#include <userver/decimal64/decimal64.hpp>

Detailed Description

template<int Prec, typename RoundPolicy_ = DefRoundPolicy>
class decimal64::Decimal< Prec, RoundPolicy_ >

Fixed-point decimal data type for use in deterministic calculations, oftentimes involving money.

Template Parameters

Prec	The number of fractional digits
RoundPolicy	Specifies how to round in lossy operations

Decimal is internally represented as int64_t. It means that it can be passed around by value. It also means that operations with huge numbers can overflow and trap. For example, with Prec == 6, the maximum representable number is about 10 trillion.

Decimal should be serialized and stored as a string, NOT as double. Use Decimal{str} constructor (or Decimal::FromStringPermissive if rounding is allowed) to read a Decimal, and ToString(dec) (or ToStringTrailingZeros(dec)/ToStringFixed<N>(dec)) to write a Decimal.

Use arithmetic with caution! Multiplication and division operations involve rounding. You may want to cast to Decimal with another Prec or RoundPolicy beforehand. For that purpose you can use decimal64::decimal_cast<NewDec>(dec).

Usage example:

// create a single alias instead of specifying Decimal everywhere
using Money = decimal64::Decimal<4, decimal64::HalfEvenRoundPolicy>;
 
std::vector<std::string> cart = ...;
Money sum{0};
for (const std::string& cost_string : cart) {
  // or use FromStringPermissive to enable rounding
  sum += Money{cost_string};
}
return ToString(sum);

Definition at line 437 of file decimal64.hpp.

Public Types
using	RoundPolicy = RoundPolicy_
	Specifies how to round in lossy operations.

Public Member Functions
constexpr	Decimal () noexcept=default
	Zero by default.

template<typename Int, impl::EnableIfInt< Int > = 0>
constexpr	Decimal (Int value)
	Convert from an integer.

constexpr	Decimal (std::string_view value)
	Convert from a string.

template<int Prec2>
Decimal &	operator= (Decimal< Prec2, RoundPolicy > rhs)
	Assignment from another `Decimal`

template<typename Int, impl::EnableIfInt< Int > = 0>
constexpr Decimal &	operator= (Int rhs)
	Assignment from an integer.

constexpr auto	operator<=> (const Decimal &rhs) const =default

constexpr Decimal	operator+ () const

constexpr Decimal	operator- () const

template<int Prec2>
constexpr auto	operator+ (Decimal< Prec2, RoundPolicy > rhs) const

template<typename Int, impl::EnableIfInt< Int > = 0>
constexpr Decimal	operator+ (Int rhs) const

template<int Prec2>
constexpr Decimal &	operator+= (Decimal< Prec2, RoundPolicy > rhs)

template<typename Int, impl::EnableIfInt< Int > = 0>
constexpr Decimal &	operator+= (Int rhs)

template<int Prec2>
constexpr auto	operator- (Decimal< Prec2, RoundPolicy > rhs) const

template<typename Int, impl::EnableIfInt< Int > = 0>
constexpr Decimal	operator- (Int rhs) const

template<int Prec2>
constexpr Decimal &	operator-= (Decimal< Prec2, RoundPolicy > rhs)

template<typename Int, impl::EnableIfInt< Int > = 0>
constexpr Decimal &	operator-= (Int rhs)

template<typename Int, typename = impl::EnableIfInt<Int>>
constexpr Decimal	operator* (Int rhs) const

template<typename Int, impl::EnableIfInt< Int > = 0>
constexpr Decimal &	operator*= (Int rhs)

template<int Prec2>
constexpr Decimal	operator* (Decimal< Prec2, RoundPolicy > rhs) const

template<int Prec2>
constexpr Decimal &	operator*= (Decimal< Prec2, RoundPolicy > rhs)

template<typename Int, typename = impl::EnableIfInt<Int>>
constexpr Decimal	operator/ (Int rhs) const

