如何使用XSLT 1.0按日期和ID分组

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
  <xsl:key name="group-by-date" match="item" use="date" />
  <xsl:key name="group-by-id" match="item" use="id" />

  <xsl:template match="/">
    <xsl:for-each select="root/item">
      <xsl:sort select="date" order="ascending" />
      <xsl:sort select="id" order="ascending" />
      <xsl:if test="generate-id() = generate-id(key('group-by-date', date)[1])">
        <xsl:value-of select="concat('Group by date: ', date)" />
        <xsl:for-each select="key('group-by-date', date)">
          <xsl:if test="generate-id() = generate-id(key('group-by-id', id)[1])">
            <xsl:value-of select="concat('Group by ID: ', id)" />
            <!-- 在此处添加其他处理逻辑 -->
          </xsl:if>
        </xsl:for-each>
      </xsl:if>
    </xsl:for-each>
  </xsl:template>
</xsl:stylesheet>