8th day of python challenges 111-117

venv/lib/python3.6/site-packages/pandas/_config/localization.py

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+"""
+Helpers for configuring locale settings.
+
+Name `localization` is chosen to avoid overlap with builtin `locale` module.
+"""
+from contextlib import contextmanager
+import locale
+import re
+import subprocess
+
+from pandas._config.config import options
+
+
+@contextmanager
+def set_locale(new_locale, lc_var=locale.LC_ALL):
+    """
+    Context manager for temporarily setting a locale.
+
+    Parameters
+    ----------
+    new_locale : str or tuple
+        A string of the form <language_country>.<encoding>. For example to set
+        the current locale to US English with a UTF8 encoding, you would pass
+        "en_US.UTF-8".
+    lc_var : int, default `locale.LC_ALL`
+        The category of the locale being set.
+
+    Notes
+    -----
+    This is useful when you want to run a particular block of code under a
+    particular locale, without globally setting the locale. This probably isn't
+    thread-safe.
+    """
+    current_locale = locale.getlocale()
+
+    try:
+        locale.setlocale(lc_var, new_locale)
+        normalized_locale = locale.getlocale()
+        if all(x is not None for x in normalized_locale):
+            yield ".".join(normalized_locale)
+        else:
+            yield new_locale
+    finally:
+        locale.setlocale(lc_var, current_locale)
+
+
+def can_set_locale(lc, lc_var=locale.LC_ALL):
+    """
+    Check to see if we can set a locale, and subsequently get the locale,
+    without raising an Exception.
+
+    Parameters
+    ----------
+    lc : str
+        The locale to attempt to set.
+    lc_var : int, default `locale.LC_ALL`
+        The category of the locale being set.
+
+    Returns
+    -------
+    is_valid : bool
+        Whether the passed locale can be set
+    """
+
+    try:
+        with set_locale(lc, lc_var=lc_var):
+            pass
+    except (ValueError, locale.Error):
+        # horrible name for a Exception subclass
+        return False
+    else:
+        return True
+
+
+def _valid_locales(locales, normalize):
+    """
+    Return a list of normalized locales that do not throw an ``Exception``
+    when set.
+
+    Parameters
+    ----------
+    locales : str
+        A string where each locale is separated by a newline.
+    normalize : bool
+        Whether to call ``locale.normalize`` on each locale.
+
+    Returns
+    -------
+    valid_locales : list
+        A list of valid locales.
+    """
+    if normalize:
+        normalizer = lambda x: locale.normalize(x.strip())
+    else:
+        normalizer = lambda x: x.strip()
+
+    return list(filter(can_set_locale, map(normalizer, locales)))
+
+
+def _default_locale_getter():
+    try:
+        raw_locales = subprocess.check_output(["locale -a"], shell=True)
+    except subprocess.CalledProcessError as e:
+        raise type(e)(
+            "{exception}, the 'locale -a' command cannot be found "
+            "on your system".format(exception=e)
+        )
+    return raw_locales
+
+
+def get_locales(prefix=None, normalize=True, locale_getter=_default_locale_getter):
+    """
+    Get all the locales that are available on the system.
+
+    Parameters
+    ----------
+    prefix : str
+        If not ``None`` then return only those locales with the prefix
+        provided. For example to get all English language locales (those that
+        start with ``"en"``), pass ``prefix="en"``.
+    normalize : bool
+        Call ``locale.normalize`` on the resulting list of available locales.
+        If ``True``, only locales that can be set without throwing an
+        ``Exception`` are returned.
+    locale_getter : callable
+        The function to use to retrieve the current locales. This should return
+        a string with each locale separated by a newline character.
+
+    Returns
+    -------
+    locales : list of strings
+        A list of locale strings that can be set with ``locale.setlocale()``.
+        For example::
+
+            locale.setlocale(locale.LC_ALL, locale_string)
+
+    On error will return None (no locale available, e.g. Windows)
+
+    """
+    try:
+        raw_locales = locale_getter()
+    except Exception:
+        return None
+
+    try:
+        # raw_locales is "\n" separated list of locales
+        # it may contain non-decodable parts, so split
+        # extract what we can and then rejoin.
+        raw_locales = raw_locales.split(b"\n")
+        out_locales = []
+        for x in raw_locales:
+            out_locales.append(str(x, encoding=options.display.encoding))
+
+    except TypeError:
+        pass
+
+    if prefix is None:
+        return _valid_locales(out_locales, normalize)
+
+    pattern = re.compile("{prefix}.*".format(prefix=prefix))
+    found = pattern.findall("\n".join(out_locales))
+    return _valid_locales(found, normalize)