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// Copyright 2016 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.!
#include "sentencepiece_processor.h"
#include <map>
#include <random>
#include <set>
#include <utility>
#include "common.h"
#include "model_factory.h"
#include "model_interface.h"
#include "normalizer.h"
#include "sentencepiece.pb.h"
#include "unigram_model.h"
#include "util.h"
namespace sentencepiece {
namespace {
// Replaces white space with U+2581 (LOWER ONE EIGHT BLOCK).
const char kSpaceSymbol[] = "\xe2\x96\x81";
// Encodes <unk> into U+2047 (DOUBLE QUESTION MARK),
// since this character can be useful both for user and
// developer. We can easily figure out that <unk> is emitted.
const char kDefaultUnknownSymbol[] = " \xE2\x81\x87 ";
} // namespace
SentencePieceProcessor::SentencePieceProcessor() {}
SentencePieceProcessor::~SentencePieceProcessor() {}
util::Status SentencePieceProcessor::Load(util::min_string_view filename) {
std::ifstream ifs(filename.data(), std::ios::binary | std::ios::in);
if (!ifs) {
return util::StatusBuilder(util::error::NOT_FOUND)
<< "\"" << filename.data() << "\": " << util::StrError(errno);
}
return Load(&ifs);
}
void SentencePieceProcessor::LoadOrDie(util::min_string_view filename) {
CHECK_OK(Load(filename));
}
util::Status SentencePieceProcessor::Load(std::istream *is) {
CHECK_OR_RETURN(is) << "input ifstream is null";
auto model_proto = port::MakeUnique<ModelProto>();
CHECK_OR_RETURN(model_proto->ParseFromIstream(is)) << "Model file is broken";
return Load(std::move(model_proto));
}
util::Status SentencePieceProcessor::Load(const ModelProto &model_proto) {
auto model_proto_copy = port::MakeUnique<ModelProto>();
*model_proto_copy = model_proto;
return Load(std::move(model_proto_copy));
}
util::Status SentencePieceProcessor::LoadFromSerializedProto(
util::min_string_view serialized) {
auto model_proto = port::MakeUnique<ModelProto>();
CHECK_OR_RETURN(
model_proto->ParseFromArray(serialized.data(), serialized.size()));
return Load(std::move(model_proto));
}
util::Status SentencePieceProcessor::Load(
std::unique_ptr<ModelProto> &&model_proto) {
model_proto_ = std::move(model_proto);
model_ = ModelFactory::Create(*model_proto_);
normalizer_ =
port::MakeUnique<normalizer::Normalizer>(model_proto_->normalizer_spec());
return status();
}
util::Status SentencePieceProcessor::SetEncodeExtraOptions(
util::min_string_view extra_options) {
return ParseExtraOptions(extra_options, &encode_extra_options_);
}
util::Status SentencePieceProcessor::SetDecodeExtraOptions(
util::min_string_view extra_options) {
return ParseExtraOptions(extra_options, &decode_extra_options_);
}
util::Status SentencePieceProcessor::status() const {
CHECK_OR_RETURN(model_) << "Model is not initialized.";
CHECK_OR_RETURN(normalizer_) << "Normalizer is not initialized.";
RETURN_IF_ERROR(model_->status());
RETURN_IF_ERROR(normalizer_->status());
return util::OkStatus();
}
util::Status SentencePieceProcessor::SetVocabulary(
const std::vector<std::string> &valid_vocab) {
RETURN_IF_ERROR(status());
// TODO(taku): supports vocabulary constraint in BPE model.
