060281e5ff
This is a first step for #42. Since most access to the scraper classes is through instances, modules can now dynamically override url and name (name is now a property).
586 lines
20 KiB
Python
586 lines
20 KiB
Python
# -*- coding: utf-8 -*-
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# Copyright (C) 2004-2005 Tristan Seligmann and Jonathan Jacobs
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# Copyright (C) 2012-2014 Bastian Kleineidam
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# Copyright (C) 2014-2016 Tobias Gruetzmacher
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import time
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import random
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import os
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import re
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try:
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from urllib.parse import urljoin
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except ImportError:
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from urlparse import urljoin
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try:
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from lxml import html
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from lxml.html.defs import link_attrs as html_link_attrs
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except ImportError:
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html = None
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try:
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import cssselect
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except ImportError:
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cssselect = None
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try:
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import pycountry
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except ImportError:
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pycountry = None
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from . import loader, configuration, languages
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from .util import (get_page, makeSequence, get_system_uid, urlopen, getDirname,
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unescape, tagre, normaliseURL, prettyMatcherList,
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requests_session)
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from .comic import ComicStrip
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from .output import out
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from .events import getHandler
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class Scraper(object):
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'''Base class for all comic scraper, but without a specific scrape
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implementation.'''
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# The URL for the comic strip
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url = None
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# A string that is interpolated with the strip index to yield the URL for a
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# particular strip.
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stripUrl = None
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# Stop search for previous URLs at this URL
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firstStripUrl = None
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# if more than one image per URL is expected
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multipleImagesPerStrip = False
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# set to False if previous URLs do not match the strip URL (ie. because of
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# redirects)
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prevUrlMatchesStripUrl = True
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# set to True if this comic contains adult content
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adult = False
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# set to True if this comic will not get updated anymore
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endOfLife = False
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# langauge of the comic (two-letter ISO 639-1 code)
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lang = 'en'
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# an expression that will locate the URL for the previous strip in a page
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# this can also be a list or tuple
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prevSearch = None
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# an expression that will locate the strip image URLs strip in a page
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# this can also be a list or tuple
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imageSearch = None
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# an expression to store a text together with the image
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# sometimes comic strips have additional text info for each comic
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textSearch = None
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# Is the additional text required or optional? When it is required (the
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# default), you see an error message whenever a comic page is encountered
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# that does not have the text
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textOptional = False
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# usually the index format help
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help = ''
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# HTTP session for configuration & cookies
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session = requests_session()
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@property
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def indexes(self):
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return self._indexes
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@indexes.setter
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def indexes(self, val):
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if val:
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self._indexes = tuple(sorted(val))
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def __init__(self):
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"""Initialize internal variables."""
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self.urls = set()
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self._indexes = tuple()
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self.skippedUrls = set()
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self.hitFirstStripUrl = False
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def __cmp__(self, other):
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"""Compare scraper by name and index list."""
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if not isinstance(other, Scraper):
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return 1
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# first, order by name
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d = cmp(self.name, other.name)
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if d != 0:
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return d
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# then by indexes
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return cmp(self.indexes, other.indexes)
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def __hash__(self):
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"""Get hash value from name and index list."""
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return hash((self.name, self.indexes))
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def shouldSkipUrl(self, url, data):
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"""Determine if search for images in given URL should be skipped."""
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return False
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def getComicStrip(self, url, data):
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"""Get comic strip downloader for given URL and data."""
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imageUrls = self.fetchUrls(url, data, self.imageSearch)
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# map modifier function on image URLs
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imageUrls = [self.imageUrlModifier(x, data) for x in imageUrls]
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# remove duplicate URLs
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imageUrls = set(imageUrls)
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if len(imageUrls) > 1 and not self.multipleImagesPerStrip:
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out.warn(
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u"Found %d images instead of 1 at %s with expressions %s" %
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(len(imageUrls), url, prettyMatcherList(self.imageSearch)))
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image = sorted(imageUrls)[0]
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out.warn(u"Choosing image %s" % image)
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imageUrls = (image,)
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elif not imageUrls:
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out.warn(u"Found no images at %s with expressions %s" % (url,
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prettyMatcherList(self.imageSearch)))
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if self.textSearch:
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text = self.fetchText(url, data, self.textSearch,
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optional=self.textOptional)
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else:
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text = None
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return ComicStrip(self.name, url, imageUrls, self.namer,
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self.session, text=text)
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def getStrips(self, maxstrips=None):
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"""Get comic strips."""
