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#include "lm/builder/corpus_count.hh"
#include "lm/builder/ngram.hh"
#include "lm/lm_exception.hh"
#include "lm/word_index.hh"
#include "util/file.hh"
#include "util/file_piece.hh"
#include "util/murmur_hash.hh"
#include "util/probing_hash_table.hh"
#include "util/scoped.hh"
#include "util/stream/chain.hh"
#include "util/stream/timer.hh"
#include "util/tokenize_piece.hh"
#include <boost/unordered_set.hpp>
#include <boost/unordered_map.hpp>
#include <functional>
#include <stdint.h>
namespace lm {
namespace builder {
namespace {
class VocabHandout {
public:
explicit VocabHandout(int fd) {
util::scoped_fd duped(util::DupOrThrow(fd));
word_list_.reset(util::FDOpenOrThrow(duped));
Lookup("<unk>"); // Force 0
Lookup("<s>"); // Force 1
Lookup("</s>"); // Force 2
}
WordIndex Lookup(const StringPiece &word) {
uint64_t hashed = util::MurmurHashNative(word.data(), word.size());
std::pair<Seen::iterator, bool> ret(seen_.insert(std::pair<uint64_t, lm::WordIndex>(hashed, seen_.size())));
if (ret.second) {
char null_delimit = 0;
util::WriteOrThrow(word_list_.get(), word.data(), word.size());
util::WriteOrThrow(word_list_.get(), &null_delimit, 1);
UTIL_THROW_IF(seen_.size() >= std::numeric_limits<lm::WordIndex>::max(), VocabLoadException, "Too many vocabulary words. Change WordIndex to uint64_t in lm/word_index.hh.");
}
return ret.first->second;
}
WordIndex Size() const {
return seen_.size();
}
private:
typedef boost::unordered_map<uint64_t, lm::WordIndex> Seen;
Seen seen_;
util::scoped_FILE word_list_;
};
class DedupeHash : public std::unary_function<const WordIndex *, bool> {
public:
explicit DedupeHash(std::size_t order) : size_(order * sizeof(WordIndex)) {}
std::size_t operator()(const WordIndex *start) const {
return util::MurmurHashNative(start, size_);
}
private:
const std::size_t size_;
};
class DedupeEquals : public std::binary_function<const WordIndex *, const WordIndex *, bool> {
public:
explicit DedupeEquals(std::size_t order) : size_(order * sizeof(WordIndex)) {}
bool operator()(const WordIndex *first, const WordIndex *second) const {
return !memcmp(first, second, size_);
}
private:
const std::size_t size_;
};
struct DedupeEntry {
typedef WordIndex *Key;
Key GetKey() const { return key; }
Key key;
static DedupeEntry Construct(WordIndex *at) {
DedupeEntry ret;
ret.key = at;
return ret;
}
};
typedef util::ProbingHashTable<DedupeEntry, DedupeHash, DedupeEquals> Dedupe;
const float kProbingMultiplier = 1.5;
class Writer {
public:
Writer(std::size_t order, const util::stream::ChainPosition &position, void *dedupe_mem, std::size_t dedupe_mem_size)
: block_(position), gram_(block_->Get(), order),
dedupe_invalid_(order, std::numeric_limits<WordIndex>::max()),
dedupe_(dedupe_mem, dedupe_mem_size, &dedupe_invalid_[0], DedupeHash(order), DedupeEquals(order)),
buffer_(new WordIndex[order - 1]),
block_size_(position.GetChain().BlockSize()) {
dedupe_.Clear(DedupeEntry::Construct(&dedupe_invalid_[0]));
assert(Dedupe::Size(position.GetChain().BlockSize() / position.GetChain().EntrySize(), kProbingMultiplier) == dedupe_mem_size);
if (order == 1) {
// Add special words. AdjustCounts is responsible if order != 1.
