Changed CSS color and set Tooltips and default value on dockWidget

1 files changed, 990 insertions, 0 deletions

diff --git a/venv/Lib/site-packages/pip-19.0.3-py3.7.egg/pip/_internal/index.py b/venv/Lib/site-packages/pip-19.0.3-py3.7.egg/pip/_internal/index.py
new file mode 100644
index 0000000..9eda3a3
--- /dev/null
+++ b/venv/Lib/site-packages/pip-19.0.3-py3.7.egg/pip/_internal/index.py
@@ -0,0 +1,990 @@
+"""Routines related to PyPI, indexes"""
+from __future__ import absolute_import
+
+import cgi
+import itertools
+import logging
+import mimetypes
+import os
+import posixpath
+import re
+import sys
+from collections import namedtuple
+
+from pip._vendor import html5lib, requests, six
+from pip._vendor.distlib.compat import unescape
+from pip._vendor.packaging import specifiers
+from pip._vendor.packaging.utils import canonicalize_name
+from pip._vendor.packaging.version import parse as parse_version
+from pip._vendor.requests.exceptions import RetryError, SSLError
+from pip._vendor.six.moves.urllib import parse as urllib_parse
+from pip._vendor.six.moves.urllib import request as urllib_request
+
+from pip._internal.download import HAS_TLS, is_url, path_to_url, url_to_path
+from pip._internal.exceptions import (
+    BestVersionAlreadyInstalled, DistributionNotFound, InvalidWheelFilename,
+    UnsupportedWheel,
+)
+from pip._internal.models.candidate import InstallationCandidate
+from pip._internal.models.format_control import FormatControl
+from pip._internal.models.index import PyPI
+from pip._internal.models.link import Link
+from pip._internal.pep425tags import get_supported
+from pip._internal.utils.compat import ipaddress
+from pip._internal.utils.logging import indent_log
+from pip._internal.utils.misc import (
+    ARCHIVE_EXTENSIONS, SUPPORTED_EXTENSIONS, WHEEL_EXTENSION, normalize_path,
+    redact_password_from_url,
+)
+from pip._internal.utils.packaging import check_requires_python
+from pip._internal.utils.typing import MYPY_CHECK_RUNNING
+from pip._internal.wheel import Wheel
+
+if MYPY_CHECK_RUNNING:
+    from logging import Logger  # noqa: F401
+    from typing import (  # noqa: F401
+        Tuple, Optional, Any, List, Union, Callable, Set, Sequence,
+        Iterable, MutableMapping
+    )
+    from pip._vendor.packaging.version import _BaseVersion  # noqa: F401
+    from pip._vendor.requests import Response  # noqa: F401
+    from pip._internal.req import InstallRequirement  # noqa: F401
+    from pip._internal.download import PipSession  # noqa: F401
+
+    SecureOrigin = Tuple[str, str, Optional[str]]
+    BuildTag = Tuple[Any, ...]  # either emply tuple or Tuple[int, str]
+    CandidateSortingKey = Tuple[int, _BaseVersion, BuildTag, Optional[int]]
+
+__all__ = ['FormatControl', 'PackageFinder']
+
+
+SECURE_ORIGINS = [
+    # protocol, hostname, port
+    # Taken from Chrome's list of secure origins (See: http://bit.ly/1qrySKC)
+    ("https", "*", "*"),
+    ("*", "localhost", "*"),
+    ("*", "127.0.0.0/8", "*"),
+    ("*", "::1/128", "*"),
+    ("file", "*", None),
+    # ssh is always secure.
+    ("ssh", "*", "*"),
+]  # type: List[SecureOrigin]
+
+
+logger = logging.getLogger(__name__)
+
+
+def _match_vcs_scheme(url):
+    # type: (str) -> Optional[str]
+    """Look for VCS schemes in the URL.
+
+    Returns the matched VCS scheme, or None if there's no match.
+    """
+    from pip._internal.vcs import VcsSupport
+    for scheme in VcsSupport.schemes:
+        if url.lower().startswith(scheme) and url[len(scheme)] in '+:':
+            return scheme
+    return None
+
+
+def _is_url_like_archive(url):
+    # type: (str) -> bool
+    """Return whether the URL looks like an archive.
