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"""Classes wrapping a file-like object to do fancy output on it."""
import errno
import io
import locale
import os
from functools import partial
from .klass import GetAttrProxy, steal_docs
from .mappings import defaultdictkey
__all__ = (
"Formatter",
"PlainTextFormatter",
"get_formatter",
"decorate_forced_wrapping",
)
class StreamClosed(KeyboardInterrupt):
"""Raised by :py:func:`Formatter.write` if the stream it prints to was closed.
This inherits from :py:class:`KeyboardInterrupt` because it should usually
be handled the same way: a common way of triggering this exception
is by closing a pager before the script finished outputting, which
should be handled like control+c, not like an error.
"""
# "Invalid name" (for fg and bg methods, too short)
# pylint: disable=C0103
class Formatter:
"""Abstract formatter base class.
The types of most of the instance attributes is undefined (depends
on the implementation of the particular Formatter subclass).
:ivar bold: object to pass to :py:func:`write` to switch to bold mode.
:ivar underline: object to pass to :py:func:`write` to switch to underlined mode.
:ivar reset: object to pass to :py:func:`write` to turn off bold and underline.
:ivar wrap: boolean indicating we auto-linewrap (defaults to off).
:ivar autoline: boolean indicating we are in auto-newline mode
(defaults to on).
"""
def __init__(self):
self.autoline = True
self.wrap = False
def write(self, *args, **kwargs):
"""Write something to the stream.
Acceptable arguments are:
* Strings are simply written to the stream.
* None is ignored.
* Functions are called with the formatter as argument.
Their return value is then used the same way as the other
arguments.
* Formatter subclasses might special-case certain objects.
Accepts wrap and autoline as keyword arguments. Effect is
the same as setting them before the write call and resetting
them afterwards.
Accepts first_prefixes and later_prefixes as keyword
arguments. They should be sequences that are temporarily
appended to the first_prefix and later_prefix attributes.
Accepts prefixes as a keyword argument. Effect is the same as
setting first_prefixes and later_prefixes to the same value.
Accepts first_prefix, later_prefix and prefix as keyword
argument. Effect is the same as setting first_prefixes,
later_prefixes or prefixes to a one-element tuple.
The formatter has a couple of attributes that are useful as argument
to write.
"""
def fg(self, color=None):
"""Change foreground color.
:param color: color to change to. A default is used if omitted.
if passed None, resets to the default color.
:return: object representing changing the foreground to the requested
color, if possible for this formatter.
"""
def bg(self, color=None):
"""Change background color.
:param color: color to change to. A default is used if omitted.
if passed None, resets to the default color.
:return: object representing changing the background to the requested
color, if possible for this formatter.
"""
def error(self, message):
"""Format a string as an error message."""
self.write(message, prefixes=(self.fg("red"), self.bold, "!!! ", self.reset))
def warn(self, message):
"""Format a string as a warning message."""
self.write(message, prefixes=(self.fg("yellow"), self.bold, "*** ", self.reset))
def title(self, string):
"""Set the title to string"""
def flush(self):
"""Flush the underlying stream buffer."""
class PlainTextFormatter(Formatter):
"""Formatter writing plain text to a file-like object.
:ivar width: contains the current maximum line length.
:ivar encoding: the encoding unicode strings should be converted to.
:ivar first_prefix: prefixes to output at the beginning of every write.
:ivar later_prefix: prefixes to output on each line after the first of
every write.
"""
bold = underline = reset = ""
def __init__(self, stream, width=79, encoding=None):
"""Initialize.
:type stream: file-like object.
:param stream: stream to output to.
:param width: maximum line width (defaults to 79).
:param encoding: encoding unicode strings are converted to.
