>
<chapter>
     <long-name>Chapter C</long-name> <!-- 1.2-->
</chapter>
 </chapter>
   <chapter>
      <long-name>Chapter 2</long-name> <!-- 2 -->
       <chapter>
          <long-name>Chapter D</long-name> <!-- 2.1-->
       </chapter>
       <chapter>
          <long-name>Chapter E</long-name> <!-- 2.2-->
       </chapter>
  </chapter>
</xml>

1. Chapter 1
  1.1 chapter A
    1.1.1 Chapter B
  1.2 Chapter C

2.Chapter 2
  2.1 Chapter D
  2.2 Chapter E

I want to create a dynamic Table of contents and the chapters should be aligned. Below is my xslt which I am using for creating TOC and this works. But I do not know how to indent the chapters according to their level.

XSLT:

<xsl:template name="generateTOC">
    <fo:block break-after="page">       
            <xsl:apply-templates select="chapter"
                mode="TOC" />
        </fo:block>
    </fo:block>
</xsl:template>

<xsl:template match="chapter" mode="TOC">

    <fo:block text-align-last="justify" font-style="italic"
            font-size="8pt" >
        <fo:basic-link internal-destination="{generate-id(.)}" color="blue">
            <xsl:number format="1.1 " level="multiple"
                 />
            <xsl:value-of select="longname" />
            <fo:leader leader-pattern="dots" />
            <fo:page-number-citation
                ref-id="{generate-id(.)}" />
        </fo:basic-link>
    </fo:block>
    <xsl:apply-templates select="chapter" mode="TOC" />
</xsl:template>

Please help with indentation.

Answer 1

To simplify the situation, let us consider a stylesheet with text output:

XSLT 1.0

<xsl:stylesheet version="1.0" 
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="text" encoding="UTF-8"/>

<xsl:template match="/xml">
    <TOC>
        <xsl:apply-templates select="chapter" mode="TOC"/>
    </TOC>
</xsl:template>

<xsl:template match="chapter" mode="TOC">
    <xsl:call-template name="indent">
        <xsl:with-param name="amount" select="count(ancestor::chapter)"/>
    </xsl:call-template>
    <xsl:number format="1. " level="multiple"/>
    <xsl:value-of select="long-name" />
    <xsl:text>&#10;</xsl:text>
    <xsl:apply-templates select="chapter" mode="TOC" />
</xsl:template>

<xsl:template name="indent">
    <xsl:param name="amount"/>
    <xsl:param name="char" select="'&#9;'"/>
    <xsl:if test="$amount">
        <xsl:value-of select="$char"/>
        <!-- recursive call -->
        <xsl:call-template name="indent">
            <xsl:with-param name="amount" select="$amount - 1" />
        </xsl:call-template>
    </xsl:if>
</xsl:template>

</xsl:stylesheet>

Applied to a (corrected)input of:

<?xml version="1.0" encoding="UTF-8"?>
<xml>
   <chapter>
      <long-name>Chapter 1</long-name>
      <chapter>
         <long-name>Chapter A</long-name>
         <chapter>
            <long-name>Chapter B</long-name>
         </chapter>
      </chapter>
      <chapter>
         <long-name>Chapter C</long-name>
      </chapter>
   </chapter>
   <chapter>
      <long-name>Chapter 2</long-name>
      <chapter>
         <long-name>Chapter D</long-name>
      </chapter>
      <chapter>
         <long-name>Chapter E</long-name>
      </chapter>
   </chapter>
</xml>

produces the following result:

1. Chapter 1
    1.1. Chapter A
        1.1.1. Chapter B
    1.2. Chapter C
2. Chapter 2
    2.1. Chapter D
    2.2. Chapter E