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#ifndef LM_FILTER_VOCAB_H
#define LM_FILTER_VOCAB_H
// Vocabulary-based filters for language models.
#include "util/multi_intersection.hh"
#include "util/string_piece.hh"
#include "util/string_piece_hash.hh"
#include "util/tokenize_piece.hh"
#include <boost/noncopyable.hpp>
#include <boost/range/iterator_range.hpp>
#include <boost/unordered/unordered_map.hpp>
#include <boost/unordered/unordered_set.hpp>
#include <string>
#include <vector>
namespace lm {
namespace vocab {
void ReadSingle(std::istream &in, boost::unordered_set<std::string> &out);
// Read one sentence vocabulary per line. Return the number of sentences.
unsigned int ReadMultiple(std::istream &in, boost::unordered_map<std::string, std::vector<unsigned int> > &out);
/* Is this a special tag like <s> or <UNK>? This actually includes anything
* surrounded with < and >, which most tokenizers separate for real words, so
* this should not catch real words as it looks at a single token.
*/
inline bool IsTag(const StringPiece &value) {
// The parser should never give an empty string.
assert(!value.empty());
return (value.data()[0] == '<' && value.data()[value.size() - 1] == '>');
}
class Single {
public:
typedef boost::unordered_set<std::string> Words;
explicit Single(const Words &vocab) : vocab_(vocab) {}
template <class Iterator> bool PassNGram(const Iterator &begin, const Iterator &end) {
for (Iterator i = begin; i != end; ++i) {
if (IsTag(*i)) continue;
if (FindStringPiece(vocab_, *i) == vocab_.end()) return false;
}
return true;
}
private:
const Words &vocab_;
};
class Union {
public:
typedef boost::unordered_map<std::string, std::vector<unsigned int> > Words;
explicit Union(const Words &vocabs) : vocabs_(vocabs) {}
template <class Iterator> bool PassNGram(const Iterator &begin, const Iterator &end) {
sets_.clear();
for (Iterator i(begin); i != end; ++i) {
if (IsTag(*i)) continue;
Words::const_iterator found(FindStringPiece(vocabs_, *i));
if (vocabs_.end() == found) return false;
sets_.push_back(boost::iterator_range<const unsigned int*>(&*found->second.begin(), &*found->second.end()));
}
return (sets_.empty() || util::FirstIntersection(sets_));
}
private:
const Words &vocabs_;
std::vector<boost::iterator_range<const unsigned int*> > sets_;
};
class Multiple {
public:
typedef boost::unordered_map<std::string, std::vector<unsigned int> > Words;
Multiple(const Words &vocabs) : vocabs_(vocabs) {}
private:
// Callback from AllIntersection that does AddNGram.
template <class Output> class Callback {
public:
Callback(Output &out, const StringPiece &line) : out_(out), line_(line) {}
void operator()(unsigned int index) {
out_.SingleAddNGram(index, line_);
}
private:
Output &out_;
const StringPiece &line_;
};
public:
template <class Iterator, class Output> void AddNGram(const Iterator &begin, const Iterator &end, const StringPiece &line, Output &output) {
sets_.clear();
for (Iterator i(begin); i != end; ++i) {
if (IsTag(*i)) continue;
Words::const_iterator found(FindStringPiece(vocabs_, *i));
if (vocabs_.end() == found) return;
sets_.push_back(boost::iterator_range<const unsigned int*>(&*found->second.begin(), &*found->second.end()));
}
if (sets_.empty()) {
output.AddNGram(line);
return;
}
Callback<Output> cb(output, line);
util::AllIntersection(sets_, cb);
}
template <class Output> void AddNGram(const StringPiece &ngram, const StringPiece &line, Output &output) {
AddNGram(util::TokenIter<util::SingleCharacter, true>(ngram, ' '), util::TokenIter<util::SingleCharacter, true>::end(), line, output);
}
void Flush() const {}
private:
const Words &vocabs_;
std::vector<boost::iterator_range<const unsigned int*> > sets_;
};
} // namespace vocab
} // namespace lm
#endif // LM_FILTER_VOCAB_H
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