--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/lib/python3.8/site-packages/pip/_internal/req/constructors.py	Mon Jul 27 03:47:31 2020 -0400
@@ -0,0 +1,436 @@
+"""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.
+"""
+
+# The following comment should be removed at some point in the future.
+# mypy: strict-optional=False
+
+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.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.cache import WheelCache
+
+
+__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, Optional[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, None
+
+    for version_control in vcs:
+        if url.lower().startswith('%s:' % version_control):
+            url = '%s+%s' % (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):
+        error_message = 'For --editable=%s only ' % editable_req + \
+            ', '.join([backend.name + '+URL' for backend in vcs.backends]) + \
+            ' is currently supported'
+        raise InstallationError(error_message)
+
+    package_name = Link(url).egg_fragment
+    if not package_name:
+        raise InstallationError(
+            "Could not detect requirement name for '%s', please specify one "
+            "with #egg=your_package_name" % editable_req
+        )
+    return package_name, url, None
+
+
+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 " + \
+                    "(%s) appears to be a" % (req) + \
+                    " requirements file. If that is the" + \
+                    " case, use the '-r' flag to install" + \
+                    " the packages specified within it."
+        except RequirementParseError:
+            logger.debug("Cannot parse '%s' as requirements \
+            file" % (req), exc_info=True)
+    else:
+        msg += " File '%s' does not exist." % (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: '%s'" % 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[str]
+    use_pep517=None,  # type: Optional[bool]
+    isolated=False,  # type: bool
+    options=None,  # type: Optional[Dict[str, Any]]
+    wheel_cache=None,  # type: Optional[WheelCache]
+    constraint=False  # type: bool
+):
+    # type: (...) -> InstallRequirement
+
+    parts = parse_req_from_editable(editable_req)
+
+    source_dir = parts.link.file_path if parts.link.scheme == 'file' else None
+
+    return InstallRequirement(
+        parts.requirement, comes_from, source_dir=source_dir,
+        editable=True,
+        link=parts.link,
+        constraint=constraint,
+        use_pep517=use_pep517,
+        isolated=isolated,
+        options=options if options else {},
+        wheel_cache=wheel_cache,
+        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) -> 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 %r is not installable. Neither 'setup.py' "
+            "nor 'pyproject.toml' found." % name
+        )
+    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 = "%s==%s" % (wheel.name, wheel.version)
+        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:
+        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]]
+    wheel_cache=None,  # type: Optional[WheelCache]
+    constraint=False,  # type: bool
+    line_source=None,  # type: Optional[str]
+):
+    # 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,
+        options=options if options else {},
+        wheel_cache=wheel_cache,
+        constraint=constraint,
+        extras=parts.extras,
+    )
+
+
+def install_req_from_req_string(
+    req_string,  # type: str
+    comes_from=None,  # type: Optional[InstallRequirement]
+    isolated=False,  # type: bool
+    wheel_cache=None,  # type: Optional[WheelCache]
+    use_pep517=None  # type: Optional[bool]
+):
+    # type: (...) -> InstallRequirement
+    try:
+        req = Requirement(req_string)
+    except InvalidRequirement:
+        raise InstallationError("Invalid requirement: '%s'" % 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"
+            "%s depends on %s " % (comes_from.name, req)
+        )
+
+    return InstallRequirement(
+        req, comes_from, isolated=isolated, wheel_cache=wheel_cache,
+        use_pep517=use_pep517
+    )