const auto type = model_proto_->trainer_spec().model_type();
CHECK_OR_RETURN(type == TrainerSpec::UNIGRAM || type == TrainerSpec::BPE)
<< "Vocabulary constraint is only enabled in subword units.";
const std::set<std::string> vocab(valid_vocab.begin(), valid_vocab.end());
for (int i = 0; i < model_proto_->pieces_size(); ++i) {
auto *piece = model_proto_->mutable_pieces(i);
if (vocab.find(piece->piece()) != vocab.end() ||
string_util::OneCharLen(piece->piece().c_str()) ==
piece->piece().size()) {
piece->set_type(ModelProto::SentencePiece::NORMAL);
} else {
piece->set_type(ModelProto::SentencePiece::UNUSED);
}
}
return util::OkStatus();
}
util::Status SentencePieceProcessor::ResetVocabulary() {
RETURN_IF_ERROR(status());
for (auto &piece : *(model_proto_->mutable_pieces())) {
if (piece.type() == ModelProto::SentencePiece::UNUSED)
piece.set_type(ModelProto::SentencePiece::NORMAL);
}
return util::OkStatus();
}
util::Status SentencePieceProcessor::LoadVocabulary(
util::min_string_view filename, int threshold) {
io::InputBuffer input(string_util::ToSV(filename));
RETURN_IF_ERROR(input.status());
std::string line;
std::vector<std::string> vocab;
while (input.ReadLine(&line)) {
const std::vector<std::string> v = string_util::Split(line, "\t");
CHECK_GE_OR_RETURN(v.size(), 1);
CHECK_OR_RETURN(!v[0].empty());
int32 freq = 1;
if (v.size() >= 2) freq = atoi(v[1].c_str());
if (freq >= threshold) vocab.emplace_back(v[0]);
}
return SetVocabulary(vocab);
}
#define CHECK_OR_RETURN_STATUS_STL(container) \
RETURN_IF_ERROR(status()); \
CHECK_OR_RETURN(container) << "output container is null"; \
container->clear();
#define CHECK_OR_RETURN_STATUS_PROTO(proto) \
RETURN_IF_ERROR(status()); \
CHECK_OR_RETURN(proto) << "output proto is null"; \
proto->Clear();
//////////////////////////////////////////////////////////////
// Simple API.
util::Status SentencePieceProcessor::Encode(
util::min_string_view input, std::vector<std::string> *pieces) const {
CHECK_OR_RETURN_STATUS_STL(pieces);
SentencePieceText spt;
RETURN_IF_ERROR(Encode(input, &spt));
for (const auto &sp : spt.pieces()) {
pieces->emplace_back(sp.piece());
}
return util::OkStatus();
}
util::Status SentencePieceProcessor::Encode(util::min_string_view input,
std::vector<int> *ids) const {
CHECK_OR_RETURN_STATUS_STL(ids);
SentencePieceText spt;
RETURN_IF_ERROR(Encode(input, &spt));
for (const auto &sp : spt.pieces()) {
ids->emplace_back(sp.id());
}
return util::OkStatus();
}
util::Status SentencePieceProcessor::Decode(
const std::vector<std::string> &pieces, std::string *detokenized) const {
CHECK_OR_RETURN_STATUS_STL(detokenized);
SentencePieceText spt;
RETURN_IF_ERROR(Decode(pieces, &spt));
*detokenized = std::move(spt.text());
return util::OkStatus();
}
util::Status SentencePieceProcessor::Decode(const std::vector<int> &ids,
std::string *detokenized) const {
CHECK_OR_RETURN_STATUS_STL(detokenized);
SentencePieceText spt;
RETURN_IF_ERROR(Decode(ids, &spt));
*detokenized = std::move(spt.text());
return util::OkStatus();
}
util::Status SentencePieceProcessor::NBestEncode(
util::min_string_view input, int nbest_size,
std::vector<std::vector<std::string>> *pieces) const {
CHECK_OR_RETURN_STATUS_STL(pieces);
NBestSentencePieceText spt;
RETURN_IF_ERROR(NBestEncode(input, nbest_size, &spt));
for (const auto &nbest : spt.nbests()) {
std::vector<std::string> result;
for (const auto &sp : nbest.pieces()) {
result.emplace_back(sp.piece());
}
pieces->emplace_back(result);
}
return util::OkStatus();
}
util::Status SentencePieceProcessor::NBestEncode(
util::min_string_view input, int nbest_size,
std::vector<std::vector<int>> *ids) const {
CHECK_OR_RETURN_STATUS_STL(ids);
NBestSentencePieceText spt;