+    """
+    filename = Link(url).filename
+    for bad_ext in ARCHIVE_EXTENSIONS:
+        if filename.endswith(bad_ext):
+            return True
+    return False
+
+
+class _NotHTML(Exception):
+    def __init__(self, content_type, request_desc):
+        # type: (str, str) -> None
+        super(_NotHTML, self).__init__(content_type, request_desc)
+        self.content_type = content_type
+        self.request_desc = request_desc
+
+
+def _ensure_html_header(response):
+    # type: (Response) -> None
+    """Check the Content-Type header to ensure the response contains HTML.
+
+    Raises `_NotHTML` if the content type is not text/html.
+    """
+    content_type = response.headers.get("Content-Type", "")
+    if not content_type.lower().startswith("text/html"):
+        raise _NotHTML(content_type, response.request.method)
+
+
+class _NotHTTP(Exception):
+    pass
+
+
+def _ensure_html_response(url, session):
+    # type: (str, PipSession) -> None
+    """Send a HEAD request to the URL, and ensure the response contains HTML.
+
+    Raises `_NotHTTP` if the URL is not available for a HEAD request, or
+    `_NotHTML` if the content type is not text/html.
+    """
+    scheme, netloc, path, query, fragment = urllib_parse.urlsplit(url)
+    if scheme not in {'http', 'https'}:
+        raise _NotHTTP()
+
+    resp = session.head(url, allow_redirects=True)
+    resp.raise_for_status()
+
+    _ensure_html_header(resp)
+
+
+def _get_html_response(url, session):
+    # type: (str, PipSession) -> Response
+    """Access an HTML page with GET, and return the response.
+
+    This consists of three parts:
+
+    1. If the URL looks suspiciously like an archive, send a HEAD first to
+       check the Content-Type is HTML, to avoid downloading a large file.
+       Raise `_NotHTTP` if the content type cannot be determined, or
+       `_NotHTML` if it is not HTML.
+    2. Actually perform the request. Raise HTTP exceptions on network failures.
+    3. Check the Content-Type header to make sure we got HTML, and raise
+       `_NotHTML` otherwise.
+    """
+    if _is_url_like_archive(url):
+        _ensure_html_response(url, session=session)
+
+    logger.debug('Getting page %s', url)
+
+    resp = session.get(
+        url,
+        headers={
+            "Accept": "text/html",
+            # We don't want to blindly returned cached data for
+            # /simple/, because authors generally expecting that
+            # twine upload && pip install will function, but if
+            # they've done a pip install in the last ~10 minutes
+            # it won't. Thus by setting this to zero we will not
+            # blindly use any cached data, however the benefit of
+            # using max-age=0 instead of no-cache, is that we will
+            # still support conditional requests, so we will still
+            # minimize traffic sent in cases where the page hasn't
+            # changed at all, we will just always incur the round
+            # trip for the conditional GET now instead of only
+            # once per 10 minutes.
+            # For more information, please see pypa/pip#5670.
+            "Cache-Control": "max-age=0",
+        },
+    )
+    resp.raise_for_status()
+
+    # The check for archives above only works if the url ends with
+    # something that looks like an archive. However that is not a
+    # requirement of an url. Unless we issue a HEAD request on every
+    # url we cannot know ahead of time for sure if something is HTML
+    # or not. However we can check after we've downloaded it.
+    _ensure_html_header(resp)
+
+    return resp
+
+
+def _handle_get_page_fail(
+    link,  # type: Link
+    reason,  # type: Union[str, Exception]
+    meth=None  # type: Optional[Callable[..., None]]
+):
+    # type: (...) -> None
+    if meth is None:
+        meth = logger.debug
+    meth("Could not fetch URL %s: %s - skipping", link, reason)
+
+
+def _get_html_page(link, session=None):
+    # type: (Link, Optional[PipSession]) -> Optional[HTMLPage]
+    if session is None:
+        raise TypeError(
+            "_get_html_page() missing 1 required keyword argument: 'session'"
+        )
+
+    url = link.url.split('#', 1)[0]
+
+    # Check for VCS schemes that do not support lookup as web pages.
