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#ifndef LM_MODEL__
#define LM_MODEL__
#include "lm/binary_format.hh"
#include "lm/config.hh"
#include "lm/facade.hh"
#include "lm/max_order.hh"
#include "lm/search_hashed.hh"
#include "lm/search_trie.hh"
#include "lm/vocab.hh"
#include "lm/weights.hh"
#include <algorithm>
#include <vector>
#include <string.h>
namespace util { class FilePiece; }
namespace lm {
namespace ngram {
// This is a POD but if you want memcmp to return the same as operator==, call
// ZeroRemaining first.
class State {
public:
bool operator==(const State &other) const {
if (valid_length_ != other.valid_length_) return false;
const WordIndex *end = history_ + valid_length_;
for (const WordIndex *first = history_, *second = other.history_;
first != end; ++first, ++second) {
if (*first != *second) return false;
}
// If the histories are equal, so are the backoffs.
return true;
}
// Three way comparison function.
int Compare(const State &other) const {
if (valid_length_ == other.valid_length_) {
return memcmp(history_, other.history_, valid_length_ * sizeof(WordIndex));
}
return (valid_length_ < other.valid_length_) ? -1 : 1;
}
// Call this before using raw memcmp.
void ZeroRemaining() {
for (unsigned char i = valid_length_; i < kMaxOrder - 1; ++i) {
history_[i] = 0;
backoff_[i] = 0.0;
}
}
unsigned char ValidLength() const { return valid_length_; }
// You shouldn't need to touch anything below this line, but the members are public so FullState will qualify as a POD.
// This order minimizes total size of the struct if WordIndex is 64 bit, float is 32 bit, and alignment of 64 bit integers is 64 bit.
WordIndex history_[kMaxOrder - 1];
float backoff_[kMaxOrder - 1];
unsigned char valid_length_;
};
size_t hash_value(const State &state);
namespace detail {
// Should return the same results as SRI.
// Why VocabularyT instead of just Vocabulary? ModelFacade defines Vocabulary.
template <class Search, class VocabularyT> class GenericModel : public base::ModelFacade<GenericModel<Search, VocabularyT>, State, VocabularyT> {
private:
typedef base::ModelFacade<GenericModel<Search, VocabularyT>, State, VocabularyT> P;
public:
// Get the size of memory that will be mapped given ngram counts. This
// does not include small non-mapped control structures, such as this class
// itself.
static size_t Size(const std::vector<uint64_t> &counts, const Config &config = Config());
GenericModel(const char *file, const Config &config = Config());
FullScoreReturn FullScore(const State &in_state, const WordIndex new_word, State &out_state) const;
/* Slower call without in_state. Don't use this if you can avoid it. This
* is mostly a hack for Hieu to integrate it into Moses which sometimes
* forgets LM state (i.e. it doesn't store it with the phrase). Sigh.
* The context indices should be in an array.
* If context_rbegin != context_rend then *context_rbegin is the word
* before new_word.
*/
FullScoreReturn FullScoreForgotState(const WordIndex *context_rbegin, const WordIndex *context_rend, const WordIndex new_word, State &out_state) const;
/* Get the state for a context. Don't use this if you can avoid it. Use
* BeginSentenceState or EmptyContextState and extend from those. If
* you're only going to use this state to call FullScore once, use
* FullScoreForgotState. */
void GetState(const WordIndex *context_rbegin, const WordIndex *context_rend, State &out_state) const;
private:
friend void LoadLM<>(const char *file, const Config &config, GenericModel<Search, VocabularyT> &to);
float SlowBackoffLookup(const WordIndex *const context_rbegin, const WordIndex *const context_rend, unsigned char start) const;
FullScoreReturn ScoreExceptBackoff(const WordIndex *context_rbegin, const WordIndex *context_rend, const WordIndex new_word, State &out_state) const;
// Appears after Size in the cc file.
void SetupMemory(void *start, const std::vector<uint64_t> &counts, const Config &config);
void InitializeFromBinary(void *start, const Parameters ¶ms, const Config &config, int fd);
void InitializeFromARPA(const char *file, const Config &config);
Backing &MutableBacking() { return backing_; }
static const ModelType kModelType = Search::kModelType;
Backing backing_;
VocabularyT vocab_;
typedef typename Search::Unigram Unigram;
typedef typename Search::Middle Middle;
typedef typename Search::Longest Longest;
Search search_;
};
} // namespace detail
// These must also be instantiated in the cc file.
typedef ::lm::ngram::ProbingVocabulary Vocabulary;
typedef detail::GenericModel<detail::ProbingHashedSearch, Vocabulary> ProbingModel;
// Default implementation. No real reason for it to be the default.
typedef ProbingModel Model;
typedef ::lm::ngram::SortedVocabulary SortedVocabulary;
typedef detail::GenericModel<detail::SortedHashedSearch, SortedVocabulary> SortedModel;
typedef detail::GenericModel<trie::TrieSearch, SortedVocabulary> TrieModel;
} // namespace ngram
} // namespace lm
#endif // LM_MODEL__
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