XSLT 1.0: How to remove only one whitespace from a string? - xslt-1.0

Question

For example I have input string like 000 FF0 F4F CV1. Output for this string should be 000FF0F4F CV1. As you can see only one whitespace character was removed: if there was one whitespace - there is no whitespace at all; if there were two whitespaces - one is removed and one is left (if there were three whitespaces - one is removed and two are left and so on).
More examples:
000 FF0 F4F CV1 -> 000 FF0 F4FCV1
000 FF0 F4F CV1 -> 000FF0 F4FCV1
There is now specified format for input string, you don't know length and number of whitespaces. The only requirement is to remove one whitespace. So generic solution is required. Is there any idea how to implement that using XSLT 1.0?

Answer 1

If - as it seems - you want to remove one character from every group of consecutive whitespace characters (including a group of 1), you could do something like:
XML
<root>
<string>000 FF0 F4F CV1</string>
<string>000 FF0 F4F CV1</string>
<string>000 FF0 F4F CV1</string>
</root>
XSLT 1.0
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="xml" version="1.0" encoding="UTF-8" indent="yes"/>
<xsl:strip-space elements="*"/>
<!-- identity transform -->
<xsl:template match="#*|node()">
<xsl:copy>
<xsl:apply-templates select="#*|node()"/>
</xsl:copy>
</xsl:template>
<xsl:template match="string">
<xsl:copy>
<xsl:call-template name="process">
<xsl:with-param name="text" select="."/>
</xsl:call-template>
</xsl:copy>
</xsl:template>
<xsl:template name="process">
<xsl:param name="text"/>
<xsl:choose>
<xsl:when test="contains($text, ' ')">
<xsl:value-of select="substring-before($text, ' ')"/>
<xsl:variable name="tail" select="substring-after($text, ' ')"/>
<xsl:variable name="first-char" select="substring(normalize-space($tail), 1, 1)" />
<xsl:value-of select="substring-before($tail, $first-char)"/>
<!-- recursive call -->
<xsl:call-template name="process">
<xsl:with-param name="text" select="concat($first-char, substring-after($tail, $first-char))" />
</xsl:call-template>
</xsl:when>
<xsl:otherwise>
<xsl:value-of select="$text"/>
</xsl:otherwise>
</xsl:choose>
</xsl:template>
</xsl:stylesheet>
Result
<?xml version="1.0" encoding="UTF-8"?>
<root>
<string>000FF0F4F CV1</string>
<string>000 FF0 F4FCV1</string>
<string>000FF0 F4FCV1</string>
</root>
Note that this assumes the first character in any group of consecutive whitespace characters is a space. And that the string does not end with a whitespace character.