Created starter files for the project.

venv/Lib/site-packages/pip/_internal/req/__init__.py

@@ -0,0 +1,103 @@
+from __future__ import absolute_import
+
+import collections
+import logging
+
+from pip._internal.utils.logging import indent_log
+from pip._internal.utils.typing import MYPY_CHECK_RUNNING
+
+from .req_file import parse_requirements
+from .req_install import InstallRequirement
+from .req_set import RequirementSet
+
+if MYPY_CHECK_RUNNING:
+    from typing import Iterator, List, Optional, Sequence, Tuple
+
+__all__ = [
+    "RequirementSet", "InstallRequirement",
+    "parse_requirements", "install_given_reqs",
+]
+
+logger = logging.getLogger(__name__)
+
+
+class InstallationResult(object):
+    def __init__(self, name):
+        # type: (str) -> None
+        self.name = name
+
+    def __repr__(self):
+        # type: () -> str
+        return "InstallationResult(name={!r})".format(self.name)
+
+
+def _validate_requirements(
+    requirements,  # type: List[InstallRequirement]
+):
+    # type: (...) -> Iterator[Tuple[str, InstallRequirement]]
+    for req in requirements:
+        assert req.name, "invalid to-be-installed requirement: {}".format(req)
+        yield req.name, req
+
+
+def install_given_reqs(
+    requirements,  # type: List[InstallRequirement]
+    install_options,  # type: List[str]
+    global_options,  # type: Sequence[str]
+    root,  # type: Optional[str]
+    home,  # type: Optional[str]
+    prefix,  # type: Optional[str]
+    warn_script_location,  # type: bool
+    use_user_site,  # type: bool
+    pycompile,  # type: bool
+):
+    # type: (...) -> List[InstallationResult]
+    """
+    Install everything in the given list.
+
+    (to be called after having downloaded and unpacked the packages)
+    """
+    to_install = collections.OrderedDict(_validate_requirements(requirements))
+
+    if to_install:
+        logger.info(
+            'Installing collected packages: %s',
+            ', '.join(to_install.keys()),
+        )
+
+    installed = []
+
+    with indent_log():
+        for req_name, requirement in to_install.items():
+            if requirement.should_reinstall:
+                logger.info('Attempting uninstall: %s', req_name)
+                with indent_log():
+                    uninstalled_pathset = requirement.uninstall(
+                        auto_confirm=True
+                    )
+            else:
+                uninstalled_pathset = None
+
+            try:
+                requirement.install(
+                    install_options,
+                    global_options,
+                    root=root,
+                    home=home,
+                    prefix=prefix,
+                    warn_script_location=warn_script_location,
+                    use_user_site=use_user_site,
+                    pycompile=pycompile,
+                )
+            except Exception:
+                # if install did not succeed, rollback previous uninstall
+                if uninstalled_pathset and not requirement.install_succeeded:
+                    uninstalled_pathset.rollback()
+                raise
+            else:
+                if uninstalled_pathset and requirement.install_succeeded:
+                    uninstalled_pathset.commit()
+
+            installed.append(InstallationResult(req_name))
+
+    return installed

venv/Lib/site-packages/pip/_internal/req/constructors.py

@@ -0,0 +1,486 @@
+"""Backing implementation for InstallRequirement's various constructors
+
+The idea here is that these formed a major chunk of InstallRequirement's size
+so, moving them and support code dedicated to them outside of that class
+helps creates for better understandability for the rest of the code.
+
+These are meant to be used elsewhere within pip to create instances of
+InstallRequirement.
+"""
+
+import logging
+import os
+import re
+
+from pip._vendor.packaging.markers import Marker
+from pip._vendor.packaging.requirements import InvalidRequirement, Requirement
+from pip._vendor.packaging.specifiers import Specifier
+from pip._vendor.pkg_resources import RequirementParseError, parse_requirements
+
+from pip._internal.exceptions import InstallationError
+from pip._internal.models.index import PyPI, TestPyPI
+from pip._internal.models.link import Link
+from pip._internal.models.wheel import Wheel
+from pip._internal.pyproject import make_pyproject_path
+from pip._internal.req.req_install import InstallRequirement
+from pip._internal.utils.deprecation import deprecated
+from pip._internal.utils.filetypes import ARCHIVE_EXTENSIONS
+from pip._internal.utils.misc import is_installable_dir, splitext
+from pip._internal.utils.typing import MYPY_CHECK_RUNNING
+from pip._internal.utils.urls import path_to_url
+from pip._internal.vcs import is_url, vcs
+
+if MYPY_CHECK_RUNNING:
+    from typing import (
+        Any, Dict, Optional, Set, Tuple, Union,
+    )
+    from pip._internal.req.req_file import ParsedRequirement
+
+
+__all__ = [
+    "install_req_from_editable", "install_req_from_line",
+    "parse_editable"
+]
+
+logger = logging.getLogger(__name__)
+operators = Specifier._operators.keys()
+
+
+def is_archive_file(name):
+    # type: (str) -> bool
+    """Return True if `name` is a considered as an archive file."""
+    ext = splitext(name)[1].lower()
+    if ext in ARCHIVE_EXTENSIONS:
+        return True
+    return False
+
+
+def _strip_extras(path):
+    # type: (str) -> Tuple[str, Optional[str]]
+    m = re.match(r'^(.+)(\[[^\]]+\])$', path)
+    extras = None
+    if m:
+        path_no_extras = m.group(1)
+        extras = m.group(2)
+    else:
+        path_no_extras = path
+
+    return path_no_extras, extras
+
+
+def convert_extras(extras):
+    # type: (Optional[str]) -> Set[str]
+    if not extras:
+        return set()
+    return Requirement("placeholder" + extras.lower()).extras
+
+
+def parse_editable(editable_req):
+    # type: (str) -> Tuple[Optional[str], str, Set[str]]
+    """Parses an editable requirement into:
+        - a requirement name
+        - an URL
+        - extras
+        - editable options
+    Accepted requirements:
+        svn+http://blahblah@rev#egg=Foobar[baz]&subdirectory=version_subdir
+        .[some_extra]
+    """
+
+    url = editable_req
+
+    # If a file path is specified with extras, strip off the extras.
+    url_no_extras, extras = _strip_extras(url)
+
+    if os.path.isdir(url_no_extras):
+        if not os.path.exists(os.path.join(url_no_extras, 'setup.py')):
+            msg = (
+                'File "setup.py" not found. Directory cannot be installed '
+                'in editable mode: {}'.format(os.path.abspath(url_no_extras))
+            )
+            pyproject_path = make_pyproject_path(url_no_extras)
+            if os.path.isfile(pyproject_path):
+                msg += (
+                    '\n(A "pyproject.toml" file was found, but editable '
+                    'mode currently requires a setup.py based build.)'
+                )
+            raise InstallationError(msg)
+
+        # Treating it as code that has already been checked out
+        url_no_extras = path_to_url(url_no_extras)
+
+    if url_no_extras.lower().startswith('file:'):
+        package_name = Link(url_no_extras).egg_fragment
+        if extras:
+            return (
+                package_name,
+                url_no_extras,
+                Requirement("placeholder" + extras.lower()).extras,
+            )
+        else:
+            return package_name, url_no_extras, set()
+
+    for version_control in vcs:
+        if url.lower().startswith('{}:'.format(version_control)):
+            url = '{}+{}'.format(version_control, url)
+            break
+
+    if '+' not in url:
+        raise InstallationError(
+            '{} is not a valid editable requirement. '
+            'It should either be a path to a local project or a VCS URL '
+            '(beginning with svn+, git+, hg+, or bzr+).'.format(editable_req)
+        )
+
+    vc_type = url.split('+', 1)[0].lower()
+
+    if not vcs.get_backend(vc_type):
+        backends = ", ".join([bends.name + '+URL' for bends in vcs.backends])
+        error_message = "For --editable={}, " \
+                        "only {} are currently supported".format(
+                            editable_req, backends)
+        raise InstallationError(error_message)
+
+    package_name = Link(url).egg_fragment
+    if not package_name:
+        raise InstallationError(
+            "Could not detect requirement name for '{}', please specify one "
+            "with #egg=your_package_name".format(editable_req)
+        )
+    return package_name, url, set()
+
+
+def deduce_helpful_msg(req):
+    # type: (str) -> str
+    """Returns helpful msg in case requirements file does not exist,
+    or cannot be parsed.
+
+    :params req: Requirements file path
+    """
+    msg = ""
+    if os.path.exists(req):
+        msg = " It does exist."
+        # Try to parse and check if it is a requirements file.
+        try:
+            with open(req, 'r') as fp:
+                # parse first line only
+                next(parse_requirements(fp.read()))
+                msg += (
+                    "The argument you provided "
+                    "({}) appears to be a"
+                    " requirements file. If that is the"
+                    " case, use the '-r' flag to install"
+                    " the packages specified within it."
+                ).format(req)
+        except RequirementParseError:
+            logger.debug(
+                "Cannot parse '%s' as requirements file", req, exc_info=True
+            )
+    else:
+        msg += " File '{}' does not exist.".format(req)
+    return msg
+
+
+class RequirementParts(object):
+    def __init__(
+            self,
+            requirement,  # type: Optional[Requirement]
+            link,         # type: Optional[Link]
+            markers,      # type: Optional[Marker]
+            extras,       # type: Set[str]
+    ):
+        self.requirement = requirement
+        self.link = link
+        self.markers = markers
+        self.extras = extras
+
+
+def parse_req_from_editable(editable_req):
+    # type: (str) -> RequirementParts
+    name, url, extras_override = parse_editable(editable_req)
+
+    if name is not None:
+        try:
+            req = Requirement(name)
+        except InvalidRequirement:
+            raise InstallationError("Invalid requirement: '{}'".format(name))
+    else:
+        req = None
+
+    link = Link(url)
+
+    return RequirementParts(req, link, None, extras_override)
+
+
+# ---- The actual constructors follow ----
+
+
+def install_req_from_editable(
+    editable_req,  # type: str
+    comes_from=None,  # type: Optional[Union[InstallRequirement, str]]
+    use_pep517=None,  # type: Optional[bool]
+    isolated=False,  # type: bool
+    options=None,  # type: Optional[Dict[str, Any]]
+    constraint=False,  # type: bool
+    user_supplied=False,  # type: bool
+):
+    # type: (...) -> InstallRequirement
+
+    parts = parse_req_from_editable(editable_req)
+
+    return InstallRequirement(
+        parts.requirement,
+        comes_from=comes_from,
+        user_supplied=user_supplied,
+        editable=True,
+        link=parts.link,
+        constraint=constraint,
+        use_pep517=use_pep517,
+        isolated=isolated,
+        install_options=options.get("install_options", []) if options else [],
+        global_options=options.get("global_options", []) if options else [],
+        hash_options=options.get("hashes", {}) if options else {},
+        extras=parts.extras,
+    )
+
+
+def _looks_like_path(name):
+    # type: (str) -> bool
+    """Checks whether the string "looks like" a path on the filesystem.
+
+    This does not check whether the target actually exists, only judge from the
+    appearance.
+
+    Returns true if any of the following conditions is true:
+    * a path separator is found (either os.path.sep or os.path.altsep);
+    * a dot is found (which represents the current directory).
+    """
+    if os.path.sep in name:
+        return True
+    if os.path.altsep is not None and os.path.altsep in name:
+        return True
+    if name.startswith("."):
+        return True
+    return False
+
+
+def _get_url_from_path(path, name):
+    # type: (str, str) -> Optional[str]
+    """
+    First, it checks whether a provided path is an installable directory
+    (e.g. it has a setup.py). If it is, returns the path.
+
+    If false, check if the path is an archive file (such as a .whl).
+    The function checks if the path is a file. If false, if the path has
+    an @, it will treat it as a PEP 440 URL requirement and return the path.
+    """
+    if _looks_like_path(name) and os.path.isdir(path):
+        if is_installable_dir(path):
+            return path_to_url(path)
+        raise InstallationError(
+            "Directory {name!r} is not installable. Neither 'setup.py' "
+            "nor 'pyproject.toml' found.".format(**locals())
+        )
+    if not is_archive_file(path):
+        return None
+    if os.path.isfile(path):
+        return path_to_url(path)
+    urlreq_parts = name.split('@', 1)
+    if len(urlreq_parts) >= 2 and not _looks_like_path(urlreq_parts[0]):
+        # If the path contains '@' and the part before it does not look
+        # like a path, try to treat it as a PEP 440 URL req instead.
