Question

In XSLT, there is a remove() function for sequences. Given a sequence and a position, it returns the sequence minus the item at the given position.

The question is: How do I employ this function in an actual XSLT file?

The only place I’ve found mention of an example that isn’t just a regurgitation of the function spec completely devoid of context is here: http://books.google.com/books?id=W6SpffnfEPoC&pg=PA776&lpg=PA776&dq=xslt+%22remove+function%22&source=bl&ots=DQQrnXF_nB&sig=nrJtpEvYjBaZU0K8iAtdPTGUIbI&hl=en&sa=X&ei=QOq8T7aPDOyI6AHh-JBP&ved=0CEQQ6AEwAQ#v=onepage&q=xslt%20%22remove%20function%22&f=false

Unfortunately, the stylesheet examples are on pages 777 and 778, which are, of course, not included. And I don’t own that book.

So, does anyone have an example of using the remove() XSLT function in an actual stylesheet?

Edit: Let’s provide a slightly more concrete example, shall we?

I have a sequence in an XSLT. This sequence is comprised of all of the lines from a text file.

<xsl:variable name="lines" select="tokenize(unparsed-text($filePath), '\r?\n')" />

Every one of these lines is a record…except for one, which gives me the record count. So I have the following code for finding that line:

<xsl:variable name="recordCount">
  <xsl:for-each select="$lines[position()]">
    <xsl:variable name="i" select="position()" />
    <xsl:analyze-string select="$lines[$i]" regex="RECORD COUNT = \d+">
      <xsl:matching-substring>
        <xsl:value-of select="replace($lines[$i], '[^0-9]', '')" />
      </xsl:matching-substring>
    </xsl:analyze-string>
  </xsl:for-each>
</xsl:variable>

I do the above before I start looping through the lines to get all the actual records, so my goal here is to remove the “RECORD COUNT” line from the $lines sequence when I find it. That way when I’m looping through grabbing records I don’t have to do a check every time asking “Is this actually not a record, but in fact the RECORD COUNT line? You know, that thing I looked for and found already?”

Edit (2): Based on Martin Honnen’s answer(s), my final XSLT:

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="2.0">
  <!-- I want to produce an XML document. -->
  <xsl:output method="xml" indent="yes" />

  <!-- Path to input text file. -->
  <xsl:param name="filePath" select="TestFile.txt" />

  <!-- Regex in replace() removes leading and trailing blank space. -->
  <xsl:variable name="text" select="replace(unparsed-text($filePath), '(^[\r\n]*\s*[\r\n]+)|([\r\n]+\s*[\r\n]*$)', '')" />

  <!-- Regex in tokenize() sets the delimiter to be any blank space between record lines. -->
  <!-- This effectively removes any blank lines. -->
  <xsl:variable name="lines" select="tokenize($text, '[\r\n]+\s*[\r\n]*')" />

  <!-- This finds the "RECORD COUNT = ?" line. -->
  <xsl:variable name="recordCountIndex"
    select="for $pos in 1 to count($lines) return $pos[matches($lines[$pos], 'RECORD COUNT = \d+')]" />

  <!-- Regex in replace() strips everything that's not a number, leaving only the numeric count. -->
  <!-- Example: "RECORD COUNT = 25" -> "25" -->
  <xsl:variable name="recordCount" select="replace($lines[$recordCountIndex], '[^0-9]', '')" />

  <xsl:template name="main">
    <root>
      <recordCount>
        <!-- The record count value being inserted. -->
        <xsl:value-of select="$recordCount" />
      </recordCount>
      <records>
        <!-- Iterate over the $lines minus the line containing the record count. -->
        <xsl:for-each select="remove($lines, $recordCountIndex)">
          <!-- Items in each record, split by blank space. -->
          <!-- Example: "a b c" -> "[a, b, c]" -->
          <xsl:variable name="record" select="tokenize(., ' ')[position()]" />
          <record>
            <aThing>
              <xsl:value-of select="$record[1]" />
            </aThing>
            <aDifferentThing>
              <xsl:value-of select="$record[2]" />
            </aDifferentThing>
            <someStuff>
              <xsl:value-of select="$record[3]" />
            </someStuff>
          </record>
        </xsl:for-each>
      </records>
    </root>
  </xsl:template>
</xsl:stylesheet>

Answer 1

Well

<xsl:variable name="seq1" select="1, 2, 3, 4"/>
<xsl:variable name="seq2" select="remove($seq1, 2)"/>

makes the value of the variable seq2 a sequence of three number values 1, 3, 4.

[edit]

Here is an example based on your edited problem description:

<?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"
  exclude-result-prefixes="xs"
  version="2.0">

  <xsl:output method="text"/>

  <xsl:param name="filePath" select="'test2012052301.txt'"/>

  <xsl:variable name="lines" select="tokenize(unparsed-text($filePath), '\r?\n')" />

  <xsl:variable name="index" as="xs:integer"
    select="for $pos in 1 to count($lines) return $pos[matches($lines[$pos], 'RECORD COUNT = [0-9]+')]"/>

  <xsl:variable name="recordCount" as="xs:integer"
    select="xs:integer(replace($lines[$index], '[^0-9]', ''))"/>

  <xsl:template name="main">
    <xsl:value-of select="remove($lines, $index)" separator="&#10;"/>
    <xsl:text>count is: </xsl:text>
    <xsl:value-of select="$recordCount"/>
  </xsl:template>

</xsl:stylesheet>

With the text file being for instance

foo
bar
RECORD COUNT = 3
baz

the stylesheet outputs

foo
bar
baz
count is: 3

[edit2]
I think you can shorten the section

  <records>
    <!-- The $lines sequence trimmed down to only consist of valid records. -->
    <!-- (I have found no way around having this intermediate variable.) -->
    <xsl:variable name="records" select="remove($lines, $recordCountIndex)" />
    <xsl:for-each select="$records[position()]">
      <!-- Variable for iteration. Perhaps there's a more elegant way to do this. -->
      <xsl:variable name="i" select="position()" />
      <!-- Items in each record, split by blank space. -->
      <!-- Example: "a b c" -> "[a, b, c]" -->
      <xsl:variable name="recordItems" select="tokenize($records[$i], ' ')" />
      <record>
        <item1>
          <xsl:value-of select="$recordItems[1]" />
        </item1>
        <item2>
          <xsl:value-of select="$recordItems[2]" />
        </item2>
        <item3>
          <xsl:value-of select="$recordItems[3]" />
        </item3>
      </record>
    </xsl:for-each>
  </records>

of your stylesheet to

  <records>
    <xsl:for-each select="remove($lines, $recordCountIndex)">
      <record>
        <xsl:for-each select="tokenize(., ' ')[position() lt 4]">
          <xsl:element name="item{position()}">
            <xsl:value-of select="."/>
          </xsl:element>
        </xsl:for-each>
      </record>
    </xsl:for-each>
  </records>

Actually the predicate position() lt 4 is only needed if a line can contain more than three tokens.

And as a note, I have now seen a construct like for-each select="$records[position()] two times in your post, that predicate with [position()] is complete useless, you can simply use for-each select="$records".