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    1/*  Part of SWI-Prolog
    2
    3    Author:        Jan Wielemaker
    4    E-mail:        J.Wielemaker@vu.nl
    5    WWW:           http://www.swi-prolog.org
    6    Copyright (c)  2010-2015, VU University, Amsterdam
    7    All rights reserved.
    8
    9    Redistribution and use in source and binary forms, with or without
   10    modification, are permitted provided that the following conditions
   11    are met:
   12
   13    1. Redistributions of source code must retain the above copyright
   14       notice, this list of conditions and the following disclaimer.
   15
   16    2. Redistributions in binary form must reproduce the above copyright
   17       notice, this list of conditions and the following disclaimer in
   18       the documentation and/or other materials provided with the
   19       distribution.
   20
   21    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   22    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   23    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
   24    FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
   25    COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
   26    INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
   27    BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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   29    CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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   33*/
   34
   35:- module(snowball,
   36          [ snowball/3,                  % +Algorithm, +In, -Out
   37            snowball_current_algorithm/1 % ?algorithm
   38          ]).   39:- autoload(library(apply),[maplist/3]).

The Snowball multi-lingual stemmer library

This module encapsulates "The C version of the libstemmer library" from the Snowball project. This library provides stemmers in a variety of languages. The interface to this library is very simple:

Here is an example:

?- snowball(english, walking, S).
S = walk.
See also
- http://snowball.tartarus.org/ */
   60:- use_foreign_library(foreign(snowball)).
 snowball(+Algorithm, +Input, -Stem) is det
Apply the Snowball Algorithm on Input and unify the result (an atom) with Stem.

The implementation maintains a cache of stemmers for each thread that accesses snowball/3, providing high-perfomance and thread-safety without locking.

Arguments:
Algorithm- is the (english) name for desired algorithm or an 2 or 3 letter ISO 639 language code.
Input- is the word to be stemmed. It is either an atom, string or list of chars/codes. The library accepts Unicode characters. Input must be lowercase. See downcase_atom/2.
Errors
- domain_error(snowball_algorithm, Algorithm)
- type_error(atom, Algorithm)
- type_error(text, Input)



 snowball_current_algorithm(?Algorithm) is nondet
True if Algorithm is the official name of an algorithm suported
by snowball/3. The predicate is semidet if Algorithm is given.


   86term_expansion(snowball_current_algorithm(dummy), Clauses) :-
   87    snowball_algorithms(Algos),
   88    maplist(wrap, Algos, Clauses).
   89
   90wrap(X, snowball_current_algorithm(X)).
   91
   92snowball_current_algorithm(dummy).
   93
   94:- multifile
   95    sandbox:safe_primitive/1.   96
   97sandbox:safe_primitive(snowball:snowball(_,_,_))