Make _LxmlFrameParser more extensible

[cancan101]

Allow creating a _LiberalLxmlFrameParser (see conversation on: #4469 (comment))

For now I will factor out:

parser = HTMLParser(recover=False)

so that subclass can change the behavior.

Would there be an issue with adding _LiberalLxmlFrameParser to the Pandas codebase?

[cpcloud]

no issues... would be happy to have your contrib... i think you could have a parameter that controls this like strict=True

[cpcloud]

marking for 0.14

[cpcloud]

@cancan101 FYI i'm going to assign myself to this issue to follow it so that it doens't get lost in the mix

[cpcloud]

not sure if that's visible to non repo collabs ... just letting you know

[cancan101]

@cpcloud That's fine. Yes it does show up that it was assigned to you.

[cancan101]

@cpcloud That reason to make another class (as opposed to just a parameter) is the valid parsers are specified as classes:

_valid_parsers = {'lxml': _LxmlFrameParser, None: _LxmlFrameParser,
                  'html5lib': _BeautifulSoupHtml5LibFrameParser,
                  'bs4': _BeautifulSoupHtml5LibFrameParser}

I suppose I could use a closure / partial (http://docs.python.org/2/library/functools.html#functools.partial) but that seems a bit messy.

[cpcloud]

class is fine ... i was thinking about the user facing API

[cancan101]

ah. Actually I could create a method with signature func(io, match, attrs):

def _LiberalLxmlFrameParser(io, match, attrs):
   return _LxmlFrameParser(io, match, attrs, strict=False)

and then:

_valid_parsers = {'lxml': _LxmlFrameParser, None: _LxmlFrameParser,
                  'html5lib': _BeautifulSoupHtml5LibFrameParser,
                  'bs4': _BeautifulSoupHtml5LibFrameParser,
                  'lxml-liberal': _LiberalLxmlFrameParser,}

[cpcloud]

i would prefer if you didn't mix my class naming convention with function names