--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/lib/python3.8/site-packages/pip/_internal/utils/ui.py	Mon Jul 27 03:47:31 2020 -0400
@@ -0,0 +1,428 @@
+# The following comment should be removed at some point in the future.
+# mypy: strict-optional=False
+# mypy: disallow-untyped-defs=False
+
+from __future__ import absolute_import, division
+
+import contextlib
+import itertools
+import logging
+import sys
+import time
+from signal import SIGINT, default_int_handler, signal
+
+from pip._vendor import six
+from pip._vendor.progress import HIDE_CURSOR, SHOW_CURSOR
+from pip._vendor.progress.bar import Bar, FillingCirclesBar, IncrementalBar
+from pip._vendor.progress.spinner import Spinner
+
+from pip._internal.utils.compat import WINDOWS
+from pip._internal.utils.logging import get_indentation
+from pip._internal.utils.misc import format_size
+from pip._internal.utils.typing import MYPY_CHECK_RUNNING
+
+if MYPY_CHECK_RUNNING:
+    from typing import Any, Iterator, IO
+
+try:
+    from pip._vendor import colorama
+# Lots of different errors can come from this, including SystemError and
+# ImportError.
+except Exception:
+    colorama = None
+
+logger = logging.getLogger(__name__)
+
+
+def _select_progress_class(preferred, fallback):
+    encoding = getattr(preferred.file, "encoding", None)
+
+    # If we don't know what encoding this file is in, then we'll just assume
+    # that it doesn't support unicode and use the ASCII bar.
+    if not encoding:
+        return fallback
+
+    # Collect all of the possible characters we want to use with the preferred
+    # bar.
+    characters = [
+        getattr(preferred, "empty_fill", six.text_type()),
+        getattr(preferred, "fill", six.text_type()),
+    ]
+    characters += list(getattr(preferred, "phases", []))
+
+    # Try to decode the characters we're using for the bar using the encoding
+    # of the given file, if this works then we'll assume that we can use the
+    # fancier bar and if not we'll fall back to the plaintext bar.
+    try:
+        six.text_type().join(characters).encode(encoding)
+    except UnicodeEncodeError:
+        return fallback
+    else:
+        return preferred
+
+
+_BaseBar = _select_progress_class(IncrementalBar, Bar)  # type: Any
+
+
+class InterruptibleMixin(object):
+    """
+    Helper to ensure that self.finish() gets called on keyboard interrupt.
+
+    This allows downloads to be interrupted without leaving temporary state
+    (like hidden cursors) behind.
+
+    This class is similar to the progress library's existing SigIntMixin
+    helper, but as of version 1.2, that helper has the following problems:
+
+    1. It calls sys.exit().
+    2. It discards the existing SIGINT handler completely.
+    3. It leaves its own handler in place even after an uninterrupted finish,
+       which will have unexpected delayed effects if the user triggers an
+       unrelated keyboard interrupt some time after a progress-displaying
+       download has already completed, for example.
+    """
+
+    def __init__(self, *args, **kwargs):
+        """
+        Save the original SIGINT handler for later.
+        """
+        super(InterruptibleMixin, self).__init__(*args, **kwargs)
+
+        self.original_handler = signal(SIGINT, self.handle_sigint)
+
+        # If signal() returns None, the previous handler was not installed from
+        # Python, and we cannot restore it. This probably should not happen,
+        # but if it does, we must restore something sensible instead, at least.
+        # The least bad option should be Python's default SIGINT handler, which
+        # just raises KeyboardInterrupt.
+        if self.original_handler is None:
+            self.original_handler = default_int_handler
+
+    def finish(self):
+        """
+        Restore the original SIGINT handler after finishing.
+
+        This should happen regardless of whether the progress display finishes
+        normally, or gets interrupted.
+        """
+        super(InterruptibleMixin, self).finish()
+        signal(SIGINT, self.original_handler)
+
+    def handle_sigint(self, signum, frame):
+        """
+        Call self.finish() before delegating to the original SIGINT handler.
+
+        This handler should only be in place while the progress display is
+        active.
+        """
+        self.finish()
+        self.original_handler(signum, frame)
+
+
+class SilentBar(Bar):
+
+    def update(self):
+        pass
+
+
+class BlueEmojiBar(IncrementalBar):
+
+    suffix = "%(percent)d%%"
+    bar_prefix = " "
+    bar_suffix = " "
+    phases = (u"\U0001F539", u"\U0001F537", u"\U0001F535")  # type: Any
+
+
+class DownloadProgressMixin(object):
+
+    def __init__(self, *args, **kwargs):
+        super(DownloadProgressMixin, self).__init__(*args, **kwargs)
+        self.message = (" " * (get_indentation() + 2)) + self.message
+
+    @property
+    def downloaded(self):
+        return format_size(self.index)
+
+    @property
+    def download_speed(self):
+        # Avoid zero division errors...
