mnx::FractionValue Class Reference

Represents a detached arithmetic fraction with normalization. More...

#include <CommonClasses.h>

Public Types
using	NumType = unsigned
	Unsigned integer type used for numerator and denominator.

Public Member Functions
constexpr	FractionValue ()=default
	Default constructor initializes the value to 0/1.
	FractionValue (NumType num, NumType den)
	Constructs a fraction from a numerator and denominator.
constexpr	FractionValue (NumType value)
	Constructs a Fraction object from an integer.
constexpr NumType	numerator () const noexcept
	Returns the numerator.
constexpr NumType	denominator () const noexcept
	Returns the denominator.
constexpr NumType	quotient () const
	Returns the integer (whole number) part of the fraction.
FractionValue constexpr	remainder () const
	Returns the fractional part of the fraction.
constexpr FractionValue &	operator+= (const FractionValue &rhs)
	Adds another FractionValue to this one.
constexpr FractionValue &	operator-= (const FractionValue &rhs)
	Subtracts another FractionValue from this one.
constexpr FractionValue &	operator*= (const FractionValue &rhs)
	Multiplies this fraction by another.
FractionValue &	operator/= (const FractionValue &rhs)
	Divides this fraction by another.
constexpr void	reduce ()
	Reduces the fraction to lowest terms using std::gcd.
constexpr bool	expressWithDenominator (NumType targetDenominator)
	Attempts to express this fraction with the given denominator.

Static Public Member Functions
static constexpr FractionValue	max () noexcept
	Constructs the max fractional value.

Detailed Description

Represents a detached arithmetic fraction with normalization.

This class provides arithmetic operations on rational numbers without attaching them to the JSON DOM. It is intended for musical-duration and proportional calculations where a simple fraction is needed independently of the MNX DOM structure.

A FractionValue constructed from a numerator and denominator preserves the values exactly as provided. Arithmetic operations (+=, -=, *=, /=) reduce the result to lowest terms using std::gcd. Call reduce() explicitly if you need a reduced form immediately after construction.

The class supports:

• Exact rational arithmetic (addition, subtraction, multiplication, division)
• Normalization to lowest terms after each operation
• Comparison operators (in helper section)

Compound assignment operators (+=, -=, *=, /=) are implemented as members. Binary operators (+, -, *, /) are implemented as non-member functions to allow symmetric conversions and correct C++ arithmetic semantics.

Constructor & Destructor Documentation

FractionValue() [1/2]

mnx::FractionValue::FractionValue ( NumType  num, NumType  den  )

inline

Constructs a fraction from a numerator and denominator.

The fraction is not automatically reduced. Use reduce() if you need the value in lowest terms. However, fractions are automatically reduced after arithmetical operations.

Parameters

num	The numerator.
den	The denominator. Must not be zero.

Exceptions

std::invalid_argument

if den is zero.

Todo:

Make this constructor constexpr when we drop C++17 support.

FractionValue() [2/2]

constexpr mnx::FractionValue::FractionValue ( NumType  value )

inlineconstexpr

Constructs a Fraction object from an integer.

Parameters

value

The integer value of the fraction.

Exceptions

std::invalid_argument

if the m_denominator is zero.

Member Function Documentation

expressWithDenominator()

constexpr bool mnx::FractionValue::expressWithDenominator ( NumType  targetDenominator )

inlineconstexpr

Attempts to express this fraction with the given denominator.

If the current value can be written exactly with targetDenominator using an integer numerator, the numerator and denominator are updated to use that denominator and the function returns true. Otherwise, the fraction is left unchanged and the function returns false.

This function does not require the fraction to be in reduced form. It computes a reduced logical form internally when determining whether the requested denominator is compatible.

Examples:

• 1/1 expressed with denominator 4 becomes 4/4 and returns true.
• 3/2 expressed with denominator 4 becomes 6/4 and returns true.
• 2/6 (i.e. 1/3) expressed with denominator 3 becomes 1/3 and returns true.
• 1/3 expressed with denominator 4 cannot be represented exactly with an integer numerator, so the call returns false and the fraction remains 1/3.

A zero fraction (0 / d) can always be expressed with any nonzero targetDenominator; in that case the result becomes 0 / targetDenominator.

Parameters

targetDenominator

The desired denominator. If zero, the call fails and the fraction is left unchanged.

Returns

true if the fraction was successfully rewritten with the given denominator; false if no exact integer representation exists or if targetDenominator is zero.

operator*=()

constexpr FractionValue & mnx::FractionValue::operator*= ( const FractionValue &  rhs )

inlineconstexpr

Multiplies this fraction by another.

Parameters

rhs	The fraction to multiply with.

Returns

Reference to this object after modification.

The result is normalized.

operator+=()

constexpr FractionValue & mnx::FractionValue::operator+= ( const FractionValue &  rhs )

inlineconstexpr

Adds another FractionValue to this one.

Parameters

rhs	The fraction to add.

Returns

Reference to this object after modification.

The result is normalized.

operator-=()

constexpr FractionValue & mnx::FractionValue::operator-= ( const FractionValue &  rhs )

inlineconstexpr

Subtracts another FractionValue from this one.

Parameters

rhs	The fraction to subtract.

Returns

Reference to this object after modification.

The result is normalized.

operator/=()

FractionValue & mnx::FractionValue::operator/= ( const FractionValue &  rhs )

inline

Divides this fraction by another.

Parameters

rhs	The divisor.

Returns

Reference to this object after modification.

Exceptions

std::invalid_argument

if rhs has a numerator of zero.

The result is normalized.

quotient()

constexpr NumType mnx::FractionValue::quotient ( ) const

inlineconstexpr

Returns the integer (whole number) part of the fraction.

Returns

The integer part of the fraction.

remainder()

FractionValue constexpr mnx::FractionValue::remainder ( ) const

inlineconstexpr

Returns the fractional part of the fraction.

Returns

The remainder as a fraction, satisfying -1 < remainder < 1.