+        return None
+    logger.warning(
+        'Requirement %r looks like a filename, but the '
+        'file does not exist',
+        name
+    )
+    return path_to_url(path)
+
+
+def parse_req_from_line(name, line_source):
+    # type: (str, Optional[str]) -> RequirementParts
+    if is_url(name):
+        marker_sep = '; '
+    else:
+        marker_sep = ';'
+    if marker_sep in name:
+        name, markers_as_string = name.split(marker_sep, 1)
+        markers_as_string = markers_as_string.strip()
+        if not markers_as_string:
+            markers = None
+        else:
+            markers = Marker(markers_as_string)
+    else:
+        markers = None
+    name = name.strip()
+    req_as_string = None
+    path = os.path.normpath(os.path.abspath(name))
+    link = None
+    extras_as_string = None
+
+    if is_url(name):
+        link = Link(name)
+    else:
+        p, extras_as_string = _strip_extras(path)
+        url = _get_url_from_path(p, name)
+        if url is not None:
+            link = Link(url)
+
+    # it's a local file, dir, or url
+    if link:
+        # Handle relative file URLs
+        if link.scheme == 'file' and re.search(r'\.\./', link.url):
+            link = Link(
+                path_to_url(os.path.normpath(os.path.abspath(link.path))))
+        # wheel file
+        if link.is_wheel:
+            wheel = Wheel(link.filename)  # can raise InvalidWheelFilename
+            req_as_string = "{wheel.name}=={wheel.version}".format(**locals())
+        else:
+            # set the req to the egg fragment.  when it's not there, this
+            # will become an 'unnamed' requirement
+            req_as_string = link.egg_fragment
+
+    # a requirement specifier
+    else:
+        req_as_string = name
+
+    extras = convert_extras(extras_as_string)
+
+    def with_source(text):
+        # type: (str) -> str
+        if not line_source:
+            return text
+        return '{} (from {})'.format(text, line_source)
+
+    if req_as_string is not None:
+        try:
+            req = Requirement(req_as_string)
+        except InvalidRequirement:
+            if os.path.sep in req_as_string:
+                add_msg = "It looks like a path."
+                add_msg += deduce_helpful_msg(req_as_string)
+            elif ('=' in req_as_string and
+                  not any(op in req_as_string for op in operators)):
+                add_msg = "= is not a valid operator. Did you mean == ?"
+            else:
+                add_msg = ''
+            msg = with_source(
+                'Invalid requirement: {!r}'.format(req_as_string)
+            )
+            if add_msg:
+                msg += '\nHint: {}'.format(add_msg)
+            raise InstallationError(msg)
+        else:
+            # Deprecate extras after specifiers: "name>=1.0[extras]"
+            # This currently works by accident because _strip_extras() parses
+            # any extras in the end of the string and those are saved in
+            # RequirementParts
+            for spec in req.specifier:
+                spec_str = str(spec)
+                if spec_str.endswith(']'):
+                    msg = "Extras after version '{}'.".format(spec_str)
+                    replace = "moving the extras before version specifiers"
+                    deprecated(msg, replacement=replace, gone_in="21.0")
+    else:
+        req = None
+
+    return RequirementParts(req, link, markers, extras)
+
+
+def install_req_from_line(
+    name,  # type: str
+    comes_from=None,  # type: Optional[Union[str, InstallRequirement]]
+    use_pep517=None,  # type: Optional[bool]
+    isolated=False,  # type: bool
+    options=None,  # type: Optional[Dict[str, Any]]
+    constraint=False,  # type: bool
+    line_source=None,  # type: Optional[str]
+    user_supplied=False,  # type: bool
+):
+    # type: (...) -> InstallRequirement
+    """Creates an InstallRequirement from a name, which might be a
+    requirement, directory containing 'setup.py', filename, or URL.
+
+    :param line_source: An optional string describing where the line is from,
+        for logging purposes in case of an error.
+    """
+    parts = parse_req_from_line(name, line_source)
+
+    return InstallRequirement(
+        parts.requirement, comes_from, link=parts.link, markers=parts.markers,
+        use_pep517=use_pep517, isolated=isolated,
+        install_options=options.get("install_options", []) if options else [],
+        global_options=options.get("global_options", []) if options else [],
+        hash_options=options.get("hashes", {}) if options else {},
+        constraint=constraint,
+        extras=parts.extras,
+        user_supplied=user_supplied,
+    )
+
+
+def install_req_from_req_string(
+    req_string,  # type: str
+    comes_from=None,  # type: Optional[InstallRequirement]
+    isolated=False,  # type: bool
+    use_pep517=None,  # type: Optional[bool]
+    user_supplied=False,  # type: bool
+):
+    # type: (...) -> InstallRequirement
+    try:
+        req = Requirement(req_string)
+    except InvalidRequirement:
+        raise InstallationError("Invalid requirement: '{}'".format(req_string))
+
+    domains_not_allowed = [
+        PyPI.file_storage_domain,
+        TestPyPI.file_storage_domain,
+    ]
+    if (req.url and comes_from and comes_from.link and
+            comes_from.link.netloc in domains_not_allowed):
+        # Explicitly disallow pypi packages that depend on external urls
+        raise InstallationError(
+            "Packages installed from PyPI cannot depend on packages "
+            "which are not also hosted on PyPI.\n"
+            "{} depends on {} ".format(comes_from.name, req)
+        )
+
+    return InstallRequirement(
+        req,
+        comes_from,
+        isolated=isolated,
+        use_pep517=use_pep517,
+        user_supplied=user_supplied,
+    )
+
+
+def install_req_from_parsed_requirement(
+    parsed_req,  # type: ParsedRequirement
+    isolated=False,  # type: bool
+    use_pep517=None,  # type: Optional[bool]
+    user_supplied=False,  # type: bool
+):
+    # type: (...) -> InstallRequirement
+    if parsed_req.is_editable:
+        req = install_req_from_editable(
+            parsed_req.requirement,
+            comes_from=parsed_req.comes_from,
+            use_pep517=use_pep517,
+            constraint=parsed_req.constraint,
+            isolated=isolated,
+            user_supplied=user_supplied,
+        )
+
+    else:
+        req = install_req_from_line(
+            parsed_req.requirement,
+            comes_from=parsed_req.comes_from,
+            use_pep517=use_pep517,
+            isolated=isolated,
+            options=parsed_req.options,
+            constraint=parsed_req.constraint,
+            line_source=parsed_req.line_source,
+            user_supplied=user_supplied,
+        )
+    return req

venv/Lib/site-packages/pip/_internal/req/req_file.py

@@ -0,0 +1,592 @@
+"""
+Requirements file parsing
+"""
+
+from __future__ import absolute_import
+
+import optparse
+import os
+import re
+import shlex
+import sys
+
+from pip._vendor.six.moves.urllib import parse as urllib_parse
+
+from pip._internal.cli import cmdoptions
+from pip._internal.exceptions import (
+    InstallationError,
+    RequirementsFileParseError,
+)
+from pip._internal.models.search_scope import SearchScope
+from pip._internal.network.utils import raise_for_status
+from pip._internal.utils.encoding import auto_decode
+from pip._internal.utils.typing import MYPY_CHECK_RUNNING
+from pip._internal.utils.urls import get_url_scheme
+
+if MYPY_CHECK_RUNNING:
+    from optparse import Values
+    from typing import (
+        Any, Callable, Dict, Iterator, List, NoReturn, Optional, Text, Tuple,
+    )
+
+    from pip._internal.index.package_finder import PackageFinder
+    from pip._internal.network.session import PipSession
+
+    ReqFileLines = Iterator[Tuple[int, Text]]
+
+    LineParser = Callable[[Text], Tuple[str, Values]]
+
+
+__all__ = ['parse_requirements']
+
+SCHEME_RE = re.compile(r'^(http|https|file):', re.I)
+COMMENT_RE = re.compile(r'(^|\s+)#.*$')
+
+# Matches environment variable-style values in '${MY_VARIABLE_1}' with the
+# variable name consisting of only uppercase letters, digits or the '_'
+# (underscore). This follows the POSIX standard defined in IEEE Std 1003.1,
+# 2013 Edition.
+ENV_VAR_RE = re.compile(r'(?P<var>\$\{(?P<name>[A-Z0-9_]+)\})')
+
+SUPPORTED_OPTIONS = [
+    cmdoptions.index_url,
+    cmdoptions.extra_index_url,
+    cmdoptions.no_index,
+    cmdoptions.constraints,
+    cmdoptions.requirements,
+    cmdoptions.editable,
+    cmdoptions.find_links,
+    cmdoptions.no_binary,
+    cmdoptions.only_binary,
+    cmdoptions.prefer_binary,
+    cmdoptions.require_hashes,
+    cmdoptions.pre,
+    cmdoptions.trusted_host,
+    cmdoptions.use_new_feature,
+]  # type: List[Callable[..., optparse.Option]]
+
+# options to be passed to requirements
+SUPPORTED_OPTIONS_REQ = [
+    cmdoptions.install_options,
+    cmdoptions.global_options,
+    cmdoptions.hash,
+]  # type: List[Callable[..., optparse.Option]]
+
+# the 'dest' string values
+SUPPORTED_OPTIONS_REQ_DEST = [str(o().dest) for o in SUPPORTED_OPTIONS_REQ]
+
+
+class ParsedRequirement(object):
+    def __init__(
+        self,
+        requirement,  # type:str
+        is_editable,  # type: bool
+        comes_from,  # type: str
+        constraint,  # type: bool
+        options=None,  # type: Optional[Dict[str, Any]]
+        line_source=None,  # type: Optional[str]
+    ):
+        # type: (...) -> None
+        self.requirement = requirement
+        self.is_editable = is_editable
+        self.comes_from = comes_from
+        self.options = options
+        self.constraint = constraint
+        self.line_source = line_source
+
+
+class ParsedLine(object):
+    def __init__(
+        self,
+        filename,  # type: str
+        lineno,  # type: int
+        comes_from,  # type: Optional[str]
+        args,  # type: str
+        opts,  # type: Values
+        constraint,  # type: bool
+    ):
+        # type: (...) -> None
+        self.filename = filename
+        self.lineno = lineno
+        self.comes_from = comes_from
+        self.opts = opts
+        self.constraint = constraint
+
+        if args:
+            self.is_requirement = True
+            self.is_editable = False
+            self.requirement = args
+        elif opts.editables:
+            self.is_requirement = True
+            self.is_editable = True
+            # We don't support multiple -e on one line
+            self.requirement = opts.editables[0]
+        else:
+            self.is_requirement = False
+
+
+def parse_requirements(
+    filename,  # type: str
+    session,  # type: PipSession
+    finder=None,  # type: Optional[PackageFinder]
+    comes_from=None,  # type: Optional[str]
+    options=None,  # type: Optional[optparse.Values]
+    constraint=False,  # type: bool
+):
+    # type: (...) -> Iterator[ParsedRequirement]
+    """Parse a requirements file and yield ParsedRequirement instances.
+
+    :param filename:    Path or url of requirements file.
+    :param session:     PipSession instance.
+    :param finder:      Instance of pip.index.PackageFinder.
+    :param comes_from:  Origin description of requirements.
+    :param options:     cli options.
+    :param constraint:  If true, parsing a constraint file rather than
+        requirements file.
+    """
+    line_parser = get_line_parser(finder)
+    parser = RequirementsFileParser(session, line_parser, comes_from)
+
+    for parsed_line in parser.parse(filename, constraint):
+        parsed_req = handle_line(
+            parsed_line,
+            options=options,
+            finder=finder,
+            session=session
+        )
+        if parsed_req is not None:
+            yield parsed_req
+
+
+def preprocess(content):
+    # type: (Text) -> ReqFileLines
+    """Split, filter, and join lines, and return a line iterator
+
+    :param content: the content of the requirements file
+    """
+    lines_enum = enumerate(content.splitlines(), start=1)  # type: ReqFileLines
+    lines_enum = join_lines(lines_enum)
+    lines_enum = ignore_comments(lines_enum)
+    lines_enum = expand_env_variables(lines_enum)
+    return lines_enum
+
+
+def handle_requirement_line(
+    line,  # type: ParsedLine
+    options=None,  # type: Optional[optparse.Values]
+):
+    # type: (...) -> ParsedRequirement
+
+    # preserve for the nested code path
+    line_comes_from = '{} {} (line {})'.format(
+        '-c' if line.constraint else '-r', line.filename, line.lineno,
+    )
+
+    assert line.is_requirement
+
+    if line.is_editable:
+        # For editable requirements, we don't support per-requirement
+        # options, so just return the parsed requirement.