RETURN_IF_ERROR(NBestEncode(input, nbest_size, &spt));
for (const auto &nbest : spt.nbests()) {
std::vector<int> result;
for (const auto &sp : nbest.pieces()) {
result.emplace_back(sp.id());
}
ids->emplace_back(result);
}
return util::OkStatus();
}
util::Status SentencePieceProcessor::SampleEncode(
util::min_string_view input, int nbest_size, float alpha,
std::vector<std::string> *pieces) const {
CHECK_OR_RETURN_STATUS_STL(pieces);
SentencePieceText spt;
RETURN_IF_ERROR(SampleEncode(input, nbest_size, alpha, &spt));
for (const auto &sp : spt.pieces()) {
pieces->emplace_back(sp.piece());
}
return util::OkStatus();
}
util::Status SentencePieceProcessor::SampleEncode(util::min_string_view input,
int nbest_size, float alpha,
std::vector<int> *ids) const {
CHECK_OR_RETURN_STATUS_STL(ids);
SentencePieceText spt;
RETURN_IF_ERROR(SampleEncode(input, nbest_size, alpha, &spt));
for (const auto &sp : spt.pieces()) {
ids->emplace_back(sp.id());
}
return util::OkStatus();
}
util::Status SentencePieceProcessor::PopulateSentencePieceText(
util::min_string_view input, util::min_string_view normalized,
const std::vector<size_t> &norm_to_orig, const EncodeResult &result,
SentencePieceText *spt) const {
size_t consumed = 0;
bool is_prev_unk = false;
for (const auto &p : result) {
const absl::string_view w = p.first; // piece
const int id = p.second; // id
CHECK_OR_RETURN(!w.empty()) << "Empty piece is not allowed.";
const bool is_unk = IsUnknown(id);
if (IsControl(id)) {
// Control symbol has no corresponding source surface, so begin == end.
auto *sp = spt->add_pieces();
sp->set_piece(w.data(), w.size());
sp->set_id(id);
sp->set_begin(norm_to_orig[consumed]);
sp->set_end(norm_to_orig[consumed]);
} else {
const size_t begin = consumed;
const size_t end = consumed + w.size();
CHECK_LT_OR_RETURN(begin, norm_to_orig.size());
CHECK_LT_OR_RETURN(end, norm_to_orig.size());
const size_t orig_begin = norm_to_orig[begin];
const size_t orig_end = norm_to_orig[end];
CHECK_LE_OR_RETURN(orig_begin, input.size());
CHECK_LE_OR_RETURN(orig_end, input.size());
CHECK_LE_OR_RETURN(orig_begin, orig_end);
const auto surface =
absl::ClippedSubstr(input.data(), orig_begin, orig_end - orig_begin);
// Merges continuous run of unknown pieces so that decoder
// can copy or generate unknown tokens easily.
// Note that merged tokens are still unknown,
// since known pieces never consist of unknown characters.
if (is_prev_unk && is_unk) {
auto *sp = spt->mutable_pieces(spt->pieces_size() - 1);
sp->set_piece(sp->piece() + std::string(w));
sp->set_surface(sp->surface() + std::string(surface));
sp->set_end(orig_end);
} else {
auto *sp = spt->add_pieces();
sp->set_piece(w.data(), w.size());
sp->set_id(id);
sp->set_surface(surface.data(), surface.size());
sp->set_begin(orig_begin);
sp->set_end(orig_end);
}
consumed += w.size();
}
is_prev_unk = is_unk;
}
CHECK_EQ_OR_RETURN(consumed, normalized.size())
<< "all normalized characters are not consumed.";
RETURN_IF_ERROR(ApplyExtraOptions(encode_extra_options_, spt));
spt->set_text(input.data(), input.size());
return util::OkStatus();
} // namespace sentencepiece
util::Status SentencePieceProcessor::Encode(util::min_string_view input,
SentencePieceText *spt) const {
CHECK_OR_RETURN_STATUS_PROTO(spt);
std::string normalized;
std::vector<size_t> norm_to_orig;
RETURN_IF_ERROR(normalizer_->Normalize(string_util::ToSV(input), &normalized,
&norm_to_orig));
const auto result = model_->Encode(normalized);
RETURN_IF_ERROR(
PopulateSentencePieceText(input, normalized, norm_to_orig, result, spt));
return util::OkStatus();
}
util::Status SentencePieceProcessor::NBestEncode(
util::min_string_view input, int nbest_size,
NBestSentencePieceText *nbest_spt) const {
