insert page-break after all elements except the last, when position() is not reliable

Question

How would I avoid the last page-break element in the result:

<pages>
    <page title="Manchuria"/>
    <page-break/>
    <page title="Zombie Librarian"/>
    <page-break/>
    <page title="Perfect the first time"/>
    <page-break/>
</pages>

Given the following source xml:

<articles>
    <article id="az401" title="The Long Goodbye" publishable="true" version="3">
        <original>
            <article id="aw301" version="1"/>
        </original>
        <edits>
            <article id="az401" version="3"/>
            <article id="pe814" version="2"/>
            <article id="we453" version="4"/>
        </edits>
    </article>
    <article id="yu475" title="Manchuria" publishable="true" version="4">
        <original>
            <article id="xc141" version="1"/>
        </original>
        <edits>
            <article id="er111" version="2"/>
            <article id="yu475" version="4"/>
            <article id="iu931" version="3"/>
        </edits>
    </article>
    <article id="nb741" title="Zombie Librarian" publishable="true" version="2">
        <original>
            <article id="nc441" version="1"/>
        </original>
        <edits>
            <article id="nb741" version="2"/>
        </edits>
    </article>
    <article id="ww555" title="Perfect the first time" publishable="true" version="1">
        <original>
            <article id="ww555" version="1"/>
        </original>
        <edits/>
    </article>
    <article id="kl922" title="Here we go again" publishable="true" version="1">
        <original>
            <article id="kl922" version="1"/>
        </original>
        <edits>
            <article id="uy541" version="2"/>
        </edits>
    </article>
</articles>

And the following xslt code:

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
    <xsl:output method="xml"/>

    <xsl:key name="article-by-id" match="article" use="@id"/>

    <xsl:template match="/">
        <pages>
            <xsl:apply-templates select="/articles/article[@publishable='true']" mode="subfilter"/>
        </pages>
    </xsl:template>
    
    <xsl:template match="article" mode="subfilter">
        <xsl:variable name="id_of_latest_edit">
            <xsl:for-each select="edits/article">
                <xsl:sort data-type="number" select="@version"/>
                <xsl:if test="position()=last()"><xsl:value-of select="@id"/></xsl:if>
            </xsl:for-each>
        </xsl:variable>
        <xsl:variable name="is_latest_edit" select="@id = key('article-by-id',$id_of_latest_edit)/@id"/>
        <xsl:variable name="has_no_edits" select="not(edits/article)"/>
        
        <xsl:if test="$is_latest_edit or $has_no_edits">
            <xsl:apply-templates select="self::article" mode="layout">
                <xsl:with-param name="is_last_page" select="position()=last()"/>
            </xsl:apply-templates>
        </xsl:if>
    </xsl:template>

    <xsl:template match="article" mode="layout">
        <xsl:param name="is_last_page"/>
        <page title="{@title}"/>
        <xsl:if test="not($is_last_page)">
            <page-break/>
        </xsl:if>
    </xsl:template>
</xsl:stylesheet>

notes

1. The problem is the use of an extra template for further filtering the original node-set whereby the position() is no longer reliable.
2. using <xsl:with-param name="is_first_page" select="position()=1"/> would also not work with the example xml.

Answer 1

If it's not possible to filter the articles directly by using a predicate, then you can use a variable to hold the filtered set. Then using the position() function on the result will work correctly:

XSLT 1.0 (+ EXSLT node-set() function)

<xsl:stylesheet version="1.0" 
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:exsl="http://exslt.org/common"
extension-element-prefixes="exsl">
<xsl:output method="xml" version="1.0" encoding="UTF-8" indent="yes"/>

<xsl:template match="/">
    <pages>
        <xsl:variable name="pages">
            <xsl:apply-templates select="/articles/article[@publishable='true']" mode="subfilter"/>
        </xsl:variable>
        <xsl:apply-templates select="exsl:node-set($pages)/article"/>
    </pages>
</xsl:template>
    
<xsl:template match="article" mode="subfilter">
    <xsl:variable name="id_of_latest_edit">
        <xsl:for-each select="edits/article">
            <xsl:sort data-type="number" select="@version"/>
            <xsl:if test="position()=last()">
                <xsl:value-of select="@id"/>
            </xsl:if>
        </xsl:for-each>
    </xsl:variable>
    <xsl:if test="@id = $id_of_latest_edit or not(edits/article)">
        <xsl:copy-of select="."/>
    </xsl:if>
</xsl:template>

<xsl:template match="article">
    <page title="{@title}"/>
    <xsl:if test="position()!=last()">
        <page-break/>
    </xsl:if>
</xsl:template>

</xsl:stylesheet>