TestON/core/xmldict.py

'''
Created on 03-Dec-2012
Copyright 2012 Open Networking Foundation (ONF)

Please refer questions to either the onos test mailing list at <onos-test@onosproject.org>,
the System Testing Plans and Results wiki page at <https://wiki.onosproject.org/x/voMg>,
or the System Testing Guide page at <https://wiki.onosproject.org/x/WYQg>

@author: Anil Kumar (anilkumar.s@paxterrasolutions.com)

    TestON is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 2 of the License, or
    (at your option) any later version.

    TestON is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with TestON.  If not, see <http://www.gnu.org/licenses/>.

'''

"""
    xmldict
    ~~~~~~~~~~~~~~~~~~~~~~~~~

    Convert xml to python dictionaries.
"""
import datetime

def xml_to_dict( root_or_str, strict=True ):
    """
    Converts `root_or_str` which can be parsed xml or a xml string to dict.

    """
    root = root_or_str
    if isinstance( root, str ):
        import xml.etree.cElementTree as ElementTree
        root = ElementTree.XML( root_or_str )
    try:
        return { root.tag: _from_xml( root, strict ) }
    except StandardError:
        return None

def dict_to_xml( dict_xml ):
    """
    Converts `dict_xml` which is a python dict to corresponding xml.
    """
    return _to_xml( dict_xml )

def _to_xml( el ):
    """
    Converts `el` to its xml representation.
    """
    val = None
    if isinstance( el, dict ):
        val = _dict_to_xml( el )
    elif isinstance( el, bool ):
        val = str( el ).lower()
    else:
        val = el
    if val is None:
        val = 'null'
    return val

def _extract_attrs( els ):
    """
    Extracts attributes from dictionary `els`. Attributes are keys which start
    with '@'
    """
    if not isinstance( els, dict ):
        return ''
    return ''.join( ' %s="%s"' % ( key[ 1: ], value ) for key, value in els.iteritems() if key.startswith( '@' ) )

def _dict_to_xml( els ):
    """
    Converts `els` which is a python dict to corresponding xml.
    """
    def process_content( tag, content ):
        attrs = _extract_attrs( content )
        text = isinstance( content, dict ) and content.get( '#text', '' ) or ''
        return '<%s%s>%s%s</%s>' % ( tag, attrs, _to_xml( content ), text, tag )

    tags = []
    for tag, content in els.iteritems():
        # Text and attributes
        if tag.startswith( '@' ) or tag == '#text':
            continue
        elif isinstance( content, list ):
            for el in content:
                tags.append( process_content( tag, el ) )
        elif isinstance( content, dict ):
            tags.append( process_content( tag, content ) )
        else:
            tags.append( '<%s>%s</%s>' % ( tag, _to_xml( content ), tag ) )
    return ''.join( tags )

def _is_xml_el_dict( el ):
    """
    Returns true if `el` is supposed to be a dict.
    This function makes sense only in the context of making dicts out of xml.
    """
    if len( el ) == 1 or el[ 0 ].tag != el[ 1 ].tag:
        return True
    return False

def _is_xml_el_list( el ):
    """
    Returns true if `el` is supposed to be a list.
    This function makes sense only in the context of making lists out of xml.
    """
    if len( el ) > 1 and el[ 0 ].tag == el[ 1 ].tag:
        return True
    return False

def _str_to_datetime( date_str ):
    try:
        val = datetime.datetime.strptime( date_str, "%Y-%m-%dT%H:%M:%SZ" )
    except ValueError:
        val = date_str
    return val

def _str_to_boolean( bool_str ):
    if bool_str.lower() != 'false' and bool( bool_str ):
        return True
    return False

def _from_xml( el, strict ):
    """
    Extracts value of xml element element `el`.
    """
    val = None
    # Parent node.
    if el:
        if _is_xml_el_dict( el ):
            val = _dict_from_xml( el, strict )
        elif _is_xml_el_list( el ):
            val = _list_from_xml( el, strict )
    # Simple node.
    else:
        attribs = el.items()
        # An element with attributes.
        if attribs and strict:
            val = dict( ( '@%s' % k, v ) for k, v in dict( attribs ).iteritems() )
            if el.text:
                converted = _val_and_maybe_convert( el )
                val[ '#text' ] = el.text
                if converted != el.text:
                    val[ '#value' ] = converted
        elif el.text:
            # An element with no subelements but text.
            val = _val_and_maybe_convert( el )
        elif attribs:
            val = dict( attribs )
    return val

def _val_and_maybe_convert( el ):
    """
    Converts `el.text` if `el` has attribute `type` with valid value.
    """
    text = el.text.strip()
    data_type = el.get( 'type' )
    convertor = _val_and_maybe_convert.convertors.get( data_type )
    if convertor:
        return convertor( text )
    else:
        return text
_val_and_maybe_convert.convertors = {
    'boolean': _str_to_boolean,
    'datetime': _str_to_datetime,
    'integer': int
}

def _list_from_xml( els, strict ):
    """
    Converts xml elements list `el_list` to a python list.
    """

    temp = {}
    for el in els:
        tag = el.attrib[ "name" ]
        temp[ tag ] = ( _from_xml( el, strict ) )
    return temp

def _dict_from_xml( els, strict ):
    """
    Converts xml doc with root `root` to a python dict.
    """
    # An element with subelements.
    res = {}
    for el in els:
        res[ el.tag ] = _from_xml( el, strict )
    return res