+        return ParsedRequirement(
+            requirement=line.requirement,
+            is_editable=line.is_editable,
+            comes_from=line_comes_from,
+            constraint=line.constraint,
+        )
+    else:
+        if options:
+            # Disable wheels if the user has specified build options
+            cmdoptions.check_install_build_global(options, line.opts)
+
+        # get the options that apply to requirements
+        req_options = {}
+        for dest in SUPPORTED_OPTIONS_REQ_DEST:
+            if dest in line.opts.__dict__ and line.opts.__dict__[dest]:
+                req_options[dest] = line.opts.__dict__[dest]
+
+        line_source = 'line {} of {}'.format(line.lineno, line.filename)
+        return ParsedRequirement(
+            requirement=line.requirement,
+            is_editable=line.is_editable,
+            comes_from=line_comes_from,
+            constraint=line.constraint,
+            options=req_options,
+            line_source=line_source,
+        )
+
+
+def handle_option_line(
+    opts,  # type: Values
+    filename,  # type: str
+    lineno,  # type: int
+    finder=None,  # type: Optional[PackageFinder]
+    options=None,  # type: Optional[optparse.Values]
+    session=None,  # type: Optional[PipSession]
+):
+    # type:  (...) -> None
+
+    if options:
+        # percolate options upward
+        if opts.require_hashes:
+            options.require_hashes = opts.require_hashes
+        if opts.features_enabled:
+            options.features_enabled.extend(
+                f for f in opts.features_enabled
+                if f not in options.features_enabled
+            )
+
+    # set finder options
+    if finder:
+        find_links = finder.find_links
+        index_urls = finder.index_urls
+        if opts.index_url:
+            index_urls = [opts.index_url]
+        if opts.no_index is True:
+            index_urls = []
+        if opts.extra_index_urls:
+            index_urls.extend(opts.extra_index_urls)
+        if opts.find_links:
+            # FIXME: it would be nice to keep track of the source
+            # of the find_links: support a find-links local path
+            # relative to a requirements file.
+            value = opts.find_links[0]
+            req_dir = os.path.dirname(os.path.abspath(filename))
+            relative_to_reqs_file = os.path.join(req_dir, value)
+            if os.path.exists(relative_to_reqs_file):
+                value = relative_to_reqs_file
+            find_links.append(value)
+
+        search_scope = SearchScope(
+            find_links=find_links,
+            index_urls=index_urls,
+        )
+        finder.search_scope = search_scope
+
+        if opts.pre:
+            finder.set_allow_all_prereleases()
+
+        if opts.prefer_binary:
+            finder.set_prefer_binary()
+
+        if session:
+            for host in opts.trusted_hosts or []:
+                source = 'line {} of {}'.format(lineno, filename)
+                session.add_trusted_host(host, source=source)
+
+
+def handle_line(
+    line,  # type: ParsedLine
+    options=None,  # type: Optional[optparse.Values]
+    finder=None,  # type: Optional[PackageFinder]
+    session=None,  # type: Optional[PipSession]
+):
+    # type: (...) -> Optional[ParsedRequirement]
+    """Handle a single parsed requirements line; This can result in
+    creating/yielding requirements, or updating the finder.
+
+    :param line:        The parsed line to be processed.
+    :param options:     CLI options.
+    :param finder:      The finder - updated by non-requirement lines.
+    :param session:     The session - updated by non-requirement lines.
+
+    Returns a ParsedRequirement object if the line is a requirement line,
+    otherwise returns None.
+
+    For lines that contain requirements, the only options that have an effect
+    are from SUPPORTED_OPTIONS_REQ, and they are scoped to the
+    requirement. Other options from SUPPORTED_OPTIONS may be present, but are
+    ignored.
+
+    For lines that do not contain requirements, the only options that have an
+    effect are from SUPPORTED_OPTIONS. Options from SUPPORTED_OPTIONS_REQ may
+    be present, but are ignored. These lines may contain multiple options
+    (although our docs imply only one is supported), and all our parsed and
+    affect the finder.
+    """
+
+    if line.is_requirement:
+        parsed_req = handle_requirement_line(line, options)
+        return parsed_req
+    else:
+        handle_option_line(
+            line.opts,
+            line.filename,
+            line.lineno,
+            finder,
+            options,
+            session,
+        )
+        return None
+
+
+class RequirementsFileParser(object):
+    def __init__(
+        self,
+        session,  # type: PipSession
+        line_parser,  # type: LineParser
+        comes_from,  # type: Optional[str]
+    ):
+        # type: (...) -> None
+        self._session = session
+        self._line_parser = line_parser
+        self._comes_from = comes_from
+
+    def parse(self, filename, constraint):
+        # type: (str, bool) -> Iterator[ParsedLine]
+        """Parse a given file, yielding parsed lines.
+        """
+        for line in self._parse_and_recurse(filename, constraint):
+            yield line
+
+    def _parse_and_recurse(self, filename, constraint):
+        # type: (str, bool) -> Iterator[ParsedLine]
+        for line in self._parse_file(filename, constraint):
+            if (
+                not line.is_requirement and
+                (line.opts.requirements or line.opts.constraints)
+            ):
+                # parse a nested requirements file
+                if line.opts.requirements:
+                    req_path = line.opts.requirements[0]
+                    nested_constraint = False
+                else:
+                    req_path = line.opts.constraints[0]
+                    nested_constraint = True
+
+                # original file is over http
+                if SCHEME_RE.search(filename):
+                    # do a url join so relative paths work
+                    req_path = urllib_parse.urljoin(filename, req_path)
+                # original file and nested file are paths
+                elif not SCHEME_RE.search(req_path):
+                    # do a join so relative paths work
+                    req_path = os.path.join(
+                        os.path.dirname(filename), req_path,
+                    )
+
+                for inner_line in self._parse_and_recurse(
+                    req_path, nested_constraint,
+                ):
+                    yield inner_line
+            else:
+                yield line
+
+    def _parse_file(self, filename, constraint):
+        # type: (str, bool) -> Iterator[ParsedLine]
+        _, content = get_file_content(
+            filename, self._session, comes_from=self._comes_from
+        )
+
+        lines_enum = preprocess(content)
+
+        for line_number, line in lines_enum:
+            try:
+                args_str, opts = self._line_parser(line)
+            except OptionParsingError as e:
+                # add offending line
+                msg = 'Invalid requirement: {}\n{}'.format(line, e.msg)
+                raise RequirementsFileParseError(msg)
+
+            yield ParsedLine(
+                filename,
+                line_number,
+                self._comes_from,
+                args_str,
+                opts,
+                constraint,
+            )
+
+
+def get_line_parser(finder):
+    # type: (Optional[PackageFinder]) -> LineParser
+    def parse_line(line):
+        # type: (Text) -> Tuple[str, Values]
+        # Build new parser for each line since it accumulates appendable
+        # options.
+        parser = build_parser()
+        defaults = parser.get_default_values()
+        defaults.index_url = None
+        if finder:
+            defaults.format_control = finder.format_control
+
+        args_str, options_str = break_args_options(line)
+        # Prior to 2.7.3, shlex cannot deal with unicode entries
+        if sys.version_info < (2, 7, 3):
+            # https://github.com/python/mypy/issues/1174
+            options_str = options_str.encode('utf8')  # type: ignore
+
+        # https://github.com/python/mypy/issues/1174
+        opts, _ = parser.parse_args(
+            shlex.split(options_str), defaults)  # type: ignore
+
+        return args_str, opts
+
+    return parse_line
+
+
+def break_args_options(line):
+    # type: (Text) -> Tuple[str, Text]
+    """Break up the line into an args and options string.  We only want to shlex
+    (and then optparse) the options, not the args.  args can contain markers
+    which are corrupted by shlex.
+    """
+    tokens = line.split(' ')
+    args = []
+    options = tokens[:]
+    for token in tokens:
+        if token.startswith('-') or token.startswith('--'):
+            break
+        else:
+            args.append(token)
+            options.pop(0)
+    return ' '.join(args), ' '.join(options)  # type: ignore
+
+
+class OptionParsingError(Exception):
+    def __init__(self, msg):
+        # type: (str) -> None
+        self.msg = msg
+
+
+def build_parser():
+    # type: () -> optparse.OptionParser
+    """
+    Return a parser for parsing requirement lines
+    """
+    parser = optparse.OptionParser(add_help_option=False)
+
+    option_factories = SUPPORTED_OPTIONS + SUPPORTED_OPTIONS_REQ
+    for option_factory in option_factories:
+        option = option_factory()
+        parser.add_option(option)
+
+    # By default optparse sys.exits on parsing errors. We want to wrap
+    # that in our own exception.
+    def parser_exit(self, msg):
+        # type: (Any, str) -> NoReturn
+        raise OptionParsingError(msg)
+    # NOTE: mypy disallows assigning to a method
+    #       https://github.com/python/mypy/issues/2427
+    parser.exit = parser_exit  # type: ignore
+
+    return parser
+
+
+def join_lines(lines_enum):
+    # type: (ReqFileLines) -> ReqFileLines
+    """Joins a line ending in '\' with the previous line (except when following
+    comments).  The joined line takes on the index of the first line.
+    """
+    primary_line_number = None
+    new_line = []  # type: List[Text]
+    for line_number, line in lines_enum:
+        if not line.endswith('\\') or COMMENT_RE.match(line):
+            if COMMENT_RE.match(line):
+                # this ensures comments are always matched later
+                line = ' ' + line
+            if new_line:
+                new_line.append(line)
+                assert primary_line_number is not None
+                yield primary_line_number, ''.join(new_line)
+                new_line = []
+            else:
+                yield line_number, line
+        else:
+            if not new_line:
+                primary_line_number = line_number
+            new_line.append(line.strip('\\'))
+
+    # last line contains \
+    if new_line:
+        assert primary_line_number is not None
+        yield primary_line_number, ''.join(new_line)
+
+    # TODO: handle space after '\'.
+
+
+def ignore_comments(lines_enum):
+    # type: (ReqFileLines) -> ReqFileLines
+    """
+    Strips comments and filter empty lines.
+    """
+    for line_number, line in lines_enum:
+        line = COMMENT_RE.sub('', line)
+        line = line.strip()
+        if line:
+            yield line_number, line
+
+
+def expand_env_variables(lines_enum):
+    # type: (ReqFileLines) -> ReqFileLines
+    """Replace all environment variables that can be retrieved via `os.getenv`.
+
+    The only allowed format for environment variables defined in the
+    requirement file is `${MY_VARIABLE_1}` to ensure two things:
+
+    1. Strings that contain a `$` aren't accidentally (partially) expanded.
+    2. Ensure consistency across platforms for requirement files.
+
+    These points are the result of a discussion on the `github pull
+    request #3514 <https://github.com/pypa/pip/pull/3514>`_.
+
+    Valid characters in variable names follow the `POSIX standard
+    <http://pubs.opengroup.org/onlinepubs/9699919799/>`_ and are limited
+    to uppercase letter, digits and the `_` (underscore).
+    """
+    for line_number, line in lines_enum:
+        for env_var, var_name in ENV_VAR_RE.findall(line):
+            value = os.getenv(var_name)
+            if not value:
+                continue
+
+            line = line.replace(env_var, value)
+
+        yield line_number, line
+
+
+def get_file_content(url, session, comes_from=None):
+    # type: (str, PipSession, Optional[str]) -> Tuple[str, Text]
+    """Gets the content of a file; it may be a filename, file: URL, or
+    http: URL.  Returns (location, content).  Content is unicode.
+    Respects # -*- coding: declarations on the retrieved files.
+
+    :param url:         File path or url.
+    :param session:     PipSession instance.
+    :param comes_from:  Origin description of requirements.
+    """
+    scheme = get_url_scheme(url)
+
+    if scheme in ['http', 'https']:
+        # FIXME: catch some errors
+        resp = session.get(url)
+        raise_for_status(resp)
+        return resp.url, resp.text
+
+    elif scheme == 'file':
+        if comes_from and comes_from.startswith('http'):
+            raise InstallationError(
+                'Requirements file {} references URL {}, '
+                'which is local'.format(comes_from, url)
+            )
+
+        path = url.split(':', 1)[1]
+        path = path.replace('\\', '/')
+        match = _url_slash_drive_re.match(path)
+        if match:
+            path = match.group(1) + ':' + path.split('|', 1)[1]
+        path = urllib_parse.unquote(path)
+        if path.startswith('/'):
+            path = '/' + path.lstrip('/')
+        url = path
+
+    try:
+        with open(url, 'rb') as f:
+            content = auto_decode(f.read())
+    except IOError as exc:
+        raise InstallationError(
+            'Could not open requirements file: {}'.format(exc)
+        )
+    return url, content
+
+
+_url_slash_drive_re = re.compile(r'/*([a-z])\|', re.I)

venv/Lib/site-packages/pip/_internal/req/req_install.py

@@ -0,0 +1,905 @@
+# The following comment should be removed at some point in the future.
