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#include "lm/builder/interpolate.hh"
#include "lm/builder/joint_order.hh"
#include "lm/builder/multi_stream.hh"
#include "lm/builder/sort.hh"
#include "lm/lm_exception.hh"
#include <assert.h>
namespace lm { namespace builder {
namespace {
class Callback {
public:
Callback(float uniform_prob, const ChainPositions &backoffs) : backoffs_(backoffs.size()), probs_(backoffs.size() + 2) {
probs_[0] = uniform_prob;
for (std::size_t i = 0; i < backoffs.size(); ++i) {
backoffs_.push_back(backoffs[i]);
}
}
~Callback() {
for (std::size_t i = 0; i < backoffs_.size(); ++i) {
if (backoffs_[i]) {
std::cerr << "Backoffs do not match for order " << (i + 1) << std::endl;
abort();
}
}
}
void Enter(unsigned order_minus_1, NGram &gram) {
Payload &pay = gram.Value();
pay.complete.prob = pay.uninterp.prob + pay.uninterp.gamma * probs_[order_minus_1];
probs_[order_minus_1 + 1] = pay.complete.prob;
pay.complete.prob = log10(pay.complete.prob);
// TODO: this is a hack to skip n-grams that don't appear as context. Pruning will require some different handling.
if (order_minus_1 < backoffs_.size() && *(gram.end() - 1) != kUNK && *(gram.end() - 1) != kEOS) {
pay.complete.backoff = log10(*static_cast<const float*>(backoffs_[order_minus_1].Get()));
++backoffs_[order_minus_1];
} else {
// Not a context.
pay.complete.backoff = 0.0;
}
}
void Exit(unsigned, const NGram &) const {}
private:
FixedArray<util::stream::Stream> backoffs_;
std::vector<float> probs_;
};
} // namespace
Interpolate::Interpolate(uint64_t unigram_count, const ChainPositions &backoffs)
: uniform_prob_(1.0 / static_cast<float>(unigram_count - 1)), backoffs_(backoffs) {}
// perform order-wise interpolation
void Interpolate::Run(const ChainPositions &positions) {
assert(positions.size() == backoffs_.size() + 1);
Callback callback(uniform_prob_, backoffs_);
JointOrder<Callback, SuffixOrder>(positions, callback);
}
}} // namespaces
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