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# Copyright 2016 The Android Open Source Project
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""Terminal utilities
This module handles terminal interaction including ANSI color codes.
"""
import os
import sys
_path = os.path.realpath(__file__ + '/../..')
if sys.path[0] != _path:
sys.path.insert(0, _path)
del _path
# pylint: disable=wrong-import-position
import rh.shell
# This will erase all content in the current line after the cursor. This is
# useful for partial updates & progress messages as the terminal can display
# it better.
CSI_ERASE_LINE_AFTER = '\x1b[K'
class Color(object):
"""Conditionally wraps text in ANSI color escape sequences."""
BLACK, RED, GREEN, YELLOW, BLUE, MAGENTA, CYAN, WHITE = range(8)
BOLD = -1
COLOR_START = '\033[1;%dm'
BOLD_START = '\033[1m'
RESET = '\033[m'
def __init__(self, enabled=None):
"""Create a new Color object, optionally disabling color output.
Args:
enabled: True if color output should be enabled. If False then this
class will not add color codes at all.
"""
self._enabled = enabled
def start(self, color):
"""Returns a start color code.
Args:
color: Color to use, e.g. BLACK, RED, etc...
Returns:
If color is enabled, returns an ANSI sequence to start the given
color, otherwise returns empty string
"""
if self.enabled:
return self.COLOR_START % (color + 30)
return ''
def stop(self):
"""Returns a stop color code.
Returns:
If color is enabled, returns an ANSI color reset sequence, otherwise
returns empty string
"""
if self.enabled:
return self.RESET
return ''
def color(self, color, text):
"""Returns text with conditionally added color escape sequences.
Args:
color: Text color -- one of the color constants defined in this class.
text: The text to color.
Returns:
If self._enabled is False, returns the original text. If it's True,
returns text with color escape sequences based on the value of color.
"""
if not self.enabled:
return text
if color == self.BOLD:
start = self.BOLD_START
else:
start = self.COLOR_START % (color + 30)
return start + text + self.RESET
@property
def enabled(self):
"""See if the colorization is enabled."""
if self._enabled is None:
if 'NOCOLOR' in os.environ:
self._enabled = not rh.shell.boolean_shell_value(
os.environ['NOCOLOR'], False)
else:
self._enabled = sys.stderr.isatty()
return self._enabled
def print_status_line(line, print_newline=False):
"""Clears the current terminal line, and prints |line|.
Args:
line: String to print.
print_newline: Print a newline at the end, if sys.stderr is a TTY.
"""
if sys.stderr.isatty():
output = '\r' + line + CSI_ERASE_LINE_AFTER
if print_newline:
output += '\n'
else:
output = line + '\n'
sys.stderr.write(output)
sys.stderr.flush()
def boolean_prompt(prompt='Do you want to continue?', default=True,
true_value='yes', false_value='no', prolog=None):
"""Helper function for processing boolean choice prompts.
Args:
prompt: The question to present to the user.
default: Boolean to return if the user just presses enter.
true_value: The text to display that represents a True returned.
false_value: The text to display that represents a False returned.
prolog: The text to display before prompt.
Returns:
True or False.
"""
true_value, false_value = true_value.lower(), false_value.lower()
true_text, false_text = true_value, false_value
if true_value == false_value:
raise ValueError(
f'true_value and false_value must differ: got {true_value!r}')
if default:
true_text = true_text[0].upper() + true_text[1:]
else:
false_text = false_text[0].upper() + false_text[1:]
prompt = f'\n{prompt} ({true_text}/{false_text})? '
if prolog:
prompt = f'\n{prolog}\n{prompt}'
while True:
try:
response = input(prompt).lower() # pylint: disable=bad-builtin
except EOFError:
# If the user hits CTRL+D, or stdin is disabled, use the default.
print()
response = None
except KeyboardInterrupt:
# If the user hits CTRL+C, just exit the process.
print()
raise
if not response:
return default
if true_value.startswith(response):
if not false_value.startswith(response):
return True
# common prefix between the two...
elif false_value.startswith(response):
return False
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