+# mypy: strict-optional=False
+
+from __future__ import absolute_import
+
+import logging
+import os
+import shutil
+import sys
+import uuid
+import zipfile
+
+from pip._vendor import pkg_resources, six
+from pip._vendor.packaging.requirements import Requirement
+from pip._vendor.packaging.utils import canonicalize_name
+from pip._vendor.packaging.version import Version
+from pip._vendor.packaging.version import parse as parse_version
+from pip._vendor.pep517.wrappers import Pep517HookCaller
+
+from pip._internal.build_env import NoOpBuildEnvironment
+from pip._internal.exceptions import InstallationError
+from pip._internal.locations import get_scheme
+from pip._internal.models.link import Link
+from pip._internal.operations.build.metadata import generate_metadata
+from pip._internal.operations.build.metadata_legacy import \
+    generate_metadata as generate_metadata_legacy
+from pip._internal.operations.install.editable_legacy import \
+    install_editable as install_editable_legacy
+from pip._internal.operations.install.legacy import LegacyInstallFailure
+from pip._internal.operations.install.legacy import install as install_legacy
+from pip._internal.operations.install.wheel import install_wheel
+from pip._internal.pyproject import load_pyproject_toml, make_pyproject_path
+from pip._internal.req.req_uninstall import UninstallPathSet
+from pip._internal.utils.deprecation import deprecated
+from pip._internal.utils.direct_url_helpers import direct_url_from_link
+from pip._internal.utils.hashes import Hashes
+from pip._internal.utils.logging import indent_log
+from pip._internal.utils.misc import (
+    ask_path_exists,
+    backup_dir,
+    display_path,
+    dist_in_site_packages,
+    dist_in_usersite,
+    get_distribution,
+    get_installed_version,
+    hide_url,
+    redact_auth_from_url,
+)
+from pip._internal.utils.packaging import get_metadata
+from pip._internal.utils.temp_dir import TempDirectory, tempdir_kinds
+from pip._internal.utils.typing import MYPY_CHECK_RUNNING
+from pip._internal.utils.virtualenv import running_under_virtualenv
+from pip._internal.vcs import vcs
+
+if MYPY_CHECK_RUNNING:
+    from typing import (
+        Any, Dict, Iterable, List, Optional, Sequence, Union,
+    )
+    from pip._internal.build_env import BuildEnvironment
+    from pip._vendor.pkg_resources import Distribution
+    from pip._vendor.packaging.specifiers import SpecifierSet
+    from pip._vendor.packaging.markers import Marker
+
+
+logger = logging.getLogger(__name__)
+
+
+def _get_dist(metadata_directory):
+    # type: (str) -> Distribution
+    """Return a pkg_resources.Distribution for the provided
+    metadata directory.
+    """
+    dist_dir = metadata_directory.rstrip(os.sep)
+
+    # Build a PathMetadata object, from path to metadata. :wink:
+    base_dir, dist_dir_name = os.path.split(dist_dir)
+    metadata = pkg_resources.PathMetadata(base_dir, dist_dir)
+
+    # Determine the correct Distribution object type.
+    if dist_dir.endswith(".egg-info"):
+        dist_cls = pkg_resources.Distribution
+        dist_name = os.path.splitext(dist_dir_name)[0]
+    else:
+        assert dist_dir.endswith(".dist-info")
+        dist_cls = pkg_resources.DistInfoDistribution
+        dist_name = os.path.splitext(dist_dir_name)[0].split("-")[0]
+
+    return dist_cls(
+        base_dir,
+        project_name=dist_name,
+        metadata=metadata,
+    )
+
+
+class InstallRequirement(object):
+    """
+    Represents something that may be installed later on, may have information
+    about where to fetch the relevant requirement and also contains logic for
+    installing the said requirement.
+    """
+
+    def __init__(
+        self,
+        req,  # type: Optional[Requirement]
+        comes_from,  # type: Optional[Union[str, InstallRequirement]]
+        editable=False,  # type: bool
+        link=None,  # type: Optional[Link]
+        markers=None,  # type: Optional[Marker]
+        use_pep517=None,  # type: Optional[bool]
+        isolated=False,  # type: bool
+        install_options=None,  # type: Optional[List[str]]
+        global_options=None,  # type: Optional[List[str]]
+        hash_options=None,  # type: Optional[Dict[str, List[str]]]
+        constraint=False,  # type: bool
+        extras=(),  # type: Iterable[str]
+        user_supplied=False,  # type: bool
+    ):
+        # type: (...) -> None
+        assert req is None or isinstance(req, Requirement), req
+        self.req = req
+        self.comes_from = comes_from
+        self.constraint = constraint
+        self.editable = editable
+        self.legacy_install_reason = None  # type: Optional[int]
+
+        # source_dir is the local directory where the linked requirement is
+        # located, or unpacked. In case unpacking is needed, creating and
+        # populating source_dir is done by the RequirementPreparer. Note this
+        # is not necessarily the directory where pyproject.toml or setup.py is
+        # located - that one is obtained via unpacked_source_directory.
+        self.source_dir = None  # type: Optional[str]
+        if self.editable:
+            assert link
+            if link.is_file:
+                self.source_dir = os.path.normpath(
+                    os.path.abspath(link.file_path)
+                )
+
+        if link is None and req and req.url:
+            # PEP 508 URL requirement
+            link = Link(req.url)
+        self.link = self.original_link = link
+        self.original_link_is_in_wheel_cache = False
+
+        # Path to any downloaded or already-existing package.
+        self.local_file_path = None  # type: Optional[str]
+        if self.link and self.link.is_file:
+            self.local_file_path = self.link.file_path
+
+        if extras:
+            self.extras = extras
+        elif req:
+            self.extras = {
+                pkg_resources.safe_extra(extra) for extra in req.extras
+            }
+        else:
+            self.extras = set()
+        if markers is None and req:
+            markers = req.marker
+        self.markers = markers
+
+        # This holds the pkg_resources.Distribution object if this requirement
+        # is already available:
+        self.satisfied_by = None  # type: Optional[Distribution]
+        # Whether the installation process should try to uninstall an existing
+        # distribution before installing this requirement.
+        self.should_reinstall = False
+        # Temporary build location
+        self._temp_build_dir = None  # type: Optional[TempDirectory]
+        # Set to True after successful installation
+        self.install_succeeded = None  # type: Optional[bool]
+        # Supplied options
+        self.install_options = install_options if install_options else []
+        self.global_options = global_options if global_options else []
+        self.hash_options = hash_options if hash_options else {}
+        # Set to True after successful preparation of this requirement
+        self.prepared = False
+        # User supplied requirement are explicitly requested for installation
+        # by the user via CLI arguments or requirements files, as opposed to,
+        # e.g. dependencies, extras or constraints.
+        self.user_supplied = user_supplied
+
+        # Set by the legacy resolver when the requirement has been downloaded
+        # TODO: This introduces a strong coupling between the resolver and the
+        #       requirement (the coupling was previously between the resolver
+        #       and the requirement set). This should be refactored to allow
+        #       the requirement to decide for itself when it has been
+        #       successfully downloaded - but that is more tricky to get right,
+        #       se we are making the change in stages.
+        self.successfully_downloaded = False
+
+        self.isolated = isolated
+        self.build_env = NoOpBuildEnvironment()  # type: BuildEnvironment
+
+        # For PEP 517, the directory where we request the project metadata
+        # gets stored. We need this to pass to build_wheel, so the backend
+        # can ensure that the wheel matches the metadata (see the PEP for
+        # details).
+        self.metadata_directory = None  # type: Optional[str]
+
+        # The static build requirements (from pyproject.toml)
+        self.pyproject_requires = None  # type: Optional[List[str]]
+
+        # Build requirements that we will check are available
+        self.requirements_to_check = []  # type: List[str]
+
+        # The PEP 517 backend we should use to build the project
+        self.pep517_backend = None  # type: Optional[Pep517HookCaller]
+
+        # Are we using PEP 517 for this requirement?
+        # After pyproject.toml has been loaded, the only valid values are True
+        # and False. Before loading, None is valid (meaning "use the default").
+        # Setting an explicit value before loading pyproject.toml is supported,
+        # but after loading this flag should be treated as read only.
+        self.use_pep517 = use_pep517
+
+    def __str__(self):
+        # type: () -> str
+        if self.req:
+            s = str(self.req)
+            if self.link:
+                s += ' from {}'.format(redact_auth_from_url(self.link.url))
+        elif self.link:
+            s = redact_auth_from_url(self.link.url)
+        else:
+            s = '<InstallRequirement>'
+        if self.satisfied_by is not None:
+            s += ' in {}'.format(display_path(self.satisfied_by.location))
+        if self.comes_from:
+            if isinstance(self.comes_from, six.string_types):
+                comes_from = self.comes_from  # type: Optional[str]
+            else:
+                comes_from = self.comes_from.from_path()
+            if comes_from:
+                s += ' (from {})'.format(comes_from)
+        return s
+
+    def __repr__(self):
+        # type: () -> str
+        return '<{} object: {} editable={!r}>'.format(
+            self.__class__.__name__, str(self), self.editable)
+
+    def format_debug(self):
+        # type: () -> str
+        """An un-tested helper for getting state, for debugging.
+        """
+        attributes = vars(self)
+        names = sorted(attributes)
+
+        state = (
+            "{}={!r}".format(attr, attributes[attr]) for attr in sorted(names)
+        )
+        return '<{name} object: {{{state}}}>'.format(
+            name=self.__class__.__name__,
+            state=", ".join(state),
+        )
+
+    # Things that are valid for all kinds of requirements?
+    @property
+    def name(self):
+        # type: () -> Optional[str]
+        if self.req is None:
+            return None
+        return six.ensure_str(pkg_resources.safe_name(self.req.name))
+
+    @property
+    def specifier(self):
+        # type: () -> SpecifierSet
+        return self.req.specifier
+
+    @property
+    def is_pinned(self):
+        # type: () -> bool
+        """Return whether I am pinned to an exact version.
+
+        For example, some-package==1.2 is pinned; some-package>1.2 is not.
+        """
+        specifiers = self.specifier
+        return (len(specifiers) == 1 and
+                next(iter(specifiers)).operator in {'==', '==='})
+
+    @property
+    def installed_version(self):
+        # type: () -> Optional[str]
+        return get_installed_version(self.name)
+
+    def match_markers(self, extras_requested=None):
+        # type: (Optional[Iterable[str]]) -> bool
+        if not extras_requested:
+            # Provide an extra to safely evaluate the markers
+            # without matching any extra
+            extras_requested = ('',)
+        if self.markers is not None:
+            return any(
+                self.markers.evaluate({'extra': extra})
+                for extra in extras_requested)
+        else:
+            return True
+
+    @property
+    def has_hash_options(self):
+        # type: () -> bool
+        """Return whether any known-good hashes are specified as options.
+
+        These activate --require-hashes mode; hashes specified as part of a
+        URL do not.
+
+        """
+        return bool(self.hash_options)
+
+    def hashes(self, trust_internet=True):
+        # type: (bool) -> Hashes
+        """Return a hash-comparer that considers my option- and URL-based
+        hashes to be known-good.
+
+        Hashes in URLs--ones embedded in the requirements file, not ones
+        downloaded from an index server--are almost peers with ones from
+        flags. They satisfy --require-hashes (whether it was implicitly or
+        explicitly activated) but do not activate it. md5 and sha224 are not
+        allowed in flags, which should nudge people toward good algos. We
+        always OR all hashes together, even ones from URLs.
+
+        :param trust_internet: Whether to trust URL-based (#md5=...) hashes
+            downloaded from the internet, as by populate_link()
+
+        """
+        good_hashes = self.hash_options.copy()
+        link = self.link if trust_internet else self.original_link
+        if link and link.hash:
+            good_hashes.setdefault(link.hash_name, []).append(link.hash)
+        return Hashes(good_hashes)
+
+    def from_path(self):
+        # type: () -> Optional[str]
+        """Format a nice indicator to show where this "comes from"
+        """
+        if self.req is None:
+            return None
+        s = str(self.req)
+        if self.comes_from:
+            if isinstance(self.comes_from, six.string_types):
+                comes_from = self.comes_from
+            else:
+                comes_from = self.comes_from.from_path()
+            if comes_from:
+                s += '->' + comes_from
+        return s
+
+    def ensure_build_location(self, build_dir, autodelete, parallel_builds):
+        # type: (str, bool, bool) -> str
+        assert build_dir is not None
+        if self._temp_build_dir is not None:
+            assert self._temp_build_dir.path
+            return self._temp_build_dir.path
+        if self.req is None:
+            # Some systems have /tmp as a symlink which confuses custom
+            # builds (such as numpy). Thus, we ensure that the real path
+            # is returned.
