prefixTreeLogic.py

#!/usr/bin/python3
# PyElly - rule-based tool for analyzing natural language (Python v3.8)
#
# prefixTreeLogic.py : 16nov2019 CPM
# ------------------------------------------------------------------------------
# Copyright (c) 2019, Clinton Prentiss Mah
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# -----------------------------------------------------------------------------

"""
morphological analyzer for prefixes
"""

import treeLogic
import ellyException

class PrefixTreeLogic(treeLogic.TreeLogic):

    """
    encapsulated stemmer for prefix removal

    attributes:
    """

    addn = '+'  # special addition for root modification, overrides TreeLogic

    def __init__ ( self , inp ):

        """
        initialization

        arguments:
            self  -
            inp   - definition reader

        exceptions:
            TableFailure on error
        """

        super(PrefixTreeLogic,self).__init__(inp)

    def sequence ( self , lstg ):

        """
        obtain list of chars for tree logic processing (overrides parent class)

        arguments:
            self  -
            lstg  - listing of chars in word to stem

        returns:
            list of chars on success, None otherwise
        """

        return lstg  # i.e.  no reversal of chars

    def rewrite ( self , token , leng , node ):

        """
        rewrite token with new reduced root and suffixes

        arguments:
            self  -
            token - Elly token for results of stemming
            leng  - number of chars matched by tree logic
            node  - node for match

        returns:
            True on success, False otherwise
        """

        return node.actns.applyFWD(token,leng)

#
# unit test
#

if __name__ == '__main__':

    import sys
    import ellyToken
    import ellyConfiguration
    import ellyDefinitionReader

    system = sys.argv[1] if len(sys.argv) > 1 else 'test'
    print ( 'system=' , system )

    base = ellyConfiguration.baseSource + '/'
    dfn = ellyDefinitionReader.EllyDefinitionReader(base + system + '.ptl.elly')
    if dfn.error != None:
        print ( dfn.error , file=sys.stderr )
        sys.exit(1)
    n = dfn.linecount()
    print ( n , 'definition lines' )
    if n == 0: sys.exit(0)

    try:
        pre = PrefixTreeLogic(dfn)
    except ellyException.TableFailure:
        print ( 'cannot load prefix table' , file=sys.stderr )
        sys.exit(1)

    print ( 'pre=' , pre )

    treeLogic.dumpLT(pre.indx)

    xs = [                           # test cases
        'telegraph +graph' ,
        'telephone +phone'   ,
        'transportation +portation' ,
        'pseudopod +pod'
    ]

    nfail = 0

    for x in xs:
        rec = x.strip().split()      # next test case
        if len(rec) != 2: continue   # better be [ input , expected output ]

        w = rec[0]                   # get separate components
        r = rec[1]

        t = ellyToken.EllyToken(w)   # make token for matching
        b = pre.match(t)
        a = ''.join(t.root)
        if not b:
            print ( ' NO MATCH=' , rec )
        m = (r == a)
        if not m:
            print ( '     FAIL=' , rec , '!= <' + a + '>' )
            nfail += 1

    print ( nfail , 'examples failed' )