multireplace.py

# devplayer@gmail.com
# 2011-Nov-04

# This is my first text parsing program.

# This is my first implementation of a simple
# string parser and transform (I call recompile)
# of a given string into a new string based on
# a list of given (valid) keyword strings.

# From within Python instead of a MS-DOS script
# I wanted to compile/transform/convert
# the value of the MS-DOS PROMPT envar variable,
# usaually PROMPT = "$P$G",
# to what would be displayed by MS-DOS.

# But it can be used for a lot more.

# globals()['__doc__'] =
'''Parse (partition) a string in to a list of valid and
invalid words (strings), while retaining the same order of
both.

Valid words are supplied by the caller in a list of strings.

An invalid word is anything between valid words, before any
valid words or after any valid words.

Then recompile the string with values from a dict whose keys
are the valid words yet keep the invalid words in place.

Example:
    "invalid00;Valid00Invalid02Valid01I.n'valid03"
where Valid00 remaps to " HELLO " and "Valid01" remaps to " WORLD! "
you should get:
    "invalid00; HELLO Invalid02 WORLD! I.n'valid03"
'''


# These are the main functions
def getValidWord(keywords, string):
    for word in keywords:
        if string.startswith(word):
            return word
    return ''

def getInvalidWord(keywords, string):
    lstring = len(string)
    for i in range(lstring):
        for word in keywords:
            if string[i:].startswith(word):
                return string[0:i]
    return string


def parse(string, keywords):
    # copy original string as this function is destructive to string
    s = string[:]
    words = []
    word = ''
    interations = 0
    while len(s) > 0:

        # try and get a keyword
        word = getValidWord(keywords, s)
        if word and s.startswith(word):
            words.append(word)
            s = s.replace(word, '', 1)

        # try and get whatever is not a keyword
        word = getInvalidWord(keywords, s)
        if word and s.startswith(word):
            words.append(word)
            s = s.replace(word, '', 1)

        interations += 1
    return words

# similar to map() i guess
def recompile(string, mapping):
    keywords = mapping.keys()
    words = parse(string, keywords)

    new_words = []
    for word in words:
        if word in keywords:
            if callable(mapping[word]):
                ret_word = mapping[word]()
                new_words.append( str( ret_word ) )
            else:
                new_words.append( str( mapping[word] ) )
        else:
            new_words.append( str( word ) )

    new_string = ''.join(new_words)

    return new_string


# These functions support DOS prompt conversion/tranform/recompile
def getcwdrive():
    import os
    return os.path.splitdrive(os.getcwd())[0]

def msdosdate():
    import datetime
    now = datetime.datetime.today()
    dosformat = now.strftime('%a %m/%d/%Y')
    return dosformat

def msdostime():
    import datetime
    now = datetime.datetime.today()
    dosformat = now.strftime('%X.00')
    return dosformat

def msdosprompt():
    '''Processes the DOS "PROMPT" environment variable
    and returns it's string.'''
    import os
    prompt = os.getenv('prompt', '$P$G')
    prompt_mapper = msdosprompt_mapper()
    transformed = recompile(prompt, prompt_mapper)
    return transformed


def msdosprompt_mapper():
    import os
    import sys
    import collections
    special_codes = collections.OrderedDict()
    sc = special_codes
    sc['$A'] = '&'
    sc['$B'] = '|'
    sc['$C'] = '('
    sc['$D'] = msdosdate
    sc['$E'] = chr(27)
    sc['$F'] = ')'
    sc['$G'] = '>'
    sc['$H'] = '\b'
    sc['$I'] = '$I'
    sc['$J'] = '$J'
    sc['$K'] = '$K'
    sc['$L'] = '>'
    sc['$M'] = '$M'
    sc['$N'] = getcwdrive
    sc['$O'] = '$O'
    sc['$P'] = os.getcwd
    sc['$Q'] = '='
    sc['$R'] = '$R'
    sc['$S'] = ' '
    sc['$T'] = msdostime
    sc['$U'] = '$U'
    sc['$V'] = sys.version
    sc['$W'] = '$W'
    sc['$X'] = '$X'
    sc['$Y'] = '$Y'
    sc['$Z'] = '$Z'
    sc['$_'] = '\r\n'
    sc['$$'] = '$'
    sc['$+'] = '$+'
    sc['$M'] = ''
    return special_codes

def mdosprompthelp():
    # Warning: copy directly from Microsoft Windows XP without permission.
    print('''
Changes the cmd.exe command prompt.

