# -*- coding: utf-8 -*-

"""

    sphinx.util.stemmer

    ~~~~~~~~~~~~~~~~~~~

    Porter Stemming Algorithm

    This is the Porter stemming algorithm, ported to Python from the

    version coded up in ANSI C by the author. It may be be regarded

    as canonical, in that it follows the algorithm presented in

    Porter, 1980, An algorithm for suffix stripping, Program, Vol. 14,

    no. 3, pp 130-137,

    only differing from it at the points maked --DEPARTURE-- below.

    See also http://www.tartarus.org/~martin/PorterStemmer

    The algorithm as described in the paper could be exactly replicated

    by adjusting the points of DEPARTURE, but this is barely necessary,

    because (a) the points of DEPARTURE are definitely improvements, and

    (b) no encoding of the Porter stemmer I have seen is anything like

    as exact as this version, even with the points of DEPARTURE!

    Release 1: January 2001

    :copyright: 2001 by Vivake Gupta <v@nano.com>.

    :license: Public Domain ("can be used free of charge for any purpose").

"""

class PorterStemmer(object):

    def __init__(self):

        """The main part of the stemming algorithm starts here.

        b is a buffer holding a word to be stemmed. The letters are in b[k0],

        b[k0+1] ... ending at b[k]. In fact k0 = 0 in this demo program. k is

        readjusted downwards as the stemming progresses. Zero termination is

        not in fact used in the algorithm.

        Note that only lower case sequences are stemmed. Forcing to lower case

        should be done before stem(...) is called.

        """

        self.b = ""  # buffer for word to be stemmed

        self.k = 0

        self.k0 = 0

        self.j = 0   # j is a general offset into the string

    def cons(self, i):

        """cons(i) is TRUE <=> b[i] is a consonant."""

        if self.b[i] == 'a' or self.b[i] == 'e' or self.b[i] == 'i' \

            or self.b[i] == 'o' or self.b[i] == 'u':

            return 0

        if self.b[i] == 'y':

            if i == self.k0:

                return 1

            else:

                return (not self.cons(i - 1))

        return 1

    def m(self):

        """m() measures the number of consonant sequences between k0 and j.

        if c is a consonant sequence and v a vowel sequence, and <..>

        indicates arbitrary presence,

           <c><v>       gives 0

           <c>vc<v>     gives 1

           <c>vcvc<v>   gives 2

           <c>vcvcvc<v> gives 3

           ....

        """

        n = 0

        i = self.k0

        while 1:

            if i > self.j:

                return n

            if not self.cons(i):

                break

            i = i + 1

        i = i + 1

        while 1:

            while 1:

                if i > self.j:

                    return n

                if self.cons(i):

                    break

                i = i + 1

            i = i + 1

            n = n + 1

            while 1:

                if i > self.j:

                    return n

                if not self.cons(i):

                    break

                i = i + 1

            i = i + 1

    def vowelinstem(self):

        """vowelinstem() is TRUE <=> k0,...j contains a vowel"""

        for i in range(self.k0, self.j + 1):

            if not self.cons(i):

                return 1

        return 0

    def doublec(self, j):

        """doublec(j) is TRUE <=> j,(j-1) contain a double consonant."""

        if j < (self.k0 + 1):

            return 0

        if (self.b[j] != self.b[j-1]):

            return 0

        return self.cons(j)

    def cvc(self, i):

        """cvc(i) is TRUE <=> i-2,i-1,i has the form consonant - vowel - consonant

        and also if the second c is not w,x or y. this is used when trying to

        restore an e at the end of a short  e.g.

           cav(e), lov(e), hop(e), crim(e), but

           snow, box, tray.