template<typename Int, typename = impl::EnableIfInt<Int>>
constexpr Decimal &	operator/= (Int rhs)

template<int Prec2>
constexpr Decimal	operator/ (Decimal< Prec2, RoundPolicy > rhs) const

template<int Prec2>
constexpr Decimal &	operator/= (Decimal< Prec2, RoundPolicy > rhs)

constexpr int	Sign () const
	Returns one of {-1, 0, +1}, depending on the sign of the `Decimal`

constexpr Decimal	Abs () const
	Returns the absolute value of the `Decimal`

constexpr Decimal	RoundToMultipleOf (Decimal base) const
	Rounds `this` to the nearest multiple of `base` according to `RoundPolicy`

constexpr int64_t	ToInteger () const
	Returns the value rounded to integer using the active rounding policy.

constexpr double	ToDoubleInexact () const
	Returns the value converted to `double`

constexpr int64_t	AsUnbiased () const
	Retrieve the internal representation.

Static Public Member Functions
template<typename T>
static constexpr Decimal	FromFloatInexact (T value)
	Lossy conversion from a floating-point number.

static constexpr Decimal	FromStringPermissive (std::string_view input)
	Convert from a string, allowing rounding, spaces and boundary dot.

static constexpr Decimal	FromUnbiased (int64_t value) noexcept
	Reconstruct from the internal representation, as acquired with `AsUnbiased`

static constexpr Decimal	FromBiased (int64_t original_unbiased, int original_precision)
	Convert from `original_unbiased / 10^original_precision`, rounding according to `RoundPolicy` if necessary.

Static Public Attributes
static constexpr int	kDecimalPoints = Prec
	The number of fractional digits.

static constexpr int64_t	kDecimalFactor = kPow10<Prec>
	The denominator of the decimal fraction.

Member Typedef Documentation

◆ RoundPolicy

template<int Prec, typename RoundPolicy_ = DefRoundPolicy>

using decimal64::Decimal< Prec, RoundPolicy_ >::RoundPolicy = RoundPolicy_

Specifies how to round in lossy operations.

Definition at line 443 of file decimal64.hpp.

Constructor & Destructor Documentation

◆ Decimal() [1/2]

template<int Prec, typename RoundPolicy_ = DefRoundPolicy>

template<typename Int, impl::EnableIfInt< Int > = 0>

decimal64::Decimal< Prec, RoundPolicy_ >::Decimal ( Int value )

inlineexplicitconstexpr

Convert from an integer.

Definition at line 453 of file decimal64.hpp.

◆ Decimal() [2/2]

template<int Prec, typename RoundPolicy>

decimal64::Decimal< Prec, RoundPolicy >::Decimal ( std::string_view value )

explicitconstexpr

Convert from a string.

The string must match the following regexp exactly:

[+-]?\d+(\.\d+)?

No extra characters, including spaces, are allowed. Extra leading and trailing zeros (within Prec) are discarded. Input containing more fractional digits that Prec is not allowed (no implicit rounding).

Exceptions

decimal64::ParseError on invalid input

See also: FromStringPermissive

Definition at line 1221 of file decimal64.hpp.

Member Function Documentation

◆ Abs()

template<int Prec, typename RoundPolicy_ = DefRoundPolicy>

Decimal decimal64::Decimal< Prec, RoundPolicy_ >::Abs ( ) const

inlineconstexpr

Returns the absolute value of the Decimal

Definition at line 713 of file decimal64.hpp.

◆ AsUnbiased()

template<int Prec, typename RoundPolicy_ = DefRoundPolicy>

int64_t decimal64::Decimal< Prec, RoundPolicy_ >::AsUnbiased ( ) const

inlineconstexpr

Retrieve the internal representation.

The internal representation of Decimal is real_value * kDecimalFactor. Use for storing the value of Decimal efficiently when Prec is guaranteed not to change.

See also: FromUnbiased

Definition at line 759 of file decimal64.hpp.

