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#ifndef LM_LEFT__
#define LM_LEFT__
#include "lm/max_order.hh"
#include "lm/model.hh"
#include "lm/return.hh"
#include <algorithm>
namespace lm {
namespace ngram {
struct Left {
bool operator==(const Left &other) const {
return
(length == other.length) &&
pointers[length - 1] == other.pointers[length - 1];
}
int Compare(const Left &other) const {
if (length != other.length) {
return (int)length - (int)other.length;
}
if (pointers[length - 1] > other.pointers[length - 1]) return 1;
if (pointers[length - 1] < other.pointers[length - 1]) return -1;
return 0;
}
uint64_t pointers[kMaxOrder - 1];
unsigned char length;
};
struct ChartState {
bool operator==(const ChartState &other) {
return (left == other.left) && (right == other.right) && (full == other.full);
}
int Compare(const ChartState &other) const {
int lres = left.Compare(other.left);
if (lres) return lres;
int rres = right.Compare(other.right);
if (rres) return rres;
return (int)full - (int)other.full;
}
Left left;
State right;
bool full;
};
template <class M> class RuleScore {
public:
explicit RuleScore(const M &model, ChartState &out) : model_(model), out_(out), left_done_(false), left_write_(out.left.pointers), prob_(0.0) {
out.left.length = 0;
out.right.length = 0;
}
void BeginSentence() {
out_.right = model_.BeginSentenceState();
// out_.left is empty.
left_done_ = true;
}
void Terminal(WordIndex word) {
State copy(out_.right);
FullScoreReturn ret = model_.FullScore(copy, word, out_.right);
ProcessRet(ret);
if (out_.right.length != copy.length + 1) left_done_ = true;
}
// Faster version of NonTerminal for the case where the rule begins with a non-terminal.
void BeginNonTerminal(const ChartState &in, float prob) {
prob_ = prob;
out_ = in;
left_write_ = out_.left.pointers + out_.left.length;
left_done_ = in.full;
}
void NonTerminal(const ChartState &in, float prob) {
prob_ += prob;
if (!in.left.length) {
if (in.full) {
for (const float *i = out_.right.backoff; i < out_.right.backoff + out_.right.length; ++i) prob_ += *i;
left_done_ = true;
out_.right = in.right;
}
return;
}
if (!out_.right.length) {
out_.right = in.right;
if (left_done_) return;
if (left_write_ != out_.left.pointers) {
left_done_ = true;
} else {
out_.left = in.left;
left_write_ = out_.left.pointers + in.left.length;
left_done_ = in.full;
}
return;
}
float backoffs[kMaxOrder - 1], backoffs2[kMaxOrder - 1];
float *back = backoffs, *back2 = backoffs2;
unsigned char next_use;
FullScoreReturn ret;
ProcessRet(ret = model_.ExtendLeft(out_.right.words, out_.right.words + out_.right.length, out_.right.backoff, in.left.pointers[0], 1, back, next_use));
if (!next_use) {
left_done_ = true;
out_.right = in.right;
return;
}
unsigned char extend_length = 2;
for (const uint64_t *i = in.left.pointers + 1; i < in.left.pointers + in.left.length; ++i, ++extend_length) {
ProcessRet(ret = model_.ExtendLeft(out_.right.words, out_.right.words + next_use, back, *i, extend_length, back2, next_use));
if (!next_use) {
left_done_ = true;
out_.right = in.right;
return;
}
std::swap(back, back2);
}
if (in.full) {
for (const float *i = back; i != back + next_use; ++i) prob_ += *i;
left_done_ = true;
out_.right = in.right;
return;
}
// Right state was minimized, so it's already independent of the new words to the left.
if (in.right.length < in.left.length) {
out_.right = in.right;
return;
}
// Shift exisiting words down.
for (WordIndex *i = out_.right.words + next_use - 1; i >= out_.right.words; --i) {
*(i + in.right.length) = *i;
}
// Add words from in.right.
std::copy(in.right.words, in.right.words + in.right.length, out_.right.words);
// Assemble backoff composed on the existing state's backoff followed by the new state's backoff.
std::copy(in.right.backoff, in.right.backoff + in.right.length, out_.right.backoff);
std::copy(back, back + next_use, out_.right.backoff + in.right.length);
out_.right.length = in.right.length + next_use;
}
float Finish() {
out_.left.length = left_write_ - out_.left.pointers;
out_.full = left_done_;
return prob_;
}
private:
void ProcessRet(const FullScoreReturn &ret) {
prob_ += ret.prob;
if (left_done_) return;
if (ret.independent_left) {
left_done_ = true;
return;
}
*(left_write_++) = ret.extend_left;
}
const M &model_;
ChartState &out_;
bool left_done_;
uint64_t *left_write_;
float prob_;
};
} // namespace ngram
} // namespace lm
#endif // LM_LEFT__
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