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67 lines
2.3 KiB
67 lines
2.3 KiB
/*
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* Copyright (C) 2018 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "utils/grammar/parsing/lexer.h"
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namespace libtextclassifier3::grammar {
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Symbol::Type Lexer::GetSymbolType(const UnicodeText::const_iterator& it) const {
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if (unilib_.IsPunctuation(*it)) {
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return Symbol::Type::TYPE_PUNCTUATION;
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} else if (unilib_.IsDigit(*it)) {
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return Symbol::Type::TYPE_DIGITS;
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} else {
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return Symbol::Type::TYPE_TERM;
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}
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}
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void Lexer::AppendTokenSymbols(const StringPiece value, int match_offset,
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const CodepointSpan codepoint_span,
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std::vector<Symbol>* symbols) const {
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// Possibly split token.
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UnicodeText token_unicode = UTF8ToUnicodeText(value.data(), value.size(),
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/*do_copy=*/false);
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int next_match_offset = match_offset;
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auto token_end = token_unicode.end();
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auto it = token_unicode.begin();
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Symbol::Type type = GetSymbolType(it);
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CodepointIndex sub_token_start = codepoint_span.first;
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while (it != token_end) {
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auto next = std::next(it);
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int num_codepoints = 1;
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Symbol::Type next_type;
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while (next != token_end) {
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next_type = GetSymbolType(next);
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if (type == Symbol::Type::TYPE_PUNCTUATION || next_type != type) {
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break;
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}
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++next;
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++num_codepoints;
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}
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symbols->emplace_back(
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type, CodepointSpan{sub_token_start, sub_token_start + num_codepoints},
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/*match_offset=*/next_match_offset,
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/*lexeme=*/
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StringPiece(it.utf8_data(), next.utf8_data() - it.utf8_data()));
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next_match_offset = sub_token_start + num_codepoints;
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it = next;
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type = next_type;
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sub_token_start = next_match_offset;
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}
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}
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} // namespace libtextclassifier3::grammar
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