+    vcs_scheme = _match_vcs_scheme(url)
+    if vcs_scheme:
+        logger.debug('Cannot look at %s URL %s', vcs_scheme, link)
+        return None
+
+    # Tack index.html onto file:// URLs that point to directories
+    scheme, _, path, _, _, _ = urllib_parse.urlparse(url)
+    if (scheme == 'file' and os.path.isdir(urllib_request.url2pathname(path))):
+        # add trailing slash if not present so urljoin doesn't trim
+        # final segment
+        if not url.endswith('/'):
+            url += '/'
+        url = urllib_parse.urljoin(url, 'index.html')
+        logger.debug(' file: URL is directory, getting %s', url)
+
+    try:
+        resp = _get_html_response(url, session=session)
+    except _NotHTTP as exc:
+        logger.debug(
+            'Skipping page %s because it looks like an archive, and cannot '
+            'be checked by HEAD.', link,
+        )
+    except _NotHTML as exc:
+        logger.debug(
+            'Skipping page %s because the %s request got Content-Type: %s',
+            link, exc.request_desc, exc.content_type,
+        )
+    except requests.HTTPError as exc:
+        _handle_get_page_fail(link, exc)
+    except RetryError as exc:
+        _handle_get_page_fail(link, exc)
+    except SSLError as exc:
+        reason = "There was a problem confirming the ssl certificate: "
+        reason += str(exc)
+        _handle_get_page_fail(link, reason, meth=logger.info)
+    except requests.ConnectionError as exc:
+        _handle_get_page_fail(link, "connection error: %s" % exc)
+    except requests.Timeout:
+        _handle_get_page_fail(link, "timed out")
+    else:
+        return HTMLPage(resp.content, resp.url, resp.headers)
+    return None
+
+
+class PackageFinder(object):
+    """This finds packages.
+
+    This is meant to match easy_install's technique for looking for
+    packages, by reading pages and looking for appropriate links.
+    """
+
+    def __init__(
+        self,
+        find_links,  # type: List[str]
+        index_urls,  # type: List[str]
+        allow_all_prereleases=False,  # type: bool
+        trusted_hosts=None,  # type: Optional[Iterable[str]]
+        session=None,  # type: Optional[PipSession]
+        format_control=None,  # type: Optional[FormatControl]
+        platform=None,  # type: Optional[str]
+        versions=None,  # type: Optional[List[str]]
+        abi=None,  # type: Optional[str]
+        implementation=None,  # type: Optional[str]
+        prefer_binary=False  # type: bool
+    ):
+        # type: (...) -> None
+        """Create a PackageFinder.
+
+        :param format_control: A FormatControl object or None. Used to control
+            the selection of source packages / binary packages when consulting
+            the index and links.
+        :param platform: A string or None. If None, searches for packages
+            that are supported by the current system. Otherwise, will find
+            packages that can be built on the platform passed in. These
+            packages will only be downloaded for distribution: they will
+            not be built locally.
+        :param versions: A list of strings or None. This is passed directly
+            to pep425tags.py in the get_supported() method.
+        :param abi: A string or None. This is passed directly
+            to pep425tags.py in the get_supported() method.
+        :param implementation: A string or None. This is passed directly
+            to pep425tags.py in the get_supported() method.
+        """
+        if session is None:
+            raise TypeError(
+                "PackageFinder() missing 1 required keyword argument: "
+                "'session'"
+            )
+
+        # Build find_links. If an argument starts with ~, it may be
+        # a local file relative to a home directory. So try normalizing
+        # it and if it exists, use the normalized version.
+        # This is deliberately conservative - it might be fine just to
+        # blindly normalize anything starting with a ~...
+        self.find_links = []  # type: List[str]
+        for link in find_links:
+            if link.startswith('~'):
+                new_link = normalize_path(link)
+                if os.path.exists(new_link):
+                    link = new_link
+            self.find_links.append(link)
+
+        self.index_urls = index_urls
+
+        # These are boring links that have already been logged somehow:
+        self.logged_links = set()  # type: Set[Link]
+
+        self.format_control = format_control or FormatControl(set(), set())
+
+        # Domains that we won't emit warnings for when not using HTTPS
+        self.secure_origins = [
+            ("*", host, "*")
+            for host in (trusted_hosts if trusted_hosts else [])
+        ]  # type: List[SecureOrigin]
+
+        # Do we want to allow _all_ pre-releases?
+        self.allow_all_prereleases = allow_all_prereleases
+
+        # The Session we'll use to make requests
+        self.session = session
+
+        # The valid tags to check potential found wheel candidates against
+        self.valid_tags = get_supported(
+            versions=versions,
+            platform=platform,
+            abi=abi,
+            impl=implementation,
+        )
+
+        # Do we prefer old, but valid, binary dist over new source dist
+        self.prefer_binary = prefer_binary
+
+        # If we don't have TLS enabled, then WARN if anyplace we're looking
+        # relies on TLS.
