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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 "model_interface.h"
#include <algorithm>
#include "sentencepiece_model.pb.h"
#include "util.h"
namespace sentencepiece {
PrefixMatcher::PrefixMatcher(const std::set<absl::string_view> &dic) {
if (dic.empty()) return;
std::vector<const char *> key;
key.reserve(dic.size());
for (const auto &it : dic) key.push_back(it.data());
trie_ = port::MakeUnique<Darts::DoubleArray>();
CHECK_EQ(0, trie_->build(key.size(), const_cast<char **>(&key[0]), nullptr,
nullptr));
}
int PrefixMatcher::PrefixMatch(absl::string_view w, bool *found) const {
if (trie_ == nullptr) {
if (found) *found = false;
return std::min<int>(w.size(), string_util::OneCharLen(w.data()));
}
constexpr int kResultSize = 64;
Darts::DoubleArray::result_pair_type trie_results[kResultSize];
const int num_nodes =
trie_->commonPrefixSearch(w.data(), trie_results, kResultSize, w.size());
if (found) *found = (num_nodes > 0);
if (num_nodes == 0) {
return std::min<int>(w.size(), string_util::OneCharLen(w.data()));
}
int mblen = 0;
for (int i = 0; i < num_nodes; ++i) {
mblen = std::max<int>(trie_results[i].length, mblen);
}
return mblen;
}
std::string PrefixMatcher::GlobalReplace(absl::string_view w,
absl::string_view out) const {
std::string result;
while (!w.empty()) {
bool found = false;
const int mblen = PrefixMatch(w, &found);
if (found) {
result.append(out.data(), out.size());
} else {
result.append(w.data(), mblen);
}
w.remove_prefix(mblen);
}
return result;
}
const char *ModelInterface::kUNK() { return "<unk>"; }
const char *ModelInterface::kBOS() { return "<s>"; }
const char *ModelInterface::kEOS() { return "</s>"; }
const char *ModelInterface::kPAD() { return "<pad>"; };
ModelInterface::ModelInterface(const ModelProto &model_proto)
: model_proto_(&model_proto), status_(util::OkStatus()) {}
ModelInterface::~ModelInterface() {}
int ModelInterface::PieceToId(absl::string_view piece) const {
auto it = reserved_id_map_.find(piece);
if (it != reserved_id_map_.end()) {
return it->second;
}
auto it2 = pieces_.find(piece);
if (it2 != pieces_.end()) {
return it2->second;
}
return unk_id_;
}
int ModelInterface::GetPieceSize() const { return model_proto_->pieces_size(); }
std::string ModelInterface::IdToPiece(int id) const {
return model_proto_->pieces(id).piece();
}
float ModelInterface::GetScore(int id) const {
return model_proto_->pieces(id).score();
}
bool ModelInterface::IsControl(int id) const {
return (model_proto_->pieces(id).type() ==
ModelProto::SentencePiece::CONTROL);
}
bool ModelInterface::IsUnknown(int id) const {
return (model_proto_->pieces(id).type() ==
ModelProto::SentencePiece::UNKNOWN);
}
bool ModelInterface::IsUnused(int id) const {
return (model_proto_->pieces(id).type() == ModelProto::SentencePiece::UNUSED);
}
bool ModelInterface::IsUserDefined(int id) const {
return (model_proto_->pieces(id).type() ==
ModelProto::SentencePiece::USER_DEFINED);
}
void ModelInterface::InitializePieces(bool use_prefix_matcher) {
pieces_.clear();
reserved_id_map_.clear();
unk_id_ = -1;
std::set<absl::string_view> user_defined_symbols;
for (int i = 0; i < model_proto_->pieces_size(); ++i) {
const auto &sp = model_proto_->pieces(i);
if (sp.piece().empty()) {
status_ = util::InternalError("piece must not be empty.");
return;
}
const bool is_normal_piece =
(sp.type() == ModelProto::SentencePiece::NORMAL ||
sp.type() == ModelProto::SentencePiece::USER_DEFINED ||
sp.type() == ModelProto::SentencePiece::UNUSED);
if (!port::InsertIfNotPresent(
is_normal_piece ? &pieces_ : &reserved_id_map_, sp.piece(), i)) {
status_ = util::InternalError(sp.piece() + " is already defined.");
return;
}
if (use_prefix_matcher &&
sp.type() == ModelProto::SentencePiece::USER_DEFINED) {
user_defined_symbols.insert(sp.piece());
}
if (sp.type() == ModelProto::SentencePiece::UNKNOWN) {
if (unk_id_ >= 0) {
status_ = util::InternalError("unk is already defined.");
return;
}
unk_id_ = i;
}
}
if (unk_id_ == -1) {
status_ = util::InternalError("unk is not defined.");
return;
}
if (use_prefix_matcher) {
matcher_ = port::MakeUnique<PrefixMatcher>(user_defined_symbols);
}
}
std::vector<absl::string_view> SplitIntoWords(absl::string_view text) {
const char *begin = text.data();
const char *end = text.data() + text.size();
// Space symbol (U+2581)
const absl::string_view kSpaceSymbol = "\xe2\x96\x81";
std::vector<absl::string_view> result;
while (begin < end) {
const int mblen =
std::min<int>(string_util::OneCharLen(begin), end - begin);
if (begin == text.data() ||
absl::string_view(begin, mblen) == kSpaceSymbol) {
result.emplace_back(begin, 0); // add empty string piece.
}
result.back() =
absl::string_view(result.back().data(), result.back().size() + mblen);
begin += mblen;
}
return result;
}
} // namespace sentencepiece
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