◆ FromBiased()

template<int Prec, typename RoundPolicy_ = DefRoundPolicy>

static constexpr Decimal decimal64::Decimal< Prec, RoundPolicy_ >::FromBiased	(	int64_t	original_unbiased,
		int	original_precision )

inlinestaticconstexpr

Convert from original_unbiased / 10^original_precision, rounding according to RoundPolicy if necessary.

Usage examples:

Decimal<4>::FromBiased(123, 6) -> 0.0001
Decimal<4>::FromBiased(123, 2) -> 1.23
Decimal<4>::FromBiased(123, -1) -> 1230

Parameters

original_unbiased	The original mantissa
original_precision	The original precision (negated exponent)

Definition at line 525 of file decimal64.hpp.

◆ FromFloatInexact()

template<int Prec, typename RoundPolicy_ = DefRoundPolicy>

template<typename T>

static constexpr Decimal decimal64::Decimal< Prec, RoundPolicy_ >::FromFloatInexact ( T value )

inlinestaticconstexpr

Lossy conversion from a floating-point number.

To somewhat resist the accumulated error, the number is always rounded to the nearest Decimal, regardless of RoundPolicy.

Warning: Prefer storing and sending Decimal as string, and performing the computations between Decimals.

Definition at line 477 of file decimal64.hpp.

◆ FromStringPermissive()

template<int Prec, typename RoundPolicy>

Decimal< Prec, RoundPolicy > decimal64::Decimal< Prec, RoundPolicy >::FromStringPermissive ( std::string_view input )

staticconstexpr

Convert from a string, allowing rounding, spaces and boundary dot.

In addition to the Decimal(str) constructor, allows:

rounding (as per RoundPolicy), e.g. "12.3456789" with Prec == 2
space characters, e.g. " \t42 \n"
leading and trailing dot, e.g. "5." and ".5"

Exceptions

decimal64::ParseError on invalid input

See also: Decimal(std::string_view)

Definition at line 1231 of file decimal64.hpp.

◆ FromUnbiased()

template<int Prec, typename RoundPolicy_ = DefRoundPolicy>

static constexpr Decimal decimal64::Decimal< Prec, RoundPolicy_ >::FromUnbiased ( int64_t value )

inlinestaticconstexprnoexcept

Reconstruct from the internal representation, as acquired with AsUnbiased

The Decimal value will be equal to value/kDecimalFactor.

See also: AsUnbiased

Definition at line 508 of file decimal64.hpp.

◆ operator*() [1/2]

template<int Prec, typename RoundPolicy_ = DefRoundPolicy>

template<int Prec2>

Decimal decimal64::Decimal< Prec, RoundPolicy_ >::operator* ( Decimal< Prec2, RoundPolicy > rhs ) const

inlineconstexpr

Definition at line 672 of file decimal64.hpp.

◆ operator*() [2/2]

template<int Prec, typename RoundPolicy_ = DefRoundPolicy>

template<typename Int, typename = impl::EnableIfInt<Int>>

Decimal decimal64::Decimal< Prec, RoundPolicy_ >::operator* ( Int rhs ) const

inlineconstexpr

Definition at line 652 of file decimal64.hpp.

◆ operator*=() [1/2]

template<int Prec, typename RoundPolicy_ = DefRoundPolicy>

template<int Prec2>

Decimal & decimal64::Decimal< Prec, RoundPolicy_ >::operator*= ( Decimal< Prec2, RoundPolicy > rhs )

inlineconstexpr

Definition at line 677 of file decimal64.hpp.

◆ operator*=() [2/2]

template<int Prec, typename RoundPolicy_ = DefRoundPolicy>

template<typename Int, impl::EnableIfInt< Int > = 0>

Decimal & decimal64::Decimal< Prec, RoundPolicy_ >::operator*= ( Int rhs )

inlineconstexpr

Definition at line 666 of file decimal64.hpp.

