61 lines
2.5 KiB
C++
61 lines
2.5 KiB
C++
/*------------------------------------------------------------------------------*
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* Architecture & Implementation of DBMS *
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*------------------------------------------------------------------------------*
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* Copyright 2022 Databases and Information Systems Group TU Dortmund *
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* Visit us at *
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* http://dbis.cs.tu-dortmund.de/cms/en/home/ *
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* *
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS *
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* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, *
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL *
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR *
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* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, *
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* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR *
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* OTHER DEALINGS IN THE SOFTWARE. *
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* *
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* Authors: *
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* Maximilian Berens <maximilian.berens@tu-dortmund.de> *
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* Roland Kühn <roland.kuehn@cs.tu-dortmund.de> *
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* Jan Mühlig <jan.muehlig@tu-dortmund.de> *
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*------------------------------------------------------------------------------*
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*/
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#pragma once
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#include "unary_operator.h"
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#include <cstdint>
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#include <table/schema.h>
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#include <table/tuple.h>
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#include <vector>
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namespace beedb::execution
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{
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/**
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* Limits the output result.
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*/
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class LimitOperator final : public UnaryOperator
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{
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public:
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LimitOperator(concurrency::Transaction *transaction, const table::Schema &schema, const std::uint64_t limit,
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const std::uint64_t offset);
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~LimitOperator() override = default;
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void open() override;
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util::optional<table::Tuple> next() override;
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void close() override;
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[[nodiscard]] const table::Schema &schema() const override
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{
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return _schema;
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};
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private:
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const table::Schema &_schema;
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const std::uint64_t _limit;
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const std::uint64_t _offset;
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bool _has_skipped = false;
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std::uint64_t _count = 0;
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};
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} // namespace beedb::execution
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