Translator Translator::intersection(const Translator &first, const Translator &second){
multimap <string, string> fst_dict = first.dictionary, snd_dict = second.dictionary;
multimap <string, string>::iterator fst_it = fst_dict.begin(),
fst_end = fst_dict.end(), snd_it, snd_curr_key, snd_end = snd_dict.end(),
fst_stop, snd_stop;
pair <multimap <string, string>::iterator, multimap<string, string>::iterator> key_range;
string origin, mid;
set <string> curr_translations;
Word curr_entry;
Translator intersection;
while(fst_it != fst_end){
origin = fst_it->first;
snd_curr_key = snd_dict.find(origin);
fst_stop = fst_dict.upper_bound(origin);
if(snd_curr_key != snd_end){ // the key is on the second translator too
curr_translations.clear(); // empty the translations for this key
snd_stop = snd_dict.upper_bound(origin);
for(; fst_it != fst_stop; ++fst_it){ // iterate over the A->B translations
for(snd_it = snd_curr_key; snd_it != snd_stop; ++snd_it){ // iterate over the C->B
if(fst_it->second == snd_it->second){ // translations match
curr_translations.insert(fst_it->second);
}
}
}
if(not curr_translations.empty()){
curr_entry = Word(origin, curr_translations);
intersection.addEntry(curr_entry);
}
}
fst_it = fst_stop;
}
return intersection;
}
Translator Translator::compose(const Translator &first, const Translator &second){
multimap <string, string> fst_dict = first.dictionary, snd_dict = second.dictionary;
multimap <string, string>::iterator fst_it = fst_dict.begin(),
fst_end = fst_dict.end(), snd_it, stop;
pair <multimap <string, string>::iterator, multimap<string, string>::iterator> key_range;
string origin, mid;
set <string> curr_translations;
Word curr_entry;
Translator composition;
while(fst_it != fst_end){
origin = fst_it->first;
stop = fst_dict.upper_bound(origin);
curr_translations.clear(); // empty the translations for this key
for(; fst_it != stop; ++fst_it){
mid = fst_it->second;
key_range = snd_dict.equal_range(mid);
for(snd_it = key_range.first; snd_it != key_range.second; ++snd_it){
curr_translations.insert(snd_it->second);
}
}
curr_entry = Word(origin, curr_translations);
composition.addEntry(curr_entry);
}
return composition;
}