        """

        if i < (self.k0 + 2) or not self.cons(i) or self.cons(i-1) or not self.cons(i-2):

            return 0

        ch = self.b[i]

        if ch == 'w' or ch == 'x' or ch == 'y':

            return 0

        return 1

    def ends(self, s):

        """ends(s) is TRUE <=> k0,...k ends with the string s."""

        length = len(s)

        if s[length - 1] != self.b[self.k]: # tiny speed-up

            return 0

        if length > (self.k - self.k0 + 1):

            return 0

        if self.b[self.k-length+1:self.k+1] != s:

            return 0

        self.j = self.k - length

        return 1

    def setto(self, s):

        """setto(s) sets (j+1),...k to the characters in the string s, readjusting k."""

        length = len(s)

        self.b = self.b[:self.j+1] + s + self.b[self.j+length+1:]

        self.k = self.j + length

    def r(self, s):

        """r(s) is used further down."""

        if self.m() > 0:

            self.setto(s)

    def step1ab(self):

        """step1ab() gets rid of plurals and -ed or -ing. e.g.

           caresses  ->  caress

           ponies    ->  poni

           ties      ->  ti

           caress    ->  caress

           cats      ->  cat

           feed      ->  feed

           agreed    ->  agree

           disabled  ->  disable

           matting   ->  mat

           mating    ->  mate

           meeting   ->  meet

           milling   ->  mill

           messing   ->  mess

           meetings  ->  meet

        """

        if self.b[self.k] == 's':

            if self.ends("sses"):

                self.k = self.k - 2

            elif self.ends("ies"):

                self.setto("i")

            elif self.b[self.k - 1] != 's':

                self.k = self.k - 1

        if self.ends("eed"):

            if self.m() > 0:

                self.k = self.k - 1

        elif (self.ends("ed") or self.ends("ing")) and self.vowelinstem():

            self.k = self.j

            if self.ends("at"):   self.setto("ate")

            elif self.ends("bl"): self.setto("ble")

            elif self.ends("iz"): self.setto("ize")

            elif self.doublec(self.k):

                self.k = self.k - 1

                ch = self.b[self.k]

                if ch == 'l' or ch == 's' or ch == 'z':

                    self.k = self.k + 1

            elif (self.m() == 1 and self.cvc(self.k)):

                self.setto("e")

    def step1c(self):

        """step1c() turns terminal y to i when there is another vowel in the stem."""

        if (self.ends("y") and self.vowelinstem()):

            self.b = self.b[:self.k] + 'i' + self.b[self.k+1:]

    def step2(self):

        """step2() maps double suffices to single ones.

        so -ization ( = -ize plus -ation) maps to -ize etc. note that the

        string before the suffix must give m() > 0.

        """

        if self.b[self.k - 1] == 'a':

            if self.ends("ational"):   self.r("ate")

            elif self.ends("tional"):  self.r("tion")

        elif self.b[self.k - 1] == 'c':

            if self.ends("enci"):      self.r("ence")

            elif self.ends("anci"):    self.r("ance")

        elif self.b[self.k - 1] == 'e':

            if self.ends("izer"):      self.r("ize")

        elif self.b[self.k - 1] == 'l':

            if self.ends("bli"):       self.r("ble") # --DEPARTURE--

            # To match the published algorithm, replace this phrase with

            #   if self.ends("abli"):      self.r("able")

            elif self.ends("alli"):    self.r("al")

            elif self.ends("entli"):   self.r("ent")

            elif self.ends("eli"):     self.r("e")

            elif self.ends("ousli"):   self.r("ous")

        elif self.b[self.k - 1] == 'o':

            if self.ends("ization"):   self.r("ize")

            elif self.ends("ation"):   self.r("ate")

            elif self.ends("ator"):    self.r("ate")

        elif self.b[self.k - 1] == 's':

            if self.ends("alism"):     self.r("al")

            elif self.ends("iveness"): self.r("ive")

            elif self.ends("fulness"): self.r("ful")

            elif self.ends("ousness"): self.r("ous")

        elif self.b[self.k - 1] == 't':

            if self.ends("aliti"):     self.r("al")

            elif self.ends("iviti"):   self.r("ive")

            elif self.ends("biliti"):  self.r("ble")

        elif self.b[self.k - 1] == 'g': # --DEPARTURE--

            if self.ends("logi"):      self.r("log")

