write get_best_match

src/lookup/pinyin_lookup2.cpp

@@ -373,3 +373,146 @@ bool PinyinLookup2::search_bigram2(GPtrArray * topresults, int nstep,
     g_array_free(bigram_phrase_items, TRUE);
     return found;
 }
+
+
+bool PinyinLookup2::unigram_gen_next_step(int nstep,
+                                          lookup_value_t * cur_step,
+                                          phrase_token_t token) {
+
+    if (m_phrase_index->get_phrase_item(token, m_cache_phrase_item))
+	return false;
+
+    size_t phrase_length = m_cache_phrase_item.get_phrase_length();
+    gdouble elem_poss = m_cache_phrase_item.get_unigram_frequency() / (gdouble)
+	m_phrase_index->get_phrase_index_total_freq();
+    if ( elem_poss < DBL_EPSILON )
+	return false;
+
+    ChewingKey * pinyin_keys = ((ChewingKey *)m_keys->data) + nstep;
+    gfloat pinyin_poss = m_cache_phrase_item.get_pronunciation_possibility(m_options, pinyin_keys);
+    if (pinyin_poss < FLT_EPSILON )
+	return false;
+
+    lookup_value_t next_step;
+    next_step.m_handles[0] = cur_step->m_handles[1]; next_step.m_handles[1] = token;
+    next_step.m_poss = cur_step->m_poss + log(elem_poss * pinyin_poss * unigram_lambda);
+    next_step.m_last_step = nstep;
+
+    return save_next_step(nstep + phrase_length, cur_step, &next_step);
+}
+
+bool PinyinLookup2::bigram_gen_next_step(int nstep,
+                                         lookup_value_t * cur_step,
+                                         phrase_token_t token,
+                                         gfloat bigram_poss) {
+
+    if (m_phrase_index->get_phrase_item(token, m_cache_phrase_item))
+	return false;
+
+    size_t phrase_length = m_cache_phrase_item.get_phrase_length();
+    gdouble unigram_poss = m_cache_phrase_item.get_unigram_frequency() /
+        (gdouble) m_phrase_index->get_phrase_index_total_freq();
+    if ( bigram_poss < FLT_EPSILON && unigram_poss < DBL_EPSILON )
+	return false;
+
+    ChewingKey * pinyin_keys = ((ChewingKey *)m_keys->data) + nstep;
+    gfloat pinyin_poss = m_cache_phrase_item.get_pronunciation_possibility(m_options, pinyin_keys);
+    if ( pinyin_poss < FLT_EPSILON )
+	return false;
+
+    lookup_value_t next_step;
+    next_step.m_handles[0] = cur_step->m_handles[1]; next_step.m_handles[1] = token;
+    next_step.m_poss = cur_step->m_poss +
+	log((bigram_lambda * bigram_poss + unigram_lambda * unigram_poss) * pinyin_poss);
+    next_step.m_last_step = nstep;
+
+    return save_next_step(nstep + phrase_length, cur_step, &next_step);
+}
+
+bool PinyinLookup2::save_next_step(int next_step_pos,
+                                   lookup_value_t * cur_step,
+                                   lookup_value_t * next_step){
+
+    lookup_key_t next_key = next_step->m_handles[1];
+    LookupStepIndex next_lookup_index = (LookupStepIndex)
+        g_ptr_array_index(m_steps_index, next_step_pos);
+    LookupStepContent next_lookup_content = (LookupStepContent)
+        g_ptr_array_index(m_steps_content, next_step_pos);
+
+    gpointer key = NULL, value = NULL;
+    gboolean lookup_result = g_hash_table_lookup_extended
+        (next_lookup_index, GUINT_TO_POINTER(next_key), &key, &value);
+
+    if ( !lookup_result ){
+	g_array_append_val(next_lookup_content, *next_step);
+	g_hash_table_insert(next_lookup_index, GUINT_TO_POINTER(next_key), GUINT_TO_POINTER(next_lookup_content->len - 1));
+	return true;
+    }else{
+        size_t step_index = GPOINTER_TO_UINT(value);
+	lookup_value_t * orig_next_value = &g_array_index
+            (next_lookup_content, lookup_value_t, step_index);
+
+	if ( orig_next_value->m_poss < next_step->m_poss) {
+            /* found better result. */
+	    orig_next_value->m_handles[0] = next_step->m_handles[0];
+	    assert(orig_next_value->m_handles[1] == next_step->m_handles[1]);
+	    orig_next_value->m_poss = next_step->m_poss;
+	    orig_next_value->m_last_step = next_step->m_last_step;
+	    return true;
+	}
+
+	return false;
+    }
+}
+
+bool PinyinLookup2::final_step(MatchResults & results){
+
+    /* reset results */
+    g_array_set_size(results, m_steps_content->len - 1);
+    for (size_t i = 0; i < results->len; ++i){
+	phrase_token_t * token = &g_array_index(results, phrase_token_t, i);
+	*token = null_token;
+    }
+
+    /* find max element */
+    size_t last_step_pos = m_steps_content->len - 1;
+    GArray * last_step_array = (GArray *)g_ptr_array_index(m_steps_content, last_step_pos);
+    if ( last_step_array->len == 0 )
+	return false;
+
+    lookup_value_t * max_value = &g_array_index(last_step_array, lookup_value_t, 0);
+    for ( size_t i = 1; i < last_step_array->len; ++i){
+	lookup_value_t * cur_value = &g_array_index(last_step_array, lookup_value_t, i);
+	if ( cur_value->m_poss > max_value->m_poss )
+	    max_value = cur_value;
+    }
+
+    /* backtracing */
+    while( true ){
+	int cur_step_pos = max_value->m_last_step;
+	if ( -1 == cur_step_pos )
+	    break;
+
+	phrase_token_t * token = &g_array_index
+            (results, phrase_token_t, cur_step_pos);
+	*token = max_value->m_handles[1];
+
+	phrase_token_t last_token = max_value->m_handles[0];
+	LookupStepIndex lookup_step_index = (LookupStepIndex)
+            g_ptr_array_index(m_steps_index, cur_step_pos);
+
+	gpointer key = NULL, value = NULL;
+	gboolean result = g_hash_table_lookup_extended
+            (lookup_step_index, GUINT_TO_POINTER(last_token), &key, &value);
+	if (!result)
+	    return false;
+
+	LookupStepContent lookup_step_content = (LookupStepContent)
+            g_ptr_array_index(m_steps_content, cur_step_pos);
+	max_value = &g_array_index
+            (lookup_step_content, lookup_value_t, GPOINTER_TO_UINT(value));
+    }
+
+    /* no need to reverse the result */
+    return true;
+}