dashify.py

#!/usr/bin/env python3.3

# Convert LaTeX type dashes: - for hyphen, -- for en-dash, --- for
# em-dash to html: -, –, — in markdown.
#
# Usage:
# python dashify FILE_PATH
# ./dashify FILE_PATH
#
# One file allowed at a time. A backup file will be created each time
# in case of accidents. To remove the backup file, run the
# accompanying ./remove_backup.sh.
#
# Caveat:
# "---" at the beginning of a line (after '\n') is regarded as a
# header indicator or a horizontal rule, hence not converted.

import sys

usage = '''usage:
python dashify FILE_PATH
./dashify FILE_PATH'''

if sys.argv[0] == 'python':
    if len(sys.argv) != 3:
        print(usage)
        exit(1)
    file_path = sys.argv[2]
else:
    if len(sys.argv) != 2:
        print(usage)
        exit(1)
    file_path = sys.argv[1]

inbuf = open(file_path, 'r')
intext = inbuf.read()
inbuf.close()

# backup the file in case of accident
outbuf = open(file_path + '.backup', 'w')
outbuf.write(intext)
outbuf.close()

# convert dashes
converted = ''
length = len(intext)
i = 0;
while i < length:
    if intext[i] != '-':
        converted += intext[i]
        i += 1
        continue
    else:
        if i + 2 < length:
            if (intext[i + 1] == intext[i + 2] == '-'):
                # check if --- is at the beginning of a line (header
                # or horizontal rule); if so, skip all subsequent
                # hyphens
                if i == 0 or intext[i - 1] == '\n':
                    while i < length and intext[i] == '-':
                        converted += '-'
                        i += 1
                    continue
                converted += '&mdash;'
                i += 3
                continue
        if i + 1 < length:
            if (intext[i + 1] == '-'):
                converted += '&ndash;'
                i += 2
                continue
        converted += '-'
        i += 1
        continue

# write to the original file
outbuf = open(file_path, 'w')
outbuf.write(converted)
outbuf.close()

remove_backup.sh

#!/bin/zsh
rm -i **/*.backup