appypod-rattail/shared/xml_parser.py

444 lines
20 KiB
Python
Executable file

# ------------------------------------------------------------------------------
# Appy is a framework for building applications in the Python language.
# Copyright (C) 2007 Gaetan Delannay
# This program 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.
# This program 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 this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,USA.
# ------------------------------------------------------------------------------
import xml.sax
from xml.sax.handler import ContentHandler, ErrorHandler
from xml.sax.xmlreader import InputSource
from StringIO import StringIO
# ------------------------------------------------------------------------------
class XmlElement:
'''Represents an XML tag.'''
def __init__(self, elem, attrs=None, nsUri=None):
'''An XmlElement instance may represent:
- an already parsed tag (in this case, p_elem may be prefixed with a
namespace);
- the definition of an XML element (in this case, no namespace can be
found in p_elem; but a namespace URI may be defined in p_nsUri).'''
self.elem = elem
self.attrs = attrs
if elem.find(':') != -1:
self.ns, self.name = elem.split(':')
else:
self.ns = ''
self.name = elem
self.nsUri = nsUri
def equalsTo(self, other, namespaces=None):
'''Does p_elem == p_other? If a p_namespaces dict is given, p_other must
define a nsUri.'''
res = None
if namespaces:
res = self.elem == ('%s:%s' % (namespaces[other.nsUri], other.name))
else:
res = self.elem == other.elem
return res
def __repr__(self):
res = self.elem
if self.attrs:
res += '('
for attrName, attrValue in self.attrs.items():
res += '%s="%s"' % (attrName, attrValue)
res += ')'
return res
def getFullName(self, namespaces=None):
'''Gets the name of the element including the namespace prefix.'''
if not namespaces:
res = self.elem
else:
res = '%s:%s' % (namespaces[self.nsUri], self.name)
return res
class XmlEnvironment:
'''An XML environment remembers a series of elements during a SAX parsing.
This class is an abstract class that gathers basic things like
namespaces.'''
def __init__(self):
# This dict contains the xml namespace declarations encountered so far
self.namespaces = {} # ~{s_namespaceUri:s_namespaceName}~
self.currentElem = None # The currently parsed element
self.parser = None
def manageNamespaces(self, attrs):
'''Manages namespaces definitions encountered in p_attrs.'''
for attrName, attrValue in attrs.items():
if attrName.startswith('xmlns:'):
self.namespaces[attrValue] = attrName[6:]
def ns(self, nsUri):
'''Returns the namespace corresponding to o_nsUri.'''
return self.namespaces[nsUri]
class XmlParser(ContentHandler, ErrorHandler):
'''Basic XML content handler that does things like :
- remembering the currently parsed element;
- managing namespace declarations.'''
def __init__(self, env=None, caller=None):
'''p_env should be an instance of a class that inherits from
XmlEnvironment: it specifies the environment to use for this SAX
parser.'''
ContentHandler.__init__(self)
if not env: env = XmlEnvironment()
self.env = env
self.env.parser = self
self.caller = caller # The class calling this parser
self.parser = xml.sax.make_parser() # Fast, standard expat parser
self.res = None # The result of parsing.
def setDocumentLocator(self, locator):
self.locator = locator
return self.env
def endDocument(self):
return self.env
def startElement(self, elem, attrs):
self.env.manageNamespaces(attrs)
if self.env.currentElem == None:
self.env.currentElem = XmlElement(elem, attrs=attrs)
else:
# Reuse the exiting instance in order to avoid creating one instance
# every time an elem is met in the XML file.
self.env.currentElem.__init__(elem, attrs)
return self.env
def endElement(self, elem):
self.env.currentElem.__init__(elem)
return self.env
def characters(self, content):
return self.env
def parse(self, xmlContent, source='string'):
'''Parsers the XML file or string p_xmlContent.'''
