access temporary tree when transformation not finished - xslt-3.0

Question

I have a two phases XSLT transformation with xml as output. When I set a breakpoint in one of templates during my first phase and start my xslt transformation in debug mode with XML Spy Professional 2020, I can see an xml structure in XSL Output.xml as the processed result before my template with breakpoint is applied.
My question is, is there a way in one template in the same phase to access this structure, which is a temporary result of transformation, which is not yet completed?
For development I use XML Spy Professional 2020 and for transformation in application I use Saxon Professional Edition SaxonPE9-9-1-3J.
My problem is following:
Input is a plain text https://gist.github.com/jia2/35143e79213864153b57ad0323a440a8#file-input-txt
Based on this format rules https://gist.github.com/jia2/76d676b90935cb7f33f5028180557af3,
the expected XML output like this:
https://gist.github.com/jia2/daaa4b2de5d1dadcb834f9f91c65d45b
Here my template:
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:fn="http://www.w3.org/2005/xpath-functions" xmlns:csb="http://www.dbcargo.org/csb" exclude-result-prefixes="#all" version="3.0">
<!-- <xsl:param name="msg" as="xs:string">H0 EVU_DBSRD PVG Z24 ABF-RF IR ExternalPartnerID_uuuuuuuuuuuuuuuuu0202017-03-16-07.27.40.864320NJNJ M1 80281261300008 M2 16.03.201707:27:00Z1 H62430 16.03.2017 16.03.201707:00:00+0027R1 00131800820664780201703154023641201703151159043706346965 000 JJ R1 02031800819657480201703154045545201703151159306557346965 000 NN </xsl:param> -->
<xsl:param name="msg" as="xs:string">H0 EVU_DBSRD PVG Z24 ABF-RF IR ExternalPartnerID_uuuuuuuuuuuuuuuuu0202017-03-16-07.27.40.864320NJNJJJ M1 80281261300008 M2 16.03.201707:27:00Z1 H62430 16.03.2017 16.03.201707:00:00+0027R1 00131800820664780201703154023641201703151159043706346965 000 JJ R1 02031800819657480201703154045545201703151159306557346965 000 NN </xsl:param>
<xsl:param name="relatviePath2MFL" as="xs:string" select="'./format.xml'"/>
<xsl:variable name="MFL" select="document($relatviePath2MFL)"/>
<xsl:output method="xml" indent="yes"/>
<xsl:mode name="unroll" on-no-match="shallow-copy"/>
<xsl:strip-space elements="*"/>
<xsl:template match="StructFormat[#repeat]" mode="unroll">
<xsl:variable name="this" select="."/>
<xsl:choose>
<xsl:when test="$this/#repeat != '*' ">
<xsl:for-each select="1 to #repeat">
<xsl:choose>
<xsl:when test="$this/#delimOptional = 'n' and $this/TagField and contains($msg, $this/TagField)">
<xsl:copy select="$this">
<xsl:apply-templates select="#* except #repeat, node()" mode="#current"/>
</xsl:copy>
</xsl:when>
<xsl:otherwise/>
</xsl:choose>
</xsl:for-each>
</xsl:when>
<xsl:otherwise>
<xsl:variable name="repeat" select="count(tokenize($msg, $this/TagField/#value)) - 1"/>
<xsl:for-each select="1 to $repeat">
<xsl:copy select="$this">
<xsl:apply-templates select="#* except #repeat, node()" mode="#current"/>
</xsl:copy>
</xsl:for-each>
</xsl:otherwise>
</xsl:choose>
</xsl:template>
<xsl:template match="StructFormat[not(#repeat)]" mode="unroll">
<xsl:variable name="this" select="."/>
<xsl:choose>
<xsl:when test="$this/TagField and not(contains($msg, $this/TagField/#value)) ">
</xsl:when>
<xsl:otherwise>
<xsl:copy select="$this">
<xsl:apply-templates select="#* except #repeat, node()" mode="#current"/>
</xsl:copy>
</xsl:otherwise>
</xsl:choose>
</xsl:template>
<xsl:template match="FieldFormat[#repeat]" mode="unroll">
<xsl:variable name="this" select="."/>
<xsl:for-each select="1 to #repeat">
<xsl:copy select="$this">
<xsl:apply-templates select="#* except #repeat, node()" mode="#current"/>
</xsl:copy>
</xsl:for-each>
</xsl:template>
<xsl:variable name="complete-struct">
<xsl:apply-templates select="$MFL/*" mode="unroll"/>
</xsl:variable>
<xsl:template match="/">
<xsl:element name="{$MFL/MessageFormat/#name}">
<xsl:apply-templates select="$complete-struct/*"/>
