xmlutils.py

一个工作流设计及定义的系统,可以直接与数据库结合进行系统工作流程的定义及应用.

#
# Copyright (c) 2005, John Mettraux, OpenWFE.org
# All rights reserved.
# 
# Redistribution and use in source and binary forms, with or without 
# modification, are permitted provided that the following conditions are met:
# 
# . Redistributions of source code must retain the above copyright notice, this
#   list of conditions and the following disclaimer.  
# 
# . Redistributions in binary form must reproduce the above copyright notice, 
#   this list of conditions and the following disclaimer in the documentation 
#   and/or other materials provided with the distribution.
# 
# . Neither the name of the "OpenWFE" nor the names of its contributors may be
#   used to endorse or promote products derived from this software without
#   specific prior written permission.
# 
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 
# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE 
# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 
# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 
# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 
# POSSIBILITY OF SUCH DAMAGE.
#
# $Id: xmlutils.py,v 1.9 2005/03/21 15:44:49 jmettraux Exp $
#

"""

    Some methods to help parsing/generating XML with minidom

    $Id: xmlutils.py,v 1.9 2005/03/21 15:44:49 jmettraux Exp $

"""

from os import environ
from urllib import urlopen
from xml.dom.minidom import parse



def getContent (elt, subEltName):
    """
        Extracts the text contained in a named subelement of the parameter
        element.

        For example, for the element

            <alpha>
                <bravo>x-ray</bravo>
                toto
                <charly>zoulou</charly>
            </alpha>
        
        the call

            getContent(element, 'charly')
        
        will yield 'zoulou'.
    """
    l = getChildrenByTagName(elt, subEltName)
    if len(l) < 1: return None
    subElt = l[0]
    return extractText(subElt)


def extractText (elt):
    """
        Returns the text contained in the element.

        For example, for the element
            <toto>nada</toto>
        the method will return 'nada'.

        warning : will certainly return an Unicode string
    """
    if (elt.firstChild == None):
        #print 'extractText didn''t find anything'
        return ''

    text = elt.firstChild.data.strip()

    #print 'text is >%s<' % text
    #print 'text type is %s' % type(text)

    return text


def firstChild (elt):
    """
        Returns the element that is the first child of the parameter element.
        If there are no children in the parameter element, None will be 
        returned.

        For example, for the element

            <alpha>
                <bravo/>
                <charly/>
            </alpha>

        the element

            <bravo/>
        
        will be returned.
    """
    for c in elt.childNodes:
        if not c.nodeName[0:1] == '#': return c
    return None
    

def children (elt):
    """
        Returns a list of the children of the parameter element that are
        elements themselves

        For example, for the element

            <alpha>
                toto
                <bravo>echo</bravo>
                <charly/>
                tutu
            </alpha>
        
        the list containing the elements

            <bravo>echo</bravo>
        and
            <charly/>

        will be returned.
    """
    l = []
    for c in elt.childNodes:
        if not c.nodeName[0:1] == '#': l.append(c)
    return l


def getChildrenByTagName (elt, childTagName):
    """
        Returns a list of the direct children of an element that have a given
        tag name.
    """
    l = []
    lchildren = children(elt)
    for c in lchildren:
        if c.nodeName == childTagName: l.append(c)
    return l


def parseUrl (url):
    """
        parse an XML doc located by its URL
    """
    if (url.find(':') < 0):
        f = open(url)
    else:
        f = urlopen(url)
    return parse(f)


#
# fetchParams()
#

NAME = 'name'
VALUE = 'value'
PARAM = 'param'
PARAM_NAME = 'param-name'
PARAM_VALUE = 'param-value'


def fetchParams (elt):

    result = dict()
    elts = getChildrenByTagName(elt, PARAM)
    for e in elts:
        #
        # variant 1 : 
        #
        # <param name="x" value="y" />
        #
        name = e.getAttribute(NAME)
        value = e.getAttribute(VALUE)

        if name != None and name != '' and value != '':
            result[str(name)] = str(value)
            continue
        
        #
        # variant 2 : 
        #
        #   <param>
        #     <param-name>x</param-name>
        #     <param-value>y</param-value>
        #   </param>
        #
        name = getContent(e, PARAM_NAME)
        value = getContent(e, PARAM_VALUE)

        if (name != None and value != None):
            result[str(name)] = str(value)

    #print result

    return result


def fetchAttributes (elt):
    result = dict()
    for k in elt._get_attributes().keys():
        result[str(k)] = str(elt._get_attributes()[k].value)
    return result


def fetchParamsAndAttributes (elt):
    paramMap = fetchParams(elt)
    paramMap.update(fetchAttributes(elt))
    return paramMap


#
# getEncoding()
#

def getEncoding ():
    """
        returns the encoding the system should use 
        as found in the environment variable 'OPENWFE_XML_ENCODING'
        by default, 'ISO-8859-1' is returned
    """
    encoding = environ.get('OPENWFE_XML_ENCODING')
    if encoding: return encoding
    return 'ISO-8859-1'

#
# toMinidomString()
#
#
#def toMinidomString (o):
#    """
#       turns anything into an unicode string
#    """
#    #if not isinstance(o, basestring): return unicode(o).encode("utf-8")
#    #print 'toMinidomString() type(o) >%s<' % type(o)
#    #return o.encode("utf-8")
#    return unicode(o).encode('utf-8')
#    #return unicode(o)