ellyToken.py

#!/usr/bin/python3
# PyElly - rule-based tool for analyzing natural language (python v3.8)
#
# ellyToken.py : 14nov2019 CPM
# ------------------------------------------------------------------------------
# Copyright (c) 2019, Clinton Prentiss Mah
# All rights reserved.
#
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#   Redistributions of source code must retain the above copyright notice, this
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# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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"""
encapsulation of a token string and results of its analysis
"""

import unicodedata

class EllyToken(object):

    """
    lexical token for morphological analysis

    attributes:
        orig - original word
        root - root from analysis
        pres - prefix list
        sufs - suffix list
        capn - capitalization flag
        dvdd - divided flag
    """

    def __init__ ( self , x=None ):

        """
        construct token from string

        arguments:
            self  -
            x     - Unicode input string or list of chars
        """

        if x != None:
            self.set(x)
        else:
            self.set()

    def __str__ ( self ):

        """
        how to show token for debugging

        arguments:
            self

        returns:
            Unicode string representation
        """

        p =   '[' + ' '.join(self.pres) + ']+' if len(self.pres) > 0 else ''
        s = ' -[' + ' '.join(self.sufs) + ']'  if len(self.sufs) > 0 else ''
        c = 'CAP' if self.capn else ''
        return 'EllyToken: ' + p + str(self.root) + s + ' (orig= "' + self.orig + '") ' + c

    def set ( self , x='' ):

        """
        set token to specified string

        arguments:
            self  -
            x     - Unicode input string or list of chars
        """

        if not isinstance(x,str):
            x = ''.join(x)
        if len(x) > 0:
            self.capn = x[0].isupper()
        else:
            self.capn = False
        self.orig = x
        self.pres = [ ]
        self.sufs = [ ]
        self.root = list(x.lower())
        self.dvdd = False

    def store ( self , s ):

        """
        store sequence in token

        arguments:
            self  -
            s     - sequence of Unicode chars
        """

        self.set(''.join(s))

    def getOrig ( self ):

        """
        get original token string

        arguments:
            self
        returns:
            Unicode string
        """

        return self.orig

    def getRoot ( self ):

        """
        get root for token

        arguments:
            self
        returns:
            list of chars
        """

        return self.root

    def getPrefixes ( self ):

        """
        get merged suffixes for token

        arguments:
            self
        returns:
            list of strings
        """

        return self.pres

    def getSuffixes ( self ):

        """
        get merged suffixes for token

        arguments:
            self
        returns:
            list of strings
        """

        return self.sufs

    def chopPrefix ( self , n ):

        """
        drop first n chars in token and add as prefix

        arguments:
            self
            n     - length of prefix
        """

        if n > len(self.root):
            x = ''.join(self.root[:n])
            self.root = self.root[n:]
            self.pres.append(x)
            self.dvdd = True

    def chopSuffix (self , n ):

        """
        drop last n chars in token and add as suffix

        arguments:
            self
            n     - length of suffix
        """

        if n > len(self.root):
            x = ''.join(self.root[-n:])
            self.root = self.root[:-n]
            self.sufs.insert(0,x)
            self.dvdd = True

    def addSuffix ( self , x ):

        """
        add suffix to list for token

        arguments:
            self
            x     - suffix string
        """

        self.sufs.insert(0,x)
        self.dvdd = True

    def addPrefix ( self , x ):

        """
        add prefix to list for token

        arguments:
            self
            x     - prefix string
        """

        self.pres.append(x)
        self.dvdd = True

    def getLength ( self ):

        """
        get char count in token less suffixes

        arguments:
            self

        returns:
            length
        """

        return len(self.root)

    def shortenBy ( self , n , both=False ):

        """
        drop chars from token

        arguments:
            self  -
            n     - char count
            both  - shorten both root and orig
        """

        m = len(self.root)
        if both and m != len(self.orig):
            return
        if m < n:
            return
        nm = m - n
        self.root = self.root[:nm]
        if both:
            self.orig = self.orig[:nm]

    def isSplit ( self ):

        """
        check if suffixes have been removed from token

        arguments:
            self

        returns:
            True if suffixes removed, otherwise False
        """

        return self.dvdd

    def isCapitalized ( self ):

        """
        check if first char is upper case

        arguments:
            self

        returns:
            True if upper case, otherwise False
        """

        return self.capn

    def isAffix ( self ):

        """
        check if token is itself an affix

        arguments:
            self

        returns:
            True if affix, False otherwise
        """

        return self.root[0] == '-' or self.root[-1] == '+'

    def charAt ( self , n ):

        """
        get nth character in token

        arguments:
            self  -
            n     - index of character in token

        returns:
            indexed character
        """

        if n >= len(self.root): return ''

        return self.root[n]

    def toStr ( self ):

        """
        get Unicode string representation of token root

        arguments:
            self

        returns:
            Unicode token string
        """

        return ''.join(self.root)

if __name__ == "__main__":

    import sys

    if len(sys.argv) < 2:
        ux = 'Taxed'
    else:
        ux = sys.argv[1]
        print ( len(ux) , type(ux) , ux )

    t = EllyToken(ux)
    print ( 'initial definition' )
    print ( 'token=' , t )

    t.addSuffix('xxx')
    t.addSuffix('yy')
    t.addSuffix('z')

    print ( 'capn=' , t.capn )
    print ( "suffixes=" , [ '-' + sx for sx in t.getSuffixes() ] )
    print ( 'dvdd=' , t.dvdd )
    print ()

    t.shortenBy(1,both=True)

    print ( 'shorten token and root by 1' )
    print ( t )
    print ()

    t.shortenBy(1)

    print ( 'shorten only root by 1' )
    print ( t )
    print ()

    print ( 'unicode=' , str(t) )

    tls = EllyToken([ 'x' , 'y' , 'z' ])
    print ( 'tls=' , tls )