try:
from cStringIO import StringIO
except ImportError:
from StringIO import StringIO
self.parser.setContentHandler(self)
self.parser.setErrorHandler(self)
inputSource = InputSource()
if source == 'string':
inputSource.setByteStream(StringIO(xmlContent))
else:
inputSource.setByteStream(xmlContent)
self.parser.parse(inputSource)
return self.res
# ------------------------------------------------------------------------------
from appy.shared import UnmarshalledObject, UnmarshalledFile
try:
from DateTime import DateTime
except ImportError:
DateTime = 'unicode'
class XmlUnmarshaller(XmlParser):
'''This class allows to parse a XML file and recreate the corresponding web
of Python objects. This parser assumes that the XML file respects this
convention: any tag may define in attribute "type" storing the type of
its content, which may be:
bool * int * float * long * DateTime * tuple * list * object
If "object" is specified, it means that the tag contains sub-tags, each
one corresponding to the value of an attribute for this object.
if "tuple" is specified, it will be converted to a list.'''
def __init__(self, klass=None, tagTypes={}):
XmlParser.__init__(self)
self.klass = klass # If a klass is given here, instead of creating
# a root UnmarshalledObject instance, we will create an instance of this
# class (only if the root object is an object; this does not apply if
# it is a list or tuple; yes, technically the root tag can be a list or
# tuple even if it is silly because only one root tag can exist). But be
# careful: we will not call the constructor of this class. We will
# simply create an instance of UnmarshalledObject and dynamically change
# the class of the created instance to this class.
self.tagTypes = tagTypes
# We expect that the parsed XML file will follow some conventions
# (ie, a tag that corresponds to a list has attribute type="list" or a
# tag that corresponds to an object has attribute type="object".). If
# it is not the case of p_xmlContent, you can provide the missing type
# information in p_tagTypes. Here is an example of p_tagTypes:
# {"information": "list", "days": "list", "person": "object"}.
def startDocument(self):
self.res = None # The resulting web of Python objects
# (UnmarshalledObject instances).
self.env.containerStack = [] # The stack of current "containers" where
# to store the next parsed element. A container can be a list, a tuple,
# an object (the root object of the whole web or a sub-object).
self.env.currentBasicType = None # Will hold the name of the currently
# parsed basic type (unicode, float...)
self.env.currentContent = '' # We store here the content of tags.
containerTags = ('tuple', 'list', 'object', 'file')
numericTypes = ('bool', 'int', 'float', 'long')
def startElement(self, elem, attrs):
e = XmlParser.startElement(self, elem, attrs)
# Determine the type of the element.
elemType = 'unicode' # Default value
if attrs.has_key('type'):
elemType = attrs['type']
elif self.tagTypes.has_key(elem):
elemType = self.tagTypes[elem]
if elemType in self.containerTags:
# I must create a new container object.
if elemType == 'object': newObject = UnmarshalledObject()
elif elemType == 'tuple': newObject = [] # Tuples become lists
elif elemType == 'list': newObject = []
elif elemType == 'file':
newObject = UnmarshalledFile()
if attrs.has_key('name'):
newObject.name = attrs['name']
if attrs.has_key('mimeType'):
newObject.mimeType = attrs['mimeType']
else: newObject = UnmarshalledObject()
# Store the value on the last container, or on the root object.
self.storeValue(elem, newObject)
# Push the new object on the container stack
e.containerStack.append(newObject)
else:
e.currentBasicType = elemType
def storeValue(self, name, value):
'''Stores the newly parsed p_value (contained in tag p_name) on the
current container in environment p_e.'''