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if maxstrips:
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word = u"strip" if maxstrips == 1 else "strips"
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msg = u'Retrieving %d %s' % (maxstrips, word)
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else:
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msg = u'Retrieving all strips'
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if self.indexes:
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if len(self.indexes) == 1:
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msg += u" for index %s" % self.indexes[0]
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else:
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msg += u" for indexes %s" % self.indexes
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# Always call starter() since it might initialize cookies.
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# See for example Oglaf comic.
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self.starter()
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urls = [self.getIndexStripUrl(index) for index in self.indexes]
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else:
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urls = [self.getLatestUrl()]
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if self.adult:
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msg += u" (including adult content)"
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out.info(msg)
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for url in urls:
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for strip in self.getStripsFor(url, maxstrips):
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yield strip
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def getStripsFor(self, url, maxstrips):
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"""Get comic strips for an URL. If maxstrips is a positive number, stop after
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retrieving the given number of strips."""
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self.hitFirstStripUrl = False
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seen_urls = set()
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while url:
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out.info(u'Get strip URL %s' % url, level=1)
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data = self.getPage(url)
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if self.shouldSkipUrl(url, data):
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out.info(u'Skipping URL %s' % url)
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self.skippedUrls.add(url)
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else:
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try:
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yield self.getComicStrip(url, data)
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except ValueError as msg:
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# image not found
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out.exception(msg)
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if self.firstStripUrl == url:
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out.debug(u"Stop at first URL %s" % url)
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self.hitFirstStripUrl = True
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break
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if maxstrips is not None:
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maxstrips -= 1
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if maxstrips <= 0:
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break
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prevUrl = self.getPrevUrl(url, data)
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seen_urls.add(url)
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if prevUrl in seen_urls:
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# avoid recursive URL loops
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out.warn(u"Already seen previous URL %r" % prevUrl)
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break
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url = prevUrl
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if url:
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# wait up to 2 seconds for next URL
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time.sleep(1.0 + random.random())
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def getPrevUrl(self, url, data):
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"""Find previous URL."""
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prevUrl = None
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if self.prevSearch:
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try:
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prevUrl = self.fetchUrl(url, data, self.prevSearch)
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except ValueError as msg:
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# assume there is no previous URL, but print a warning
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out.warn(u"%s Assuming no previous comic strips exist." % msg)
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else:
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prevUrl = self.prevUrlModifier(prevUrl)
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out.debug(u"Found previous URL %s" % prevUrl)
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getHandler().comicPageLink(self.name, url, prevUrl)
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return prevUrl
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def getIndexStripUrl(self, index):
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"""Get comic strip URL from index."""
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return self.stripUrl % index
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@property
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def name(self):
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"""Get scraper name."""
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return self.__class__.__name__
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def starter(self):
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"""Get starter URL from where to scrape comic strips."""
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return self.url
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@classmethod
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def namer(cls, imageUrl, pageUrl):
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"""Return filename for given image and page URL."""
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return None
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@classmethod
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def prevUrlModifier(cls, prevUrl):
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"""Optional modification of parsed previous URLs. Useful if
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there are domain redirects. The default implementation does
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not modify the URL.
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"""
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return prevUrl
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@classmethod
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def imageUrlModifier(cls, imageUrl, data):
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"""Optional modification of parsed image URLs. Useful if the URL
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needs to be fixed before usage. The default implementation does
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not modify the URL. The given data is the URL page data.
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"""
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return imageUrl
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def getLatestUrl(self):
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"""Get starter URL from where to scrape comic strips."""
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return self.starter()
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def vote(self):
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"""Cast a public vote for this comic."""
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url = configuration.VoteUrl + 'count/'
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uid = get_system_uid()
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data = {"name": self.name.replace('/', '_'), "uid": uid}
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page = urlopen(url, self.session, data=data)
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return page.text
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def getCompleteFile(self, basepath):
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"""Get filename indicating all comics are downloaded."""
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dirname = getDirname(self.name)
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return os.path.join(basepath, dirname, "complete.txt")
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def isComplete(self, basepath):
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"""Check if all comics are downloaded."""
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return os.path.isfile(self.getCompleteFile(basepath))
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def setComplete(self, basepath):
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"""Set complete flag for this comic, ie. all comics are downloaded."""
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if self.endOfLife:
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filename = self.getCompleteFile(basepath)
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if not os.path.exists(filename):
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with open(filename, 'w') as f:
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f.write('All comics should be downloaded here.')
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@classmethod
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def getPage(cls, url):
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"""
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Fetch a page and return the opaque repesentation for the data parameter
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of fetchUrls and fetchText.
