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/*
* Copyright (C) 2018 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.
*/
#ifndef LIBTEXTCLASSIFIER_UTILS_GRAMMAR_PARSING_PARSER_H_
#define LIBTEXTCLASSIFIER_UTILS_GRAMMAR_PARSING_PARSER_H_
#include <vector>
#include "annotator/types.h"
#include "utils/base/arena.h"
#include "utils/grammar/parsing/derivation.h"
#include "utils/grammar/parsing/lexer.h"
#include "utils/grammar/parsing/matcher.h"
#include "utils/grammar/rules_generated.h"
#include "utils/grammar/text-context.h"
#include "utils/i18n/locale.h"
#include "utils/utf8/unilib.h"
namespace libtextclassifier3::grammar {
// Syntactic parsing pass.
// The parser validates and deduplicates candidates produced by the grammar
// matcher. It augments the parse trees with derivation information for semantic
// evaluation.
class Parser {
public:
explicit Parser(const UniLib* unilib, const RulesSet* rules);
// Parses an input text and returns the root rule derivations.
std::vector<Derivation> Parse(const TextContext& input,
UnsafeArena* arena) const;
private:
struct RegexAnnotator {
std::unique_ptr<UniLib::RegexPattern> pattern;
Nonterm nonterm;
};
// Uncompresses and build the defined regex annotators.
std::vector<RegexAnnotator> BuildRegexAnnotators() const;
// Produces symbols for a text input to feed to a matcher.
// These are symbols for each tokens from the lexer, existing text annotations
// and regex annotations.
// The symbols are sorted with increasing end-positions to satisfy the matcher
// requirements.
std::vector<Symbol> SortedSymbolsForInput(const TextContext& input,
UnsafeArena* arena) const;
// Emits a symbol to the matcher.
void EmitSymbol(const Symbol& symbol, UnsafeArena* arena,
Matcher* matcher) const;
const UniLib& unilib_;
const RulesSet* rules_;
const Lexer lexer_;
// Pre-defined nonterminals.
const RulesSet_::Nonterminals* nonterminals_;
// Pre-parsed locales of the rules.
const std::vector<std::vector<Locale>> rules_locales_;
std::vector<RegexAnnotator> regex_annotators_;
};
} // namespace libtextclassifier3::grammar
#endif // LIBTEXTCLASSIFIER_UTILS_GRAMMAR_PARSING_PARSER_H_