tformat.py

# MIT license

'''
Module for formatting text for display in a terminal. Colored output is
provided through the use of ISO 6429 terminal escape sequences.
'''

# Terminal colors are defined by the ISO 6429 standard.
# To convert this list to foreground colors, add 30;
# for a background color, add 40.
iso_colors = {
    'black': 0,
    'red': 1,
    'green': 2,
    'yellow': 3,
    'blue': 4,
    'purple': 5,
    'cyan': 6,
    'white': 7
}

# Terminal text effects as defined by the ISO 6429 standard.
iso_fx = {
    'bold': 1,
    'underline': 4,
    'blink': 5
}


def tprint(string, severity='log'):
    '''
    Prints debugging strings to the terminal, colorized according to severity.
    '''
    # This function simply calls cprint() with a number of standard arguments
    # based on the severity of the log. All calls are underlined to distinguish
    # them from the Flask debugging output.
    color = None
    fx = ['underline']
    
    if severity == 'info':
        color = 'blue'
        
    if severity == 'warn':
        color = 'yellow'
        
    if severity == 'error':
        color = 'red'
    
    return cprint(string, color, None, fx)


def cprint(string, fgcolor='white', bgcolor=None, fx=[]):
    '''
    Prints a colorized string according to a foreground color
    and optionally a background color and effects list.
    '''
    print(cdecorate(string, fgcolor, bgcolor, fx))


def cdecorate(string, fgcolor='white', bgcolor=None, fx=[]):
    '''
    Returns a colorized string according to a foreground color
    and optionally a background color and effects list.
    '''
    # Fetch the color numbers, defaulting to white for the foreground.
    fgcolor = iso_colors.get(fgcolor, None)
    bgcolor = iso_colors.get(bgcolor, None)
    
    # Set the correct foreground and background ISO color values,
    # and add a semicolon to the background color if it has been set.
    if fgcolor is not None:
        fgcolor += 30
    if bgcolor is not None:
        bgcolor += 40
    
    # Modify the effects list so that it contains ISO values
    # instead of the alias.
    fx = [str(iso_fx[n]) for n in fx if n in iso_fx]
    
    # Separate the colors with a semicolon if we've set both of them.
    colors = [str(n) for n in (bgcolor, fgcolor) if n is not None]
    colors = ';'.join(colors)
    
    # Same goes for the effects.
    fx = ';' + ';'.join(fx) if fx is [] else ''
    
    # Return the decorated string.
    return '\033[%s%sm%s\033[0m' % (colors, fx, string)