+        if self.avg == 0.0:
+            return "..."
+        return format_size(1 / self.avg) + "/s"
+
+    @property
+    def pretty_eta(self):
+        if self.eta:
+            return "eta %s" % self.eta_td
+        return ""
+
+    def iter(self, it):
+        for x in it:
+            yield x
+            self.next(len(x))
+        self.finish()
+
+
+class WindowsMixin(object):
+
+    def __init__(self, *args, **kwargs):
+        # The Windows terminal does not support the hide/show cursor ANSI codes
+        # even with colorama. So we'll ensure that hide_cursor is False on
+        # Windows.
+        # This call needs to go before the super() call, so that hide_cursor
+        # is set in time. The base progress bar class writes the "hide cursor"
+        # code to the terminal in its init, so if we don't set this soon
+        # enough, we get a "hide" with no corresponding "show"...
+        if WINDOWS and self.hide_cursor:
+            self.hide_cursor = False
+
+        super(WindowsMixin, self).__init__(*args, **kwargs)
+
+        # Check if we are running on Windows and we have the colorama module,
+        # if we do then wrap our file with it.
+        if WINDOWS and colorama:
+            self.file = colorama.AnsiToWin32(self.file)
+            # The progress code expects to be able to call self.file.isatty()
+            # but the colorama.AnsiToWin32() object doesn't have that, so we'll
+            # add it.
+            self.file.isatty = lambda: self.file.wrapped.isatty()
+            # The progress code expects to be able to call self.file.flush()
+            # but the colorama.AnsiToWin32() object doesn't have that, so we'll
+            # add it.
+            self.file.flush = lambda: self.file.wrapped.flush()
+
+
+class BaseDownloadProgressBar(WindowsMixin, InterruptibleMixin,
+                              DownloadProgressMixin):
+
+    file = sys.stdout
+    message = "%(percent)d%%"
+    suffix = "%(downloaded)s %(download_speed)s %(pretty_eta)s"
+
+# NOTE: The "type: ignore" comments on the following classes are there to
+#       work around https://github.com/python/typing/issues/241
+
+
+class DefaultDownloadProgressBar(BaseDownloadProgressBar,
+                                 _BaseBar):
+    pass
+
+
+class DownloadSilentBar(BaseDownloadProgressBar, SilentBar):  # type: ignore
+    pass
+
+
+class DownloadBar(BaseDownloadProgressBar,  # type: ignore
+                  Bar):
+    pass
+
+
+class DownloadFillingCirclesBar(BaseDownloadProgressBar,  # type: ignore
+                                FillingCirclesBar):
+    pass
+
+
+class DownloadBlueEmojiProgressBar(BaseDownloadProgressBar,  # type: ignore
+                                   BlueEmojiBar):
+    pass
+
+
+class DownloadProgressSpinner(WindowsMixin, InterruptibleMixin,
+                              DownloadProgressMixin, Spinner):
+
+    file = sys.stdout
+    suffix = "%(downloaded)s %(download_speed)s"
+
+    def next_phase(self):
+        if not hasattr(self, "_phaser"):
+            self._phaser = itertools.cycle(self.phases)
+        return next(self._phaser)
+
+    def update(self):
+        message = self.message % self
+        phase = self.next_phase()
+        suffix = self.suffix % self
+        line = ''.join([
+            message,
+            " " if message else "",
+            phase,
+            " " if suffix else "",
+            suffix,
+        ])
+
+        self.writeln(line)
+
+
+BAR_TYPES = {
+    "off": (DownloadSilentBar, DownloadSilentBar),
+    "on": (DefaultDownloadProgressBar, DownloadProgressSpinner),
+    "ascii": (DownloadBar, DownloadProgressSpinner),
+    "pretty": (DownloadFillingCirclesBar, DownloadProgressSpinner),
+    "emoji": (DownloadBlueEmojiProgressBar, DownloadProgressSpinner)
+}
+
+
+def DownloadProgressProvider(progress_bar, max=None):
+    if max is None or max == 0:
+        return BAR_TYPES[progress_bar][1]().iter
+    else:
+        return BAR_TYPES[progress_bar][0](max=max).iter
+
+
+################################################################
+# Generic "something is happening" spinners
+#
+# We don't even try using progress.spinner.Spinner here because it's actually
+# simpler to reimplement from scratch than to coerce their code into doing
+# what we need.
