solidity/tools/yulPhaser/Selections.h
2021-05-17 11:35:07 +01:00

146 lines
4.5 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 elements from a collection
* and its concrete implementations.
*/
#pragma once
#include <cassert>
#include <cstddef>
#include <vector>
namespace solidity::phaser
{
/**
* Abstract base class for selections of elements from a collection.
*
* An instance of this class represents a specific method of selecting a set of elements from
* containers of arbitrary sizes. The set of selected elements is always a subset of the container
* but may indicate the same element more than once. 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 indices of selected elements given the size of the collection.
*/
class Selection
{
public:
Selection() = default;
Selection(Selection const&) = delete;
Selection& operator=(Selection const&) = delete;
virtual ~Selection() = default;
virtual std::vector<size_t> materialise(size_t _poolSize) const = 0;
};
/**
* A selection that selects a contiguous slice of the container. Start and end of this part are
* specified as percentages of its size.
*/
class RangeSelection: public Selection
{
public:
explicit RangeSelection(double _startPercent = 0.0, double _endPercent = 1.0):
m_startPercent(_startPercent),
m_endPercent(_endPercent)
{
assert(0 <= m_startPercent && m_startPercent <= m_endPercent && m_endPercent <= 1.0);
}
std::vector<size_t> materialise(size_t _poolSize) const override;
private:
double m_startPercent;
double m_endPercent;
};
/**
* A selection that selects 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 elements as the size of the container multiplied by
* @a _selectionSize (unless the container is empty).
*
* E.g. if the pattern is {0, 9} and collection size is 5, the selection will materialise into
* {0, 4, 0, 4, 0}. If the size is 3, it will be {0, 2, 0}.
*/
class MosaicSelection: public Selection
{
public:
explicit MosaicSelection(std::vector<size_t> _pattern, double _selectionSize = 1.0):
m_pattern(move(_pattern)),
m_selectionSize(_selectionSize)
{
assert(m_pattern.size() > 0 || _selectionSize == 0.0);
}
std::vector<size_t> materialise(size_t _poolSize) const override;
private:
std::vector<size_t> m_pattern;
double m_selectionSize;
};
/**
* A selection that randomly selects elements from a container. The resulting set of indices may
* contain duplicates and is different on each call to @a materialise(). Always selects as many
* elements as the size of the container multiplied by @a _selectionSize (unless the container is
* empty).
*/
class RandomSelection: public Selection
{
public:
explicit RandomSelection(double _selectionSize):
m_selectionSize(_selectionSize)
{
assert(_selectionSize >= 0);
}
std::vector<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 deciding
* whether to select it or not. Each element has the same chance of being selected and can be
* selected at most once. The order of selected elements is the same as the order of elements in
* the container. The number of selected elements is random and can be different with each call
* to @a materialise().
*/
class RandomSubset: public Selection
{
public:
explicit RandomSubset(double _selectionChance):
m_selectionChance(_selectionChance)
{
assert(0.0 <= _selectionChance && _selectionChance <= 1.0);
}
std::vector<size_t> materialise(size_t _poolSize) const override;
private:
double m_selectionChance;
};
}