python-peps/PyRSS2Gen.py

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"""PyRSS2Gen - A Python library for generating RSS 2.0 feeds."""
__name__ = "PyRSS2Gen"
__version__ = (1, 1, 0)
__author__ = "Andrew Dalke <dalke@dalkescientific.com>"
_generator_name = __name__ + "-" + ".".join(map(str, __version__))
import datetime
import sys
if sys.version_info[0] == 3:
# Python 3
basestring = str
from io import StringIO
else:
# Python 2
try:
from cStringIO import StringIO
except ImportError:
# Very old (or memory constrained) systems might
# have left out the compiled C version. Fall back
# to the pure Python one. Haven't seen this sort
# of system since the early 2000s.
from StringIO import StringIO
# Could make this the base class; will need to add 'publish'
class WriteXmlMixin:
def write_xml(self, outfile, encoding = "iso-8859-1"):
from xml.sax import saxutils
handler = saxutils.XMLGenerator(outfile, encoding)
handler.startDocument()
self.publish(handler)
handler.endDocument()
def to_xml(self, encoding = "iso-8859-1"):
f = StringIO()
self.write_xml(f, encoding)
return f.getvalue()
def _element(handler, name, obj, d = {}):
if isinstance(obj, basestring) or obj is None:
# special-case handling to make the API easier
# to use for the common case.
handler.startElement(name, d)
if obj is not None:
handler.characters(obj)
handler.endElement(name)
else:
# It better know how to emit the correct XML.
obj.publish(handler)
def _opt_element(handler, name, obj):
if obj is None:
return
_element(handler, name, obj)
def _format_date(dt):
"""convert a datetime into an RFC 822 formatted date
Input date must be in GMT.
"""
# Looks like:
# Sat, 07 Sep 2002 00:00:01 GMT
# Can't use strftime because that's locale dependent
#
# Isn't there a standard way to do this for Python? The
# rfc822 and email.Utils modules assume a timestamp. The
# following is based on the rfc822 module.
return "%s, %02d %s %04d %02d:%02d:%02d GMT" % (
["Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"][dt.weekday()],
dt.day,
["Jan", "Feb", "Mar", "Apr", "May", "Jun",
"Jul", "Aug", "Sep", "Oct", "Nov", "Dec"][dt.month-1],
dt.year, dt.hour, dt.minute, dt.second)
##
# A couple simple wrapper objects for the fields which
# take a simple value other than a string.
class IntElement:
"""implements the 'publish' API for integers
Takes the tag name and the integer value to publish.
(Could be used for anything which uses str() to be published
to text for XML.)
"""
element_attrs = {}
def __init__(self, name, val):
self.name = name
self.val = val
def publish(self, handler):
handler.startElement(self.name, self.element_attrs)
handler.characters(str(self.val))
handler.endElement(self.name)
class DateElement:
"""implements the 'publish' API for a datetime.datetime
Takes the tag name and the datetime to publish.
Converts the datetime to RFC 2822 timestamp (4-digit year).
"""
def __init__(self, name, dt):
self.name = name
self.dt = dt
def publish(self, handler):
_element(handler, self.name, _format_date(self.dt))
####
class Category:
"""Publish a category element"""
def __init__(self, category, domain = None):
self.category = category
self.domain = domain
def publish(self, handler):
d = {}
if self.domain is not None:
d["domain"] = self.domain
_element(handler, "category", self.category, d)
class Cloud:
"""Publish a cloud"""
def __init__(self, domain, port, path,
registerProcedure, protocol):
self.domain = domain
self.port = port
self.path = path
self.registerProcedure = registerProcedure
self.protocol = protocol
def publish(self, handler):
_element(handler, "cloud", None, {
"domain": self.domain,
"port": str(self.port),
"path": self.path,
"registerProcedure": self.registerProcedure,
"protocol": self.protocol})
class Image:
"""Publish a channel Image"""
element_attrs = {}
def __init__(self, url, title, link,
width = None, height = None, description = None):
self.url = url
self.title = title
self.link = link
self.width = width
self.height = height
self.description = description
def publish(self, handler):
handler.startElement("image", self.element_attrs)
_element(handler, "url", self.url)
_element(handler, "title", self.title)
_element(handler, "link", self.link)
width = self.width
if isinstance(width, int):
width = IntElement("width", width)
_opt_element(handler, "width", width)
height = self.height
if isinstance(height, int):
height = IntElement("height", height)
_opt_element(handler, "height", height)
_opt_element(handler, "description", self.description)
handler.endElement("image")
class Guid:
"""Publish a guid
Defaults to being a permalink, which is the assumption if it's
omitted. Hence strings are always permalinks.
"""
def __init__(self, guid, isPermaLink = 1):
self.guid = guid
self.isPermaLink = isPermaLink
def publish(self, handler):
d = {}
if self.isPermaLink:
d["isPermaLink"] = "true"
else:
d["isPermaLink"] = "false"
_element(handler, "guid", self.guid, d)
class TextInput:
"""Publish a textInput
Apparently this is rarely used.
"""
element_attrs = {}
def __init__(self, title, description, name, link):
self.title = title
self.description = description
self.name = name
self.link = link
def publish(self, handler):
handler.startElement("textInput", self.element_attrs)
_element(handler, "title", self.title)
_element(handler, "description", self.description)
_element(handler, "name", self.name)
_element(handler, "link", self.link)
handler.endElement("textInput")
class Enclosure:
"""Publish an enclosure"""
def __init__(self, url, length, type):
self.url = url
self.length = length
self.type = type
def publish(self, handler):
_element(handler, "enclosure", None,
{"url": self.url,
"length": str(self.length),
"type": self.type,
})
class Source:
"""Publish the item's original source, used by aggregators"""
def __init__(self, name, url):
self.name = name
self.url = url
def publish(self, handler):
_element(handler, "source", self.name, {"url": self.url})
class SkipHours:
"""Publish the skipHours
This takes a list of hours, as integers.
