1 
2 /******************************************************
3  *  Presage, an extensible predictive text entry system
4  *  ---------------------------------------------------
5  *
6  *  Copyright (C) 2008  Matteo Vescovi <matteo.vescovi@yahoo.co.uk>
7 
8     This program is free software; you can redistribute it and/or modify
9     it under the terms of the GNU General Public License as published by
10     the Free Software Foundation; either version 2 of the License, or
11     (at your option) any later version.
12 
13     This program is distributed in the hope that it will be useful,
14     but WITHOUT ANY WARRANTY; without even the implied warranty of
15     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16     GNU General Public License for more details.
17 
18     You should have received a copy of the GNU General Public License along
19     with this program; if not, write to the Free Software Foundation, Inc.,
20     51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
21                                                                              *
22                                                                 **********(*)*/
23 
24 
25 #ifndef PRESAGE_SMOOTHEDNGRAMPREDICTOR
26 #define PRESAGE_SMOOTHEDNGRAMPREDICTOR
27 
28 #include "predictor.h"
29 #include "../core/logger.h"
30 #include "../core/dispatcher.h"
31 #include "dbconnector/sqliteDatabaseConnector.h"
32 
33 #include <assert.h>
34 
35 #if defined(HAVE_SQLITE3_H)
36 # include <sqlite3.h>
37 #elif defined(HAVE_SQLITE_H)
38 # include <sqlite.h>
39 #else
40 # error "SQLite is required. Please install SQLite."
41 #endif
42 
43 
44 /** Smoothed n-gram statistical predictor.
45  *
46  */
47 class SmoothedNgramPredictor : public Predictor, public Observer {
48 public:
49     SmoothedNgramPredictor(Configuration*, ContextTracker*, const char*);
50     ~SmoothedNgramPredictor();
51 
52     virtual Prediction predict(const size_t size, const char** filter) const;
53 
54     virtual void learn(const std::vector<std::string>& change);
55 
56     virtual void update (const Observable* variable);
57 
58 private:
59     std::string LOGGER;
60     std::string DBFILENAME;
61     std::string DELTAS;
62     std::string LEARN;
63     std::string DATABASE_LOGGER;
64 
65     unsigned int count(const std::vector<std::string>& tokens, int offset, int ngram_size) const;
66     void check_learn_consistency(const Ngram& name) const;
67 
68     void set_dbfilename (const std::string& filename);
69     void set_deltas (const std::string& deltas);
70     void set_database_logger_level (const std::string& level);
71     void set_learn (const std::string& learn_mode);
72 
73     void init_database_connector_if_ready ();
74 
75     DatabaseConnector*  db;
76     std::string         dbfilename;
77     std::string         dbloglevel;
78     std::vector<double> deltas;
79     size_t              cardinality; // cardinality == what is the n in n-gram?
80     bool                learn_mode;
81     bool                learn_mode_set;
82 
83     Dispatcher<SmoothedNgramPredictor> dispatcher;
84 };
85 
86 #endif // PRESAGE_SMOOTHEDNGRAMPREDICTOR
87