+            self._temp_build_dir = TempDirectory(
+                kind=tempdir_kinds.REQ_BUILD, globally_managed=True
+            )
+
+            return self._temp_build_dir.path
+
+        # When parallel builds are enabled, add a UUID to the build directory
+        # name so multiple builds do not interfere with each other.
+        dir_name = canonicalize_name(self.name)
+        if parallel_builds:
+            dir_name = "{}_{}".format(dir_name, uuid.uuid4().hex)
+
+        # FIXME: Is there a better place to create the build_dir? (hg and bzr
+        # need this)
+        if not os.path.exists(build_dir):
+            logger.debug('Creating directory %s', build_dir)
+            os.makedirs(build_dir)
+        actual_build_dir = os.path.join(build_dir, dir_name)
+        # `None` indicates that we respect the globally-configured deletion
+        # settings, which is what we actually want when auto-deleting.
+        delete_arg = None if autodelete else False
+        return TempDirectory(
+            path=actual_build_dir,
+            delete=delete_arg,
+            kind=tempdir_kinds.REQ_BUILD,
+            globally_managed=True,
+        ).path
+
+    def _set_requirement(self):
+        # type: () -> None
+        """Set requirement after generating metadata.
+        """
+        assert self.req is None
+        assert self.metadata is not None
+        assert self.source_dir is not None
+
+        # Construct a Requirement object from the generated metadata
+        if isinstance(parse_version(self.metadata["Version"]), Version):
+            op = "=="
+        else:
+            op = "==="
+
+        self.req = Requirement(
+            "".join([
+                self.metadata["Name"],
+                op,
+                self.metadata["Version"],
+            ])
+        )
+
+    def warn_on_mismatching_name(self):
+        # type: () -> None
+        metadata_name = canonicalize_name(self.metadata["Name"])
+        if canonicalize_name(self.req.name) == metadata_name:
+            # Everything is fine.
+            return
+
+        # If we're here, there's a mismatch. Log a warning about it.
+        logger.warning(
+            'Generating metadata for package %s '
+            'produced metadata for project name %s. Fix your '
+            '#egg=%s fragments.',
+            self.name, metadata_name, self.name
+        )
+        self.req = Requirement(metadata_name)
+
+    def check_if_exists(self, use_user_site):
+        # type: (bool) -> None
+        """Find an installed distribution that satisfies or conflicts
+        with this requirement, and set self.satisfied_by or
+        self.should_reinstall appropriately.
+        """
+        if self.req is None:
+            return
+        existing_dist = get_distribution(self.req.name)
+        if not existing_dist:
+            return
+
+        existing_version = existing_dist.parsed_version
+        if not self.req.specifier.contains(existing_version, prereleases=True):
+            self.satisfied_by = None
+            if use_user_site:
+                if dist_in_usersite(existing_dist):
+                    self.should_reinstall = True
+                elif (running_under_virtualenv() and
+                        dist_in_site_packages(existing_dist)):
+                    raise InstallationError(
+                        "Will not install to the user site because it will "
+                        "lack sys.path precedence to {} in {}".format(
+                            existing_dist.project_name, existing_dist.location)
+                    )
+            else:
+                self.should_reinstall = True
+        else:
+            if self.editable:
+                self.should_reinstall = True
+                # when installing editables, nothing pre-existing should ever
+                # satisfy
+                self.satisfied_by = None
+            else:
+                self.satisfied_by = existing_dist
+
+    # Things valid for wheels
+    @property
+    def is_wheel(self):
+        # type: () -> bool
+        if not self.link:
+            return False
+        return self.link.is_wheel
+
+    # Things valid for sdists
+    @property
+    def unpacked_source_directory(self):
+        # type: () -> str
+        return os.path.join(
+            self.source_dir,
+            self.link and self.link.subdirectory_fragment or '')
+
+    @property
+    def setup_py_path(self):
+        # type: () -> str
+        assert self.source_dir, "No source dir for {}".format(self)
+        setup_py = os.path.join(self.unpacked_source_directory, 'setup.py')
+
+        # Python2 __file__ should not be unicode
+        if six.PY2 and isinstance(setup_py, six.text_type):
+            setup_py = setup_py.encode(sys.getfilesystemencoding())
+
+        return setup_py
+
+    @property
+    def pyproject_toml_path(self):
+        # type: () -> str
+        assert self.source_dir, "No source dir for {}".format(self)
+        return make_pyproject_path(self.unpacked_source_directory)
+
+    def load_pyproject_toml(self):
+        # type: () -> None
+        """Load the pyproject.toml file.
+
+        After calling this routine, all of the attributes related to PEP 517
+        processing for this requirement have been set. In particular, the
+        use_pep517 attribute can be used to determine whether we should
+        follow the PEP 517 or legacy (setup.py) code path.
+        """
+        pyproject_toml_data = load_pyproject_toml(
+            self.use_pep517,
+            self.pyproject_toml_path,
+            self.setup_py_path,
+            str(self)
+        )
+
+        if pyproject_toml_data is None:
+            self.use_pep517 = False
+            return
+
+        self.use_pep517 = True
+        requires, backend, check, backend_path = pyproject_toml_data
+        self.requirements_to_check = check
+        self.pyproject_requires = requires
+        self.pep517_backend = Pep517HookCaller(
+            self.unpacked_source_directory, backend, backend_path=backend_path,
+        )
+
+    def _generate_metadata(self):
+        # type: () -> str
+        """Invokes metadata generator functions, with the required arguments.
+        """
+        if not self.use_pep517:
+            assert self.unpacked_source_directory
+
+            return generate_metadata_legacy(
+                build_env=self.build_env,
+                setup_py_path=self.setup_py_path,
+                source_dir=self.unpacked_source_directory,
+                isolated=self.isolated,
+                details=self.name or "from {}".format(self.link)
+            )
+
+        assert self.pep517_backend is not None
+
+        return generate_metadata(
+            build_env=self.build_env,
+            backend=self.pep517_backend,
+        )
+
+    def prepare_metadata(self):
+        # type: () -> None
+        """Ensure that project metadata is available.
+
+        Under PEP 517, call the backend hook to prepare the metadata.
+        Under legacy processing, call setup.py egg-info.
+        """
+        assert self.source_dir
+
+        with indent_log():
+            self.metadata_directory = self._generate_metadata()
+
+        # Act on the newly generated metadata, based on the name and version.
+        if not self.name:
+            self._set_requirement()
+        else:
+            self.warn_on_mismatching_name()
+
+        self.assert_source_matches_version()
+
+    @property
+    def metadata(self):
+        # type: () -> Any
+        if not hasattr(self, '_metadata'):
+            self._metadata = get_metadata(self.get_dist())
+
+        return self._metadata
+
+    def get_dist(self):
+        # type: () -> Distribution
+        return _get_dist(self.metadata_directory)
+
+    def assert_source_matches_version(self):
+        # type: () -> None
+        assert self.source_dir
+        version = self.metadata['version']
+        if self.req.specifier and version not in self.req.specifier:
+            logger.warning(
+                'Requested %s, but installing version %s',
+                self,
+                version,
+            )
+        else:
+            logger.debug(
+                'Source in %s has version %s, which satisfies requirement %s',
+                display_path(self.source_dir),
+                version,
+                self,
+            )
+
+    # For both source distributions and editables
+    def ensure_has_source_dir(
+        self,
+        parent_dir,
+        autodelete=False,
+        parallel_builds=False,
+    ):
+        # type: (str, bool, bool) -> None
+        """Ensure that a source_dir is set.
+
+        This will create a temporary build dir if the name of the requirement
+        isn't known yet.
+
+        :param parent_dir: The ideal pip parent_dir for the source_dir.
+            Generally src_dir for editables and build_dir for sdists.
+        :return: self.source_dir
+        """
+        if self.source_dir is None:
+            self.source_dir = self.ensure_build_location(
+                parent_dir,
+                autodelete=autodelete,
+                parallel_builds=parallel_builds,
+            )
+
+    # For editable installations
+    def update_editable(self, obtain=True):
+        # type: (bool) -> None
+        if not self.link:
+            logger.debug(
+                "Cannot update repository at %s; repository location is "
+                "unknown",
+                self.source_dir,
+            )
+            return
+        assert self.editable
+        assert self.source_dir
+        if self.link.scheme == 'file':
+            # Static paths don't get updated
+            return
+        assert '+' in self.link.url, \
+            "bad url: {self.link.url!r}".format(**locals())
+        vc_type, url = self.link.url.split('+', 1)
+        vcs_backend = vcs.get_backend(vc_type)
+        if vcs_backend:
+            if not self.link.is_vcs:
+                reason = (
+                    "This form of VCS requirement is being deprecated: {}."
+                ).format(
+                    self.link.url
+                )
+                replacement = None
+                if self.link.url.startswith("git+git@"):
+                    replacement = (
+                        "git+https://git@example.com/..., "
+                        "git+ssh://git@example.com/..., "
+                        "or the insecure git+git://git@example.com/..."
+                    )
+                deprecated(reason, replacement, gone_in="21.0", issue=7554)
+            hidden_url = hide_url(self.link.url)
+            if obtain:
+                vcs_backend.obtain(self.source_dir, url=hidden_url)
+            else:
+                vcs_backend.export(self.source_dir, url=hidden_url)
+        else:
+            assert 0, (
+                'Unexpected version control type (in {}): {}'.format(
+                    self.link, vc_type))
+
+    # Top-level Actions
+    def uninstall(self, auto_confirm=False, verbose=False):
+        # type: (bool, bool) -> Optional[UninstallPathSet]
+        """
+        Uninstall the distribution currently satisfying this requirement.
+
+        Prompts before removing or modifying files unless
+        ``auto_confirm`` is True.
+
+        Refuses to delete or modify files outside of ``sys.prefix`` -
+        thus uninstallation within a virtual environment can only
+        modify that virtual environment, even if the virtualenv is
+        linked to global site-packages.
+
+        """
+        assert self.req
+        dist = get_distribution(self.req.name)
+        if not dist:
+            logger.warning("Skipping %s as it is not installed.", self.name)
+            return None
+        logger.info('Found existing installation: %s', dist)
+
+        uninstalled_pathset = UninstallPathSet.from_dist(dist)
+        uninstalled_pathset.remove(auto_confirm, verbose)
+        return uninstalled_pathset
+
+    def _get_archive_name(self, path, parentdir, rootdir):
+        # type: (str, str, str) -> str
+
+        def _clean_zip_name(name, prefix):
+            # type: (str, str) -> str
+            assert name.startswith(prefix + os.path.sep), (
+                "name {name!r} doesn't start with prefix {prefix!r}"
+                .format(**locals())
+            )
+            name = name[len(prefix) + 1:]
+            name = name.replace(os.path.sep, '/')
+            return name
+
+        path = os.path.join(parentdir, path)
+        name = _clean_zip_name(path, rootdir)
+        return self.name + '/' + name
+
+    def archive(self, build_dir):
+        # type: (str) -> None
+        """Saves archive to provided build_dir.
+
+        Used for saving downloaded VCS requirements as part of `pip download`.
