Filter List using multiple sub/child elements in XSLT

<xsl:for-each select="//DocumentList/DocumentDetails[./DocumentSource=$DocumentSource or $DocumentSource= ''][./Category = $Category or $Category = '']">

I have Request something like below:

<DocumentList>
  <DocumentDetails>
    <DocumentID>Document1</DocumentID>
    <DocumentSource>DocumentSource1</DocumentSource>
    <Category>Category1</Categoty>
  </DocumentDetails>
<DocumentDetails>
    <DocumentID>Document2</DocumentID>
    <DocumentSource>DocumentSource2</DocumentSource>
    <Category>Category2</Categoty>
  </DocumentDetails>
  <DocumentDetails>
    <DocumentID>Document3</DocumentID>
    <DocumentSource>DocumentSource2</DocumentSource>
    <Category>Category2</Categoty>
  </DocumentDetails>
</DocumentList>


Expected Output:


The DocumentList has to be filtered out using DocumentSource and Category.

For Ex: DocumentSource=DocumentSource2 and Category=Category2
Result:

<DocumentList>
  <DocumentDetails>
    <DocumentID>Document2</DocumentID>
    <DocumentSource>DocumentSource2</DocumentSource>
    <Category>Category2</Categoty>
  </DocumentDetails>
  <DocumentDetails>
    <DocumentID>Document3</DocumentID>
    <DocumentSource>DocumentSource2</DocumentSource>
    <Category>Category2</Categoty>
  </DocumentDetails>
</DocumentList>

Solution:

<xsl:for-each select="/ns0:DocumentList/ns0:DocDetails[./ns0:DocumentSource=$DocumentSource or $DocumentSource=''][./ns0:Category=$Category or $Category=''][./ns0:SubCategory=$SubCategory or $SubCategory='']">

$DocumentSource and $Category are variable holding the data "DocumentSource2" and "Category2" respectively.