"""
super().__init__()
# We used to require a TextIOWrapper on py3. We still accept
# one, guess the encoding from it and grab its underlying
# bytestream.
# It would probably be saner to shift the encoding-guessing up
# a layer, but keep it here for backwards compat for now.
if isinstance(stream, io.TextIOWrapper):
self.stream = stream.buffer
else:
self.stream = stream
if encoding is None:
encoding = getattr(self.stream, "encoding", None)
if encoding is None:
try:
encoding = locale.getpreferredencoding()
except locale.Error:
encoding = "ascii"
self.encoding = encoding
self.width = width
self._pos = 0
self._in_first_line = True
self._wrote_something = False
self.first_prefix = []
self.later_prefix = []
def _encoding_conversion_needed(self, val):
return True
def _force_encoding(self, val):
return val.encode(self.encoding, "replace")
def _write_prefix(self, wrap):
if self._in_first_line:
prefix = self.first_prefix
else:
prefix = self.later_prefix
# This is a bit braindead since it duplicates a lot of code
# from write. Avoids fun things like word wrapped prefix though.
for thing in prefix:
while callable(thing):
thing = thing(self)
if thing is None:
continue
if not isinstance(thing, str):
thing = str(thing)
self._pos += len(thing)
thing = self._force_encoding(thing)
self.stream.write(thing)
if wrap and self._pos >= self.width:
# XXX What to do? Our prefix does not fit.
# This makes sure we still output something,
# but it is completely arbitrary.
self._pos = self.width - 10
@steal_docs(Formatter)
def write(self, *args, **kwargs):
wrap = kwargs.get("wrap", self.wrap)
autoline = kwargs.get("autoline", self.autoline)
prefixes = kwargs.get("prefixes")
first_prefixes = kwargs.get("first_prefixes")
later_prefixes = kwargs.get("later_prefixes")
if prefixes is not None:
if first_prefixes is not None or later_prefixes is not None:
raise TypeError(
"do not pass first_prefixes or later_prefixes "
"if prefixes is passed"
)
first_prefixes = later_prefixes = prefixes
prefix = kwargs.get("prefix")
first_prefix = kwargs.get("first_prefix")
later_prefix = kwargs.get("later_prefix")
if prefix is not None:
if first_prefix is not None or later_prefix is not None:
raise TypeError("do not pass first_prefix or later_prefix with prefix")
first_prefix = later_prefix = prefix
if first_prefix is not None:
if first_prefixes is not None:
raise TypeError("do not pass both first_prefix and first_prefixes")
first_prefixes = (first_prefix,)
if later_prefix is not None:
if later_prefixes is not None:
raise TypeError("do not pass both later_prefix and later_prefixes")
later_prefixes = (later_prefix,)
if first_prefixes is not None:
self.first_prefix.extend(first_prefixes)
if later_prefixes is not None:
self.later_prefix.extend(later_prefixes)
try:
for arg in args:
# If we're at the start of the line, write our prefix.
# There is a deficiency here: if neither our arg nor our
# prefix affect _pos (both are escape sequences or empty)
# we will write prefix more than once. This should not
# matter.
if not self._pos:
self._write_prefix(wrap)
while callable(arg):
arg = arg(self)
if arg is None:
continue
if not isinstance(arg, str):
arg = str(arg)
conversion_needed = self._encoding_conversion_needed(arg)
while wrap and self._pos + len(arg) > self.width:
# We have to split.
maxlen = self.width - self._pos
space = arg.rfind(" ", 0, maxlen)
if space == -1:
