问题
<td></td><td>foo</td>
I would like to return ['', 'foo'] but libxml's xpath //td/text() returns just ['foo']. How do I find the empty tag as '' instead of (not matched)?
回答1:
As long as you are selecting text nodes specifically, you can't. Because there simply is no text node in the first <td>.
When you change your XPath expression to '//td', you get the two <td> nodes. Use their text value in further processing.
回答2:
While @Tomalak is perfectly right, in XPath 2.0 one can use:
//td/string(.)
and this produces a sequence of strings -- each one containing the string value of a corresponding td element.
So, in your case the result will be the desired one:
"", "foo"
来源：https://stackoverflow.com/questions/2420705/how-do-i-return-for-an-empty-nodes-text-in-xpath