--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/lib/python3.8/site-packages/pip/_internal/req/req_file.py	Mon Jul 27 03:47:31 2020 -0400
@@ -0,0 +1,546 @@
+"""
+Requirements file parsing
+"""
+
+# The following comment should be removed at some point in the future.
+# mypy: strict-optional=False
+
+from __future__ import absolute_import
+
+import optparse
+import os
+import re
+import shlex
+import sys
+
+from pip._vendor.six.moves import filterfalse
+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.req.constructors import (
+    install_req_from_editable,
+    install_req_from_line,
+)
+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, Iterator, List, NoReturn, Optional, Text, Tuple,
+    )
+
+    from pip._internal.req import InstallRequirement
+    from pip._internal.cache import WheelCache
+    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.require_hashes,
+    cmdoptions.pre,
+    cmdoptions.trusted_host,
+    cmdoptions.always_unzip,  # Deprecated
+]  # 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 ParsedLine(object):
+    def __init__(
+        self,
+        filename,  # type: str
+        lineno,  # type: int
+        comes_from,  # type: str
+        args,  # type: str
+        opts,  # type: Values
+        constraint,  # type: bool
+    ):
+        # type: (...) -> None
+        self.filename = filename
+        self.lineno = lineno
+        self.comes_from = comes_from
+        self.args = args
+        self.opts = opts
+        self.constraint = constraint
+
+
+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
+    wheel_cache=None,  # type: Optional[WheelCache]
+    use_pep517=None  # type: Optional[bool]
+):
+    # type: (...) -> Iterator[InstallRequirement]
+    """Parse a requirements file and yield InstallRequirement 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.
+    :param wheel_cache: Instance of pip.wheel.WheelCache
+    :param use_pep517:  Value of the --use-pep517 option.
+    """
+    skip_requirements_regex = (
+        options.skip_requirements_regex if options else None
+    )
+    line_parser = get_line_parser(finder)
+    parser = RequirementsFileParser(
+        session, line_parser, comes_from, skip_requirements_regex
+    )
+
+    for parsed_line in parser.parse(filename, constraint):
+        req = handle_line(
+            parsed_line, finder, options, session, wheel_cache, use_pep517
+        )
+        if req is not None:
+            yield req
+
+
+def preprocess(content, skip_requirements_regex):
+    # type: (Text, Optional[str]) -> ReqFileLines
+    """Split, filter, and join lines, and return a line iterator
+
+    :param content: the content of the requirements file
+    :param options: cli options
+    """
+    lines_enum = enumerate(content.splitlines(), start=1)  # type: ReqFileLines
+    lines_enum = join_lines(lines_enum)
+    lines_enum = ignore_comments(lines_enum)
+    if skip_requirements_regex:
+        lines_enum = skip_regex(lines_enum, skip_requirements_regex)
+    lines_enum = expand_env_variables(lines_enum)
+    return lines_enum
+
+
+def handle_line(
+    line,  # type: ParsedLine
+    finder=None,  # type: Optional[PackageFinder]
+    options=None,  # type: Optional[optparse.Values]
+    session=None,  # type: Optional[PipSession]
+    wheel_cache=None,  # type: Optional[WheelCache]
+    use_pep517=None,  # type: Optional[bool]
+):
+    # type: (...) -> Optional[InstallRequirement]
+    """Handle a single parsed requirements line; This can result in
+    creating/yielding requirements, or updating the finder.
+
+    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.
+    """
+
+    # preserve for the nested code path
+    line_comes_from = '%s %s (line %s)' % (
+        '-c' if line.constraint else '-r', line.filename, line.lineno,
+    )
+
+    # return a line requirement
+    if line.args:
+        isolated = options.isolated_mode if options else False
+        if 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 install_req_from_line(
+            line.args,
+            comes_from=line_comes_from,
+            use_pep517=use_pep517,
+            isolated=isolated,
+            options=req_options,
+            wheel_cache=wheel_cache,
+            constraint=line.constraint,
+            line_source=line_source,
+        )
+
+    # return an editable requirement
+    elif line.opts.editables:
+        isolated = options.isolated_mode if options else False
+        return install_req_from_editable(
+            line.opts.editables[0], comes_from=line_comes_from,
+            use_pep517=use_pep517,
+            constraint=line.constraint, isolated=isolated,
+            wheel_cache=wheel_cache
+        )
+
+    # percolate hash-checking option upward
+    elif line.opts.require_hashes:
+        options.require_hashes = line.opts.require_hashes
+
+    # set finder options
+    elif finder:
+        find_links = finder.find_links
+        index_urls = finder.index_urls
+        if line.opts.index_url:
+            index_urls = [line.opts.index_url]
+        if line.opts.no_index is True:
+            index_urls = []
+        if line.opts.extra_index_urls:
+            index_urls.extend(line.opts.extra_index_urls)
+        if line.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 = line.opts.find_links[0]
+            req_dir = os.path.dirname(os.path.abspath(line.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 line.opts.pre:
+            finder.set_allow_all_prereleases()
+
+        if session:
+            for host in line.opts.trusted_hosts or []:
+                source = 'line {} of {}'.format(line.lineno, line.filename)
+                session.add_trusted_host(host, source=source)
+
+    return None
+
+
+class RequirementsFileParser(object):
+    def __init__(
+        self,
+        session,  # type: PipSession
+        line_parser,  # type: LineParser
+        comes_from,  # type: str
+        skip_requirements_regex,  # type: Optional[str]
+    ):
+        # type: (...) -> None
+        self._session = session
+        self._line_parser = line_parser
+        self._comes_from = comes_from
+        self._skip_requirements_regex = skip_requirements_regex
+
+    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.args and
+                not line.opts.editables 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, self._skip_requirements_regex)
+
+        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: %s\n%s' % (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)
+                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:
+        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 skip_regex(lines_enum, pattern):
+    # type: (ReqFileLines, str) -> ReqFileLines
+    """
+    Skip lines that match the provided pattern
+
+    Note: the regex pattern is only built once
+    """
+    matcher = re.compile(pattern)
+    lines_enum = filterfalse(lambda e: matcher.search(e[1]), lines_enum)
+    return lines_enum
+
+
+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)
+        resp.raise_for_status()
+        return resp.url, resp.text
+
+    elif scheme == 'file':
+        if comes_from and comes_from.startswith('http'):
+            raise InstallationError(
+                'Requirements file %s references URL %s, which is local'
+                % (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: %s' % str(exc)
+        )
+    return url, content
+
+
+_url_slash_drive_re = re.compile(r'/*([a-z])\|', re.I)