# No space to split on.
# If we are on the first line we can simply go to
# the next (this helps if the "later" prefix is
# shorter and should not really matter if not).
# If we are on the second line and have already
# written something we can also go to the next
# line.
if self._in_first_line or self._wrote_something:
bit = ""
else:
# Forcibly split this as far to the right as
# possible.
bit = arg[:maxlen]
arg = arg[maxlen:]
else:
bit = arg[:space]
# Omit the space we split on.
arg = arg[space + 1 :]
if conversion_needed:
bit = self._force_encoding(bit)
self.stream.write(bit)
self.stream.write(self._force_encoding("\n"))
self._pos = 0
self._in_first_line = False
self._wrote_something = False
self._write_prefix(wrap)
# This fits.
self._wrote_something = True
self._pos += len(arg)
if conversion_needed:
arg = self._force_encoding(arg)
self.stream.write(arg)
if autoline:
self.stream.write(self._force_encoding("\n"))
self._wrote_something = False
self._pos = 0
self._in_first_line = True
except IOError as e:
if e.errno == errno.EPIPE:
raise StreamClosed(e)
raise
finally:
if first_prefixes is not None:
self.first_prefix = self.first_prefix[: -len(first_prefixes)]
if later_prefixes is not None:
self.later_prefix = self.later_prefix[: -len(later_prefixes)]
def fg(self, color=None):
"""change fg color
Compatibility method- no coloring escapes are returned from it.
"""
return ""
def bg(self, color=None):
"""change bg color
Compatibility method- no coloring escapes are returned from it.
"""
return ""
def flush(self):
self.stream.flush()
class TerminfoDisabled(Exception):
"""Raised if Terminfo is disabled."""
class _BogusTerminfo(ValueError):
"""Internal terminfo exception."""
class TerminfoUnsupported(Exception):
"""Raised if our terminal type is unsupported."""
def __init__(self, term):
self.term = term
def __str__(self):
return f"unsupported terminal type: {self.term!r}"
# This is necessary because the curses module is optional (and we
# should run on a very minimal python for bootstrapping).
try:
import curses
except ImportError:
TerminfoColor = None
else:
class TerminfoColor:
"""Class encapsulating a specific terminfo entry for a color.
This should not generally be invoked by hand, instead returned by
the formatter itself.
"""
__slots__ = ("mode", "color", "__weakref__")
def __init__(self, mode, color):
object.__setattr__(self, "mode", mode)
object.__setattr__(self, "color", color)
def __call__(self, formatter):
if self.color is None:
formatter._current_colors[self.mode] = None
res = formatter._color_reset
# slight abuse of boolean True/False and 1/0 equivalence
other = formatter._current_colors[not self.mode]
if other is not None:
res = res + other
else:
if self.mode == 0:
default = curses.COLOR_WHITE
else:
default = curses.COLOR_BLACK
color = formatter._colors.get(self.color, default)
# The curses module currently segfaults if handed a
# bogus template so check explicitly.
template = formatter._set_color[self.mode]
if template:
res = curses.tparm(template, color)
else:
res = b""
formatter._current_colors[self.mode] = res
formatter.stream.write(res)
def __setattr__(self, key, val):
raise AttributeError(f"{self.__class__.__name__} instances are immutable")
class TerminfoCode:
"""Encapsulates specific terminfo entry commands, reset for example.
This should not generally be invoked by hand, instead returned by
the formatter itself.
"""
__slots__ = ("value", "__weakref__")
def __init__(self, value):
if value is None:
raise _BogusTerminfo()
object.__setattr__(self, "value", value)
def __setattr__(self, key, value):
raise AttributeError(f"{self.__class__.__name__} instances are immutable")
class TerminfoMode(TerminfoCode):
__doc__ = TerminfoCode.__doc__
__slots__ = ()
def __call__(self, formatter):
formatter._modes.add(self)
formatter.stream.write(self.value)
class TerminfoReset(TerminfoCode):
__doc__ = TerminfoCode.__doc__
__slots__ = ()
def __call__(self, formatter):
formatter._modes.clear()
formatter.stream.write(self.value)
class TerminfoFormatter(PlainTextFormatter):
"""Formatter writing to a tty, using terminfo to do colors."""
_colors = dict(
black=curses.COLOR_BLACK,
red=curses.COLOR_RED,
green=curses.COLOR_GREEN,
yellow=curses.COLOR_YELLOW,
blue=curses.COLOR_BLUE,
magenta=curses.COLOR_MAGENTA,
cyan=curses.COLOR_CYAN,
white=curses.COLOR_WHITE,
)
def __init__(self, stream, term=None, encoding=None):
"""Initialize.
