263 lines
8.9 KiB
Python
263 lines
8.9 KiB
Python
# -*- coding: iso-8859-1 -*-
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# Copyright (C) 2004-2005 Tristan Seligmann and Jonathan Jacobs
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# Copyright (C) 2012-2013 Bastian Kleineidam
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import requests
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import time
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from . import loader
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from .util import fetchUrl, fetchUrls, getPageContent
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from .comic import ComicStrip
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from .output import out
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class _BasicScraper(object):
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'''Base class with scrape functions for comics.'''
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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 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 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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# a description of the comic contents
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description = ''
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# langauge of the comic (two-letter ISO 639-1 code)
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lang = 'en'
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# compiled regular 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 of compiled regular expressions
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prevSearch = None
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# compiled regular expression that will locate the strip image URLs strip in a page
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# this can also be a list or tuple of compiled regular expressions
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imageSearch = None
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# usually the index format help
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help = ''
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# wait time between downloading comic strips
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waitSeconds = 0
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# HTTP session storing cookies
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session = requests.session()
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def __init__(self, indexes=None):
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"""Initialize internal variables."""
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self.urls = set()
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if indexes:
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self.indexes = tuple(sorted(indexes))
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else:
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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, _BasicScraper):
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return 1
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# first, order by name
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d = cmp(self.getName(), other.getName())
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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.getName(), self.indexes))
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def shouldSkipUrl(self, url):
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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, baseUrl):
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"""Get comic strip downloader for given URL and data."""
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imageUrls = fetchUrls(url, data, baseUrl, self.imageSearch)
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imageUrls = set(map(self.imageUrlModifier, imageUrls))
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if len(imageUrls) > 1 and not self.multipleImagesPerStrip:
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out.warn("found %d images instead of 1 at %s with %s" % (len(imageUrls), url, self.imageSearch.pattern))
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elif not imageUrls:
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out.warn("found no images at %s with %s" % (url, self.imageSearch.pattern))
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return ComicStrip(self.getName(), url, imageUrls, self.namer, self.session)
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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 = "strip" if maxstrips == 1 else "strips"
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msg = 'Retrieving %d %s' % (maxstrips, word)
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else:
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msg = 'Retrieving all strips'
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if self.indexes:
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if len(self.indexes) == 1:
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msg += " for index %s" % self.indexes[0]
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else:
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msg += " for indexes %s" % self.indexes
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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 += " (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('Get strip URL %s' % url, level=1)
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data, baseUrl = getPageContent(url, self.session)
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if self.shouldSkipUrl(url):
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out.info('Skipping URL %s' % url)
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self.skippedUrls.add(url)
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else:
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yield self.getComicStrip(url, data, baseUrl)
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if self.firstStripUrl == url:
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out.debug("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, baseUrl)
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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("Already seen previous URL %r" % prevUrl)
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break
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url = prevUrl
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if url and self.waitSeconds:
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time.sleep(self.waitSeconds)
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def getPrevUrl(self, url, data, baseUrl):
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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 = fetchUrl(url, data, baseUrl, 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("%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("Matched previous URL %s" % 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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@classmethod
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def getName(cls):
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"""Get scraper name."""
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if hasattr(cls, 'name'):
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return cls.name
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return cls.__name__
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@classmethod
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def starter(cls):
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"""Get starter URL from where to scrape comic strips."""
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return cls.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):
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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.
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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 find_scraperclasses(comic, multiple_allowed=False):
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"""Get a list comic scraper classes. Can return more than one entries if
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multiple_allowed is True, else it raises a ValueError if multiple
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modules match. The match is a case insensitive substring search."""
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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 scraperclass in get_scraperclasses():
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lname = scraperclass.getName().lower()
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if lname == cname:
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# perfect match
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if not multiple_allowed:
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return [scraperclass]
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else:
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candidates.append(scraperclass)
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elif cname in lname:
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candidates.append(scraperclass)
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if len(candidates) > 1 and not multiple_allowed:
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comics = ", ".join(x.getName() for x in candidates)
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raise ValueError('multiple comics found: %s' % comics)
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elif not candidates:
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raise ValueError('comic %r not found' % comic)
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return candidates
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_scraperclasses = None
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def get_scraperclasses():
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"""Find all comic scraper classes in the plugins directory.
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The result is cached.
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@return: list of _BasicScraper classes
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@rtype: list of _BasicScraper
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"""
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global _scraperclasses
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if _scraperclasses is None:
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out.debug("Loading comic modules...")
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modules = loader.get_modules()
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plugins = loader.get_plugins(modules, _BasicScraper)
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_scraperclasses = list(plugins)
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check_scrapers()
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out.debug("... %d modules loaded." % len(_scraperclasses))
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return _scraperclasses
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def check_scrapers():
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"""Check for duplicate scraper class names."""
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d = {}
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for scraperclass in _scraperclasses:
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name = scraperclass.getName().lower()
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if name in d:
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name1 = scraperclass.getName()
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name2 = d[name].getName()
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raise ValueError('duplicate scrapers %s and %s found' % (name1, name2))
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d[name] = scraperclass
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def make_scraper(classname, **attributes):
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"""Make a new scraper class with given name and attributes."""
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return type(classname, (_BasicScraper,), attributes)
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