e = self.env
# Where must I store this value?
if not e.containerStack:
# I store the object at the root of the web.
self.res = value
if self.klass and isinstance(value, UnmarshalledObject):
self.res.__class__ = self.klass
else:
currentContainer = e.containerStack[-1]
if isinstance(currentContainer, list):
currentContainer.append(value)
elif isinstance(currentContainer, UnmarshalledFile):
currentContainer.content += value
else:
# Current container is an object
if hasattr(currentContainer, name):
# We have already encountered a sub-object with this name.
# Having several sub-objects with the same name, we will
# create a list.
attrValue = getattr(currentContainer, name)
if not isinstance(attrValue, list):
attrValue = [attrValue, value]
else:
attrValue.append(value)
else:
attrValue = value
setattr(currentContainer, name, attrValue)
def characters(self, content):
e = XmlParser.characters(self, content)
if e.currentBasicType:
e.currentContent += content
def endElement(self, elem):
e = XmlParser.endElement(self, elem)
if e.currentBasicType:
# Get and convert the value of this field
if e.currentBasicType in self.numericTypes:
try:
exec 'value = %s' % e.currentContent.strip()
except SyntaxError:
value = None
elif e.currentBasicType == 'DateTime':
value = DateTime(e.currentContent.strip())
elif e.currentBasicType == 'base64':
value = e.currentContent.decode('base64')
else:
value = e.currentContent.strip()
# Store the value on the last container
self.storeValue(elem, value)
# Clean the environment
e.currentBasicType = None
e.currentContent = ''
else:
e.containerStack.pop()
# Alias: "unmarshall" -> "parse"
unmarshall = XmlParser.parse
class CssParser(XmlUnmarshaller):
cssTags = {'rss': 'object', 'channel': 'object', 'item': 'object'}
def startDocument(self):
XmlUnmarshaller.startDocument(self)
self.tagTypes.update(self.cssTags)
# ------------------------------------------------------------------------------
class XmlMarshaller:
'''This class allows to produce a XML version of a Python object, which
respects some conventions as described in the doc of the corresponding
Unmarshaller (see above).'''
xmlPrologue = '<?xml version="1.0" encoding="utf-8"?>'
xmlEntities = {'<': '&lt;', '>': '&gt;', '&': '&amp;', '"': '&quot;',
"'": '&apos;'}
trueFalse = {True: 'True', False: 'False'}
sequenceTypes = (tuple, list)
rootElementName = 'xmlPythonData'
fieldsToMarshall = 'all'
fieldsToExclude = []
atFiles = ('image', 'file') # Types of archetypes fields that contain files.
def dumpString(self, res, s):
'''Dumps a string into the result.'''
# Replace special chars by XML entities
for c in s:
if self.xmlEntities.has_key(c):
res.write(self.xmlEntities[c])
else:
res.write(c)
def dumpFile(self, res, v):
'''Dumps a file into the result.'''
# p_value contains the (possibly binary) content of a file. We will
# encode it in Base64, in one or several parts.
res.write('<part type="base64" number="1">')
if hasattr(v, 'data'):
# The file is an Archetypes file.
valueType = v.data.__class__.__name__
if valueType == 'Pdata':
# There will be several parts.
res.write(v.data.data.encode('base64'))
# Write subsequent parts
nextPart = v.data.next
nextPartNumber = 2
while nextPart:
res.write('</part>') # Close the previous part
res.write('<part type="base64" number="%d">'%nextPartNumber)
res.write(nextPart.data.encode('base64'))
nextPart = nextPart.next
nextPartNumber += 1
else:
res.write(v.data.encode('base64'))
else:
res.write(v.encode('base64'))
res.write('</part>')
def dumpValue(self, res, value, fieldType):
'''Dumps the XML version of p_value to p_res.'''
if fieldType == 'file':
self.dumpFile(res, value)
elif fieldType == 'ref':
if value:
if type(value) in self.sequenceTypes:
for elem in value:
self.dumpField(res, 'url', elem.absolute_url())
else:
self.dumpField(res, 'url', value.absolute_url())
elif type(value) in self.sequenceTypes:
# The previous condition must be checked before this one because
# Referred objects may be stored in lists or tuples, too.
for elem in value:
self.dumpField(res, 'e', elem)
elif isinstance(value, basestring):
self.dumpString(res, value)
elif isinstance(value, bool):
res.write(self.trueFalse[value])
else:
res.write(value)
def dumpField(self, res, fieldName, fieldValue, fieldType='basic'):
'''Dumps in p_res, the value of the p_field for p_instance.'''