◆ operator+() [1/3]

template<int Prec, typename RoundPolicy_ = DefRoundPolicy>

Decimal decimal64::Decimal< Prec, RoundPolicy_ >::operator+ ( ) const

inlineconstexpr

Definition at line 568 of file decimal64.hpp.

◆ operator+() [2/3]

template<int Prec, typename RoundPolicy_ = DefRoundPolicy>

template<int Prec2>

auto decimal64::Decimal< Prec, RoundPolicy_ >::operator+ ( Decimal< Prec2, RoundPolicy > rhs ) const

inlineconstexpr

Definition at line 576 of file decimal64.hpp.

◆ operator+() [3/3]

template<int Prec, typename RoundPolicy_ = DefRoundPolicy>

template<typename Int, impl::EnableIfInt< Int > = 0>

Decimal decimal64::Decimal< Prec, RoundPolicy_ >::operator+ ( Int rhs ) const

inlineconstexpr

Definition at line 591 of file decimal64.hpp.

◆ operator+=() [1/2]

template<int Prec, typename RoundPolicy_ = DefRoundPolicy>

template<int Prec2>

Decimal & decimal64::Decimal< Prec, RoundPolicy_ >::operator+= ( Decimal< Prec2, RoundPolicy > rhs )

inlineconstexpr

Definition at line 601 of file decimal64.hpp.

◆ operator+=() [2/2]

template<int Prec, typename RoundPolicy_ = DefRoundPolicy>

template<typename Int, impl::EnableIfInt< Int > = 0>

Decimal & decimal64::Decimal< Prec, RoundPolicy_ >::operator+= ( Int rhs )

inlineconstexpr

Definition at line 608 of file decimal64.hpp.

◆ operator-() [1/3]

template<int Prec, typename RoundPolicy_ = DefRoundPolicy>

Decimal decimal64::Decimal< Prec, RoundPolicy_ >::operator- ( ) const

inlineconstexpr

Definition at line 570 of file decimal64.hpp.

◆ operator-() [2/3]

template<int Prec, typename RoundPolicy_ = DefRoundPolicy>

template<int Prec2>

auto decimal64::Decimal< Prec, RoundPolicy_ >::operator- ( Decimal< Prec2, RoundPolicy > rhs ) const

inlineconstexpr

Definition at line 614 of file decimal64.hpp.

◆ operator-() [3/3]

template<int Prec, typename RoundPolicy_ = DefRoundPolicy>

template<typename Int, impl::EnableIfInt< Int > = 0>

Decimal decimal64::Decimal< Prec, RoundPolicy_ >::operator- ( Int rhs ) const

inlineconstexpr

Definition at line 629 of file decimal64.hpp.

◆ operator-=() [1/2]

template<int Prec, typename RoundPolicy_ = DefRoundPolicy>

template<int Prec2>

Decimal & decimal64::Decimal< Prec, RoundPolicy_ >::operator-= ( Decimal< Prec2, RoundPolicy > rhs )

inlineconstexpr

Definition at line 639 of file decimal64.hpp.

◆ operator-=() [2/2]

template<int Prec, typename RoundPolicy_ = DefRoundPolicy>

template<typename Int, impl::EnableIfInt< Int > = 0>

Decimal & decimal64::Decimal< Prec, RoundPolicy_ >::operator-= ( Int rhs )

inlineconstexpr

Definition at line 646 of file decimal64.hpp.

◆ operator/() [1/2]

template<int Prec, typename RoundPolicy_ = DefRoundPolicy>

template<int Prec2>

Decimal decimal64::Decimal< Prec, RoundPolicy_ >::operator/ ( Decimal< Prec2, RoundPolicy > rhs ) const

inlineconstexpr

Definition at line 699 of file decimal64.hpp.

