abbreviate-file-name

#!/usr/bin/env python3

#==============================================================================
# Functionality
#==============================================================================
import pdb
import sys
import os
import re
import json
import importlib
from pprint import pprint as pp

# utility funcs, classes, etc go here.

def asserting(cond):
    if not cond:
        pdb.set_trace()
    assert(cond)

def has_stdin():
    return not sys.stdin.isatty()

def reg(pat, flags=0):
    return re.compile(pat, re.VERBOSE | flags)


# https://stackoverflow.com/a/56090741
def import_path(path):
    module_name = os.path.basename(path).replace('-', '_')
    if module_name in sys.modules:
        return sys.modules[module_name]
    spec = importlib.util.spec_from_loader(
        module_name,
        importlib.machinery.SourceFileLoader(module_name, os.path.join(os.path.dirname(__file__), path))
    )
    module = importlib.util.module_from_spec(spec)
    spec.loader.exec_module(module)
    sys.modules[module_name] = module
    return module

def function(path, name=None):
    if callable(path):
        return path
    if path.startswith('lambda') and ':' in path:
        f = eval(compile(path, '<lambda>', mode='eval'))
        f.__name__ = path
        f.__qualname__ = f'function(' + repr(path) + ')'
        return f
    module = import_path(path)
    return getattr(module, module.__name__ if name is None else name)


def abbreviate_file_name(filename):
  """Return a version of FILENAME shortened by substituting "~" for
the user's home directory."""
  filename = function('expand-file-name')(filename)
  home = os.path.expanduser('~')
  if filename.startswith(home):
    filename = '~' + filename[len(home):]
  return filename

#==============================================================================
# Cmdline
#==============================================================================
import argparse

def get_parser(parser=None):
    if parser is None:
        parser = argparse.ArgumentParser(formatter_class=argparse.RawTextHelpFormatter, 
            description=abbreviate_file_name.__doc__.strip())

    parser.add_argument('-v', '--verbose',
        action="store_true",
        help="verbose output" )

    parser.add_argument('-0', '--print0',
        action="store_true",
        help="Prints \\0 after each result rather than newline" )
    return parser

args = None

#==============================================================================
# Main
#==============================================================================

def run():
    if args.verbose:
        print(args, file=sys.stderr)
    if len(args.args) <= 0 and not has_stdin():
        # if there were no args and there was no input, prompt user.
        print('Enter input (press Ctrl-D when done):')
    if len(args.args) <= 0 or has_stdin():
        indata = sys.stdin.read()
        args.args.extend(indata.split('\0') if '\0' in indata else indata.splitlines())
    # for each arg on cmdline...
    for arg in args.args:
        result = abbreviate_file_name(arg)
        print(result, end='\0' if args.print0 else '\n')

def main():
    try:
        global args
        if not args:
            args, leftovers = get_parser().parse_known_args()
            args.args = leftovers
        return run()
    except IOError:
        # http://stackoverflow.com/questions/15793886/how-to-avoid-a-broken-pipe-error-when-printing-a-large-amount-of-formatted-data
        if e.errno != 32:
            raise
        try:
            sys.stdout.close()
        except IOError:
            pass
        try:
            sys.stderr.close()
        except IOError:
            pass

if __name__ == "__main__":
    main()