+        if not HAS_TLS:
+            for link in itertools.chain(self.index_urls, self.find_links):
+                parsed = urllib_parse.urlparse(link)
+                if parsed.scheme == "https":
+                    logger.warning(
+                        "pip is configured with locations that require "
+                        "TLS/SSL, however the ssl module in Python is not "
+                        "available."
+                    )
+                    break
+
+    def get_formatted_locations(self):
+        # type: () -> str
+        lines = []
+        if self.index_urls and self.index_urls != [PyPI.simple_url]:
+            lines.append(
+                "Looking in indexes: {}".format(", ".join(
+                    redact_password_from_url(url) for url in self.index_urls))
+            )
+        if self.find_links:
+            lines.append(
+                "Looking in links: {}".format(", ".join(self.find_links))
+            )
+        return "\n".join(lines)
+
+    @staticmethod
+    def _sort_locations(locations, expand_dir=False):
+        # type: (Sequence[str], bool) -> Tuple[List[str], List[str]]
+        """
+        Sort locations into "files" (archives) and "urls", and return
+        a pair of lists (files,urls)
+        """
+        files = []
+        urls = []
+
+        # puts the url for the given file path into the appropriate list
+        def sort_path(path):
+            url = path_to_url(path)
+            if mimetypes.guess_type(url, strict=False)[0] == 'text/html':
+                urls.append(url)
+            else:
+                files.append(url)
+
+        for url in locations:
+
+            is_local_path = os.path.exists(url)
+            is_file_url = url.startswith('file:')
+
+            if is_local_path or is_file_url:
+                if is_local_path:
+                    path = url
+                else:
+                    path = url_to_path(url)
+                if os.path.isdir(path):
+                    if expand_dir:
+                        path = os.path.realpath(path)
+                        for item in os.listdir(path):
+                            sort_path(os.path.join(path, item))
+                    elif is_file_url:
+                        urls.append(url)
+                    else:
+                        logger.warning(
+                            "Path '{0}' is ignored: "
+                            "it is a directory.".format(path),
+                        )
+                elif os.path.isfile(path):
+                    sort_path(path)
+                else:
+                    logger.warning(
+                        "Url '%s' is ignored: it is neither a file "
+                        "nor a directory.", url,
+                    )
+            elif is_url(url):
+                # Only add url with clear scheme
+                urls.append(url)
+            else:
+                logger.warning(
+                    "Url '%s' is ignored. It is either a non-existing "
+                    "path or lacks a specific scheme.", url,
+                )
+
+        return files, urls
+
+    def _candidate_sort_key(self, candidate):
+        # type: (InstallationCandidate) -> CandidateSortingKey
+        """
+        Function used to generate link sort key for link tuples.
+        The greater the return value, the more preferred it is.
+        If not finding wheels, then sorted by version only.
+        If finding wheels, then the sort order is by version, then:
+          1. existing installs
+          2. wheels ordered via Wheel.support_index_min(self.valid_tags)
+          3. source archives
+        If prefer_binary was set, then all wheels are sorted above sources.
+        Note: it was considered to embed this logic into the Link
+              comparison operators, but then different sdist links
+              with the same version, would have to be considered equal
+        """
+        support_num = len(self.valid_tags)
+        build_tag = tuple()  # type: BuildTag
+        binary_preference = 0
+        if candidate.location.is_wheel:
+            # can raise InvalidWheelFilename
+            wheel = Wheel(candidate.location.filename)
+            if not wheel.supported(self.valid_tags):
+                raise UnsupportedWheel(
+                    "%s is not a supported wheel for this platform. It "
+                    "can't be sorted." % wheel.filename
+                )
+            if self.prefer_binary:
+                binary_preference = 1
+            pri = -(wheel.support_index_min(self.valid_tags))
+            if wheel.build_tag is not None:
+                match = re.match(r'^(\d+)(.*)$', wheel.build_tag)
+                build_tag_groups = match.groups()
+                build_tag = (int(build_tag_groups[0]), build_tag_groups[1])
+        else:  # sdist
+            pri = -(support_num)
+        return (binary_preference, candidate.version, build_tag, pri)
+
+    def _validate_secure_origin(self, logger, location):
+        # type: (Logger, Link) -> bool
+        # Determine if this url used a secure transport mechanism
+        parsed = urllib_parse.urlparse(str(location))
+        origin = (parsed.scheme, parsed.hostname, parsed.port)
+
+        # The protocol to use to see if the protocol matches.