◆ operator/() [2/2]

template<int Prec, typename RoundPolicy_ = DefRoundPolicy>

template<typename Int, typename = impl::EnableIfInt<Int>>

Decimal decimal64::Decimal< Prec, RoundPolicy_ >::operator/ ( Int rhs ) const

inlineconstexpr

Definition at line 683 of file decimal64.hpp.

◆ operator/=() [1/2]

template<int Prec, typename RoundPolicy_ = DefRoundPolicy>

template<int Prec2>

Decimal & decimal64::Decimal< Prec, RoundPolicy_ >::operator/= ( Decimal< Prec2, RoundPolicy > rhs )

inlineconstexpr

Definition at line 704 of file decimal64.hpp.

◆ operator/=() [2/2]

template<int Prec, typename RoundPolicy_ = DefRoundPolicy>

template<typename Int, typename = impl::EnableIfInt<Int>>

Decimal & decimal64::Decimal< Prec, RoundPolicy_ >::operator/= ( Int rhs )

inlineconstexpr

Definition at line 693 of file decimal64.hpp.

◆ operator=() [1/2]

template<int Prec, typename RoundPolicy_ = DefRoundPolicy>

template<int Prec2>

Decimal & decimal64::Decimal< Prec, RoundPolicy_ >::operator= ( Decimal< Prec2, RoundPolicy > rhs )

inline

Assignment from another Decimal

The assignment is allowed as long as RoundPolicy is the same. Rounding will be performed according to RoundPolicy if necessary.

Definition at line 540 of file decimal64.hpp.

◆ operator=() [2/2]

template<int Prec, typename RoundPolicy_ = DefRoundPolicy>

template<typename Int, impl::EnableIfInt< Int > = 0>

Decimal & decimal64::Decimal< Prec, RoundPolicy_ >::operator= ( Int rhs )

inlineconstexpr

Assignment from an integer.

Definition at line 547 of file decimal64.hpp.

◆ RoundToMultipleOf()

template<int Prec, typename RoundPolicy_ = DefRoundPolicy>

Decimal decimal64::Decimal< Prec, RoundPolicy_ >::RoundToMultipleOf ( Decimal< Prec, RoundPolicy_ > base ) const

inlineconstexpr

Rounds this to the nearest multiple of base according to RoundPolicy

Definition at line 716 of file decimal64.hpp.

◆ Sign()

template<int Prec, typename RoundPolicy_ = DefRoundPolicy>

int decimal64::Decimal< Prec, RoundPolicy_ >::Sign ( ) const

inlineconstexpr

Returns one of {-1, 0, +1}, depending on the sign of the Decimal

Definition at line 710 of file decimal64.hpp.

◆ ToDoubleInexact()

template<int Prec, typename RoundPolicy_ = DefRoundPolicy>

double decimal64::Decimal< Prec, RoundPolicy_ >::ToDoubleInexact ( ) const

inlineconstexpr

Returns the value converted to double

Warning: Operations with double, and even the returned value, is inexact. Prefer storing and sending Decimal as string, and performing the computations between Decimals.

See also: FromFloatInexact

Definition at line 731 of file decimal64.hpp.

◆ ToInteger()

template<int Prec, typename RoundPolicy_ = DefRoundPolicy>

int64_t decimal64::Decimal< Prec, RoundPolicy_ >::ToInteger ( ) const

inlineconstexpr

Returns the value rounded to integer using the active rounding policy.

Definition at line 722 of file decimal64.hpp.

Friends And Related Symbol Documentation

◆ Decimal

template<int Prec, typename RoundPolicy_ = DefRoundPolicy>

template<int Prec2, typename RoundPolicy2>

friend class Decimal

friend

Definition at line 778 of file decimal64.hpp.

◆ decimal_cast

template<int Prec, typename RoundPolicy_ = DefRoundPolicy>

template<typename T, int OldPrec, typename OldRound>

T decimal_cast ( Decimal< OldPrec, OldRound > arg )

friend

Cast one Decimal to another Decimal type.