CHECK_OR_RETURN_STATUS_PROTO(nbest_spt);
std::string normalized;
std::vector<size_t> norm_to_orig;
RETURN_IF_ERROR(normalizer_->Normalize(string_util::ToSV(input), &normalized,
&norm_to_orig));
const auto nbests = model_->NBestEncode(normalized, nbest_size);
CHECK_OR_RETURN(!nbests.empty()) << "NBestEncode returns empty result.";
for (const auto &result : nbests) {
auto *spt = nbest_spt->add_nbests();
spt->set_score(result.second);
RETURN_IF_ERROR(PopulateSentencePieceText(input, normalized, norm_to_orig,
result.first, spt));
}
return util::OkStatus();
}
util::Status SentencePieceProcessor::SampleEncode(
util::min_string_view input, int nbest_size, float alpha,
SentencePieceText *spt) const {
CHECK_OR_RETURN_STATUS_PROTO(spt);
CHECK_LE_OR_RETURN(nbest_size, 512) << "nbest_size must be nbest_size <= 512";
std::string normalized;
std::vector<size_t> norm_to_orig;
RETURN_IF_ERROR(normalizer_->Normalize(string_util::ToSV(input), &normalized,
&norm_to_orig));
if (nbest_size == 1 || nbest_size == 0) {
const auto result = model_->Encode(normalized);
RETURN_IF_ERROR(PopulateSentencePieceText(input, normalized, norm_to_orig,
result, spt));
} else if (nbest_size > 1) {
const auto nbests = model_->NBestEncode(normalized, nbest_size);
CHECK_OR_RETURN(!nbests.empty()) << "NBestEncode returns empty result.";
std::vector<float> probs(nbests.size(), 0.0);
for (size_t i = 0; i < nbests.size(); ++i) {
probs[i] = std::exp(alpha * nbests[i].second);
}
thread_local static std::mt19937 mt(std::random_device{}());
std::discrete_distribution<int> dist(probs.begin(), probs.end());
RETURN_IF_ERROR(PopulateSentencePieceText(input, normalized, norm_to_orig,
nbests[dist(mt)].first, spt));
} else if (nbest_size < 0) {
const auto result = model_->SampleEncode(normalized, alpha);
RETURN_IF_ERROR(PopulateSentencePieceText(input, normalized, norm_to_orig,
result, spt));
}
return util::OkStatus();
}
util::Status SentencePieceProcessor::Decode(
const std::vector<std::string> &pieces, SentencePieceText *spt) const {
CHECK_OR_RETURN_STATUS_PROTO(spt);
const char *unk_surface = kDefaultUnknownSymbol;
if (model_proto_ && model_proto_->trainer_spec().has_unk_surface())
unk_surface = model_proto_->trainer_spec().unk_surface().c_str();
auto DecodeSentencePiece = [&](absl::string_view piece, int id,
bool is_bos_ws) -> std::string {
if (IsControl(id)) { // <s>, </s>
return ""; // invisible symbol.
} else if (IsUnknown(id)) {
if (IdToPiece(id) == piece) { // <unk>
return unk_surface;
} else { // return piece when piece is not <unk>.
return std::string(piece);
}
}
if (is_bos_ws) {
// Consume if the current position is bos and
// piece starts with kSpaceSymbol.
string_util::ConsumePrefix(&piece, kSpaceSymbol);
}
return string_util::StringReplace(piece, kSpaceSymbol, " ", true);
};
for (const std::string &w : pieces) {
auto *sp = spt->add_pieces();
sp->set_piece(w);
sp->set_id(PieceToId(w));
}
RETURN_IF_ERROR(ApplyExtraOptions(decode_extra_options_, spt));
std::string *text = spt->mutable_text();
for (auto &sp : *(spt->mutable_pieces())) {
sp.set_surface(DecodeSentencePiece(sp.piece(), sp.id(), text->empty()));
sp.set_begin(text->size());
sp.set_end(text->size() + sp.surface().size());
*text += sp.surface();
}
return util::OkStatus();
}
util::Status SentencePieceProcessor::Decode(const std::vector<int> &ids,
SentencePieceText *spt) const {
std::vector<std::string> pieces;
for (const int id : ids) {
pieces.emplace_back(IdToPiece(id));
}
return Decode(pieces, spt);
}
#define CHECK_STATUS_OR_RETURN_DEFAULT(value) \
if (!status().ok()) { \
LOG(ERROR) << status().error_message() << "\nReturns default value " \
<< value; \
return value; \
}
int SentencePieceProcessor::GetPieceSize() const {
