mirror of
https://github.com/ethereum/solidity
synced 2023-10-03 13:03:40 +00:00
123 lines
4.3 KiB
C++
123 lines
4.3 KiB
C++
/*
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This file is part of solidity.
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solidity is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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solidity is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with solidity. If not, see <http://www.gnu.org/licenses/>.
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*/
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// SPDX-License-Identifier: GPL-3.0
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/**
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* Contains an abstract base class representing a selection of pairs of elements from a collection
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* and its concrete implementations.
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*/
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#pragma once
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#include <cassert>
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#include <tuple>
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#include <vector>
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namespace solidity::phaser
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{
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/**
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* Abstract base class for selections of pairs elements from a collection.
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*
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* An instance of this class represents a specific method of selecting a set of pairs of elements
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* from containers of arbitrary sizes. The selected pairs always point at a subset of the elements
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* from the container but may indicate the same element more than once. The pairs themselves can
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* repeat too. The selection may or may not be fixed - it's up to a specific implementation whether
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* subsequent calls for the same container produce the same indices or not.
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*
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* Derived classes are meant to override the @a materialise() method.
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* This method is expected to produce pairs of selected elements given the size of the collection.
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*/
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class PairSelection
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{
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public:
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PairSelection() = default;
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PairSelection(PairSelection const&) = delete;
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PairSelection& operator=(PairSelection const&) = delete;
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virtual ~PairSelection() = default;
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virtual std::vector<std::tuple<size_t, size_t>> materialise(size_t _poolSize) const = 0;
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};
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/**
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* A selection that selects pairs of random elements from a container. The resulting set of pairs
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* may contain the same pair more than once but does not contain pairs of duplicates. Always
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* selects as many pairs as the size of the container multiplied by @a _selectionSize (unless the
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* container is empty).
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*/
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class RandomPairSelection: public PairSelection
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{
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public:
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explicit RandomPairSelection(double _selectionSize):
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m_selectionSize(_selectionSize) {}
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std::vector<std::tuple<size_t, size_t>> materialise(size_t _poolSize) const override;
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private:
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double m_selectionSize;
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};
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/**
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* A selection that goes over all elements in a container, for each one independently decides
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* whether to select it or not and then randomly combines those elements into pairs. If the number
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* of elements is odd, randomly decides whether to take one more or exclude one.
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*
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* Each element has the same chance of being selected and can be selected at most once.
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* The number of selected elements is random and can be different with each call to
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* @a materialise().
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*/
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class PairsFromRandomSubset: public PairSelection
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{
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public:
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explicit PairsFromRandomSubset(double _selectionChance):
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m_selectionChance(_selectionChance) {}
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std::vector<std::tuple<size_t, size_t>> materialise(size_t _poolSize) const override;
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private:
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double m_selectionChance;
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};
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/**
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* A selection that selects pairs of elements at specific, fixed positions indicated by a repeating
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* "pattern". If the positions in the pattern exceed the size of the container, they are capped at
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* the maximum available position. Always selects as many pairs as the size of the container
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* multiplied by @a _selectionSize (unless the container is empty).
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*
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* E.g. if the pattern is {{0, 1}, {3, 9}} and collection size is 5, the selection will materialise
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* into {{0, 1}, {3, 4}, {0, 1}, {3, 4}, {0, 1}}. If the size is 3, it will be
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* {{0, 1}, {2, 2}, {0, 1}}.
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*/
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class PairMosaicSelection: public PairSelection
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{
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public:
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explicit PairMosaicSelection(std::vector<std::tuple<size_t, size_t>> _pattern, double _selectionSize = 1.0):
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m_pattern(move(_pattern)),
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m_selectionSize(_selectionSize)
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{
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assert(m_pattern.size() > 0 || _selectionSize == 0.0);
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}
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std::vector<std::tuple<size_t, size_t>> materialise(size_t _poolSize) const override;
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private:
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std::vector<std::tuple<size_t, size_t>> m_pattern;
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double m_selectionSize;
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};
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}
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