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/**
* Copyright (C) 2020-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#pragma once
#include <sstream>
#include <string>
#include <vector>
#include "mongo/bson/bsonobj.h"
#include "mongo/db/cst/bson_location.h"
#include "mongo/db/cst/parser_gen.hpp"
namespace mongo {
class BSONLexer {
public:
explicit BSONLexer(BSONElement input);
/**
* Retrieves the next token in the stream.
*/
ParserGen::symbol_type getNext() {
return _tokens[_position++];
}
/**
* Sorts the object that starts at the current position, based on the enum for each of the field
* name tokens.
*/
void sortObjTokens();
/**
* Convenience for retrieving the token at the given offset.
*/
auto& operator[](int offset) {
return _tokens[offset];
}
/**
* Scoped struct which pushes a location prefix for subsequently generated tokens. Pops the
* prefix off the stack upon destruction.
*/
struct ScopedLocationTracker {
ScopedLocationTracker(BSONLexer* lexer, BSONLocation::LocationPrefix prefix)
: _lexer(lexer) {
_lexer->_locationPrefixes.emplace_back(prefix);
}
~ScopedLocationTracker() {
_lexer->_locationPrefixes.pop_back();
}
BSONLexer* _lexer{nullptr};
};
private:
// Tokenizes the given BSONElement, traversing its children if necessary. If the field name
// should not be considered, set 'includeFieldName' to false.
void tokenize(BSONElement elem, bool includeFieldName);
template <class LocationType, class... Args>
void pushToken(LocationType name, Args&&... args) {
auto token = ParserGen::symbol_type(std::forward<Args>(args)...,
BSONLocation{std::move(name), _locationPrefixes});
_tokens.emplace_back(std::move(token));
_position++;
}
// Track the position of the input, both during construction of the list of tokens as well as
// during parse.
unsigned int _position = 0; // note: counter_type is only available on 3.5+
// A set of prefix strings that describe the current location in the lexer. As we walk the input
// BSON, this will change depending on the context that we're parsing.
std::vector<BSONLocation::LocationPrefix> _locationPrefixes;
std::vector<ParserGen::symbol_type> _tokens;
};
// This is the entry point for retrieving the next token from the lexer, invoked from Bison's
// yyparse().
ParserGen::symbol_type yylex(mongo::BSONLexer& lexer);
} // namespace mongo
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