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Implementation notes: While this base class does not restrict how the
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returned data is structured, subclasses (specific scrapers) should
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specify how this data works, since the stracture is passed into
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different methods which can be defined by comic modules and these
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methods should be able to use the data if they so desire... (Affected
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methods: shouldSkipUrl, imageUrlModifier)
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"""
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raise ValueError("No implementation for getPage!")
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@classmethod
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def fetchUrls(cls, url, data, urlSearch):
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raise ValueError("No implementation for fetchUrls!")
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@classmethod
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def fetchUrl(cls, url, data, urlSearch):
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return cls.fetchUrls(url, data, urlSearch)[0]
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@classmethod
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def fetchText(cls, url, data, textSearch, optional):
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raise ValueError("No implementation for fetchText!")
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@classmethod
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def getDisabledReasons(cls):
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"""
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Get a dict of reasons why this comic module is disabled. The key is a
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short (unique) identifier, the value is a string explaining why the
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module is deactivated. If the module is not disabled, just return an
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empty dict.
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"""
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return {}
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@classmethod
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def language(cls):
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"""
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Return language of the comic as a human-readable language name instead
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of a 2-character ISO639-1 code.
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"""
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lang = 'Unknown (%s)' % cls.lang
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if pycountry is None:
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if cls.lang in languages.Languages:
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lang = languages.Languages[cls.lang]
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else:
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try:
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lang = pycountry.languages.get(alpha2=cls.lang).name
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except KeyError:
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try:
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lang = pycountry.languages.get(iso639_1_code=cls.lang).name
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except KeyError:
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pass
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return lang
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class _BasicScraper(Scraper):
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"""
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Scraper base class that matches regular expressions against HTML pages.
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Subclasses of this scraper should use compiled regular expressions as
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values for prevSearch, imageSearch and textSearch.
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Implementation note: The return value of getPage is a tuple: the first
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element is the raw HTML page text, the second element is the base URL (if
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any).
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"""
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BASE_SEARCH = re.compile(tagre("base", "href", '([^"]*)'))
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@classmethod
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def getPage(cls, url):
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content = get_page(url, cls.session).text
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# determine base URL
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baseUrl = None
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match = cls.BASE_SEARCH.search(content)
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if match:
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baseUrl = match.group(1)
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else:
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baseUrl = url
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return (content, baseUrl)
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@classmethod
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def fetchUrls(cls, url, data, urlSearch):
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"""Search all entries for given URL pattern(s) in a HTML page."""
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searchUrls = []
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searches = makeSequence(urlSearch)
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for search in searches:
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for match in search.finditer(data[0]):
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searchUrl = match.group(1)
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if not searchUrl:
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raise ValueError("Pattern %s matched empty URL at %s." %
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(search.pattern, url))
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out.debug(u'matched URL %r with pattern %s' %
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(searchUrl, search.pattern))
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searchUrls.append(normaliseURL(urljoin(data[1], searchUrl)))
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if searchUrls:
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# do not search other links if one pattern matched
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break
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if not searchUrls:
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patterns = [x.pattern for x in searches]
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raise ValueError("Patterns %s not found at URL %s." %
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(patterns, url))
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return searchUrls
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@classmethod
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def fetchText(cls, url, data, textSearch, optional):
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"""Search text entry for given text pattern in a HTML page."""
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if textSearch:
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match = textSearch.search(data[0])
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if match:
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text = match.group(1)
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out.debug(u'matched text %r with pattern %s' %
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(text, textSearch.pattern))
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return unescape(text).strip()
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if optional:
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return None
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else:
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raise ValueError("Pattern %s not found at URL %s." %
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(textSearch.pattern, url))
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else:
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return None
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class _ParserScraper(Scraper):
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"""
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Scraper base class that uses a HTML parser and XPath expressions.
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All links are resolved before XPath searches are applied, so all URLs are
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absolute!
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Subclasses of this class should use XPath expressions as values for
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prevSearch, imageSearch and textSearch. When the XPath directly selects an
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attribute, it is used as the output.
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All those searches try to do something intelligent when they match a
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complete HTML Element: prevSearch and imageSearch try to find a "link
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attribute" and use that as URL. textSearch strips all tags from the content
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of the HTML element and returns that.
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"""
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# Taken directly from LXML
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XML_DECL = re.compile(
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r'^(<\?xml[^>]+)\s+encoding\s*=\s*["\'][^"\']*["\'](\s*\?>|)', re.U)
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# Switch between CSS and XPath selectors for this class. Since CSS needs
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# another Python module, XPath is the default for now.
