presage  0.8.7
dictionaryPredictor.cpp
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00001 
00002 /******************************************************
00003  *  Presage, an extensible predictive text entry system
00004  *  ---------------------------------------------------
00005  *
00006  *  Copyright (C) 2008  Matteo Vescovi <matteo.vescovi@yahoo.co.uk>
00007 
00008     This program is free software; you can redistribute it and/or modify
00009     it under the terms of the GNU General Public License as published by
00010     the Free Software Foundation; either version 2 of the License, or
00011     (at your option) any later version.
00012 
00013     This program is distributed in the hope that it will be useful,
00014     but WITHOUT ANY WARRANTY; without even the implied warranty of
00015     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00016     GNU General Public License for more details.
00017 
00018     You should have received a copy of the GNU General Public License along
00019     with this program; if not, write to the Free Software Foundation, Inc.,
00020     51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
00021                                                                              *
00022                                                                 **********(*)*/
00023 
00024 
00025 #include "dictionaryPredictor.h"
00026 
00027 #include <assert.h>
00028 
00029 const char* DictionaryPredictor::LOGGER  = "Presage.Predictors.DictionaryPredictor.LOGGER";
00030 const char* DictionaryPredictor::DICTIONARY  = "Presage.Predictors.DictionaryPredictor.DICTIONARY";
00031 const char* DictionaryPredictor::PROBABILITY = "Presage.Predictors.DictionaryPredictor.PROBABILITY";
00032 
00033 DictionaryPredictor::DictionaryPredictor(Configuration* config, ContextTracker* ht)
00034     : Predictor(config,
00035              ht,
00036              "DictionaryPredictor",
00037              "DictionaryPredictor, dictionary lookup",
00038              "DictionaryPredictor, a dictionary based predictor that generates a prediction by extracting tokens that start with the current prefix from a given dictionary"
00039              ),
00040       dispatcher (this)
00041 {
00042     // build notification dispatch map
00043     dispatcher.map (config->find (LOGGER), & DictionaryPredictor::set_logger);
00044     dispatcher.map (config->find (DICTIONARY), & DictionaryPredictor::set_dictionary);
00045     dispatcher.map (config->find (PROBABILITY), & DictionaryPredictor::set_probability);
00046 }
00047 
00048 DictionaryPredictor::~DictionaryPredictor()
00049 {
00050     // intentionally empty
00051 }
00052 
00053 void DictionaryPredictor::set_dictionary (const std::string& value)
00054 {
00055     dictionary_path = value;
00056     logger << INFO << "DICTIONARY: " << value << endl;
00057 }
00058 
00059 
00060 void DictionaryPredictor::set_probability (const std::string& value)
00061 {
00062     probability = Utility::toDouble (value);
00063     logger << INFO << "PROBABILITY: " << value << endl;
00064 }
00065 
00066 Prediction DictionaryPredictor::predict(const size_t max_partial_predictions_size, const char** filter) const
00067 {
00068     Prediction result;
00069 
00070     std::string candidate;
00071     std::string prefix = contextTracker->getPrefix();
00072 
00073     std::ifstream dictionary_file;
00074     dictionary_file.open(dictionary_path.c_str());
00075     if(!dictionary_file)
00076         logger << ERROR << "Error opening dictionary: " << dictionary_path << endl;
00077     assert(dictionary_file); // REVISIT: handle with exceptions
00078 
00079     // scan file entries until we get enough suggestions
00080     unsigned int count = 0;
00081     while(dictionary_file >> candidate && count < max_partial_predictions_size) {
00082         if(candidate.find(prefix) == 0) {
00083             result.addSuggestion(Suggestion(candidate,probability));
00084             count++;
00085             logger << NOTICE << "Found valid token: " << candidate << endl;
00086         } else {
00087             logger << INFO << "Discarding invalid token: " << candidate << endl;
00088         }
00089     }
00090 
00091     dictionary_file.close();
00092 
00093     return result;
00094 }
00095 
00096 void DictionaryPredictor::learn(const std::vector<std::string>& change)
00097 {
00098     std::cout << "DictionaryPredictor::learn() method called" << std::endl;
00099     std::cout << "DictionaryPredictor::learn() method exited" << std::endl;
00100 }
00101 
00102 void DictionaryPredictor::update (const Observable* var)
00103 {
00104     logger << DEBUG << "About to invoke dispatcher: " << var->get_name () << " - " << var->get_value() << endl;
00105     dispatcher.dispatch (var);
00106 }