+################################################################
+
+@contextlib.contextmanager
+def hidden_cursor(file):
+    # type: (IO[Any]) -> Iterator[None]
+    # The Windows terminal does not support the hide/show cursor ANSI codes,
+    # even via colorama. So don't even try.
+    if WINDOWS:
+        yield
+    # We don't want to clutter the output with control characters if we're
+    # writing to a file, or if the user is running with --quiet.
+    # See https://github.com/pypa/pip/issues/3418
+    elif not file.isatty() or logger.getEffectiveLevel() > logging.INFO:
+        yield
+    else:
+        file.write(HIDE_CURSOR)
+        try:
+            yield
+        finally:
+            file.write(SHOW_CURSOR)
+
+
+class RateLimiter(object):
+    def __init__(self, min_update_interval_seconds):
+        # type: (float) -> None
+        self._min_update_interval_seconds = min_update_interval_seconds
+        self._last_update = 0  # type: float
+
+    def ready(self):
+        # type: () -> bool
+        now = time.time()
+        delta = now - self._last_update
+        return delta >= self._min_update_interval_seconds
+
+    def reset(self):
+        # type: () -> None
+        self._last_update = time.time()
+
+
+class SpinnerInterface(object):
+    def spin(self):
+        # type: () -> None
+        raise NotImplementedError()
+
+    def finish(self, final_status):
+        # type: (str) -> None
+        raise NotImplementedError()
+
+
+class InteractiveSpinner(SpinnerInterface):
+    def __init__(self, message, file=None, spin_chars="-\\|/",
+                 # Empirically, 8 updates/second looks nice
+                 min_update_interval_seconds=0.125):
+        self._message = message
+        if file is None:
+            file = sys.stdout
+        self._file = file
+        self._rate_limiter = RateLimiter(min_update_interval_seconds)
+        self._finished = False
+
+        self._spin_cycle = itertools.cycle(spin_chars)
+
+        self._file.write(" " * get_indentation() + self._message + " ... ")
+        self._width = 0
+
+    def _write(self, status):
+        assert not self._finished
+        # Erase what we wrote before by backspacing to the beginning, writing
+        # spaces to overwrite the old text, and then backspacing again
+        backup = "\b" * self._width
+        self._file.write(backup + " " * self._width + backup)
+        # Now we have a blank slate to add our status
+        self._file.write(status)
+        self._width = len(status)
+        self._file.flush()
+        self._rate_limiter.reset()
+
+    def spin(self):
+        # type: () -> None
+        if self._finished:
+            return
+        if not self._rate_limiter.ready():
+            return
+        self._write(next(self._spin_cycle))
+
+    def finish(self, final_status):
+        # type: (str) -> None
+        if self._finished:
+            return
+        self._write(final_status)
+        self._file.write("\n")
+        self._file.flush()
+        self._finished = True
+
+
+# Used for dumb terminals, non-interactive installs (no tty), etc.
+# We still print updates occasionally (once every 60 seconds by default) to
+# act as a keep-alive for systems like Travis-CI that take lack-of-output as
+# an indication that a task has frozen.
+class NonInteractiveSpinner(SpinnerInterface):
+    def __init__(self, message, min_update_interval_seconds=60):
+        # type: (str, float) -> None
+        self._message = message
+        self._finished = False
+        self._rate_limiter = RateLimiter(min_update_interval_seconds)
+        self._update("started")
+
+    def _update(self, status):
+        assert not self._finished
+        self._rate_limiter.reset()
+        logger.info("%s: %s", self._message, status)
+
+    def spin(self):
+        # type: () -> None
+        if self._finished:
+            return
+        if not self._rate_limiter.ready():
+            return
+        self._update("still running...")
+
+    def finish(self, final_status):
+        # type: (str) -> None
+        if self._finished:
+            return
+        self._update("finished with status '%s'" % (final_status,))
+        self._finished = True
+
+
+@contextlib.contextmanager
+def open_spinner(message):
+    # type: (str) -> Iterator[SpinnerInterface]
+    # Interactive spinner goes directly to sys.stdout rather than being routed
+    # through the logging system, but it acts like it has level INFO,
+    # i.e. it's only displayed if we're at level INFO or better.
+    # Non-interactive spinner goes through the logging system, so it is always
+    # in sync with logging configuration.
+    if sys.stdout.isatty() and logger.getEffectiveLevel() <= logging.INFO:
+        spinner = InteractiveSpinner(message)  # type: SpinnerInterface
+    else:
+        spinner = NonInteractiveSpinner(message)
+    try:
+        with hidden_cursor(sys.stdout):
+            yield spinner
+    except KeyboardInterrupt:
+        spinner.finish("canceled")
+        raise
+    except Exception:
+        spinner.finish("error")
+        raise
+    else:
+        spinner.finish("done")