+        """
+        assert self.source_dir
+
+        create_archive = True
+        archive_name = '{}-{}.zip'.format(self.name, self.metadata["version"])
+        archive_path = os.path.join(build_dir, archive_name)
+
+        if os.path.exists(archive_path):
+            response = ask_path_exists(
+                'The file {} exists. (i)gnore, (w)ipe, '
+                '(b)ackup, (a)bort '.format(
+                    display_path(archive_path)),
+                ('i', 'w', 'b', 'a'))
+            if response == 'i':
+                create_archive = False
+            elif response == 'w':
+                logger.warning('Deleting %s', display_path(archive_path))
+                os.remove(archive_path)
+            elif response == 'b':
+                dest_file = backup_dir(archive_path)
+                logger.warning(
+                    'Backing up %s to %s',
+                    display_path(archive_path),
+                    display_path(dest_file),
+                )
+                shutil.move(archive_path, dest_file)
+            elif response == 'a':
+                sys.exit(-1)
+
+        if not create_archive:
+            return
+
+        zip_output = zipfile.ZipFile(
+            archive_path, 'w', zipfile.ZIP_DEFLATED, allowZip64=True,
+        )
+        with zip_output:
+            dir = os.path.normcase(
+                os.path.abspath(self.unpacked_source_directory)
+            )
+            for dirpath, dirnames, filenames in os.walk(dir):
+                for dirname in dirnames:
+                    dir_arcname = self._get_archive_name(
+                        dirname, parentdir=dirpath, rootdir=dir,
+                    )
+                    zipdir = zipfile.ZipInfo(dir_arcname + '/')
+                    zipdir.external_attr = 0x1ED << 16  # 0o755
+                    zip_output.writestr(zipdir, '')
+                for filename in filenames:
+                    file_arcname = self._get_archive_name(
+                        filename, parentdir=dirpath, rootdir=dir,
+                    )
+                    filename = os.path.join(dirpath, filename)
+                    zip_output.write(filename, file_arcname)
+
+        logger.info('Saved %s', display_path(archive_path))
+
+    def install(
+        self,
+        install_options,  # type: List[str]
+        global_options=None,  # type: Optional[Sequence[str]]
+        root=None,  # type: Optional[str]
+        home=None,  # type: Optional[str]
+        prefix=None,  # type: Optional[str]
+        warn_script_location=True,  # type: bool
+        use_user_site=False,  # type: bool
+        pycompile=True  # type: bool
+    ):
+        # type: (...) -> None
+        scheme = get_scheme(
+            self.name,
+            user=use_user_site,
+            home=home,
+            root=root,
+            isolated=self.isolated,
+            prefix=prefix,
+        )
+
+        global_options = global_options if global_options is not None else []
+        if self.editable:
+            install_editable_legacy(
+                install_options,
+                global_options,
+                prefix=prefix,
+                home=home,
+                use_user_site=use_user_site,
+                name=self.name,
+                setup_py_path=self.setup_py_path,
+                isolated=self.isolated,
+                build_env=self.build_env,
+                unpacked_source_directory=self.unpacked_source_directory,
+            )
+            self.install_succeeded = True
+            return
+
+        if self.is_wheel:
+            assert self.local_file_path
+            direct_url = None
+            if self.original_link:
+                direct_url = direct_url_from_link(
+                    self.original_link,
+                    self.source_dir,
+                    self.original_link_is_in_wheel_cache,
+                )
+            install_wheel(
+                self.name,
+                self.local_file_path,
+                scheme=scheme,
+                req_description=str(self.req),
+                pycompile=pycompile,
+                warn_script_location=warn_script_location,
+                direct_url=direct_url,
+                requested=self.user_supplied,
+            )
+            self.install_succeeded = True
+            return
+
+        # TODO: Why don't we do this for editable installs?
+
+        # Extend the list of global and install options passed on to
+        # the setup.py call with the ones from the requirements file.
+        # Options specified in requirements file override those
+        # specified on the command line, since the last option given
+        # to setup.py is the one that is used.
+        global_options = list(global_options) + self.global_options
+        install_options = list(install_options) + self.install_options
+
+        try:
+            success = install_legacy(
+                install_options=install_options,
+                global_options=global_options,
+                root=root,
+                home=home,
+                prefix=prefix,
+                use_user_site=use_user_site,
+                pycompile=pycompile,
+                scheme=scheme,
+                setup_py_path=self.setup_py_path,
+                isolated=self.isolated,
+                req_name=self.name,
+                build_env=self.build_env,
+                unpacked_source_directory=self.unpacked_source_directory,
+                req_description=str(self.req),
+            )
+        except LegacyInstallFailure as exc:
+            self.install_succeeded = False
+            six.reraise(*exc.parent)
+        except Exception:
+            self.install_succeeded = True
+            raise
+
+        self.install_succeeded = success
+
+        if success and self.legacy_install_reason == 8368:
+            deprecated(
+                reason=(
+                    "{} was installed using the legacy 'setup.py install' "
+                    "method, because a wheel could not be built for it.".
+                    format(self.name)
+                ),
+                replacement="to fix the wheel build issue reported above",
+                gone_in="21.0",
+                issue=8368,
+            )
+
+
+def check_invalid_constraint_type(req):
+    # type: (InstallRequirement) -> str
+
+    # Check for unsupported forms
+    problem = ""
+    if not req.name:
+        problem = "Unnamed requirements are not allowed as constraints"
+    elif req.link:
+        problem = "Links are not allowed as constraints"
+    elif req.extras:
+        problem = "Constraints cannot have extras"
+
+    if problem:
+        deprecated(
+            reason=(
+                "Constraints are only allowed to take the form of a package "
+                "name and a version specifier. Other forms were originally "
+                "permitted as an accident of the implementation, but were "
+                "undocumented. The new implementation of the resolver no "
+                "longer supports these forms."
+            ),
+            replacement=(
+                "replacing the constraint with a requirement."
+            ),
+            # No plan yet for when the new resolver becomes default
+            gone_in=None,
+            issue=8210
+        )
+
+    return problem

venv/Lib/site-packages/pip/_internal/req/req_set.py

@@ -0,0 +1,203 @@
+from __future__ import absolute_import
+
+import logging
+from collections import OrderedDict
+
+from pip._vendor.packaging.utils import canonicalize_name
+
+from pip._internal.exceptions import InstallationError
+from pip._internal.models.wheel import Wheel
+from pip._internal.utils import compatibility_tags
+from pip._internal.utils.typing import MYPY_CHECK_RUNNING
+
+if MYPY_CHECK_RUNNING:
+    from typing import Dict, Iterable, List, Optional, Tuple
+    from pip._internal.req.req_install import InstallRequirement
+
+
+logger = logging.getLogger(__name__)
+
+
+class RequirementSet(object):
+
+    def __init__(self, check_supported_wheels=True):
+        # type: (bool) -> None
+        """Create a RequirementSet.
+        """
+
+        self.requirements = OrderedDict()  # type: Dict[str, InstallRequirement]  # noqa: E501
+        self.check_supported_wheels = check_supported_wheels
+
+        self.unnamed_requirements = []  # type: List[InstallRequirement]
+
+    def __str__(self):
+        # type: () -> str
+        requirements = sorted(
+            (req for req in self.requirements.values() if not req.comes_from),
+            key=lambda req: canonicalize_name(req.name),
+        )
+        return ' '.join(str(req.req) for req in requirements)
+
+    def __repr__(self):
+        # type: () -> str
+        requirements = sorted(
+            self.requirements.values(),
+            key=lambda req: canonicalize_name(req.name),
+        )
+
+        format_string = '<{classname} object; {count} requirement(s): {reqs}>'
+        return format_string.format(
+            classname=self.__class__.__name__,
+            count=len(requirements),
+            reqs=', '.join(str(req.req) for req in requirements),
+        )
+
+    def add_unnamed_requirement(self, install_req):
+        # type: (InstallRequirement) -> None
+        assert not install_req.name
+        self.unnamed_requirements.append(install_req)
+
+    def add_named_requirement(self, install_req):
+        # type: (InstallRequirement) -> None
+        assert install_req.name
+
+        project_name = canonicalize_name(install_req.name)
+        self.requirements[project_name] = install_req
+
+    def add_requirement(
+        self,
+        install_req,  # type: InstallRequirement
+        parent_req_name=None,  # type: Optional[str]
+        extras_requested=None  # type: Optional[Iterable[str]]
+    ):
+        # type: (...) -> Tuple[List[InstallRequirement], Optional[InstallRequirement]]  # noqa: E501
+        """Add install_req as a requirement to install.
+
+        :param parent_req_name: The name of the requirement that needed this
+            added. The name is used because when multiple unnamed requirements
+            resolve to the same name, we could otherwise end up with dependency
+            links that point outside the Requirements set. parent_req must
+            already be added. Note that None implies that this is a user
+            supplied requirement, vs an inferred one.
+        :param extras_requested: an iterable of extras used to evaluate the
+            environment markers.
+        :return: Additional requirements to scan. That is either [] if
+            the requirement is not applicable, or [install_req] if the
+            requirement is applicable and has just been added.
+        """
+        # If the markers do not match, ignore this requirement.
+        if not install_req.match_markers(extras_requested):
+            logger.info(
+                "Ignoring %s: markers '%s' don't match your environment",
+                install_req.name, install_req.markers,
+            )
+            return [], None
+
+        # If the wheel is not supported, raise an error.
+        # Should check this after filtering out based on environment markers to
+        # allow specifying different wheels based on the environment/OS, in a
+        # single requirements file.
+        if install_req.link and install_req.link.is_wheel:
+            wheel = Wheel(install_req.link.filename)
+            tags = compatibility_tags.get_supported()
+            if (self.check_supported_wheels and not wheel.supported(tags)):
+                raise InstallationError(
+                    "{} is not a supported wheel on this platform.".format(
+                        wheel.filename)
+                )
+
+        # This next bit is really a sanity check.
+        assert not install_req.user_supplied or parent_req_name is None, (
+            "a user supplied req shouldn't have a parent"
+        )
+
+        # Unnamed requirements are scanned again and the requirement won't be
+        # added as a dependency until after scanning.
+        if not install_req.name:
+            self.add_unnamed_requirement(install_req)
+            return [install_req], None
+
+        try:
+            existing_req = self.get_requirement(
+                install_req.name)  # type: Optional[InstallRequirement]
+        except KeyError:
+            existing_req = None
+
+        has_conflicting_requirement = (
+            parent_req_name is None and
+            existing_req and
+            not existing_req.constraint and
+            existing_req.extras == install_req.extras and
+            existing_req.req.specifier != install_req.req.specifier
+        )
+        if has_conflicting_requirement:
+            raise InstallationError(
+                "Double requirement given: {} (already in {}, name={!r})"
+                .format(install_req, existing_req, install_req.name)
+            )
+
+        # When no existing requirement exists, add the requirement as a
+        # dependency and it will be scanned again after.
+        if not existing_req:
+            self.add_named_requirement(install_req)
+            # We'd want to rescan this requirement later
+            return [install_req], install_req
+
+        # Assume there's no need to scan, and that we've already
+        # encountered this for scanning.
+        if install_req.constraint or not existing_req.constraint:
+            return [], existing_req
+
+        does_not_satisfy_constraint = (
+            install_req.link and
+            not (
+                existing_req.link and
+                install_req.link.path == existing_req.link.path
+            )
+        )
+        if does_not_satisfy_constraint:
+            raise InstallationError(
+                "Could not satisfy constraints for '{}': "
+                "installation from path or url cannot be "
+                "constrained to a version".format(install_req.name)
+            )
+        # If we're now installing a constraint, mark the existing
+        # object for real installation.
+        existing_req.constraint = False
+        # If we're now installing a user supplied requirement,
+        # mark the existing object as such.
+        if install_req.user_supplied:
+            existing_req.user_supplied = True
+        existing_req.extras = tuple(sorted(
+            set(existing_req.extras) | set(install_req.extras)
+        ))
+        logger.debug(
+            "Setting %s extras to: %s",
+            existing_req, existing_req.extras,
+        )
+        # Return the existing requirement for addition to the parent and
+        # scanning again.
+        return [existing_req], existing_req
+
+    def has_requirement(self, name):
+        # type: (str) -> bool
+        project_name = canonicalize_name(name)
+
+        return (
+            project_name in self.requirements and
+            not self.requirements[project_name].constraint
+        )
+
+    def get_requirement(self, name):
+        # type: (str) -> InstallRequirement
+        project_name = canonicalize_name(name)
+
+        if project_name in self.requirements:
+            return self.requirements[project_name]
+
+        raise KeyError("No project with the name {name!r}".format(**locals()))
+
+    @property
+    def all_requirements(self):
+        # type: () -> List[InstallRequirement]
+        return self.unnamed_requirements + list(self.requirements.values())

venv/Lib/site-packages/pip/_internal/req/req_tracker.py

@@ -0,0 +1,150 @@
+from __future__ import absolute_import
+
+import contextlib
+import errno
+import hashlib
+import logging
+import os
+
+from pip._vendor import contextlib2
+
+from pip._internal.utils.temp_dir import TempDirectory
+from pip._internal.utils.typing import MYPY_CHECK_RUNNING
+
+if MYPY_CHECK_RUNNING:
+    from types import TracebackType
+    from typing import Dict, Iterator, Optional, Set, Type, Union
+    from pip._internal.req.req_install import InstallRequirement
+    from pip._internal.models.link import Link
+
+logger = logging.getLogger(__name__)
+
+
+@contextlib.contextmanager
+def update_env_context_manager(**changes):
+    # type: (str) -> Iterator[None]
+    target = os.environ
+
+    # Save values from the target and change them.
+    non_existent_marker = object()
+    saved_values = {}  # type: Dict[str, Union[object, str]]
+    for name, new_value in changes.items():
+        try:
+            saved_values[name] = target[name]
+        except KeyError:
+            saved_values[name] = non_existent_marker
+        target[name] = new_value
+
+    try:
+        yield
+    finally:
+        # Restore original values in the target.
