solidity/tools/yulPhaser/PairSelections.h

123 lines
4.3 KiB
C++

/*
This file is part of solidity.
solidity is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
solidity 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
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with solidity. If not, see <http://www.gnu.org/licenses/>.
*/
// SPDX-License-Identifier: GPL-3.0
/**
* Contains an abstract base class representing a selection of pairs of elements from a collection
* and its concrete implementations.
*/
#pragma once
#include <cassert>
#include <tuple>
#include <vector>
namespace solidity::phaser
{
/**
* Abstract base class for selections of pairs elements from a collection.
*
* An instance of this class represents a specific method of selecting a set of pairs of elements
* from containers of arbitrary sizes. The selected pairs always point at a subset of the elements
* from the container but may indicate the same element more than once. The pairs themselves can
* repeat too. The selection may or may not be fixed - it's up to a specific implementation whether
* subsequent calls for the same container produce the same indices or not.
*
* Derived classes are meant to override the @a materialise() method.
* This method is expected to produce pairs of selected elements given the size of the collection.
*/
class PairSelection
{
public:
PairSelection() = default;
PairSelection(PairSelection const&) = delete;
PairSelection& operator=(PairSelection const&) = delete;
virtual ~PairSelection() = default;
virtual std::vector<std::tuple<size_t, size_t>> materialise(size_t _poolSize) const = 0;
};
/**
* A selection that selects pairs of random elements from a container. The resulting set of pairs
* may contain the same pair more than once but does not contain pairs of duplicates. Always
* selects as many pairs as the size of the container multiplied by @a _selectionSize (unless the
* container is empty).
*/
class RandomPairSelection: public PairSelection
{
public:
explicit RandomPairSelection(double _selectionSize):
m_selectionSize(_selectionSize) {}
std::vector<std::tuple<size_t, size_t>> materialise(size_t _poolSize) const override;
private:
double m_selectionSize;
};
/**
* A selection that goes over all elements in a container, for each one independently decides
* whether to select it or not and then randomly combines those elements into pairs. If the number
* of elements is odd, randomly decides whether to take one more or exclude one.
*
* Each element has the same chance of being selected and can be selected at most once.
* The number of selected elements is random and can be different with each call to
* @a materialise().
*/
class PairsFromRandomSubset: public PairSelection
{
public:
explicit PairsFromRandomSubset(double _selectionChance):
m_selectionChance(_selectionChance) {}
std::vector<std::tuple<size_t, size_t>> materialise(size_t _poolSize) const override;
private:
double m_selectionChance;
};
/**
* A selection that selects pairs of elements at specific, fixed positions indicated by a repeating
* "pattern". If the positions in the pattern exceed the size of the container, they are capped at
* the maximum available position. Always selects as many pairs as the size of the container
* multiplied by @a _selectionSize (unless the container is empty).
*
* E.g. if the pattern is {{0, 1}, {3, 9}} and collection size is 5, the selection will materialise
* into {{0, 1}, {3, 4}, {0, 1}, {3, 4}, {0, 1}}. If the size is 3, it will be
* {{0, 1}, {2, 2}, {0, 1}}.
*/
class PairMosaicSelection: public PairSelection
{
public:
explicit PairMosaicSelection(std::vector<std::tuple<size_t, size_t>> _pattern, double _selectionSize = 1.0):
m_pattern(move(_pattern)),
m_selectionSize(_selectionSize)
{
assert(m_pattern.size() > 0 || _selectionSize == 0.0);
}
std::vector<std::tuple<size_t, size_t>> materialise(size_t _poolSize) const override;
private:
std::vector<std::tuple<size_t, size_t>> m_pattern;
double m_selectionSize;
};
}