[xml] Strange results of xpath element search using string-value

[Алексей Алексей <aleksei spb 88 yandex ru>]

Hi,

 

Can't understand the results of the following xpath queries:

 

from lxml import etree

from io import StringIO

s = '<aaa><bbb>f<ccc>e</ccc>d</bbb></aaa>'

tree = etree.parse(StringIO(s))

print(tree.xpath('//bbb[.="fed"]')) #Returns nothing

print(tree.xpath('//bbb[contains(.,"fed")]')) #Returns bar

print(tree.xpath('//bbb[normalize-space(.)="fed"]')) #Returns bar

print(tree.xpath('//bbb[string-length(.)=3]')) #Returns bar

 

The first query doesn't find bar element by its string-value while the other three surprisingly do. Suppose that it is a bug.

 

I have already asked about the issue in the lxml mailing list and they suggested to ask here because the XPath implementation is in libxml2, not in lxml.

 

The versions used:

lxml.etree:        (4, 0, 0, 0)

libxml used:       (2, 9, 5)

libxml compiled:   (2, 9, 5)

libxslt used:      (1, 1, 30)

libxslt compiled:  (1, 1, 30)

 

Reproduction of the bug using xmllint instead of lxml:

$ echo '<aaa><bbb>f<ccc>e</ccc>d</bbb></aaa>' | \
        xmllint --xpath '//bbb[. = "fed"]' -
XPath set is empty

 

Thanks in advance for any help!

 

Aleksei