sequences in XSLT

my xml input is-

<?xml version="1.0" encoding="UTF-8"?> 
<foo>  <bar>bar</bar> 
       <bar>bar</bar> 
       <foobar>foobar</foobar> 
       <foobar>foobar</foobar> 
       <foobar>foobar</foobar>
       <bar>bar</bar>
       <bar>bar</bar> 
</foo>

Output using xslt should be

 <?xml version="1.0" encoding="UTF-8"?>

 <foo>  
 <s> 
 <s> 
 <bar>bar</bar>  
 <bar>bar</bar>
 </s>
 <s> 
 <foobar>foobar></foobar>
 <foobar>foobar></foobar>
 <foobar>foobar></foobar>
 </s> 
 <s>      
 <bar>bar</bar>  
 <bar>bar</bar> 
 </s>
 </s>
</foo>

the output should to have sequence-of elements inside a parent. Mixed sequence-of elements will be moved inside parents node “s”. Is there any xslt command that detects the sequence and process the xml accordingly.Many thanks.

Same as here, use the id of the first preceding sibling whose name is different in order to group the records:

<?xml version="1.0" encoding="utf-8"?>
<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:key name="adjacentByName" match="foo/*" use="generate-id(preceding-sibling::*[not(name()=name(current()))][1])" />

<xsl:template match="/">
<foo><s>
    <xsl:for-each select="foo/*[generate-id()=generate-id(key('adjacentByName', generate-id(preceding-sibling::*[not(name()=name(current()))][1]))[1])]">
        <s>
            <xsl:for-each select="key('adjacentByName', generate-id(preceding-sibling::*[not(name()=name(current()))][1]))">
                <xsl:copy-of select="."/>
            </xsl:for-each>
        </s>
    </xsl:for-each>
</s></foo>
</xsl:template>

</xsl:stylesheet>

Added:

But the output i am getting is not same as my desired output...

When applied to your (cleaned up) input of:

<?xml version="1.0" encoding="UTF-8"?> 
<foo>
    <bar>bar</bar> 
    <bar>bar</bar> 
    <foobar>foobar</foobar> 
    <foobar>foobar</foobar> 
    <foobar>foobar</foobar>
    <bar>bar</bar>
    <bar>bar</bar> 
</foo>

the result is:

<?xml version="1.0" encoding="utf-8"?>
<foo>
  <s>
    <s>
      <bar>bar</bar>
      <bar>bar</bar>
    </s>
    <s>
      <foobar>foobar</foobar>
      <foobar>foobar</foobar>
      <foobar>foobar</foobar>
    </s>
    <s>
      <bar>bar</bar>
      <bar>bar</bar>
    </s>
  </s>
</foo>

which to me seems to be exactly the result you have asked for:

<?xml version="1.0" encoding="UTF-8"?>

 <foo>  
 <s> 
 <s> 
 <bar>bar</bar>  
 <bar>bar</bar>
 </s>
 <s> 
 <foobar>foobar></foobar>
 <foobar>foobar></foobar>
 <foobar>foobar></foobar>
 </s> 
 <s>      
 <bar>bar</bar>  
 <bar>bar</bar> 
 </s>
 </s>
</foo>

except for the > characters inside the <foobar> elements, which I have removed from the input.