:type stream: file-like object.
:param stream: stream to output to, defaulting to :py:class:`sys.stdout`.
:type term: string.
:param term: terminal type, pulled from the environment if omitted.
"""
super().__init__(stream, encoding=encoding)
fd = stream.fileno()
if term is None:
if term := os.environ.get("TERM"):
try:
curses.setupterm(fd=fd, term=term)
except curses.error:
pass
else:
raise TerminfoDisabled("no terminfo entries")
else:
# TODO maybe do something more useful than raising curses.error
# if term is not in the terminfo db here?
curses.setupterm(fd=fd, term=term)
self._term = term
self.width = curses.tigetnum("cols")
try:
self.reset = TerminfoReset(curses.tigetstr("sgr0"))
self.bold = TerminfoMode(curses.tigetstr("bold"))
self.underline = TerminfoMode(curses.tigetstr("smul"))
self._color_reset = curses.tigetstr("op")
self._set_color = (curses.tigetstr("setaf"), curses.tigetstr("setab"))
except (_BogusTerminfo, curses.error) as e:
raise TerminfoUnsupported(self._term) from e
if not all(self._set_color):
raise TerminfoDisabled(
"setting background/foreground colors is not supported"
)
curses.tparm(self._set_color[0], curses.COLOR_WHITE)
# [fg, bg]
self._current_colors = [None, None]
self._modes = set()
self._pos = 0
self._fg_cache = defaultdictkey(partial(TerminfoColor, 0))
self._bg_cache = defaultdictkey(partial(TerminfoColor, 1))
@steal_docs(Formatter)
def fg(self, color=None):
return self._fg_cache[color]
@steal_docs(Formatter)
def bg(self, color=None):
return self._bg_cache[color]
@steal_docs(Formatter)
def write(self, *args, **kwargs):
super().write(*args, **kwargs)
try:
if self._modes:
self.reset(self)
if self._current_colors != [None, None]:
self._current_colors = [None, None]
self.stream.write(self._color_reset)
except IOError as e:
if e.errno == errno.EPIPE:
raise StreamClosed(e)
raise
@steal_docs(Formatter)
def title(self, string):
# I want to use curses.tigetflag('hs') here but at least
# the screen-s entry defines a tsl and fsl string but does
# not set the hs flag. So just check for the ability to
# jump to and out of the status line, without checking if
# the status line we're using exists.
tsl = curses.tigetstr("tsl")
fsl = curses.tigetstr("fsl")
if tsl and fsl:
self.stream.write(tsl + string.encode(self.encoding, "replace") + fsl)
self.stream.flush()
class ObserverFormatter:
def __init__(self, real_formatter):
self._formatter = real_formatter
def write(self, *args):
self._formatter.write(autoline=False, *args)
__getattr__ = GetAttrProxy("_formatter")
fileno_excepts = (AttributeError, io.UnsupportedOperation)
def get_formatter(stream, force_color=False):
"""TerminfoFormatter if the stream is a tty, else PlainTextFormatter."""
if TerminfoColor is None:
return PlainTextFormatter(stream)
try:
fd = stream.fileno()
except fileno_excepts:
pass
else:
# We do this instead of stream.isatty() because TerminfoFormatter
# needs an fd to pass to curses, not just a filelike talking to a tty.
if os.isatty(fd) or force_color:
try:
term = "ansi" if force_color else None
return TerminfoFormatter(stream, term=term)
except (curses.error, TerminfoDisabled, TerminfoUnsupported):
# This happens if TERM is unset and possibly in more cases.
# Just fall back to the PlainTextFormatter.
pass
return PlainTextFormatter(stream)
def decorate_forced_wrapping(setting=True):
"""Decorator to force a specific line wrapping state for the duration of invocation."""
def wrapped_func(func):
def f(out, *args, **kwds):
oldwrap = out.wrap
out.wrap = setting
try:
return func(out, *args, **kwds)
finally:
out.wrap = oldwrap
return f
return wrapped_func
|