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https://github.com/RGBCube/serenity
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48a3a02238
Previously, constructing a `UnsignedBigInteger::from_base()` could produce an incorrect result if the input string contained a valid Base36 digit that was out of range of the given base. The same method would also crash if the input string contained an invalid Base36 digit. An error is now returned in both these cases. Constructing a BigFraction from string is now also fallible, so that we can handle the case where we are given an input string with invalid digits.
75 lines
2.5 KiB
C++
75 lines
2.5 KiB
C++
/*
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* Copyright (c) 2022, Lucas Chollet <lucas.chollet@free.fr>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#pragma once
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#include <AK/ByteString.h>
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#include <LibCrypto/BigInt/SignedBigInteger.h>
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namespace Crypto {
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class BigFraction {
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// FIXME Make the whole API more error-friendly. This includes:
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// - Propagating errors from BigIntegers
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// - Returns errors from BigFraction(numerator, denominator);
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// - Duplicate fallible operators with a error-friendly version
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public:
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BigFraction() = default;
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explicit BigFraction(Crypto::SignedBigInteger);
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BigFraction(Crypto::SignedBigInteger numerator, Crypto::UnsignedBigInteger denominator);
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BigFraction(Crypto::BigFraction const&) = default;
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BigFraction(Crypto::BigFraction&&) = default;
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BigFraction& operator=(Crypto::BigFraction const&) = default;
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BigFraction& operator=(Crypto::BigFraction&&) = default;
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explicit BigFraction(double);
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static ErrorOr<BigFraction> from_string(StringView);
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BigFraction operator+(BigFraction const&) const;
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BigFraction operator-(BigFraction const&) const;
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BigFraction operator*(BigFraction const&) const;
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BigFraction operator/(BigFraction const&) const;
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BigFraction operator-() const;
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bool operator<(BigFraction const&) const;
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bool operator==(BigFraction const&) const;
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BigFraction invert() const;
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BigFraction sqrt() const;
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void set_to_0();
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// Return a BigFraction in "scientific notation", as an example with:
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// - m_numerator = 2
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// - m_denominator = 3
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// - rounding_threshold = 4
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// The returned BigFraction will have:
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// - m_numerator = 6667
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// - m_denominator = 10000
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BigFraction rounded(unsigned rounding_threshold) const;
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ByteString to_byte_string(unsigned rounding_threshold) const;
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double to_double() const;
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private:
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void reduce();
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// This class uses a pair of integers to store a value. The purpose is to
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// support any rational number without any numerical errors.
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// For example, if we were to represent the value -123.55 in this format,
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// the values could be -12355 for and 100 for m_denominator. However, this
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// pair of value is not unique and the value will be reduced to -2471/20.
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// This way, most operations don't have to be performed on doubles, but can
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// be performed without loss of precision on this class.
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Crypto::SignedBigInteger m_numerator { 0 };
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Crypto::UnsignedBigInteger m_denominator { 1 };
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};
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}
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