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Which keywords should not be stemmed is specified in the nostem.txt file. (Right now I have taken all the man page names, split them if they had underscores, removed common English words and converted everything to lowercase.) The tokenizer itself is based on the Porter stemming tokenizer shipped with Sqlite. The code in custom_apropos_tokenizer.c is copy of that code with some modifications to prevent stemming keywords specified in nostem.txt. Additionally, it now uses underscore `_' also as a token delimiter. Therefore, now it's possible to do query for `lwp' and all `_lwp_*' man page names will be matched. Or the query can be `unconst' and `__UNCONST' will be matched. This was not possible earlier, because underscore was not a delimiter and therefore the index would have __UNCONST as a key rather than UNCONST. The tokenizer needs fts3_tokenizer.h file, which is not shipped with the amalgamation build of Sqlite, therefore it needs to be added here (unless we decide there is a better place for it). To enforce using the new tokenizer, a schema version bump is needed Since the tokenization is done both at the indexing time (via makemandb) and also while query time (via apropos or whatis), it will be needed to bump the schema version everytime nostem.txt is modified. Otherwise the index will consist of old tokens and desired changes will not be seen with apropos. This should also fix the issue reported in PR bin/46255. Similar suggestion was also made on tech-userlevel@ recently: <http://mail-index.netbsd.org/tech-userlevel/2017/06/08/msg010620.html> Thanks to christos@ for multiple rounds of reviews of the tokenizer code.
39 lines
1.6 KiB
C
39 lines
1.6 KiB
C
/* $NetBSD: custom_apropos_tokenizer.h,v 1.1 2017/06/18 16:24:10 abhinav Exp $ */
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/*-
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* Copyright (c) 2017 Abhinav Upadhyay <abhinav@NetBSD.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#ifndef CUSTOM_APROPOS_TOKENIZER_H
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#define CUSTOM_APROPOS_TOKENIZER_H
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#include "fts3_tokenizer.h"
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void get_custom_apropos_tokenizer(sqlite3_tokenizer_module const **);
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#endif
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