VVMNativeRational.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "HAL/Platform.h"
#include "Serialization/StructuredArchive.h"
#include "Templates/TypeHash.h"
#include "VVMNativeRational.generated.h"
 
// Used to represent integer rational numbers in Verse.
USTRUCT()
struct FVerseRational
{
    GENERATED_BODY()
 
    UPROPERTY()
    int64 Numerator{0};
 
    UPROPERTY()
    int64 Denominator{0};
 
    FVerseRational ReduceAndNormalizeSigns() const
    {
        int64 A = Numerator;
        int64 B = Denominator;
        while (B)
        {
            int64 Remainder = A % B;
            A = B;
            B = Remainder;
        }
 
        FVerseRational Result;
        Result.Numerator = Numerator / A;
        Result.Denominator = Denominator / A;
 
        if (Result.Denominator < 0 && Result.Numerator != INT64_MIN && Result.Denominator != INT64_MIN)
        {
            Result.Numerator = -Result.Numerator;
            Result.Denominator = -Result.Denominator;
        }
 
        return Result;
    }
 
    friend bool operator==(const FVerseRational& A, const FVerseRational& B)
    {
        FVerseRational ReducedA = A.ReduceAndNormalizeSigns();
        FVerseRational ReducedB = B.ReduceAndNormalizeSigns();
        return ReducedA.Numerator == ReducedB.Numerator
            && ReducedA.Denominator == ReducedB.Denominator;
    }
 
    friend uint32 GetTypeHash(const FVerseRational& R)
    {
        FVerseRational ReducedR = R.ReduceAndNormalizeSigns();
        // Make sure that integers hash the same whether represented as an int64 or a FVerseRational.
        const uint32 NumeratorHash = GetTypeHash(R.Numerator);
        return R.Denominator == 1
                 ? NumeratorHash
                 : HashCombineFast(NumeratorHash, GetTypeHash(R.Denominator));
    }
 
    friend void operator<<(FStructuredArchive::FSlot Slot, FVerseRational& R)
    {
        FStructuredArchive::FRecord Record = Slot.EnterRecord();
        FStructuredArchive::FSlot NumeratorField = Record.EnterField(TEXT("Numerator"));
        NumeratorField << R.Numerator;
        FStructuredArchive::FSlot DenominatorField = Record.EnterField(TEXT("Denominator"));
        DenominatorField << R.Denominator;
    }
};