+        # Don't count the repository type as part of the protocol: in
+        # cases such as "git+ssh", only use "ssh". (I.e., Only verify against
+        # the last scheme.)
+        protocol = origin[0].rsplit('+', 1)[-1]
+
+        # Determine if our origin is a secure origin by looking through our
+        # hardcoded list of secure origins, as well as any additional ones
+        # configured on this PackageFinder instance.
+        for secure_origin in (SECURE_ORIGINS + self.secure_origins):
+            if protocol != secure_origin[0] and secure_origin[0] != "*":
+                continue
+
+            try:
+                # We need to do this decode dance to ensure that we have a
+                # unicode object, even on Python 2.x.
+                addr = ipaddress.ip_address(
+                    origin[1]
+                    if (
+                        isinstance(origin[1], six.text_type) or
+                        origin[1] is None
+                    )
+                    else origin[1].decode("utf8")
+                )
+                network = ipaddress.ip_network(
+                    secure_origin[1]
+                    if isinstance(secure_origin[1], six.text_type)
+                    # setting secure_origin[1] to proper Union[bytes, str]
+                    # creates problems in other places
+                    else secure_origin[1].decode("utf8")  # type: ignore
+                )
+            except ValueError:
+                # We don't have both a valid address or a valid network, so
+                # we'll check this origin against hostnames.
+                if (origin[1] and
+                        origin[1].lower() != secure_origin[1].lower() and
+                        secure_origin[1] != "*"):
+                    continue
+            else:
+                # We have a valid address and network, so see if the address
+                # is contained within the network.
+                if addr not in network:
+                    continue
+
+            # Check to see if the port patches
+            if (origin[2] != secure_origin[2] and
+                    secure_origin[2] != "*" and
+                    secure_origin[2] is not None):
+                continue
+
+            # If we've gotten here, then this origin matches the current
+            # secure origin and we should return True
+            return True
+
+        # If we've gotten to this point, then the origin isn't secure and we
+        # will not accept it as a valid location to search. We will however
+        # log a warning that we are ignoring it.
+        logger.warning(
+            "The repository located at %s is not a trusted or secure host and "
+            "is being ignored. If this repository is available via HTTPS we "
+            "recommend you use HTTPS instead, otherwise you may silence "
+            "this warning and allow it anyway with '--trusted-host %s'.",
+            parsed.hostname,
+            parsed.hostname,
+        )
+
+        return False
+
+    def _get_index_urls_locations(self, project_name):
+        # type: (str) -> List[str]
+        """Returns the locations found via self.index_urls
+
+        Checks the url_name on the main (first in the list) index and
+        use this url_name to produce all locations
+        """
+
+        def mkurl_pypi_url(url):
+            loc = posixpath.join(
+                url,
+                urllib_parse.quote(canonicalize_name(project_name)))
+            # For maximum compatibility with easy_install, ensure the path
+            # ends in a trailing slash.  Although this isn't in the spec
+            # (and PyPI can handle it without the slash) some other index
+            # implementations might break if they relied on easy_install's
+            # behavior.
+            if not loc.endswith('/'):
+                loc = loc + '/'
+            return loc
+
+        return [mkurl_pypi_url(url) for url in self.index_urls]
+
+    def find_all_candidates(self, project_name):
+        # type: (str) -> List[Optional[InstallationCandidate]]
+        """Find all available InstallationCandidate for project_name
+
+        This checks index_urls and find_links.
+        All versions found are returned as an InstallationCandidate list.
+
+        See _link_package_versions for details on which files are accepted
+        """
+        index_locations = self._get_index_urls_locations(project_name)
+        index_file_loc, index_url_loc = self._sort_locations(index_locations)
+        fl_file_loc, fl_url_loc = self._sort_locations(
+            self.find_links, expand_dir=True,
+        )
+
+        file_locations = (Link(url) for url in itertools.chain(
+            index_file_loc, fl_file_loc,
+        ))
+
+        # We trust every url that the user has given us whether it was given
+        #   via --index-url or --find-links.
+        # We want to filter out any thing which does not have a secure origin.
