File: teletype.py
   1 #!/usr/bin/python
   2 
   3 # The MIT License (MIT)
   4 #
   5 # Copyright (c) 2026 pacman64
   6 #
   7 # Permission is hereby granted, free of charge, to any person obtaining a copy
   8 # of this software and associated documentation files (the "Software"), to deal
   9 # in the Software without restriction, including without limitation the rights
  10 # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  11 # copies of the Software, and to permit persons to whom the Software is
  12 # furnished to do so, subject to the following conditions:
  13 #
  14 # The above copyright notice and this permission notice shall be included in
  15 # all copies or substantial portions of the Software.
  16 #
  17 # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  18 # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  19 # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  20 # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  21 # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  22 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  23 # SOFTWARE.
  24 
  25 
  26 from itertools import islice
  27 from sys import argv, exit, stderr, stdin, stdout
  28 from time import sleep
  29 
  30 
  31 info = '''
  32 teletype [options...] [files...]
  33 
  34 Simulate the cadence of old-fashioned teletype machines, by slowing down
  35 the output of ASCII/UTF-8 symbols from the inputs given.
  36 
  37 All options can start with either a single or a double leading dash:
  38 
  39     -h, -help    show this help message
  40 '''
  41 
  42 
  43 def run_teletype(src):
  44     'Emit data runes with a delay for each symbol.'
  45 
  46     prev = '\n'
  47 
  48     for line in src:
  49         # ignore trailing LF/CRLF from lines
  50         line = line.rstrip('\r\n').rstrip('\n')
  51 
  52         # emit runes with a delay, which is the whole point of this script;
  53         # the exception is ANSI-style runs of bytes, which are emitted all
  54         # together
  55         ansi = False
  56         for e in list(line):
  57             # an escape byte marks the start of an ANSI-style sequence
  58             if e == '\x1b':
  59                 ansi = True
  60 
  61             if not ansi:
  62                 # delay each visible item's appeareance by 15 ms
  63                 sleep(0.015)
  64 
  65             # an `m` means the end of an ANSI-style sequence, even if there
  66             # wasn't one preceding it
  67             if e == 'm':
  68                 ansi = False
  69 
  70             # emit the item, ensuring it shows right away
  71             stdout.write(e)
  72             stdout.flush()
  73 
  74         # time-bunch line-feeds together, by waiting only before the first
  75         # one in its run of line-feed bytes
  76         if prev != '':
  77             # wait for 750 ms before ending the line(s)
  78             sleep(0.75)
  79         prev = line
  80 
  81         # ensure a line-feed ends each line, even the last one
  82         stdout.write('\n')
  83         stdout.flush()
  84 
  85 
  86 try:
  87     # handle the help option, if given
  88     if len(argv) > 1 and argv[1] in ('-h', '--h', '-help', '--help'):
  89         print(info.strip())
  90         exit(0)
  91 
  92     # ignore leading end-of-options `--`, if present
  93     skip = 2 if len(argv) > 1 and argv[1] == '--' else 1
  94 
  95     # handle all named inputs, in the order given
  96     for name in islice(argv, skip, None):
  97         with open(name, encoding='utf-8') as inp:
  98             run_teletype(inp)
  99 
 100     # read from stdin, if no named inputs were given
 101     if len(argv) - skip < 1:
 102         run_teletype(stdin)
 103 except BrokenPipeError:
 104     # quit quietly, instead of showing a confusing error message
 105     stderr.close()
 106 except KeyboardInterrupt:
 107     exit(2)
 108 except Exception as e:
 109     # chances are, func `open` failed because some file given doesn't exist
 110     print(str(e), file=stderr)
 111     exit(1)