AddUnigramWord(kUNK);
AddUnigramWord(kBOS);
}
}
~Writer() {
block_->SetValidSize(reinterpret_cast<const uint8_t*>(gram_.begin()) - static_cast<const uint8_t*>(block_->Get()));
(++block_).Poison();
}
// Write context with a bunch of <s>
void StartSentence() {
for (WordIndex *i = gram_.begin(); i != gram_.end() - 1; ++i) {
*i = kBOS;
}
}
void Append(WordIndex word) {
*(gram_.end() - 1) = word;
Dedupe::MutableIterator at;
bool found = dedupe_.FindOrInsert(DedupeEntry::Construct(gram_.begin()), at);
if (found) {
// Already present.
NGram already(at->key, gram_.Order());
++(already.Count());
// Shift left by one.
memmove(gram_.begin(), gram_.begin() + 1, sizeof(WordIndex) * (gram_.Order() - 1));
return;
}
// Complete the write.
gram_.Count() = 1;
// Prepare the next n-gram.
if (reinterpret_cast<uint8_t*>(gram_.begin()) + gram_.TotalSize() != static_cast<uint8_t*>(block_->Get()) + block_size_) {
NGram last(gram_);
gram_.NextInMemory();
std::copy(last.begin() + 1, last.end(), gram_.begin());
return;
}
// Block end. Need to store the context in a temporary buffer.
std::copy(gram_.begin() + 1, gram_.end(), buffer_.get());
dedupe_.Clear(DedupeEntry::Construct(&dedupe_invalid_[0]));
block_->SetValidSize(block_size_);
gram_.ReBase((++block_)->Get());
std::copy(buffer_.get(), buffer_.get() + gram_.Order() - 1, gram_.begin());
}
private:
void AddUnigramWord(WordIndex index) {
*gram_.begin() = index;
gram_.Count() = 0;
gram_.NextInMemory();
if (gram_.Base() == static_cast<uint8_t*>(block_->Get()) + block_size_) {
block_->SetValidSize(block_size_);
gram_.ReBase((++block_)->Get());
}
}
util::stream::Link block_;
NGram gram_;
// This is the memory behind the invalid value in dedupe_.
std::vector<WordIndex> dedupe_invalid_;
// Hash table combiner implementation.
Dedupe dedupe_;
// Small buffer to hold existing ngrams when shifting across a block boundary.
boost::scoped_array<WordIndex> buffer_;
const std::size_t block_size_;
};
} // namespace
float CorpusCount::DedupeMultiplier(std::size_t order) {
return kProbingMultiplier * static_cast<float>(sizeof(DedupeEntry)) / static_cast<float>(NGram::TotalSize(order));
}
CorpusCount::CorpusCount(util::FilePiece &from, int vocab_write, uint64_t &token_count, WordIndex &type_count, std::size_t entries_per_block)
: from_(from), vocab_write_(vocab_write), token_count_(token_count), type_count_(type_count),
dedupe_mem_size_(Dedupe::Size(entries_per_block, kProbingMultiplier)),
dedupe_mem_(util::MallocOrThrow(dedupe_mem_size_)) {
token_count_ = 0;
type_count_ = 0;
}
void CorpusCount::Run(const util::stream::ChainPosition &position) {
UTIL_TIMER("(%w s) Counted n-grams\n");
VocabHandout vocab(vocab_write_);
const WordIndex end_sentence = vocab.Lookup("</s>");
Writer writer(NGram::OrderFromSize(position.GetChain().EntrySize()), position, dedupe_mem_.get(), dedupe_mem_size_);
uint64_t count = 0;
try {
while(true) {
StringPiece line(from_.ReadLine());
writer.StartSentence();
for (util::TokenIter<util::AnyCharacter, true> w(line, " \t"); w; ++w) {
WordIndex word = vocab.Lookup(*w);
UTIL_THROW_IF(word <= 2, FormatLoadException, "Special word " << *w << " is not allowed in the corpus. I plan to support models containing <unk> in the future.");
writer.Append(word);
++count;
}
writer.Append(end_sentence);
}
} catch (const util::EndOfFileException &e) {}
token_count_ = count;
type_count_ = vocab.Size();
}
} // namespace builder
} // namespace lm
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