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css = False
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@classmethod
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def getPage(cls, url):
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page = get_page(url, cls.session)
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if page.encoding:
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# Requests figured out the encoding, so we can deliver Unicode to
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# LXML. Unfortunatly, LXML feels betrayed if there is still an XML
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# declaration with (probably wrong!) encoding at the top of the
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# document. Web browsers ignore such if the encoding was specified
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# in the HTTP header and so do we.
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text = cls.XML_DECL.sub('\1\2', page.text, count=1)
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tree = html.document_fromstring(text)
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else:
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tree = html.document_fromstring(page.content)
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tree.make_links_absolute(url)
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return tree
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@classmethod
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def fetchUrls(cls, url, data, urlSearch):
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"""Search all entries for given XPath in a HTML page."""
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searchUrls = []
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if cls.css:
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searchFun = data.cssselect
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else:
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searchFun = data.xpath
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searches = makeSequence(urlSearch)
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for search in searches:
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for match in searchFun(search):
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try:
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for attrib in html_link_attrs:
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if attrib in match.attrib:
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searchUrls.append(match.get(attrib))
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except AttributeError:
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searchUrls.append(str(match))
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if not cls.multipleImagesPerStrip and searchUrls:
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# do not search other links if one pattern matched
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break
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if not searchUrls:
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raise ValueError("XPath %s not found at URL %s." % (searches, url))
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return searchUrls
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@classmethod
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def fetchText(cls, url, data, textSearch, optional):
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"""Search text entry for given text XPath in a HTML page."""
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if cls.css:
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searchFun = data.cssselect
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else:
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searchFun = data.xpath
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if textSearch:
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text = ''
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for match in searchFun(textSearch):
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try:
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text += u' ' + match.text_content()
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except AttributeError:
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text += u' ' + match
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if text.strip() == '':
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if optional:
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return None
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else:
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raise ValueError(
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"XPath %s did not match anything at URL %s." %
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(textSearch, url))
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out.debug(u'Matched text %r with XPath %s' % (text, textSearch))
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return unescape(text).strip()
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else:
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return None
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@classmethod
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def getDisabledReasons(cls):
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res = {}
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if cls.css and cssselect is None:
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res['css'] = (u"This module needs the cssselect " +
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u"(python-cssselect) python module which is " +
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u"not installed.")
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if html is None:
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res['lxml'] = (u"This module needs the lxml (python-lxml) " +
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u"python module which is not installed.")
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return res
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def find_scrapers(comic, multiple_allowed=False):
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"""Get a list comic scraper objects.
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Can return more than one entry if multiple_allowed is True, else it raises
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a ValueError if multiple modules match. The match is a case insensitive
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substring search.
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"""
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if not comic:
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raise ValueError("empty comic name")
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candidates = []
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cname = comic.lower()
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for scrapers in get_scrapers():
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lname = scrapers.name.lower()
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if lname == cname:
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|
# perfect match
|
|
if not multiple_allowed:
|
|
return [scrapers]
|
|
else:
|
|
candidates.append(scrapers)
|
|
elif cname in lname:
|
|
candidates.append(scrapers)
|
|
if len(candidates) > 1 and not multiple_allowed:
|
|
comics = ", ".join(x.name for x in candidates)
|
|
raise ValueError('multiple comics found: %s' % comics)
|
|
elif not candidates:
|
|
raise ValueError('comic %r not found' % comic)
|
|
return candidates
|
|
|
|
|
|
_scrapers = None
|
|
|
|
|
|
def get_scrapers():
|
|
"""Find all comic scraper classes in the plugins directory.
|
|
The result is cached.
|
|
@return: list of Scraper classes
|
|
@rtype: list of Scraper
|
|
"""
|
|
global _scrapers
|
|
if _scrapers is None:
|
|
out.debug(u"Loading comic modules...")
|
|
modules = loader.get_modules('plugins')
|
|
plugins = loader.get_plugins(modules, Scraper)
|
|
_scrapers = sorted([x() for x in plugins], key=lambda p: p.name)
|
|
check_scrapers()
|
|
out.debug(u"... %d modules loaded." % len(_scrapers))
|
|
return _scrapers
|
|
|
|
|
|
def check_scrapers():
|
|
"""Check for duplicate scraper names."""
|
|
d = {}
|
|
for scraper in _scrapers:
|
|
name = scraper.name.lower()
|
|
if name in d:
|
|
name1 = scraper.name
|
|
name2 = d[name].name
|
|
raise ValueError('duplicate scrapers %s and %s found' %
|
|
(name1, name2))
|
|
d[name] = scraper
|
|
|
|
|
|
def make_scraper(classname, scraperType=_BasicScraper, **attributes):
|
|
"""Make a new scraper class with given name and attributes."""
|
|
return type(classname, (scraperType,), attributes)
|