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from __future__ import annotations
import io
import os
import re
import sys
# types
if False:
from typing import Protocol
class Pager(Protocol):
def __call__(self, text: str, title: str = "") -> None:
...
def get_pager() -> Pager:
"""Decide what method to use for paging through text."""
if not hasattr(sys.stdin, "isatty"):
return plain_pager
if not hasattr(sys.stdout, "isatty"):
return plain_pager
if not sys.stdin.isatty() or not sys.stdout.isatty():
return plain_pager
if sys.platform == "emscripten":
return plain_pager
use_pager = os.environ.get('MANPAGER') or os.environ.get('PAGER')
if use_pager:
if sys.platform == 'win32': # pipes completely broken in Windows
return lambda text, title='': tempfile_pager(plain(text), use_pager)
elif os.environ.get('TERM') in ('dumb', 'emacs'):
return lambda text, title='': pipe_pager(plain(text), use_pager, title)
else:
return lambda text, title='': pipe_pager(text, use_pager, title)
if os.environ.get('TERM') in ('dumb', 'emacs'):
return plain_pager
if sys.platform == 'win32':
return lambda text, title='': tempfile_pager(plain(text), 'more <')
if hasattr(os, 'system') and os.system('(pager) 2>/dev/null') == 0:
return lambda text, title='': pipe_pager(text, 'pager', title)
if hasattr(os, 'system') and os.system('(less) 2>/dev/null') == 0:
return lambda text, title='': pipe_pager(text, 'less', title)
import tempfile
(fd, filename) = tempfile.mkstemp()
os.close(fd)
try:
if hasattr(os, 'system') and os.system('more "%s"' % filename) == 0:
return lambda text, title='': pipe_pager(text, 'more', title)
else:
return tty_pager
finally:
os.unlink(filename)
def escape_stdout(text: str) -> str:
# Escape non-encodable characters to avoid encoding errors later
encoding = getattr(sys.stdout, 'encoding', None) or 'utf-8'
return text.encode(encoding, 'backslashreplace').decode(encoding)
def escape_less(s: str) -> str:
return re.sub(r'([?:.%\\])', r'\\\1', s)
def plain(text: str) -> str:
"""Remove boldface formatting from text."""
return re.sub('.\b', '', text)
def tty_pager(text: str, title: str = '') -> None:
"""Page through text on a text terminal."""
lines = plain(escape_stdout(text)).split('\n')
has_tty = False
try:
import tty
import termios
fd = sys.stdin.fileno()
old = termios.tcgetattr(fd)
tty.setcbreak(fd)
has_tty = True
def getchar() -> str:
return sys.stdin.read(1)
except (ImportError, AttributeError, io.UnsupportedOperation):
def getchar() -> str:
return sys.stdin.readline()[:-1][:1]
try:
try:
h = int(os.environ.get('LINES', 0))
except ValueError:
h = 0
if h <= 1:
h = 25
r = inc = h - 1
sys.stdout.write('\n'.join(lines[:inc]) + '\n')
while lines[r:]:
sys.stdout.write('-- more --')
sys.stdout.flush()
c = getchar()
if c in ('q', 'Q'):
sys.stdout.write('\r \r')
break
elif c in ('\r', '\n'):
sys.stdout.write('\r \r' + lines[r] + '\n')
r = r + 1
continue
if c in ('b', 'B', '\x1b'):
r = r - inc - inc
if r < 0: r = 0
sys.stdout.write('\n' + '\n'.join(lines[r:r+inc]) + '\n')
r = r + inc
finally:
if has_tty:
termios.tcsetattr(fd, termios.TCSAFLUSH, old)
def plain_pager(text: str, title: str = '') -> None:
"""Simply print unformatted text. This is the ultimate fallback."""
sys.stdout.write(plain(escape_stdout(text)))
def pipe_pager(text: str, cmd: str, title: str = '') -> None:
"""Page through text by feeding it to another program."""
import subprocess
env = os.environ.copy()
if title:
title += ' '
esc_title = escape_less(title)
prompt_string = (
f' {esc_title}' +
'?ltline %lt?L/%L.'
':byte %bB?s/%s.'
'.'
'?e (END):?pB %pB\\%..'
' (press h for help or q to quit)')
env['LESS'] = '-RmPm{0}$PM{0}$'.format(prompt_string)
proc = subprocess.Popen(cmd, shell=True, stdin=subprocess.PIPE,
errors='backslashreplace', env=env)
assert proc.stdin is not None
try:
with proc.stdin as pipe:
try:
pipe.write(text)
except KeyboardInterrupt:
# We've hereby abandoned whatever text hasn't been written,
# but the pager is still in control of the terminal.
pass
except OSError:
pass # Ignore broken pipes caused by quitting the pager program.
while True:
try:
proc.wait()
break
except KeyboardInterrupt:
# Ignore ctl-c like the pager itself does. Otherwise the pager is
# left running and the terminal is in raw mode and unusable.
pass
def tempfile_pager(text: str, cmd: str, title: str = '') -> None:
"""Page through text by invoking a program on a temporary file."""
import tempfile
with tempfile.TemporaryDirectory() as tempdir:
filename = os.path.join(tempdir, 'pydoc.out')
with open(filename, 'w', errors='backslashreplace',
encoding=os.device_encoding(0) if
sys.platform == 'win32' else None
) as file:
file.write(text)
os.system(cmd + ' "' + filename + '"')
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