trunc.py

#! /usr/bin/python2.6
"""
trunc -n LENGTH -k 0,1,2,3... COMPONENTS...
"""
from __future__ import print_function,unicode_literals
from argparse import ArgumentParser
from math import floor

def shorten(length, x, suffix = "..."):
    if len(x) <= length:
        return x
    #Do word splitting
    y = x[:max(0, length - len(suffix))]
    #Get the closest whitespace to strip.
    index = y.rfind(" ")
    if index == -1:
        return x[:length].rstrip()
    else:
        return x[:index] + suffix

def main():
    p = ArgumentParser()
    p.add_argument("-n", dest = "length", default = 140, type = int)
    p.add_argument("-k", dest = "keys", default = "")
    p.add_argument("components", nargs = "+")
    args = p.parse_args()
    keys = [int(x) for x in args.keys.split(",") if x]
    def mark_comp(i, x):
        return (x, True) if i in keys else (x, False)
    components = [mark_comp(i, x) for i, x in enumerate(args.components)]
    flex_comp_len = len([x for x in components if x[1]])
    fixed_comp_str_len = sum(len(x[0]) for x in components if not x[1])
    flex_comp_str_len = max(0, floor((args.length - fixed_comp_str_len) / flex_comp_len))
    extra = 0
    out = list()
    for x, y in components:
        if y:
            z = shorten(flex_comp_str_len + extra, x)
            extra += flex_comp_str_len - len(z)
            out.append(z)
        else:
            out.append(x)
    x = ''.join(out)
    print(shorten(args.length, x), end = '')

if __name__ == "__main__":
    main()