res.write('<'); res.write(fieldName);
# Dump the type of the field as an XML attribute
fType = None # No type will mean "unicode".
if fieldType == 'file': fType ='file'
elif fieldType == 'ref': fType = 'list'
elif isinstance(fieldValue, bool): fType = 'bool'
elif isinstance(fieldValue, int): fType = 'int'
elif isinstance(fieldValue, float): fType = 'float'
elif isinstance(fieldValue, long): fType = 'long'
elif isinstance(fieldValue, tuple): fType = 'tuple'
elif isinstance(fieldValue, list): fType = 'list'
elif fieldValue.__class__.__name__ == 'DateTime': fType = 'DateTime'
if fType: res.write(' type="%s"' % fType)
# Dump other attributes if needed
if type(fieldValue) in self.sequenceTypes:
res.write(' count="%d"' % len(fieldValue))
if fieldType == 'file':
if hasattr(fieldValue, 'content_type'):
res.write(' mimeType="%s"' % fieldValue.content_type)
if hasattr(fieldValue, 'filename'):
res.write(' name="')
self.dumpString(res, fieldValue.filename)
res.write('"')
res.write('>')
# Dump the field value
self.dumpValue(res, fieldValue, fieldType)
res.write('</'); res.write(fieldName); res.write('>')
def marshall(self, instance, objectType='popo'):
'''Returns in a StringIO the XML version of p_instance. If p_instance
corresponds to a Plain Old Python Object, specify 'popo' for
p_objectType. If p_instance corresponds to an Archetypes object
(Zope/Plone), specify 'archetype' for p_objectType.'''
res = StringIO()
# Dump the XML prologue and root element
res.write(self.xmlPrologue)
res.write('<'); res.write(self.rootElementName)
res.write(' type="object">')
# Dump the value of the fields that must be dumped
if objectType == 'popo':
for fieldName, fieldValue in instance.__dict__.iteritems():
mustDump = False
if fieldName in self.fieldsToExclude:
mustDump = False
elif self.fieldsToMarshall == 'all':
mustDump = True
else:
if (type(self.fieldsToMarshall) in self.sequenceTypes) and \
(fieldName in self.fieldsToMarshall):
mustDump = True
if mustDump:
self.dumpField(res, fieldName, fieldValue)
elif objectType == 'archetype':
fields = instance.schema.fields()
for field in instance.schema.fields():
# Dump only needed fields
mustDump = False
if field.getName() in self.fieldsToExclude:
mustDump = False
elif (self.fieldsToMarshall == 'all') and \
(field.schemata != 'metadata'):
mustDump = True
elif self.fieldsToMarshall == 'all_with_metadata':
mustDump = True
else:
if (type(self.fieldsToMarshall) in self.sequenceTypes) and \
(field.getName() in self.fieldsToMarshall):
mustDump = True
if mustDump:
fieldType = 'basic'
if field.type in self.atFiles:
fieldType = 'file'
elif field.type == 'reference':
fieldType = 'ref'
self.dumpField(res, field.getName(), field.get(instance),
fieldType=fieldType)
self.marshallSpecificElements(instance, res)
# Return the result
res.write('</'); res.write(self.rootElementName); res.write('>')
data = res.getvalue()
res.close()
return data
def marshallSpecificElements(self, instance, res):
'''You can use this marshaller as a base class for creating your own.
In this case, this method will be called by the marshall method
for allowing your concrete marshaller to insert more things in the
result. p_res is the StringIO buffer where the result of the
marshalling process is currently dumped; p_instance is the instance
currently marshalled.'''
# ------------------------------------------------------------------------------