PROMPT [text]

  text    Specifies a new command prompt.

Prompt can be made up of normal characters and the following special codes:

  $A   & (Ampersand)
  $B   | (pipe)
  $C   ( (Left parenthesis)
  $D   Current date
  $E   Escape code (ASCII code 27)
  $F   ) (Right parenthesis)
  $G   > (greater-than sign)
  $H   Backspace (erases previous character)
  $L   < (less-than sign)
  $N   Current drive
  $P   Current drive and path
  $Q   = (equal sign)
  $S     (space)
  $T   Current time
  $V   Windows XP version number
  $_   Carriage return and linefeed
  $$   $ (dollar sign)

If Command Extensions are enabled the PROMPT command supports
the following additional formatting characters:

  $+   zero or more plus sign (+) characters depending upon the
       depth of the PUSHD directory stack, one character for each
       level pushed.

  $M   Displays the remote name associated with the current drive
       letter or the empty string if current drive is not a network
       drive.
    ''')



def usage():
    '''Print package usage.'''
    print( globals()['__doc__'] )


if __name__ == '__main__':
    import sys
    # ///////////////////////////////////
    def is_argv_help():
        '''See if user supplied a command line help argument,
        if so print usage and exit.'''
        import sys
        help = ['-h', '--h', '-help', '--help', '/h', '/help']
        for arg in sys.argv[1:]:
            if arg.lower() in help:
                usage()
                sys.exit(0)

    is_argv_help()
    # ///////////////////////////////////
    # ///////////////////////////////////

    # ///////////////////////////////////
    def test_parse(string, keywords):
        '''copy of parse() with interactive prompt and debug messages'''
        # copy original string as this function is destructive to string
        s = string[:]
        words = []
        word = ''
        interations = 0
        while raw_input('%d: >'% interations) <> 'q' and len(s) > 0:
            print s
            word = getValidWord(keywords, s)
            print '  valid return: ', repr(word)
            if word and s.startswith(word):
                words.append(word)
                s = string.replace(word, '', 1)

            word = getInvalidWord(keywords, s)
            print 'invalid return: ', repr(word)
            if word and s.startswith(word):
                words.append(word)
                s = s.replace(word, '', 1)

            print 'words:', words
            print
            interations += 1
        return words

    # ///////////////////////////////////
    if 'test1' in sys.argv:
        def test1(test_string, test_keywords):
            print('')
            print('Parse: %r' % test_string)
            print('')
            print(' into valid and invalid keywords: %r' % test_keywords)
            words = parse(test_string, test_keywords)
            print('')
            print('String was broken down (parsed) into:')
            print('')
            print('  %r' % words)
            print('')


    # ///////////////////////////////////
    if 'test2' in sys.argv:
        def test2(test_string, test_mapping):
            print('-'*70)
            print('')
            print('Reformat test string: %r' % test_string)
            print('')
            print(' using mapping: %r' % test_mapping)
            string = recompile(test_string, test_mapping)
            print('')
            print('String was reformatted into:')
            print('')
            print('  %r' % string)
            print(string)
            print('')


    # ///////////////////////////////////
    # test one
    if 'test1' in sys.argv:
        # pay very close attention to spaces and spelling
        # there's a few twists in this tests
        test_keywords = ['one','two','three ','five','size']
        test_string = 'one potatoe, two tomatoe, three oregano, more,fivesix'
        test1(test_string, test_keywords)


    # ///////////////////////////////////
    # test two
    if 'test2' in sys.argv:
        special_codes = msdosprompt_mapper()
        prompt = '$D $T$P$G$EmOLLy   $H $H$H$X:$S$N$.$G$G$G'
        test2(prompt, special_codes)


    # ///////////////////////////////////
    # test three
    if 'test3' in sys.argv:
        import collections
        keywords = collections.OrderedDict()
        keywords['Valid00'] = ' HELLO '
        keywords['Valid01'] = ' WORLD! '
        string = "invalid00;Valid00Invalid02Valid01I.n'valid03"
        print( 'Keywords:' )
        print( '   %r' % keywords.keys() )
        print( 'Original string:')
        print( '   %r' % string )
        print( 'Recompiled/transformed string:' )
        print( '   %r' % recompile(string, keywords) )