        # To match the published algorithm, delete this phrase

    def step3(self):

        """step3() dels with -ic-, -full, -ness etc. similar strategy to step2."""

        if self.b[self.k] == 'e':

            if self.ends("icate"):     self.r("ic")

            elif self.ends("ative"):   self.r("")

            elif self.ends("alize"):   self.r("al")

        elif self.b[self.k] == 'i':

            if self.ends("iciti"):     self.r("ic")

        elif self.b[self.k] == 'l':

            if self.ends("ical"):      self.r("ic")

            elif self.ends("ful"):     self.r("")

        elif self.b[self.k] == 's':

            if self.ends("ness"):      self.r("")

    def step4(self):

        """step4() takes off -ant, -ence etc., in context <c>vcvc<v>."""

        if self.b[self.k - 1] == 'a':

            if self.ends("al"): pass

            else: return

        elif self.b[self.k - 1] == 'c':

            if self.ends("ance"): pass

            elif self.ends("ence"): pass

            else: return

        elif self.b[self.k - 1] == 'e':

            if self.ends("er"): pass

            else: return

        elif self.b[self.k - 1] == 'i':

            if self.ends("ic"): pass

            else: return

        elif self.b[self.k - 1] == 'l':

            if self.ends("able"): pass

            elif self.ends("ible"): pass

            else: return

        elif self.b[self.k - 1] == 'n':

            if self.ends("ant"): pass

            elif self.ends("ement"): pass

            elif self.ends("ment"): pass

            elif self.ends("ent"): pass

            else: return

        elif self.b[self.k - 1] == 'o':

            if self.ends("ion") and (self.b[self.j] == 's' \

                or self.b[self.j] == 't'): pass

            elif self.ends("ou"): pass

            # takes care of -ous

            else: return

        elif self.b[self.k - 1] == 's':

            if self.ends("ism"): pass

            else: return

        elif self.b[self.k - 1] == 't':

            if self.ends("ate"): pass

            elif self.ends("iti"): pass

            else: return

        elif self.b[self.k - 1] == 'u':

            if self.ends("ous"): pass

            else: return

        elif self.b[self.k - 1] == 'v':

            if self.ends("ive"): pass

            else: return

        elif self.b[self.k - 1] == 'z':

            if self.ends("ize"): pass

            else: return

        else:

            return

        if self.m() > 1:

            self.k = self.j

    def step5(self):

        """step5() removes a final -e if m() > 1, and changes -ll to -l if

        m() > 1.

        """

        self.j = self.k

        if self.b[self.k] == 'e':

            a = self.m()

            if a > 1 or (a == 1 and not self.cvc(self.k-1)):

                self.k = self.k - 1

        if self.b[self.k] == 'l' and self.doublec(self.k) and self.m() > 1:

            self.k = self.k -1

    def stem(self, p, i, j):

        """In stem(p,i,j), p is a char pointer, and the string to be stemmed

        is from p[i] to p[j] inclusive. Typically i is zero and j is the

        offset to the last character of a string, (p[j+1] == '\0'). The

        stemmer adjusts the characters p[i] ... p[j] and returns the new

        end-point of the string, k. Stemming never increases word length, so

        i <= k <= j. To turn the stemmer into a module, declare 'stem' as

        extern, and delete the remainder of this file.

        """

        # copy the parameters into statics

        self.b = p

        self.k = j

        self.k0 = i

        if self.k <= self.k0 + 1:

            return self.b # --DEPARTURE--

        # With this line, strings of length 1 or 2 don't go through the

        # stemming process, although no mention is made of this in the

        # published algorithm. Remove the line to match the published

        # algorithm.

        self.step1ab()

        self.step1c()

        self.step2()

        self.step3()

        self.step4()

        self.step5()

        return self.b[self.k0:self.k+1]