| /* |
| * Copyright (C) 2017 The Android Open Source Project |
| * |
| * 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 "tokenizer.h" |
| |
| #include <algorithm> |
| |
| #include "util/base/logging.h" |
| #include "util/strings/utf8.h" |
| |
| namespace libtextclassifier2 { |
| |
| Tokenizer::Tokenizer( |
| const std::vector<const TokenizationCodepointRange*>& codepoint_ranges, |
| bool split_on_script_change) |
| : split_on_script_change_(split_on_script_change) { |
| for (const TokenizationCodepointRange* range : codepoint_ranges) { |
| codepoint_ranges_.emplace_back(range->UnPack()); |
| } |
| |
| std::sort(codepoint_ranges_.begin(), codepoint_ranges_.end(), |
| [](const std::unique_ptr<const TokenizationCodepointRangeT>& a, |
| const std::unique_ptr<const TokenizationCodepointRangeT>& b) { |
| return a->start < b->start; |
| }); |
| } |
| |
| const TokenizationCodepointRangeT* Tokenizer::FindTokenizationRange( |
| int codepoint) const { |
| auto it = std::lower_bound( |
| codepoint_ranges_.begin(), codepoint_ranges_.end(), codepoint, |
| [](const std::unique_ptr<const TokenizationCodepointRangeT>& range, |
| int codepoint) { |
| // This function compares range with the codepoint for the purpose of |
| // finding the first greater or equal range. Because of the use of |
| // std::lower_bound it needs to return true when range < codepoint; |
| // the first time it will return false the lower bound is found and |
| // returned. |
| // |
| // It might seem weird that the condition is range.end <= codepoint |
| // here but when codepoint == range.end it means it's actually just |
| // outside of the range, thus the range is less than the codepoint. |
| return range->end <= codepoint; |
| }); |
| if (it != codepoint_ranges_.end() && (*it)->start <= codepoint && |
| (*it)->end > codepoint) { |
| return it->get(); |
| } else { |
| return nullptr; |
| } |
| } |
| |
| void Tokenizer::GetScriptAndRole(char32 codepoint, |
| TokenizationCodepointRange_::Role* role, |
| int* script) const { |
| const TokenizationCodepointRangeT* range = FindTokenizationRange(codepoint); |
| if (range) { |
| *role = range->role; |
| *script = range->script_id; |
| } else { |
| *role = TokenizationCodepointRange_::Role_DEFAULT_ROLE; |
| *script = kUnknownScript; |
| } |
| } |
| |
| std::vector<Token> Tokenizer::Tokenize(const std::string& text) const { |
| UnicodeText text_unicode = UTF8ToUnicodeText(text, /*do_copy=*/false); |
| return Tokenize(text_unicode); |
| } |
| |
| std::vector<Token> Tokenizer::Tokenize(const UnicodeText& text_unicode) const { |
| std::vector<Token> result; |
| Token new_token("", 0, 0); |
| int codepoint_index = 0; |
| |
| int last_script = kInvalidScript; |
| for (auto it = text_unicode.begin(); it != text_unicode.end(); |
| ++it, ++codepoint_index) { |
| TokenizationCodepointRange_::Role role; |
| int script; |
| GetScriptAndRole(*it, &role, &script); |
| |
| if (role & TokenizationCodepointRange_::Role_SPLIT_BEFORE || |
| (split_on_script_change_ && last_script != kInvalidScript && |
| last_script != script)) { |
| if (!new_token.value.empty()) { |
| result.push_back(new_token); |
| } |
| new_token = Token("", codepoint_index, codepoint_index); |
| } |
| if (!(role & TokenizationCodepointRange_::Role_DISCARD_CODEPOINT)) { |
| new_token.value += std::string( |
| it.utf8_data(), |
| it.utf8_data() + GetNumBytesForNonZeroUTF8Char(it.utf8_data())); |
| ++new_token.end; |
| } |
| if (role & TokenizationCodepointRange_::Role_SPLIT_AFTER) { |
| if (!new_token.value.empty()) { |
| result.push_back(new_token); |
| } |
| new_token = Token("", codepoint_index + 1, codepoint_index + 1); |
| } |
| |
| last_script = script; |
| } |
| if (!new_token.value.empty()) { |
| result.push_back(new_token); |
| } |
| |
| return result; |
| } |
| |
| } // namespace libtextclassifier2 |