+        for name, original_value in saved_values.items():
+            if original_value is non_existent_marker:
+                del target[name]
+            else:
+                assert isinstance(original_value, str)  # for mypy
+                target[name] = original_value
+
+
+@contextlib.contextmanager
+def get_requirement_tracker():
+    # type: () -> Iterator[RequirementTracker]
+    root = os.environ.get('PIP_REQ_TRACKER')
+    with contextlib2.ExitStack() as ctx:
+        if root is None:
+            root = ctx.enter_context(
+                TempDirectory(kind='req-tracker')
+            ).path
+            ctx.enter_context(update_env_context_manager(PIP_REQ_TRACKER=root))
+            logger.debug("Initialized build tracking at %s", root)
+
+        with RequirementTracker(root) as tracker:
+            yield tracker
+
+
+class RequirementTracker(object):
+
+    def __init__(self, root):
+        # type: (str) -> None
+        self._root = root
+        self._entries = set()  # type: Set[InstallRequirement]
+        logger.debug("Created build tracker: %s", self._root)
+
+    def __enter__(self):
+        # type: () -> RequirementTracker
+        logger.debug("Entered build tracker: %s", self._root)
+        return self
+
+    def __exit__(
+        self,
+        exc_type,  # type: Optional[Type[BaseException]]
+        exc_val,  # type: Optional[BaseException]
+        exc_tb  # type: Optional[TracebackType]
+    ):
+        # type: (...) -> None
+        self.cleanup()
+
+    def _entry_path(self, link):
+        # type: (Link) -> str
+        hashed = hashlib.sha224(link.url_without_fragment.encode()).hexdigest()
+        return os.path.join(self._root, hashed)
+
+    def add(self, req):
+        # type: (InstallRequirement) -> None
+        """Add an InstallRequirement to build tracking.
+        """
+
+        assert req.link
+        # Get the file to write information about this requirement.
+        entry_path = self._entry_path(req.link)
+
+        # Try reading from the file. If it exists and can be read from, a build
+        # is already in progress, so a LookupError is raised.
+        try:
+            with open(entry_path) as fp:
+                contents = fp.read()
+        except IOError as e:
+            # if the error is anything other than "file does not exist", raise.
+            if e.errno != errno.ENOENT:
+                raise
+        else:
+            message = '{} is already being built: {}'.format(
+                req.link, contents)
+            raise LookupError(message)
+
+        # If we're here, req should really not be building already.
+        assert req not in self._entries
+
+        # Start tracking this requirement.
+        with open(entry_path, 'w') as fp:
+            fp.write(str(req))
+        self._entries.add(req)
+
+        logger.debug('Added %s to build tracker %r', req, self._root)
+
+    def remove(self, req):
+        # type: (InstallRequirement) -> None
+        """Remove an InstallRequirement from build tracking.
+        """
+
+        assert req.link
+        # Delete the created file and the corresponding entries.
+        os.unlink(self._entry_path(req.link))
+        self._entries.remove(req)
+
+        logger.debug('Removed %s from build tracker %r', req, self._root)
+
+    def cleanup(self):
+        # type: () -> None
+        for req in set(self._entries):
+            self.remove(req)
+
+        logger.debug("Removed build tracker: %r", self._root)
+
+    @contextlib.contextmanager
+    def track(self, req):
+        # type: (InstallRequirement) -> Iterator[None]
+        self.add(req)
+        yield
+        self.remove(req)

venv/Lib/site-packages/pip/_internal/req/req_uninstall.py

@@ -0,0 +1,648 @@
+from __future__ import absolute_import
+
+import csv
+import functools
+import logging
+import os
+import sys
+import sysconfig
+
+from pip._vendor import pkg_resources
+
+from pip._internal.exceptions import UninstallationError
+from pip._internal.locations import bin_py, bin_user
+from pip._internal.utils.compat import WINDOWS, cache_from_source, uses_pycache
+from pip._internal.utils.logging import indent_log
+from pip._internal.utils.misc import (
+    FakeFile,
+    ask,
+    dist_in_usersite,
+    dist_is_local,
+    egg_link_path,
+    is_local,
+    normalize_path,
+    renames,
+    rmtree,
+)
+from pip._internal.utils.temp_dir import AdjacentTempDirectory, TempDirectory
+from pip._internal.utils.typing import MYPY_CHECK_RUNNING
+
+if MYPY_CHECK_RUNNING:
+    from typing import (
+        Any, Callable, Dict, Iterable, Iterator, List, Optional, Set, Tuple,
+    )
+    from pip._vendor.pkg_resources import Distribution
+
+logger = logging.getLogger(__name__)
+
+
+def _script_names(dist, script_name, is_gui):
+    # type: (Distribution, str, bool) -> List[str]
+    """Create the fully qualified name of the files created by
+    {console,gui}_scripts for the given ``dist``.
+    Returns the list of file names
+    """
+    if dist_in_usersite(dist):
+        bin_dir = bin_user
+    else:
+        bin_dir = bin_py
+    exe_name = os.path.join(bin_dir, script_name)
+    paths_to_remove = [exe_name]
+    if WINDOWS:
+        paths_to_remove.append(exe_name + '.exe')
+        paths_to_remove.append(exe_name + '.exe.manifest')
+        if is_gui:
+            paths_to_remove.append(exe_name + '-script.pyw')
+        else:
+            paths_to_remove.append(exe_name + '-script.py')
+    return paths_to_remove
+
+
+def _unique(fn):
+    # type: (Callable[..., Iterator[Any]]) -> Callable[..., Iterator[Any]]
+    @functools.wraps(fn)
+    def unique(*args, **kw):
+        # type: (Any, Any) -> Iterator[Any]
+        seen = set()  # type: Set[Any]
+        for item in fn(*args, **kw):
+            if item not in seen:
+                seen.add(item)
+                yield item
+    return unique
+
+
+@_unique
+def uninstallation_paths(dist):
+    # type: (Distribution) -> Iterator[str]
+    """
+    Yield all the uninstallation paths for dist based on RECORD-without-.py[co]
+
+    Yield paths to all the files in RECORD. For each .py file in RECORD, add
+    the .pyc and .pyo in the same directory.
+
+    UninstallPathSet.add() takes care of the __pycache__ .py[co].
+    """
+    r = csv.reader(FakeFile(dist.get_metadata_lines('RECORD')))
+    for row in r:
+        path = os.path.join(dist.location, row[0])
+        yield path
+        if path.endswith('.py'):
+            dn, fn = os.path.split(path)
+            base = fn[:-3]
+            path = os.path.join(dn, base + '.pyc')
+            yield path
+            path = os.path.join(dn, base + '.pyo')
+            yield path
+
+
+def compact(paths):
+    # type: (Iterable[str]) -> Set[str]
+    """Compact a path set to contain the minimal number of paths
+    necessary to contain all paths in the set. If /a/path/ and
+    /a/path/to/a/file.txt are both in the set, leave only the
+    shorter path."""
+
+    sep = os.path.sep
+    short_paths = set()  # type: Set[str]
+    for path in sorted(paths, key=len):
+        should_skip = any(
+            path.startswith(shortpath.rstrip("*")) and
+            path[len(shortpath.rstrip("*").rstrip(sep))] == sep
+            for shortpath in short_paths
+        )
+        if not should_skip:
+            short_paths.add(path)
+    return short_paths
+
+
+def compress_for_rename(paths):
+    # type: (Iterable[str]) -> Set[str]
+    """Returns a set containing the paths that need to be renamed.
+
+    This set may include directories when the original sequence of paths
+    included every file on disk.
+    """
+    case_map = dict((os.path.normcase(p), p) for p in paths)
+    remaining = set(case_map)
+    unchecked = sorted(set(os.path.split(p)[0]
+                           for p in case_map.values()), key=len)
+    wildcards = set()  # type: Set[str]
+
+    def norm_join(*a):
+        # type: (str) -> str
+        return os.path.normcase(os.path.join(*a))
+
+    for root in unchecked:
+        if any(os.path.normcase(root).startswith(w)
+               for w in wildcards):
+            # This directory has already been handled.
+            continue
+
+        all_files = set()  # type: Set[str]
+        all_subdirs = set()  # type: Set[str]
+        for dirname, subdirs, files in os.walk(root):
+            all_subdirs.update(norm_join(root, dirname, d)
+                               for d in subdirs)
+            all_files.update(norm_join(root, dirname, f)
+                             for f in files)
+        # If all the files we found are in our remaining set of files to
+        # remove, then remove them from the latter set and add a wildcard
+        # for the directory.
+        if not (all_files - remaining):
+            remaining.difference_update(all_files)
+            wildcards.add(root + os.sep)
+
+    return set(map(case_map.__getitem__, remaining)) | wildcards
+
+
+def compress_for_output_listing(paths):
+    # type: (Iterable[str]) -> Tuple[Set[str], Set[str]]
+    """Returns a tuple of 2 sets of which paths to display to user
+
+    The first set contains paths that would be deleted. Files of a package
+    are not added and the top-level directory of the package has a '*' added
+    at the end - to signify that all it's contents are removed.
+
+    The second set contains files that would have been skipped in the above
+    folders.
+    """
+
+    will_remove = set(paths)
+    will_skip = set()
+
+    # Determine folders and files
+    folders = set()
+    files = set()
+    for path in will_remove:
+        if path.endswith(".pyc"):
+            continue
+        if path.endswith("__init__.py") or ".dist-info" in path:
+            folders.add(os.path.dirname(path))
+        files.add(path)
+
+    # probably this one https://github.com/python/mypy/issues/390
+    _normcased_files = set(map(os.path.normcase, files))  # type: ignore
+
+    folders = compact(folders)
+
+    # This walks the tree using os.walk to not miss extra folders
+    # that might get added.
+    for folder in folders:
+        for dirpath, _, dirfiles in os.walk(folder):
+            for fname in dirfiles:
+                if fname.endswith(".pyc"):
+                    continue
+
+                file_ = os.path.join(dirpath, fname)
+                if (os.path.isfile(file_) and
+                        os.path.normcase(file_) not in _normcased_files):
+                    # We are skipping this file. Add it to the set.
+                    will_skip.add(file_)
+
+    will_remove = files | {
+        os.path.join(folder, "*") for folder in folders
+    }
+
+    return will_remove, will_skip
+
+
+class StashedUninstallPathSet(object):
+    """A set of file rename operations to stash files while
+    tentatively uninstalling them."""
+    def __init__(self):
+        # type: () -> None
+        # Mapping from source file root to [Adjacent]TempDirectory
+        # for files under that directory.
+        self._save_dirs = {}  # type: Dict[str, TempDirectory]
+        # (old path, new path) tuples for each move that may need
+        # to be undone.
+        self._moves = []  # type: List[Tuple[str, str]]
+
+    def _get_directory_stash(self, path):
+        # type: (str) -> str
+        """Stashes a directory.
+
+        Directories are stashed adjacent to their original location if
+        possible, or else moved/copied into the user's temp dir."""
+
+        try:
+            save_dir = AdjacentTempDirectory(path)  # type: TempDirectory
+        except OSError:
+            save_dir = TempDirectory(kind="uninstall")
+        self._save_dirs[os.path.normcase(path)] = save_dir
+
+        return save_dir.path
+
+    def _get_file_stash(self, path):
+        # type: (str) -> str
+        """Stashes a file.
+
+        If no root has been provided, one will be created for the directory
+        in the user's temp directory."""
+        path = os.path.normcase(path)
+        head, old_head = os.path.dirname(path), None
+        save_dir = None
+
+        while head != old_head:
+            try:
+                save_dir = self._save_dirs[head]
+                break
+            except KeyError:
+                pass
+            head, old_head = os.path.dirname(head), head
+        else:
+            # Did not find any suitable root
+            head = os.path.dirname(path)
+            save_dir = TempDirectory(kind='uninstall')
+            self._save_dirs[head] = save_dir
+
+        relpath = os.path.relpath(path, head)
+        if relpath and relpath != os.path.curdir:
+            return os.path.join(save_dir.path, relpath)
+        return save_dir.path
+
+    def stash(self, path):
+        # type: (str) -> str
+        """Stashes the directory or file and returns its new location.
+        Handle symlinks as files to avoid modifying the symlink targets.
+        """
+        path_is_dir = os.path.isdir(path) and not os.path.islink(path)
+        if path_is_dir:
+            new_path = self._get_directory_stash(path)
+        else:
+            new_path = self._get_file_stash(path)
+
+        self._moves.append((path, new_path))
+        if (path_is_dir and os.path.isdir(new_path)):
+            # If we're moving a directory, we need to
+            # remove the destination first or else it will be
+            # moved to inside the existing directory.
+            # We just created new_path ourselves, so it will
+            # be removable.
+            os.rmdir(new_path)
+        renames(path, new_path)
+        return new_path
+
+    def commit(self):
+        # type: () -> None
+        """Commits the uninstall by removing stashed files."""
+        for _, save_dir in self._save_dirs.items():
+            save_dir.cleanup()
+        self._moves = []
+        self._save_dirs = {}
+
+    def rollback(self):
+        # type: () -> None
+        """Undoes the uninstall by moving stashed files back."""
