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ellyBufferEN.py
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ellyBufferEN.py
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#!/usr/bin/python
# PyElly - scripting tool for analyzing natural language
#
# ellyBufferEN.py : 11nov2014 CPM
# ------------------------------------------------------------------------------
# Copyright (c) 2013, Clinton Prentiss Mah
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#
# Redistributions of source code must retain the above copyright notice, this
# list of conditions and the following disclaimer.
#
# Redistributions in binary form must reproduce the above copyright notice,
# this list of conditions and the following disclaimer in the documentation
# and/or other materials provided with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
# DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
# SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
# CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
# OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
# -----------------------------------------------------------------------------
"""
framework for integrating English inflectional stemming into basic tokenization
"""
import ellyBuffer
import ellyChar
import ellyStemmer
import ellyException
import ellyConfiguration
import inflectionStemmerEN
APO = ellyChar.APO # literal apostrophe
ESS = u's' # literal S
class EllyBufferEN(ellyBuffer.EllyBuffer):
"""
input text buffer with methods for getting successive tokens
attributes:
stemmer - inflectional stemmer
"""
def __init__ ( self ):
"""
constructor to set up buffer
arguments:
self -
"""
super(EllyBufferEN,self).__init__()
if ellyConfiguration.inflectionalStemming: # English inflectional stemmer?
try: # of so, try to load
self.stemmer = inflectionStemmerEN.InflectionStemmerEN()
except ellyException.TableFailure:
self.stemmer = ellyStemmer.EllyStemmer() # null stemmer
else:
self.stemmer = ellyStemmer.EllyStemmer() # null stemmer
def getNext ( self ):
"""
get next token from buffer and automatically apply inflectional stemming
overriding EllyBuffer method
arguments:
self
returns:
a token or None if buffer is empty
exceptions:
StemmingError
"""
w = super(EllyBufferEN,self).getNext() # use getNext() without inflectional stemmer
if w == None: return None
# print 'got:' , w
if not w.isSplit(): # check for stemming
self.divide(w) # if not, do inflectional stemming
return w
def divide ( self , word ):
"""
apply inflectional analysis, including for -'s and -s'
arguments:
self -
word - ellyToken
exceptions:
StemmingError
"""
# print "divide" , word
wl = word.getLength() # if so, is word long enought to be divided
if wl < 3:
return # if not, done
if word.isAffix(): # if term is already product of division, stop
return
x = word.charAt(wl-1) # get last two chars of word
y = word.charAt(wl-2)
# print 'word= ...' , y , x
if x == u's' and y == APO: # check for -S'
word.addSuffix(APO+ESS)
word.shortenBy(2)
# print 'word=' , word
return
elif x == APO and y == ESS: # check for implied -'S
word.addSuffix(APO+ESS)
word.shortenBy(1)
# print 'word=' , word
return
if ellyChar.isLetter(word.charAt(0)):
self.stemmer.apply(word) # apply any inflectional stemmer
if word.isSplit():
sufs = word.getSuffixes()
# print 'sufs=' , sufs
while len(sufs) > 0:
if self.atToken(): self.prepend(ellyChar.SPC)
self.prepend(sufs.pop())
#
# unit test
#
if __name__ == "__main__":
import sys
buf = EllyBufferEN()
print 'enter text lines to get tokens from'
while True:
try:
sys.stdout.write("> ")
l = sys.stdin.readline()
except KeyboardInterrupt:
break
l = l.strip()
if len(l) == 0: break
buf.clear()
buf.append(list(l))
print buf.buffer
try:
while True:
print "len=" , len(buf.buffer)
t = buf.getNext()
if t == None: break
print ">>>> 0=" , t
except ellyException.StemmingError:
print >> sys.stderr , 'stemming error'
sys.exit(1)
print "------------"
sys.stdout.write("\n")