+        url_locations = [
+            link for link in itertools.chain(
+                (Link(url) for url in index_url_loc),
+                (Link(url) for url in fl_url_loc),
+            )
+            if self._validate_secure_origin(logger, link)
+        ]
+
+        logger.debug('%d location(s) to search for versions of %s:',
+                     len(url_locations), project_name)
+
+        for location in url_locations:
+            logger.debug('* %s', location)
+
+        canonical_name = canonicalize_name(project_name)
+        formats = self.format_control.get_allowed_formats(canonical_name)
+        search = Search(project_name, canonical_name, formats)
+        find_links_versions = self._package_versions(
+            # We trust every directly linked archive in find_links
+            (Link(url, '-f') for url in self.find_links),
+            search
+        )
+
+        page_versions = []
+        for page in self._get_pages(url_locations, project_name):
+            logger.debug('Analyzing links from page %s', page.url)
+            with indent_log():
+                page_versions.extend(
+                    self._package_versions(page.iter_links(), search)
+                )
+
+        file_versions = self._package_versions(file_locations, search)
+        if file_versions:
+            file_versions.sort(reverse=True)
+            logger.debug(
+                'Local files found: %s',
+                ', '.join([
+                    url_to_path(candidate.location.url)
+                    for candidate in file_versions
+                ])
+            )
+
+        # This is an intentional priority ordering
+        return file_versions + find_links_versions + page_versions
+
+    def find_requirement(self, req, upgrade):
+        # type: (InstallRequirement, bool) -> Optional[Link]
+        """Try to find a Link matching req
+
+        Expects req, an InstallRequirement and upgrade, a boolean
+        Returns a Link if found,
+        Raises DistributionNotFound or BestVersionAlreadyInstalled otherwise
+        """
+        all_candidates = self.find_all_candidates(req.name)
+
+        # Filter out anything which doesn't match our specifier
+        compatible_versions = set(
+            req.specifier.filter(
+                # We turn the version object into a str here because otherwise
+                # when we're debundled but setuptools isn't, Python will see
+                # packaging.version.Version and
+                # pkg_resources._vendor.packaging.version.Version as different
+                # types. This way we'll use a str as a common data interchange
+                # format. If we stop using the pkg_resources provided specifier
+                # and start using our own, we can drop the cast to str().
+                [str(c.version) for c in all_candidates],
+                prereleases=(
+                    self.allow_all_prereleases
+                    if self.allow_all_prereleases else None
+                ),
+            )
+        )
+        applicable_candidates = [
+            # Again, converting to str to deal with debundling.
+            c for c in all_candidates if str(c.version) in compatible_versions
+        ]
+
+        if applicable_candidates:
+            best_candidate = max(applicable_candidates,
+                                 key=self._candidate_sort_key)
+        else:
+            best_candidate = None
+
+        if req.satisfied_by is not None:
+            installed_version = parse_version(req.satisfied_by.version)
+        else:
+            installed_version = None
+
+        if installed_version is None and best_candidate is None:
+            logger.critical(
+                'Could not find a version that satisfies the requirement %s '
+                '(from versions: %s)',
+                req,
+                ', '.join(
+                    sorted(
+                        {str(c.version) for c in all_candidates},
+                        key=parse_version,
+                    )
+                )
+            )
+
+            raise DistributionNotFound(
+                'No matching distribution found for %s' % req
+            )
+
+        best_installed = False
+        if installed_version and (
+                best_candidate is None or
+                best_candidate.version <= installed_version):
+            best_installed = True
+
+        if not upgrade and installed_version is not None:
+            if best_installed:
+                logger.debug(
+                    'Existing installed version (%s) is most up-to-date and '
+                    'satisfies requirement',
+                    installed_version,
+                )
+            else:
+                logger.debug(
+                    'Existing installed version (%s) satisfies requirement '
+                    '(most up-to-date version is %s)',
+                    installed_version,
+                    best_candidate.version,
+                )
+            return None
+
+        if best_installed:
+            # We have an existing version, and its the best version
+            logger.debug(
+                'Installed version (%s) is most up-to-date (past versions: '
+                '%s)',
+                installed_version,
+                ', '.join(sorted(compatible_versions, key=parse_version)) or
+                "none",
+            )
+            raise BestVersionAlreadyInstalled
+
+        logger.debug(
+            'Using version %s (newest of versions: %s)',
+            best_candidate.version,
+            ', '.join(sorted(compatible_versions, key=parse_version))
+        )
+        return best_candidate.location
+
+    def _get_pages(self, locations, project_name):
+        # type: (Iterable[Link], str) -> Iterable[HTMLPage]
+        """
+        Yields (page, page_url) from the given locations, skipping
+        locations that have errors.