When casting to a Decimal with a lower Prec, rounding is performed according to the new RoundPolicy.

Usage example:

using Money = decimal64::Decimal<4>;
using Discount = decimal64::Decimal<4, FloorRoundPolicy>;
 
Money cost = ...;
auto discount = decimal64::decimal_cast<Discount>(cost) * Discount{"0.05"};

Definition at line 814 of file decimal64.hpp.

◆ operator*

template<int Prec, typename RoundPolicy_ = DefRoundPolicy>

template<typename Int, impl::EnableIfInt< Int > = 0>

Decimal operator*	(	Int	lhs,
		Decimal< Prec, RoundPolicy_ >	rhs )

friend

Definition at line 661 of file decimal64.hpp.

◆ operator+

template<int Prec, typename RoundPolicy_ = DefRoundPolicy>

template<typename Int, impl::EnableIfInt< Int > = 0>

Decimal operator+	(	Int	lhs,
		Decimal< Prec, RoundPolicy_ >	rhs )

friend

Definition at line 596 of file decimal64.hpp.

◆ operator-

template<int Prec, typename RoundPolicy_ = DefRoundPolicy>

template<typename Int, impl::EnableIfInt< Int > = 0>

Decimal operator-	(	Int	lhs,
		Decimal< Prec, RoundPolicy_ >	rhs )

friend

Definition at line 634 of file decimal64.hpp.

◆ operator/

template<int Prec, typename RoundPolicy_ = DefRoundPolicy>

template<typename Int, typename = impl::EnableIfInt<Int>>

Decimal operator/	(	Int	lhs,
		Decimal< Prec, RoundPolicy_ >	rhs )

friend

Definition at line 688 of file decimal64.hpp.

Member Data Documentation

◆ kDecimalFactor

template<int Prec, typename RoundPolicy_ = DefRoundPolicy>

int64_t decimal64::Decimal< Prec, RoundPolicy_ >::kDecimalFactor = kPow10<Prec>

staticconstexpr

The denominator of the decimal fraction.

Definition at line 446 of file decimal64.hpp.

◆ kDecimalPoints

template<int Prec, typename RoundPolicy_ = DefRoundPolicy>

int decimal64::Decimal< Prec, RoundPolicy_ >::kDecimalPoints = Prec

staticconstexpr

The number of fractional digits.

Definition at line 440 of file decimal64.hpp.

The documentation for this class was generated from the following file:

userver/decimal64/decimal64.hpp

Detailed Description

Public Types

Public Member Functions

Static Public Member Functions

Static Public Attributes

Member Typedef Documentation

◆ RoundPolicy

Constructor & Destructor Documentation

◆ Decimal() [1/2]

◆ Decimal() [2/2]

Member Function Documentation

◆ Abs()

◆ AsUnbiased()

◆ FromBiased()

◆ FromFloatInexact()

◆ FromStringPermissive()

◆ FromUnbiased()

◆ operator*() [1/2]

◆ operator*() [2/2]

◆ operator*=() [1/2]

◆ operator*=() [2/2]

◆ operator+() [1/3]

◆ operator+() [2/3]

◆ operator+() [3/3]

◆ operator+=() [1/2]

◆ operator+=() [2/2]

◆ operator-() [1/3]

◆ operator-() [2/3]

◆ operator-() [3/3]

◆ operator-=() [1/2]

◆ operator-=() [2/2]

◆ operator/() [1/2]

◆ operator/() [2/2]

◆ operator/=() [1/2]

◆ operator/=() [2/2]

◆ operator=() [1/2]

◆ operator=() [2/2]

◆ RoundToMultipleOf()

◆ Sign()

◆ ToDoubleInexact()

◆ ToInteger()

Friends And Related Symbol Documentation

◆ Decimal

◆ decimal_cast

◆ operator*

◆ operator+

◆ operator-

◆ operator/

Member Data Documentation

◆ kDecimalFactor

◆ kDecimalPoints