XSLT 3.0 部分流 (Saxon) [英] XSLT 3.0 partial streaming (Saxon)

问题描述

我有一个带有这种树的大 XML 文件 (6 GB):

I have a big XML file (6 GB) with this kind of tree:

<Report>
   <Document>
      <documentType>E</documentType>
      <person>
         <firstname>John</firstname>
         <lastname>Smith</lastname>
      </person>
   </Document>
   <Document>
      [...]
   </Document>
   <Document>
      [...]
   </Document>
   [... there are a lot of Documents]
</Report>

所以我使用了新的 XSLT 3.0 流功能和 Saxon 9.6 EE.我不想在 Document 中设置一次流约束.这就是我尝试使用 copy-of() 的原因.我认为，我想要做的非常接近此处描述的突发模式":http://saxonica.com/documentation/html/sourcedocs/streaming/burst-mode-streaming.html

So I used the new XSLT 3.0 streaming feature, with Saxon 9.6 EE. I don't want to have the streaming constrains once in a Document. This is why I tried to used copy-of(). I think that, what I want to do, is very close to the "burst mode" that is described here: http://saxonica.com/documentation/html/sourcedocs/streaming/burst-mode-streaming.html

这是我的 XSLT 样式表:

Here is my XSLT style sheet:

<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="3.0">
<xsl:mode streamable="yes" />

<xsl:template match="/">
    GLOBAL HEADER
        <xsl:for-each select="/Report/Document/copy-of()" >
           DOC HEADER
           documentType: <xsl:value-of select="documentType"/>
           person/firstname: <xsl:value-of select="person/firstname"/>

           <xsl:call-template name="fnc1"/>

           DOC FOOTER
        </xsl:for-each>
    GLOBAL FOOTER
</xsl:template>

<xsl:template name="fnc1">
    documentType again: <xsl:value-of select="documentType"/>
</xsl:template>

</xsl:stylesheet>

从某种意义上说，它是有效的，因为使用 copy-of() 我可以直接在 for-each (xsl:value-ofa href="https://stackoverflow.com/questions/26225551/xslt-3-0-streaming-saxon/26231701">就像这个问题).(否则我有这个错误 * 至少有两个消耗操作数:{xsl:value-of} 在第 8 行，{xsl:value-of} 在第 9 行)

In a sense it works because with the copy-of() I'm able to use several xsl:value-of directly in the for-each (like in this question). (Otherwise I have this error * There are at least two consuming operands: {xsl:value-of} on line 8, and {xsl:value-of} on line 9)

但我仍然有流限制，因为 <xsl:call-template name="fnc1"/> 产生了这个错误:

But I still have streaming constrains because <xsl:call-template name="fnc1"/> creates this error:

Error at xsl:template on line 4 column 25 of stylesheet.xsl:
  XTSE3430: Template rule is declared streamable but it does not satisfy the streamability rules.
  * xsl:call-template is not streamable in this Saxon release
Stylesheet compilation failed: 1 error reported

所以我的问题是:如何进行部分流式传输(文档被一个一个加载但完全加载)以便能够使用 call-template(和其他 apply-templates) 在文档中?

So my question is: how to do partial streaming (Documents are loaded one by one but fully) in order to be able to use call-template (and other apply-templates) in a Document?

感谢您的帮助！

推荐答案

我认为当上下文项被接地(即不是流式节点)时，调用模板应该是可流式传输的，因此我将其视为错误.同时，一种解决方法可能是将 fnc1 声明为

I think call-template should be streamable when the context item is grounded (ie. not a streamed node), so I'll treat this as a bug. Meanwhile a workaround might be to declare fnc1 as

<xsl:template name="fnc1" mode="fnc1" match="Document"/>

并将其称为

<xsl:apply-templates select="." mode="fnc1"/>

或者，用函数替换模板并提供上下文项作为显式参数.

Alternatively, replace the template with a function and supply the context item as an explicit argument.

您可以在此处跟踪错误:

You can track the bug here:

https://saxonica.plan.io/issues/2171

虽然我们还没有声称 100% 符合 XSLT 3.0 规范，但我们会将 9.6 版本中任何不必要的偏离视为错误，除非修复它们会破坏产品的稳定性.

Although we don't claim 100% conformance with the XSLT 3.0 specification yet, we'll treat any unnecessary departures in the 9.6 release as bugs unless fixing them would destabilize the product.

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