tensorflow_lite_support/cc/text/tokenizers/sentencepiece_tokenizer.h

/* Copyright 2020 The TensorFlow Authors. All Rights Reserved.

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.
==============================================================================*/

#ifndef TENSORFLOW_LITE_SUPPORT_CC_TEXT_TOKENIZERS_SENTENCEPIECE_TOKENIZER_H_
#define TENSORFLOW_LITE_SUPPORT_CC_TEXT_TOKENIZERS_SENTENCEPIECE_TOKENIZER_H_

#include <fstream>
#include <string>
#include <vector>

#include "src/sentencepiece_processor.h"
#include "tensorflow_lite_support/cc/text/tokenizers/tokenizer.h"

namespace tflite {
namespace support {
namespace text {
namespace tokenizer {

// SentencePiece tokenizer. Initialized with a model file.
class SentencePieceTokenizer : public Tokenizer {
 public:
  // Initialize the SentencePiece tokenizer from model file path.
  explicit SentencePieceTokenizer(const std::string& path_to_model) {
    CHECK_OK(sp_.Load(path_to_model));
  }

  explicit SentencePieceTokenizer(const char* spmodel_buffer_data,
                                  size_t spmodel_buffer_size) {
    absl::string_view buffer_binary(spmodel_buffer_data, spmodel_buffer_size);
    CHECK_OK(sp_.LoadFromSerializedProto(buffer_binary));
  }

  // Perform tokenization, return tokenized results.
  TokenizerResult Tokenize(const std::string& input) override {
    TokenizerResult result;
    std::vector<std::string>& subwords = result.subwords;
    CHECK_OK(sp_.Encode(input, &subwords));
    return result;
  }

  // Find the id of a string token.
  bool LookupId(absl::string_view key, int* result) const override {
    *result = sp_.PieceToId(key);
    return true;
  }

  // Find the string token of an id.
  bool LookupWord(int vocab_id, absl::string_view* result) const override {
    *result = sp_.IdToPiece(vocab_id);
    return true;
  }

 private:
  sentencepiece::SentencePieceProcessor sp_;
};

}  // namespace tokenizer
}  // namespace text
}  // namespace support
}  // namespace tflite

#endif  // TENSORFLOW_LITE_SUPPORT_CC_TEXT_TOKENIZERS_SENTENCEPIECE_TOKENIZER_H_