+        """
+        seen = set()  # type: Set[Link]
+        for location in locations:
+            if location in seen:
+                continue
+            seen.add(location)
+
+            page = _get_html_page(location, session=self.session)
+            if page is None:
+                continue
+
+            yield page
+
+    _py_version_re = re.compile(r'-py([123]\.?[0-9]?)$')
+
+    def _sort_links(self, links):
+        # type: (Iterable[Link]) -> List[Link]
+        """
+        Returns elements of links in order, non-egg links first, egg links
+        second, while eliminating duplicates
+        """
+        eggs, no_eggs = [], []
+        seen = set()  # type: Set[Link]
+        for link in links:
+            if link not in seen:
+                seen.add(link)
+                if link.egg_fragment:
+                    eggs.append(link)
+                else:
+                    no_eggs.append(link)
+        return no_eggs + eggs
+
+    def _package_versions(
+        self,
+        links,  # type: Iterable[Link]
+        search  # type: Search
+    ):
+        # type: (...) -> List[Optional[InstallationCandidate]]
+        result = []
+        for link in self._sort_links(links):
+            v = self._link_package_versions(link, search)
+            if v is not None:
+                result.append(v)
+        return result
+
+    def _log_skipped_link(self, link, reason):
+        # type: (Link, str) -> None
+        if link not in self.logged_links:
+            logger.debug('Skipping link %s; %s', link, reason)
+            self.logged_links.add(link)
+
+    def _link_package_versions(self, link, search):
+        # type: (Link, Search) -> Optional[InstallationCandidate]
+        """Return an InstallationCandidate or None"""
+        version = None
+        if link.egg_fragment:
+            egg_info = link.egg_fragment
+            ext = link.ext
+        else:
+            egg_info, ext = link.splitext()
+            if not ext:
+                self._log_skipped_link(link, 'not a file')
+                return None
+            if ext not in SUPPORTED_EXTENSIONS:
+                self._log_skipped_link(
+                    link, 'unsupported archive format: %s' % ext,
+                )
+                return None
+            if "binary" not in search.formats and ext == WHEEL_EXTENSION:
+                self._log_skipped_link(
+                    link, 'No binaries permitted for %s' % search.supplied,
+                )
+                return None
+            if "macosx10" in link.path and ext == '.zip':
+                self._log_skipped_link(link, 'macosx10 one')
+                return None
+            if ext == WHEEL_EXTENSION:
+                try:
+                    wheel = Wheel(link.filename)
+                except InvalidWheelFilename:
+                    self._log_skipped_link(link, 'invalid wheel filename')
+                    return None
+                if canonicalize_name(wheel.name) != search.canonical:
+                    self._log_skipped_link(
+                        link, 'wrong project name (not %s)' % search.supplied)
+                    return None
+
+                if not wheel.supported(self.valid_tags):
+                    self._log_skipped_link(
+                        link, 'it is not compatible with this Python')
+                    return None
+
+                version = wheel.version
+
+        # This should be up by the search.ok_binary check, but see issue 2700.
+        if "source" not in search.formats and ext != WHEEL_EXTENSION:
+            self._log_skipped_link(
+                link, 'No sources permitted for %s' % search.supplied,
+            )
+            return None
+
+        if not version:
+            version = _egg_info_matches(egg_info, search.canonical)
+        if not version:
+            self._log_skipped_link(
+                link, 'Missing project version for %s' % search.supplied)
+            return None
+
+        match = self._py_version_re.search(version)
+        if match:
+            version = version[:match.start()]
+            py_version = match.group(1)
+            if py_version != sys.version[:3]:
+                self._log_skipped_link(
+                    link, 'Python version is incorrect')
+                return None
+        try:
+            support_this_python = check_requires_python(link.requires_python)
+        except specifiers.InvalidSpecifier:
+            logger.debug("Package %s has an invalid Requires-Python entry: %s",
+                         link.filename, link.requires_python)
+            support_this_python = True
+
+        if not support_this_python:
+            logger.debug("The package %s is incompatible with the python "
+                         "version in use. Acceptable python versions are: %s",
+                         link, link.requires_python)
+            return None
+        logger.debug('Found link %s, version: %s', link, version)
+
+        return InstallationCandidate(search.supplied, version, link)
+
+
+def _find_name_version_sep(egg_info, canonical_name):
+    # type: (str, str) -> int
+    """Find the separator's index based on the package's canonical name.