CHECK_STATUS_OR_RETURN_DEFAULT(0);
return model_->GetPieceSize();
}
int SentencePieceProcessor::PieceToId(util::min_string_view piece) const {
CHECK_STATUS_OR_RETURN_DEFAULT(0);
return model_->PieceToId(string_util::ToSV(piece));
}
std::string SentencePieceProcessor::IdToPiece(int id) const {
CHECK_STATUS_OR_RETURN_DEFAULT("");
return model_->IdToPiece(id);
}
float SentencePieceProcessor::GetScore(int id) const {
CHECK_STATUS_OR_RETURN_DEFAULT(0.0);
return model_->GetScore(id);
}
bool SentencePieceProcessor::IsControl(int id) const {
CHECK_STATUS_OR_RETURN_DEFAULT(0);
return model_->IsControl(id);
}
bool SentencePieceProcessor::IsUnknown(int id) const {
CHECK_STATUS_OR_RETURN_DEFAULT(0);
return model_->IsUnknown(id);
}
bool SentencePieceProcessor::IsUnused(int id) const {
CHECK_STATUS_OR_RETURN_DEFAULT(false);
return model_->IsUnused(id);
}
int SentencePieceProcessor::unk_id() const {
const int id = PieceToId(ModelInterface::kUNK());
if (IsUnknown(id)) return id;
return -1;
}
int SentencePieceProcessor::bos_id() const {
const int id = PieceToId(ModelInterface::kBOS());
if (IsControl(id)) return id;
return -1;
}
int SentencePieceProcessor::eos_id() const {
const int id = PieceToId(ModelInterface::kEOS());
if (IsControl(id)) return id;
return -1;
}
int SentencePieceProcessor::pad_id() const {
const int id = PieceToId(ModelInterface::kPAD());
if (IsControl(id)) return id;
return -1;
}
// static
util::Status SentencePieceProcessor::ApplyExtraOptions(
const std::vector<ExtraOption> &extra_options,
SentencePieceText *spt) const {
for (const auto &extra_option : extra_options) {
switch (extra_option) {
case REVERSE:
std::reverse(spt->mutable_pieces()->begin(),
spt->mutable_pieces()->end());
break;
case EOS: {
auto *piece = spt->add_pieces();
piece->set_id(PieceToId("</s>"));
piece->set_piece("</s>");
} break;
case BOS: {
auto *array = spt->mutable_pieces();
array->Add();
for (int i = array->size() - 1; i > 0; --i) {
array->SwapElements(i - 1, i);
}
auto *piece = array->Mutable(0);
piece->set_id(PieceToId("<s>"));
piece->set_piece("<s>");
} break;
default:
return util::InternalError("unknown extra_option type.");
}
}
return util::OkStatus();
}
// static
util::Status SentencePieceProcessor::ParseExtraOptions(
util::min_string_view _extra_option,
std::vector<SentencePieceProcessor::ExtraOption> *extra_options) const {
absl::string_view extra_option(_extra_option.data(), _extra_option.size());
extra_options->clear();
if (extra_option.empty()) return util::OkStatus();
RETURN_IF_ERROR(status());
static std::map<absl::string_view, SentencePieceProcessor::ExtraOption>
extra_option_map = {{"bos", SentencePieceProcessor::BOS},
{"eos", SentencePieceProcessor::EOS},
{"reverse", SentencePieceProcessor::REVERSE}};
for (const auto &s : string_util::SplitPiece(extra_option, ":")) {
const auto it = extra_option_map.find(s);
CHECK_OR_RETURN(it != extra_option_map.end())
<< "option \"" << s << "\" is not available.";
extra_options->push_back(it->second);
if (it->second == SentencePieceProcessor::BOS) {
CHECK_OR_RETURN(!IsUnknown(PieceToId("<s>")))
<< "id for `<s>` is not defined.";
}
if (it->second == SentencePieceProcessor::EOS) {
CHECK_OR_RETURN(!IsUnknown(PieceToId("</s>")))
<< "id for `</s>` is not defined.";
}
}
return util::OkStatus();
}
void SentencePieceProcessor::SetModel(std::unique_ptr<ModelInterface> &&model) {
model_ = std::move(model);
}
void SentencePieceProcessor::SetNormalizer(
std::unique_ptr<normalizer::Normalizer> &&normalizer) {
normalizer_ = std::move(normalizer);
}
const ModelProto &SentencePieceProcessor::model_proto() const {
return *model_proto_;
}
} // namespace sentencepiece
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