terminal.py 2.54 KB
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# Copyright (c) 2011 The Chromium OS Authors.
#
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# SPDX-License-Identifier:	GPL-2.0+
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#

"""Terminal utilities

This module handles terminal interaction including ANSI color codes.
"""

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import os
import sys

# Selection of when we want our output to be colored
COLOR_IF_TERMINAL, COLOR_ALWAYS, COLOR_NEVER = range(3)

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class Color(object):
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    """Conditionally wraps text in ANSI color escape sequences."""
    BLACK, RED, GREEN, YELLOW, BLUE, MAGENTA, CYAN, WHITE = range(8)
    BOLD = -1
    BRIGHT_START = '\033[1;%dm'
    NORMAL_START = '\033[22;%dm'
    BOLD_START = '\033[1m'
    RESET = '\033[0m'
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    def __init__(self, colored=COLOR_IF_TERMINAL):
        """Create a new Color object, optionally disabling color output.
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        Args:
          enabled: True if color output should be enabled. If False then this
            class will not add color codes at all.
        """
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        try:
            self._enabled = (colored == COLOR_ALWAYS or
                    (colored == COLOR_IF_TERMINAL and
                     os.isatty(sys.stdout.fileno())))
        except:
            self._enabled = False
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    def Start(self, color, bright=True):
        """Returns a start color code.
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        Args:
          color: Color to use, .e.g BLACK, RED, etc.
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        Returns:
          If color is enabled, returns an ANSI sequence to start the given
          color, otherwise returns empty string
        """
        if self._enabled:
            base = self.BRIGHT_START if bright else self.NORMAL_START
            return base % (color + 30)
        return ''
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    def Stop(self):
        """Retruns a stop color code.
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        Returns:
          If color is enabled, returns an ANSI color reset sequence,
          otherwise returns empty string
        """
        if self._enabled:
            return self.RESET
        return ''
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    def Color(self, color, text, bright=True):
        """Returns text with conditionally added color escape sequences.
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        Keyword arguments:
          color: Text color -- one of the color constants defined in this
                  class.
          text: The text to color.
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        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:
            base = self.BRIGHT_START if bright else self.NORMAL_START
            start = base % (color + 30)
        return start + text + self.RESET