mosesdecoder/lm/read_arpa.hh
Kenneth Heafield 4bcd2c75ca KenLM c1dba12
- Reject NaNs
- Fix ChartState hashing (unused in Moses)
- Expose CreateOrThrow
- Minor portability improvement in getopt
2012-03-11 13:47:38 -04:00

89 lines
2.5 KiB
C++

#ifndef LM_READ_ARPA__
#define LM_READ_ARPA__
#include "lm/lm_exception.hh"
#include "lm/word_index.hh"
#include "lm/weights.hh"
#include "util/file_piece.hh"
#include <cstddef>
#include <iosfwd>
#include <vector>
#include <math.h>
namespace lm {
void ReadARPACounts(util::FilePiece &in, std::vector<uint64_t> &number);
void ReadNGramHeader(util::FilePiece &in, unsigned int length);
void ReadBackoff(util::FilePiece &in, Prob &weights);
void ReadBackoff(util::FilePiece &in, ProbBackoff &weights);
void ReadEnd(util::FilePiece &in);
extern const bool kARPASpaces[256];
// Positive log probability warning.
class PositiveProbWarn {
public:
PositiveProbWarn() : action_(THROW_UP) {}
explicit PositiveProbWarn(WarningAction action) : action_(action) {}
float ReadProb(util::FilePiece &f) {
float prob = f.ReadFloat();
UTIL_THROW_IF(f.get() != '\t', FormatLoadException, "Expected tab after probability");
UTIL_THROW_IF(isnan(prob), FormatLoadException, "NaN probability");
if (prob > 0.0) {
Warn(prob);
prob = 0.0;
}
return prob;
}
private:
void Warn(float prob);
WarningAction action_;
};
template <class Voc> void Read1Gram(util::FilePiece &f, Voc &vocab, ProbBackoff *unigrams, PositiveProbWarn &warn) {
try {
float prob = warn.ReadProb(f);
ProbBackoff &value = unigrams[vocab.Insert(f.ReadDelimited(kARPASpaces))];
value.prob = prob;
ReadBackoff(f, value);
} catch(util::Exception &e) {
e << " in the 1-gram at byte " << f.Offset();
throw;
}
}
// Return true if a positive log probability came out.
template <class Voc> void Read1Grams(util::FilePiece &f, std::size_t count, Voc &vocab, ProbBackoff *unigrams, PositiveProbWarn &warn) {
ReadNGramHeader(f, 1);
for (std::size_t i = 0; i < count; ++i) {
Read1Gram(f, vocab, unigrams, warn);
}
vocab.FinishedLoading(unigrams);
}
// Return true if a positive log probability came out.
template <class Voc, class Weights> void ReadNGram(util::FilePiece &f, const unsigned char n, const Voc &vocab, WordIndex *const reverse_indices, Weights &weights, PositiveProbWarn &warn) {
try {
weights.prob = warn.ReadProb(f);
for (WordIndex *vocab_out = reverse_indices + n - 1; vocab_out >= reverse_indices; --vocab_out) {
*vocab_out = vocab.Index(f.ReadDelimited(kARPASpaces));
}
ReadBackoff(f, weights);
} catch(util::Exception &e) {
e << " in the " << static_cast<unsigned int>(n) << "-gram at byte " << f.Offset();
throw;
}
}
} // namespace lm
#endif // LM_READ_ARPA__