</xsl:element>
</xsl:template>
<xsl:template match="StructFormat">
<xsl:element name="{#name}">
<xsl:apply-templates/>
</xsl:element>
</xsl:template>
<xsl:template match="FieldFormat">
<xsl:variable name="precedingFieldFormatsLength" select="sum(preceding::FieldFormat/#length)"/>
<xsl:variable name="offset">
<xsl:value-of select="string-length(string-join(./preceding::TagField/#value, ''))"/>
</xsl:variable>
<xsl:element name="{#name}">
<xsl:variable name="value" select="substring($msg, 1 + $precedingFieldFormatsLength + $offset, #length)"/>
<xsl:value-of select="csb:formatField(.,$value)"/>
</xsl:element>
</xsl:template>
<!-- format output -->
<xsl:function name="csb:formatField" as="xs:string">
<xsl:param name="field" as="element()"/>
<xsl:param name="value" as="xs:string"/>
<xsl:choose>
<xsl:when test="$field/#length = '1' and $value = ' '">
<xsl:value-of select="''"/>
</xsl:when>
<!-- remove leading and trailing space -->
<xsl:when test="$field/#trimLeading = ' ' and $field/#trimTrailing = ' '">
<xsl:value-of select="fn:replace($value, '^\s+|\s+$', '')"/>
</xsl:when>
<!-- remove ONLY leading space -->
<xsl:when test="$field/#trimLeading = ' ' and fn:not(fn:exists($field//#trimTrailing))">
<xsl:value-of select="fn:replace($value, '^\s+', '')"/>
</xsl:when>
<!-- remove ONLY trailing space -->
<xsl:when test="$field/#trimTrailing = ' ' and fn:not(fn:exists($field//#trimLeading))">
<xsl:value-of select="fn:replace($value, '\s+$', '')"/>
</xsl:when>
<!-- remove leading 0 -->
<xsl:when test="$field/#type = 'Numeric' and $field/#trimLeading = '0' and fn:not(fn:exists($field//#trimTrailing))">
<!-- <xsl:value-of select="fn:replace($value, '^0+', '')"/> -->
<xsl:if test="number($value) != number($value)">
<xsl:message terminate="yes" ><xsl:value-of select="concat('Transformation failed. The field', $field, ' has invalid value')" /></xsl:message>
</xsl:if>
<xsl:value-of select="number($value)"/>
</xsl:when>
<xsl:otherwise>
<xsl:value-of select="$value"/>
</xsl:otherwise>
</xsl:choose>
</xsl:function>
</xsl:stylesheet>
My xslt template https://gist.github.com/jia2/5f7387e549e6f83601dbfac23ceb3acf is reading this format.xml as input and the plain text is passed by as parameter. It works for some inputs. but it will fail, when the value, which is used for marking begin of "StructFormat", exist in other positions.
For example:
<StructFormat name='HandoverTakeover' delimOptional='n' optional='y'>
<TagField type='String' value='U1 '/>
This means, StructFormat should be generated, when the input has "U1 " at a position. Now I'm just checking if input text contains "U1 " (<xsl:when test="$this/TagField and not(contains($msg, $this/TagField/#value)) ">), but this is not enough, I need to check, if the "U1 " comes in the "right" position range, not in the whole input.
I though if I can access currently build result tree, I can count the length until now to to cut the text before this position where I am checking.
Thanks
Dingjun

Answer 1

XSLT is a functional language; it therefore disallows operations whose result would depend on the order of execution. The fact that particular processors organise the processing in a particular way (even when two different processors choose the same strategy) doesn't mean it is something that can be relied on; in a few years time, for example, parallel execution strategies may be much more common.
More specifically, the fact that the two phases of your transformation are executing "concurrently" (one starts before the other finishes) is an internal optimization that you cannot exploit or rely on, and this is by design.
No doubt the transformation you are trying to effect can be achieved in some completely different way within the paradigm of a declarative functional language. I haven't studied the particular problem; like many people answering questions on StackOverflow, I'm not prepared to follow links to code that's off-site.