mirror of
https://github.com/moses-smt/mosesdecoder.git
synced 2024-09-11 19:27:11 +03:00
117 lines
4.3 KiB
C++
117 lines
4.3 KiB
C++
#include "search/edge_generator.hh"
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#include "lm/left.hh"
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#include "lm/model.hh"
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#include "lm/partial.hh"
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#include "search/context.hh"
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#include "search/vertex.hh"
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#include <numeric>
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namespace search {
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namespace {
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template <class Model> void FastScore(const Context<Model> &context, Arity victim, Arity before_idx, Arity incomplete, const PartialVertex &previous_vertex, PartialEdge update) {
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lm::ngram::ChartState *between = update.Between();
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lm::ngram::ChartState *before = &between[before_idx], *after = &between[before_idx + 1];
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float adjustment = 0.0;
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const lm::ngram::ChartState &previous_reveal = previous_vertex.State();
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const PartialVertex &update_nt = update.NT()[victim];
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const lm::ngram::ChartState &update_reveal = update_nt.State();
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if ((update_reveal.left.length > previous_reveal.left.length) || (update_reveal.left.full && !previous_reveal.left.full)) {
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adjustment += lm::ngram::RevealAfter(context.LanguageModel(), before->left, before->right, update_reveal.left, previous_reveal.left.length);
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}
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if ((update_reveal.right.length > previous_reveal.right.length) || (update_nt.RightFull() && !previous_vertex.RightFull())) {
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adjustment += lm::ngram::RevealBefore(context.LanguageModel(), update_reveal.right, previous_reveal.right.length, update_nt.RightFull(), after->left, after->right);
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}
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if (update_nt.Complete()) {
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if (update_reveal.left.full) {
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before->left.full = true;
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} else {
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assert(update_reveal.left.length == update_reveal.right.length);
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adjustment += lm::ngram::Subsume(context.LanguageModel(), before->left, before->right, after->left, after->right, update_reveal.left.length);
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}
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before->right = after->right;
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// Shift the others shifted one down, covering after.
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for (lm::ngram::ChartState *cover = after; cover < between + incomplete; ++cover) {
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*cover = *(cover + 1);
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}
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}
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update.SetScore(update.GetScore() + adjustment * context.LMWeight());
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}
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} // namespace
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template <class Model> PartialEdge EdgeGenerator::Pop(Context<Model> &context) {
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assert(!generate_.empty());
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PartialEdge top = generate_.top();
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generate_.pop();
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PartialVertex *const top_nt = top.NT();
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const Arity arity = top.GetArity();
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Arity victim = 0;
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Arity victim_completed;
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Arity incomplete;
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unsigned char lowest_niceness = 255;
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// Select victim or return if complete.
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{
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Arity completed = 0;
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for (Arity i = 0; i != arity; ++i) {
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if (top_nt[i].Complete()) {
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++completed;
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} else if (top_nt[i].Niceness() < lowest_niceness) {
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lowest_niceness = top_nt[i].Niceness();
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victim = i;
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victim_completed = completed;
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}
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}
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if (lowest_niceness == 255) {
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return top;
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}
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incomplete = arity - completed;
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}
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PartialVertex old_value(top_nt[victim]);
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PartialVertex alternate_changed;
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if (top_nt[victim].Split(alternate_changed)) {
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PartialEdge alternate(partial_edge_pool_, arity, incomplete + 1);
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alternate.SetScore(top.GetScore() + alternate_changed.Bound() - old_value.Bound());
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alternate.SetNote(top.GetNote());
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alternate.SetRange(top.GetRange());
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PartialVertex *alternate_nt = alternate.NT();
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for (Arity i = 0; i < victim; ++i) alternate_nt[i] = top_nt[i];
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alternate_nt[victim] = alternate_changed;
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for (Arity i = victim + 1; i < arity; ++i) alternate_nt[i] = top_nt[i];
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memcpy(alternate.Between(), top.Between(), sizeof(lm::ngram::ChartState) * (incomplete + 1));
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// TODO: dedupe?
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generate_.push(alternate);
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}
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#ifndef NDEBUG
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Score before = top.GetScore();
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#endif
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// top is now the continuation.
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FastScore(context, victim, victim - victim_completed, incomplete, old_value, top);
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// TODO: dedupe?
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generate_.push(top);
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assert(lowest_niceness != 254 || top.GetScore() == before);
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// Invalid indicates no new hypothesis generated.
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return PartialEdge();
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}
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template PartialEdge EdgeGenerator::Pop(Context<lm::ngram::RestProbingModel> &context);
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template PartialEdge EdgeGenerator::Pop(Context<lm::ngram::ProbingModel> &context);
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template PartialEdge EdgeGenerator::Pop(Context<lm::ngram::TrieModel> &context);
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template PartialEdge EdgeGenerator::Pop(Context<lm::ngram::QuantTrieModel> &context);
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template PartialEdge EdgeGenerator::Pop(Context<lm::ngram::ArrayTrieModel> &context);
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template PartialEdge EdgeGenerator::Pop(Context<lm::ngram::QuantArrayTrieModel> &context);
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} // namespace search
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