+
+    `egg_info` must be an egg info string for the given package, and
+    `canonical_name` must be the package's canonical name.
+
+    This function is needed since the canonicalized name does not necessarily
+    have the same length as the egg info's name part. An example::
+
+    >>> egg_info = 'foo__bar-1.0'
+    >>> canonical_name = 'foo-bar'
+    >>> _find_name_version_sep(egg_info, canonical_name)
+    8
+    """
+    # Project name and version must be separated by one single dash. Find all
+    # occurrences of dashes; if the string in front of it matches the canonical
+    # name, this is the one separating the name and version parts.
+    for i, c in enumerate(egg_info):
+        if c != "-":
+            continue
+        if canonicalize_name(egg_info[:i]) == canonical_name:
+            return i
+    raise ValueError("{} does not match {}".format(egg_info, canonical_name))
+
+
+def _egg_info_matches(egg_info, canonical_name):
+    # type: (str, str) -> Optional[str]
+    """Pull the version part out of a string.
+
+    :param egg_info: The string to parse. E.g. foo-2.1
+    :param canonical_name: The canonicalized name of the package this
+        belongs to.
+    """
+    try:
+        version_start = _find_name_version_sep(egg_info, canonical_name) + 1
+    except ValueError:
+        return None
+    version = egg_info[version_start:]
+    if not version:
+        return None
+    return version
+
+
+def _determine_base_url(document, page_url):
+    """Determine the HTML document's base URL.
+
+    This looks for a ``<base>`` tag in the HTML document. If present, its href
+    attribute denotes the base URL of anchor tags in the document. If there is
+    no such tag (or if it does not have a valid href attribute), the HTML
+    file's URL is used as the base URL.
+
+    :param document: An HTML document representation. The current
+        implementation expects the result of ``html5lib.parse()``.
+    :param page_url: The URL of the HTML document.
+    """
+    for base in document.findall(".//base"):
+        href = base.get("href")
+        if href is not None:
+            return href
+    return page_url
+
+
+def _get_encoding_from_headers(headers):
+    """Determine if we have any encoding information in our headers.
+    """
+    if headers and "Content-Type" in headers:
+        content_type, params = cgi.parse_header(headers["Content-Type"])
+        if "charset" in params:
+            return params['charset']
+    return None
+
+
+_CLEAN_LINK_RE = re.compile(r'[^a-z0-9$&+,/:;=?@.#%_\\|-]', re.I)
+
+
+def _clean_link(url):
+    # type: (str) -> str
+    """Makes sure a link is fully encoded.  That is, if a ' ' shows up in
+    the link, it will be rewritten to %20 (while not over-quoting
+    % or other characters)."""
+    return _CLEAN_LINK_RE.sub(lambda match: '%%%2x' % ord(match.group(0)), url)
+
+
+class HTMLPage(object):
+    """Represents one page, along with its URL"""
+
+    def __init__(self, content, url, headers=None):
+        # type: (bytes, str, MutableMapping[str, str]) -> None
+        self.content = content
+        self.url = url
+        self.headers = headers
+
+    def __str__(self):
+        return redact_password_from_url(self.url)
+
+    def iter_links(self):
+        # type: () -> Iterable[Link]
+        """Yields all links in the page"""
+        document = html5lib.parse(
+            self.content,
+            transport_encoding=_get_encoding_from_headers(self.headers),
+            namespaceHTMLElements=False,
+        )
+        base_url = _determine_base_url(document, self.url)
+        for anchor in document.findall(".//a"):
+            if anchor.get("href"):
+                href = anchor.get("href")
+                url = _clean_link(urllib_parse.urljoin(base_url, href))
+                pyrequire = anchor.get('data-requires-python')
+                pyrequire = unescape(pyrequire) if pyrequire else None
+                yield Link(url, self.url, requires_python=pyrequire)
+
+
+Search = namedtuple('Search', 'supplied canonical formats')
+"""Capture key aspects of a search.
+
+:attribute supplied: The user supplied package.
+:attribute canonical: The canonical package name.
+:attribute formats: The formats allowed for this package. Should be a set
+    with 'binary' or 'source' or both in it.
+"""