+        for p in self._moves:
+            logger.info("Moving to %s\n from %s", *p)
+
+        for new_path, path in self._moves:
+            try:
+                logger.debug('Replacing %s from %s', new_path, path)
+                if os.path.isfile(new_path) or os.path.islink(new_path):
+                    os.unlink(new_path)
+                elif os.path.isdir(new_path):
+                    rmtree(new_path)
+                renames(path, new_path)
+            except OSError as ex:
+                logger.error("Failed to restore %s", new_path)
+                logger.debug("Exception: %s", ex)
+
+        self.commit()
+
+    @property
+    def can_rollback(self):
+        # type: () -> bool
+        return bool(self._moves)
+
+
+class UninstallPathSet(object):
+    """A set of file paths to be removed in the uninstallation of a
+    requirement."""
+    def __init__(self, dist):
+        # type: (Distribution) -> None
+        self.paths = set()  # type: Set[str]
+        self._refuse = set()  # type: Set[str]
+        self.pth = {}  # type: Dict[str, UninstallPthEntries]
+        self.dist = dist
+        self._moved_paths = StashedUninstallPathSet()
+
+    def _permitted(self, path):
+        # type: (str) -> bool
+        """
+        Return True if the given path is one we are permitted to
+        remove/modify, False otherwise.
+
+        """
+        return is_local(path)
+
+    def add(self, path):
+        # type: (str) -> None
+        head, tail = os.path.split(path)
+
+        # we normalize the head to resolve parent directory symlinks, but not
+        # the tail, since we only want to uninstall symlinks, not their targets
+        path = os.path.join(normalize_path(head), os.path.normcase(tail))
+
+        if not os.path.exists(path):
+            return
+        if self._permitted(path):
+            self.paths.add(path)
+        else:
+            self._refuse.add(path)
+
+        # __pycache__ files can show up after 'installed-files.txt' is created,
+        # due to imports
+        if os.path.splitext(path)[1] == '.py' and uses_pycache:
+            self.add(cache_from_source(path))
+
+    def add_pth(self, pth_file, entry):
+        # type: (str, str) -> None
+        pth_file = normalize_path(pth_file)
+        if self._permitted(pth_file):
+            if pth_file not in self.pth:
+                self.pth[pth_file] = UninstallPthEntries(pth_file)
+            self.pth[pth_file].add(entry)
+        else:
+            self._refuse.add(pth_file)
+
+    def remove(self, auto_confirm=False, verbose=False):
+        # type: (bool, bool) -> None
+        """Remove paths in ``self.paths`` with confirmation (unless
+        ``auto_confirm`` is True)."""
+
+        if not self.paths:
+            logger.info(
+                "Can't uninstall '%s'. No files were found to uninstall.",
+                self.dist.project_name,
+            )
+            return
+
+        dist_name_version = (
+            self.dist.project_name + "-" + self.dist.version
+        )
+        logger.info('Uninstalling %s:', dist_name_version)
+
+        with indent_log():
+            if auto_confirm or self._allowed_to_proceed(verbose):
+                moved = self._moved_paths
+
+                for_rename = compress_for_rename(self.paths)
+
+                for path in sorted(compact(for_rename)):
+                    moved.stash(path)
+                    logger.debug('Removing file or directory %s', path)
+
+                for pth in self.pth.values():
+                    pth.remove()
+
+                logger.info('Successfully uninstalled %s', dist_name_version)
+
+    def _allowed_to_proceed(self, verbose):
+        # type: (bool) -> bool
+        """Display which files would be deleted and prompt for confirmation
+        """
+
+        def _display(msg, paths):
+            # type: (str, Iterable[str]) -> None
+            if not paths:
+                return
+
+            logger.info(msg)
+            with indent_log():
+                for path in sorted(compact(paths)):
+                    logger.info(path)
+
+        if not verbose:
+            will_remove, will_skip = compress_for_output_listing(self.paths)
+        else:
+            # In verbose mode, display all the files that are going to be
+            # deleted.
+            will_remove = set(self.paths)
+            will_skip = set()
+
+        _display('Would remove:', will_remove)
+        _display('Would not remove (might be manually added):', will_skip)
+        _display('Would not remove (outside of prefix):', self._refuse)
+        if verbose:
+            _display('Will actually move:', compress_for_rename(self.paths))
+
+        return ask('Proceed (y/n)? ', ('y', 'n')) == 'y'
+
+    def rollback(self):
+        # type: () -> None
+        """Rollback the changes previously made by remove()."""
+        if not self._moved_paths.can_rollback:
+            logger.error(
+                "Can't roll back %s; was not uninstalled",
+                self.dist.project_name,
+            )
+            return
+        logger.info('Rolling back uninstall of %s', self.dist.project_name)
+        self._moved_paths.rollback()
+        for pth in self.pth.values():
+            pth.rollback()
+
+    def commit(self):
+        # type: () -> None
+        """Remove temporary save dir: rollback will no longer be possible."""
+        self._moved_paths.commit()
+
+    @classmethod
+    def from_dist(cls, dist):
+        # type: (Distribution) -> UninstallPathSet
+        dist_path = normalize_path(dist.location)
+        if not dist_is_local(dist):
+            logger.info(
+                "Not uninstalling %s at %s, outside environment %s",
+                dist.key,
+                dist_path,
+                sys.prefix,
+            )
+            return cls(dist)
+
+        if dist_path in {p for p in {sysconfig.get_path("stdlib"),
+                                     sysconfig.get_path("platstdlib")}
+                         if p}:
+            logger.info(
+                "Not uninstalling %s at %s, as it is in the standard library.",
+                dist.key,
+                dist_path,
+            )
+            return cls(dist)
+
+        paths_to_remove = cls(dist)
+        develop_egg_link = egg_link_path(dist)
+        develop_egg_link_egg_info = '{}.egg-info'.format(
+            pkg_resources.to_filename(dist.project_name))
+        egg_info_exists = dist.egg_info and os.path.exists(dist.egg_info)
+        # Special case for distutils installed package
+        distutils_egg_info = getattr(dist._provider, 'path', None)
+
+        # Uninstall cases order do matter as in the case of 2 installs of the
+        # same package, pip needs to uninstall the currently detected version
+        if (egg_info_exists and dist.egg_info.endswith('.egg-info') and
+                not dist.egg_info.endswith(develop_egg_link_egg_info)):
+            # if dist.egg_info.endswith(develop_egg_link_egg_info), we
+            # are in fact in the develop_egg_link case
+            paths_to_remove.add(dist.egg_info)
+            if dist.has_metadata('installed-files.txt'):
+                for installed_file in dist.get_metadata(
+                        'installed-files.txt').splitlines():
+                    path = os.path.normpath(
+                        os.path.join(dist.egg_info, installed_file)
+                    )
+                    paths_to_remove.add(path)
+            # FIXME: need a test for this elif block
+            # occurs with --single-version-externally-managed/--record outside
+            # of pip
+            elif dist.has_metadata('top_level.txt'):
+                if dist.has_metadata('namespace_packages.txt'):
+                    namespaces = dist.get_metadata('namespace_packages.txt')
+                else:
+                    namespaces = []
+                for top_level_pkg in [
+                        p for p
+                        in dist.get_metadata('top_level.txt').splitlines()
+                        if p and p not in namespaces]:
+                    path = os.path.join(dist.location, top_level_pkg)
+                    paths_to_remove.add(path)
+                    paths_to_remove.add(path + '.py')
+                    paths_to_remove.add(path + '.pyc')
+                    paths_to_remove.add(path + '.pyo')
+
+        elif distutils_egg_info:
+            raise UninstallationError(
+                "Cannot uninstall {!r}. It is a distutils installed project "
+                "and thus we cannot accurately determine which files belong "
+                "to it which would lead to only a partial uninstall.".format(
+                    dist.project_name,
+                )
+            )
+
+        elif dist.location.endswith('.egg'):
+            # package installed by easy_install
+            # We cannot match on dist.egg_name because it can slightly vary
+            # i.e. setuptools-0.6c11-py2.6.egg vs setuptools-0.6rc11-py2.6.egg
+            paths_to_remove.add(dist.location)
+            easy_install_egg = os.path.split(dist.location)[1]
+            easy_install_pth = os.path.join(os.path.dirname(dist.location),
+                                            'easy-install.pth')
+            paths_to_remove.add_pth(easy_install_pth, './' + easy_install_egg)
+
+        elif egg_info_exists and dist.egg_info.endswith('.dist-info'):
+            for path in uninstallation_paths(dist):
+                paths_to_remove.add(path)
+
+        elif develop_egg_link:
+            # develop egg
+            with open(develop_egg_link, 'r') as fh:
+                link_pointer = os.path.normcase(fh.readline().strip())
+            assert (link_pointer == dist.location), (
+                'Egg-link {} does not match installed location of {} '
+                '(at {})'.format(
+                    link_pointer, dist.project_name, dist.location)
+            )
+            paths_to_remove.add(develop_egg_link)
+            easy_install_pth = os.path.join(os.path.dirname(develop_egg_link),
+                                            'easy-install.pth')
+            paths_to_remove.add_pth(easy_install_pth, dist.location)
+
+        else:
+            logger.debug(
+                'Not sure how to uninstall: %s - Check: %s',
+                dist, dist.location,
+            )
+
+        # find distutils scripts= scripts
+        if dist.has_metadata('scripts') and dist.metadata_isdir('scripts'):
+            for script in dist.metadata_listdir('scripts'):
+                if dist_in_usersite(dist):
+                    bin_dir = bin_user
+                else:
+                    bin_dir = bin_py
+                paths_to_remove.add(os.path.join(bin_dir, script))
+                if WINDOWS:
+                    paths_to_remove.add(os.path.join(bin_dir, script) + '.bat')
+
+        # find console_scripts
+        _scripts_to_remove = []
+        console_scripts = dist.get_entry_map(group='console_scripts')
+        for name in console_scripts.keys():
+            _scripts_to_remove.extend(_script_names(dist, name, False))
+        # find gui_scripts
+        gui_scripts = dist.get_entry_map(group='gui_scripts')
+        for name in gui_scripts.keys():
+            _scripts_to_remove.extend(_script_names(dist, name, True))
+
+        for s in _scripts_to_remove:
+            paths_to_remove.add(s)
+
+        return paths_to_remove
+
+
+class UninstallPthEntries(object):
+    def __init__(self, pth_file):
+        # type: (str) -> None
+        self.file = pth_file
+        self.entries = set()  # type: Set[str]
+        self._saved_lines = None  # type: Optional[List[bytes]]
+
+    def add(self, entry):
+        # type: (str) -> None
+        entry = os.path.normcase(entry)
+        # On Windows, os.path.normcase converts the entry to use
+        # backslashes.  This is correct for entries that describe absolute
+        # paths outside of site-packages, but all the others use forward
+        # slashes.
+        # os.path.splitdrive is used instead of os.path.isabs because isabs
+        # treats non-absolute paths with drive letter markings like c:foo\bar
+        # as absolute paths. It also does not recognize UNC paths if they don't
+        # have more than "\\sever\share". Valid examples: "\\server\share\" or
+        # "\\server\share\folder". Python 2.7.8+ support UNC in splitdrive.
+        if WINDOWS and not os.path.splitdrive(entry)[0]:
+            entry = entry.replace('\\', '/')
+        self.entries.add(entry)
+
+    def remove(self):
+        # type: () -> None
+        logger.debug('Removing pth entries from %s:', self.file)
+
+        # If the file doesn't exist, log a warning and return
+        if not os.path.isfile(self.file):
+            logger.warning(
+                "Cannot remove entries from nonexistent file %s", self.file
+            )
+            return
+        with open(self.file, 'rb') as fh:
+            # windows uses '\r\n' with py3k, but uses '\n' with py2.x
+            lines = fh.readlines()
+            self._saved_lines = lines
+        if any(b'\r\n' in line for line in lines):
+            endline = '\r\n'
+        else:
+            endline = '\n'
+        # handle missing trailing newline
+        if lines and not lines[-1].endswith(endline.encode("utf-8")):
+            lines[-1] = lines[-1] + endline.encode("utf-8")
+        for entry in self.entries:
+            try:
+                logger.debug('Removing entry: %s', entry)
+                lines.remove((entry + endline).encode("utf-8"))
+            except ValueError:
+                pass
+        with open(self.file, 'wb') as fh:
+            fh.writelines(lines)
+
+    def rollback(self):
+        # type: () -> bool
+        if self._saved_lines is None:
+            logger.error(
+                'Cannot roll back changes to %s, none were made', self.file
+            )
+            return False
+        logger.debug('Rolling %s back to previous state', self.file)
+        with open(self.file, 'wb') as fh:
+            fh.writelines(self._saved_lines)
+        return True