highcat

#!/usr/bin/env python
import sys
import re

import argparse

CSI = "\033["
RESET = CSI + "0m"

COLORS =  dict((name, value) for value, name
               in enumerate(("black", "red", "green", "yellow", "blue",
                             "magenta", "cyan", "white")))


def parse_color_spec(color_spec):
    color_spec = re.sub(r"\s", "", color_spec).lower()
    sgr_args = []
    if color_spec.startswith("bright"):
        sgr_args.append(1)
        color_spec = color_spec[6:]
    split_spec = color_spec.split("/", 1)
    sgr_args.append(30 + COLORS[split_spec[0]])
    if len(split_spec) == 2:
        sgr_args.append(40 + COLORS[split_spec[1]])
    return "%s%sm" % (CSI, ";".join(str(arg) for arg in sgr_args))


def main(argv=None):
    if argv is None:
        argv = sys.argv
    parser = argparse.ArgumentParser(prog=argv[0])
    parser.add_argument("--ignore-case", "-i", default=False,
                        action="store_true")
    parser.add_argument("--highlight", "-m", nargs=2, action="append",
                        metavar=("REGEX", "COLOR-SPEC"), default=[])
    parser.add_argument("input_file", nargs="?", type=argparse.FileType("rt"),
                        default=sys.stdin)
    args = parser.parse_args(args=argv[1:])
    re_flags = 0
    if args.ignore_case:
        re_flags |= re.I
    patterns_and_replacements = [
        (re.compile(pattern, re_flags),
         r"%s\g<0>%s" % (parse_color_spec(color_spec), RESET))
        for pattern, color_spec in args.highlight]
    output = sys.stdout
    # This looks a little funny, but doing "for line in
    # args.input_file" uses undesirable buffering.
    while True:
        line = args.input_file.readline()
        for pattern, replacement in patterns_and_replacements:
            line = pattern.sub(replacement, line)
        output.write(line)

if __name__ == "__main__":
    main()