"""
element_attrs = {}
def __init__(self, hours):
self.hours = hours
def publish(self, handler):
if self.hours:
handler.startElement("skipHours", self.element_attrs)
for hour in self.hours:
_element(handler, "hour", str(hour))
handler.endElement("skipHours")
class SkipDays:
"""Publish the skipDays
This takes a list of days as strings.
"""
element_attrs = {}
def __init__(self, days):
self.days = days
def publish(self, handler):
if self.days:
handler.startElement("skipDays", self.element_attrs)
for day in self.days:
_element(handler, "day", day)
handler.endElement("skipDays")
class RSS2(WriteXmlMixin):
"""The main RSS class.
Stores the channel attributes, with the "category" elements under
".categories" and the RSS items under ".items".
"""
rss_attrs = {"version": "2.0"}
element_attrs = {}
def __init__(self,
title,
link,
description,
language = None,
copyright = None,
managingEditor = None,
webMaster = None,
pubDate = None, # a datetime, *in* *GMT*
lastBuildDate = None, # a datetime
categories = None, # list of strings or Category
generator = _generator_name,
docs = "http://blogs.law.harvard.edu/tech/rss",
cloud = None, # a Cloud
ttl = None, # integer number of minutes
image = None, # an Image
rating = None, # a string; I don't know how it's used
textInput = None, # a TextInput
skipHours = None, # a SkipHours with a list of integers
skipDays = None, # a SkipDays with a list of strings
items = None, # list of RSSItems
):
self.title = title
self.link = link
self.description = description
self.language = language
self.copyright = copyright
self.managingEditor = managingEditor
self.webMaster = webMaster
self.pubDate = pubDate
self.lastBuildDate = lastBuildDate
if categories is None:
categories = []
self.categories = categories
self.generator = generator
self.docs = docs
self.cloud = cloud
self.ttl = ttl
self.image = image
self.rating = rating
self.textInput = textInput
self.skipHours = skipHours
self.skipDays = skipDays
if items is None:
items = []
self.items = items
def publish(self, handler):
handler.startElement("rss", self.rss_attrs)
handler.startElement("channel", self.element_attrs)
_element(handler, "title", self.title)
_element(handler, "link", self.link)
_element(handler, "description", self.description)
self.publish_extensions(handler)
_opt_element(handler, "language", self.language)
_opt_element(handler, "copyright", self.copyright)
_opt_element(handler, "managingEditor", self.managingEditor)
_opt_element(handler, "webMaster", self.webMaster)
pubDate = self.pubDate
if isinstance(pubDate, datetime.datetime):
pubDate = DateElement("pubDate", pubDate)
_opt_element(handler, "pubDate", pubDate)
lastBuildDate = self.lastBuildDate
if isinstance(lastBuildDate, datetime.datetime):
lastBuildDate = DateElement("lastBuildDate", lastBuildDate)
_opt_element(handler, "lastBuildDate", lastBuildDate)
for category in self.categories:
if isinstance(category, basestring):
category = Category(category)
category.publish(handler)
_opt_element(handler, "generator", self.generator)
_opt_element(handler, "docs", self.docs)
if self.cloud is not None:
self.cloud.publish(handler)
ttl = self.ttl
if isinstance(self.ttl, int):
ttl = IntElement("ttl", ttl)
_opt_element(handler, "ttl", ttl)
if self.image is not None:
self.image.publish(handler)
_opt_element(handler, "rating", self.rating)
if self.textInput is not None:
self.textInput.publish(handler)
if self.skipHours is not None:
self.skipHours.publish(handler)
if self.skipDays is not None:
self.skipDays.publish(handler)
for item in self.items:
item.publish(handler)
handler.endElement("channel")
handler.endElement("rss")
def publish_extensions(self, handler):
# Derived classes can hook into this to insert
# output after the three required fields.
pass
class RSSItem(WriteXmlMixin):
"""Publish an RSS Item"""
element_attrs = {}
def __init__(self,
title = None, # string
link = None, # url as string
description = None, # string
author = None, # email address as string
categories = None, # list of string or Category
comments = None, # url as string
enclosure = None, # an Enclosure
guid = None, # a unique string
pubDate = None, # a datetime
source = None, # a Source
):
if title is None and description is None:
raise TypeError(
"must define at least one of 'title' or 'description'")
self.title = title
self.link = link
self.description = description
self.author = author
if categories is None:
categories = []
self.categories = categories
self.comments = comments
self.enclosure = enclosure
self.guid = guid
self.pubDate = pubDate
self.source = source
# It sure does get tedious typing these names three times...
def publish(self, handler):
handler.startElement("item", self.element_attrs)
_opt_element(handler, "title", self.title)
_opt_element(handler, "link", self.link)
self.publish_extensions(handler)
_opt_element(handler, "description", self.description)
_opt_element(handler, "author", self.author)
for category in self.categories:
if isinstance(category, basestring):
category = Category(category)
category.publish(handler)
_opt_element(handler, "comments", self.comments)
if self.enclosure is not None:
self.enclosure.publish(handler)
_opt_element(handler, "guid", self.guid)
pubDate = self.pubDate
if isinstance(pubDate, datetime.datetime):
pubDate = DateElement("pubDate", pubDate)
_opt_element(handler, "pubDate", pubDate)
if self.source is not None:
self.source.publish(handler)
handler.endElement("item")
def publish_extensions(self, handler):
# Derived classes can hook into this to insert
# output after the title and link elements
pass