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  • Committer: Package Import Robot
  • Author(s): Barry Warsaw
  • Date: 2015-02-19 14:13:25 UTC
  • Revision ID: package-import@ubuntu.com-20150219141325-w62bie95l6rawuuv
Tags: upstream-0.8.6
Import upstream version 0.8.6

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pex/iterator.py
 
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import itertools
 
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from .crawler import Crawler
 
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from .fetcher import PyPIFetcher
 
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from .package import EggPackage, Package, SourcePackage, WheelPackage
 
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class Iterator(object):
 
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  """A requirement iterator."""
 
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  DEFAULT_PACKAGE_PRECEDENCE = (
 
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      WheelPackage,
 
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      EggPackage,
 
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      SourcePackage,
 
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  )
 
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  @classmethod
 
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  def package_type_precedence(cls, package, precedence=DEFAULT_PACKAGE_PRECEDENCE):
 
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    for rank, package_type in enumerate(reversed(precedence)):
 
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      if isinstance(package, package_type):
 
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        return rank
 
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    # If we do not recognize the package, it gets lowest precedence
 
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    return -1
 
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  @classmethod
 
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  def package_precedence(cls, package, precedence=DEFAULT_PACKAGE_PRECEDENCE):
 
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    return (
 
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        package.version,  # highest version
 
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        cls.package_type_precedence(package, precedence=precedence),  # type preference
 
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        package.local)  # prefer not fetching over the wire
 
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  def __init__(self, fetchers=None, crawler=None, precedence=None):
 
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    self._crawler = crawler or Crawler()
 
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    self._fetchers = fetchers or [PyPIFetcher()]
 
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    self._precedence = precedence or self.DEFAULT_PACKAGE_PRECEDENCE
 
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  def _translate_href(self, href):
 
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    package = Package.from_href(href)
 
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    # Restrict this to a package found in the package precedence list, so that users of
 
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    # obtainers can restrict which distribution formats they support.
 
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    if any(isinstance(package, package_type) for package_type in self._precedence):
 
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      return package
 
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  def iter_requirement_urls(self, req):
 
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    return itertools.chain.from_iterable(fetcher.urls(req) for fetcher in self._fetchers)
 
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  def _iter_unordered(self, req, follow_links):
 
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    url_iterator = self.iter_requirement_urls(req)
 
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    crawled_url_iterator = self._crawler.crawl(url_iterator, follow_links=follow_links)
 
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    for package in filter(None, map(self._translate_href, crawled_url_iterator)):
 
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      if package.satisfies(req):
 
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        yield package
 
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  def _sort(self, package_list):
 
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    key = lambda package: self.package_precedence(package, self._precedence)
 
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    return sorted(package_list, key=key, reverse=True)
 
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  def iter(self, req, follow_links=False):
 
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    """Return a list of packages that satisfy the requirement in best match order."""
 
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    for package in self._sort(self._iter_unordered(req, follow_links)):
 
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      yield package