PHP：如何直接将xpath转换为节点/属性

Question

I wonder if in PHP there is a direct way (without iterations) to convert xpath, say:

component_volume_concentration/component[1][@formula="CH4"]
component_volume_concentration/component[1][@unit="%"]
component_volume_concentration/component[1][@min="22"]
component_volume_concentration/component[1][@norm="25"]
component_volume_concentration/component[1][@max="30"]

to XML node and attribute structure:

<component_volume_concentration> 
<component formula="CH4" unit="%" min="22" norm="25" max="30" />
<component formula="C2H6" unit="%" min="22" norm="25" max="30" />
<component formula="C3H8" unit="%" min="22" norm="25" max="30" />
<component formula="i-C4H10" unit="%" min="22" norm="25" max="30" />
<component formula="i-C5H12" unit="%" min="22" norm="25" max="30" />
</component_volume_concentration> 

Thank you!

Answer 1

No, use XQuery or XSLT .

Xpath is a query language to select nodes. It is used in XSLT and is a subset of XQuery.

It is not possible to expand all Xpath expressions to valid nodes.

How would you expand something like .//component[@formula="CH4"][last()] or count(//node[@attr]) > 0 .

You can define an own Xpath like syntax and develop an interpreter for it. But this would be a lot of work and you need a really good knowledge of XML (namespaces, node types, whitespace handling, cdata sections).