mirror of
https://github.com/moses-smt/mosesdecoder.git
synced 2024-09-11 11:25:40 +03:00
167 lines
5.9 KiB
C++
167 lines
5.9 KiB
C++
#ifndef LM_PARTIAL_H
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#define LM_PARTIAL_H
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#include "lm/return.hh"
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#include "lm/state.hh"
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#include <algorithm>
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#include <cassert>
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namespace lm {
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namespace ngram {
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struct ExtendReturn {
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float adjust;
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bool make_full;
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unsigned char next_use;
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};
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template <class Model> ExtendReturn ExtendLoop(
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const Model &model,
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unsigned char seen, const WordIndex *add_rbegin, const WordIndex *add_rend, const float *backoff_start,
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const uint64_t *pointers, const uint64_t *pointers_end,
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uint64_t *&pointers_write,
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float *backoff_write) {
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unsigned char add_length = add_rend - add_rbegin;
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float backoff_buf[2][KENLM_MAX_ORDER - 1];
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float *backoff_in = backoff_buf[0], *backoff_out = backoff_buf[1];
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std::copy(backoff_start, backoff_start + add_length, backoff_in);
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ExtendReturn value;
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value.make_full = false;
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value.adjust = 0.0;
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value.next_use = add_length;
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unsigned char i = 0;
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unsigned char length = pointers_end - pointers;
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// pointers_write is NULL means that the existing left state is full, so we should use completed probabilities.
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if (pointers_write) {
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// Using full context, writing to new left state.
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for (; i < length; ++i) {
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FullScoreReturn ret(model.ExtendLeft(
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add_rbegin, add_rbegin + value.next_use,
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backoff_in,
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pointers[i], i + seen + 1,
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backoff_out,
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value.next_use));
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std::swap(backoff_in, backoff_out);
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if (ret.independent_left) {
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value.adjust += ret.prob;
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value.make_full = true;
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++i;
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break;
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}
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value.adjust += ret.rest;
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*pointers_write++ = ret.extend_left;
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if (value.next_use != add_length) {
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value.make_full = true;
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++i;
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break;
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}
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}
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}
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// Using some of the new context.
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for (; i < length && value.next_use; ++i) {
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FullScoreReturn ret(model.ExtendLeft(
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add_rbegin, add_rbegin + value.next_use,
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backoff_in,
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pointers[i], i + seen + 1,
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backoff_out,
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value.next_use));
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std::swap(backoff_in, backoff_out);
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value.adjust += ret.prob;
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}
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float unrest = model.UnRest(pointers + i, pointers_end, i + seen + 1);
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// Using none of the new context.
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value.adjust += unrest;
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std::copy(backoff_in, backoff_in + value.next_use, backoff_write);
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return value;
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}
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template <class Model> float RevealBefore(const Model &model, const Right &reveal, const unsigned char seen, bool reveal_full, Left &left, Right &right) {
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assert(seen < reveal.length || reveal_full);
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uint64_t *pointers_write = reveal_full ? NULL : left.pointers;
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float backoff_buffer[KENLM_MAX_ORDER - 1];
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ExtendReturn value(ExtendLoop(
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model,
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seen, reveal.words + seen, reveal.words + reveal.length, reveal.backoff + seen,
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left.pointers, left.pointers + left.length,
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pointers_write,
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left.full ? backoff_buffer : (right.backoff + right.length)));
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if (reveal_full) {
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left.length = 0;
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value.make_full = true;
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} else {
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left.length = pointers_write - left.pointers;
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value.make_full |= (left.length == model.Order() - 1);
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}
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if (left.full) {
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for (unsigned char i = 0; i < value.next_use; ++i) value.adjust += backoff_buffer[i];
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} else {
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// If left wasn't full when it came in, put words into right state.
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std::copy(reveal.words + seen, reveal.words + seen + value.next_use, right.words + right.length);
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right.length += value.next_use;
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left.full = value.make_full || (right.length == model.Order() - 1);
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}
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return value.adjust;
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}
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template <class Model> float RevealAfter(const Model &model, Left &left, Right &right, const Left &reveal, unsigned char seen) {
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assert(seen < reveal.length || reveal.full);
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uint64_t *pointers_write = left.full ? NULL : (left.pointers + left.length);
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ExtendReturn value(ExtendLoop(
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model,
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seen, right.words, right.words + right.length, right.backoff,
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reveal.pointers + seen, reveal.pointers + reveal.length,
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pointers_write,
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right.backoff));
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if (reveal.full) {
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for (unsigned char i = 0; i < value.next_use; ++i) value.adjust += right.backoff[i];
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right.length = 0;
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value.make_full = true;
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} else {
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right.length = value.next_use;
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value.make_full |= (right.length == model.Order() - 1);
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}
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if (!left.full) {
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left.length = pointers_write - left.pointers;
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left.full = value.make_full || (left.length == model.Order() - 1);
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}
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return value.adjust;
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}
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template <class Model> float Subsume(const Model &model, Left &first_left, const Right &first_right, const Left &second_left, Right &second_right, const unsigned int between_length) {
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assert(first_right.length < KENLM_MAX_ORDER);
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assert(second_left.length < KENLM_MAX_ORDER);
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assert(between_length < KENLM_MAX_ORDER - 1);
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uint64_t *pointers_write = first_left.full ? NULL : (first_left.pointers + first_left.length);
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float backoff_buffer[KENLM_MAX_ORDER - 1];
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ExtendReturn value(ExtendLoop(
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model,
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between_length, first_right.words, first_right.words + first_right.length, first_right.backoff,
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second_left.pointers, second_left.pointers + second_left.length,
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pointers_write,
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second_left.full ? backoff_buffer : (second_right.backoff + second_right.length)));
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if (second_left.full) {
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for (unsigned char i = 0; i < value.next_use; ++i) value.adjust += backoff_buffer[i];
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} else {
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std::copy(first_right.words, first_right.words + value.next_use, second_right.words + second_right.length);
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second_right.length += value.next_use;
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value.make_full |= (second_right.length == model.Order() - 1);
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}
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if (!first_left.full) {
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first_left.length = pointers_write - first_left.pointers;
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first_left.full = value.make_full || second_left.full || (first_left.length == model.Order() - 1);
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}
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assert(first_left.length < KENLM_MAX_ORDER);
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assert(second_right.length < KENLM_MAX_ORDER);
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return value.adjust;
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}
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} // namespace ngram
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} // namespace lm
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#endif // LM_PARTIAL_H
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