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Quelle decimal.rs
Sprache: unbekannt
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use crate::constants::{
MAX_I128_REPR, MAX_PRECISION_U32, POWERS_10, SCALE_MASK, SCALE_SHIFT, SIGN_MASK, SIGN_ SHIFT, U32_MASK, U8_MASK,
UNSIGN_MASK,
};
use crate::ops;
use crate::Error;
use core::{
cmp::{Ordering::Equal, *},
fmt,
hash::{Hash, Hasher},
iter::{Product, Sum},
ops::{Add, AddAssign, Div, DivAssign, Mul, MulAssign, Neg, Rem, RemAssign, Sub, SubAssign},
str::FromStr,
};
// Diesel configuration
#[cfg(feature = "diesel2")]
use diesel::deserialize::FromSqlRow;
#[cfg(feature = "diesel2")]
use diesel::expression::AsExpression;
#[cfg(any(feature = "diesel1", feature = "diesel2"))]
use diesel::sql_types::Numeric;
#[allow(unused_imports)] // It's not actually dead code below, but the compiler thinks it is.
#[cfg(not(feature = "std"))]
use num_traits::float::FloatCore;
use num_traits::{FromPrimitive, Num, One, Signed, ToPrimitive, Zero};
#[cfg(feature = "rkyv")]
use rkyv::{Archive, Deserialize, Serialize};
/// The smallest value that can be represented by this decimal type.
const MIN: Decimal = Decimal {
flags: 2_147_483_648,
lo: 4_294_967_295,
mid: 4_294_967_295,
hi: 4_294_967_295,
};
/// The largest value that can be represented by this decimal type.
const MAX: Decimal = Decimal {
flags: 0,
lo: 4_294_967_295,
mid: 4_294_967_295,
hi: 4_294_967_295,
};
const ZERO: Decimal = Decimal {
flags: 0,
lo: 0,
mid: 0,
hi: 0,
};
const ONE: Decimal = Decimal {
flags: 0,
lo: 1,
mid: 0,
hi: 0,
};
const TWO: Decimal = Decimal {
flags: 0,
lo: 2,
mid: 0,
hi: 0,
};
const TEN: Decimal = Decimal {
flags: 0,
lo: 10,
mid: 0,
hi: 0,
};
const ONE_HUNDRED: Decimal = Decimal {
flags: 0,
lo: 100,
mid: 0,
hi: 0,
};
const ONE_THOUSAND: Decimal = Decimal {
flags: 0,
lo: 1000,
mid: 0,
hi: 0,
};
const NEGATIVE_ONE: Decimal = Decimal {
flags: 2147483648,
lo: 1,
mid: 0,
hi: 0,
};
/// `UnpackedDecimal` contains unpacked representation of `Decimal` where each component
/// of decimal-format stored in it's own field
#[derive(Clone, Copy, Debug, PartialEq)]
pub struct UnpackedDecimal {
pub negative: bool,
pub scale: u32,
pub hi: u32,
pub mid: u32,
pub lo: u32,
}
/// `Decimal` represents a 128 bit representation of a fixed-precision decimal number.
/// The finite set of values of type `Decimal` are of the form m / 10<sup>e</sup>,
/// where m is an integer such that -2<sup>96</sup> < m < 2<sup>96</sup>, and e is an integer
/// between 0 and 28 inclusive.
#[derive(Clone, Copy)]
#[cfg_attr(
all(feature = "diesel1", not(feature = "diesel2")),
derive(FromSqlRow, AsExpression),
sql_type = "Numeric"
)]
#[cfg_attr(feature = "diesel2", derive(FromSqlRow, AsExpression), diesel(sql_type = Numeric))]
#[cfg_attr(feature = "c-repr", repr(C))]
#[cfg_attr(
feature = "borsh",
derive(borsh::BorshDeserialize, borsh::BorshSerialize, borsh::BorshSchema)
)]
#[cfg_attr(
feature = "rkyv",
derive(Archive, Deserialize, Serialize),
archive(compare(PartialEq)),
archive_attr(derive(Clone, Copy, Debug))
)]
#[cfg_attr(feature = "rkyv-safe", archive_attr(derive(bytecheck::CheckBytes)))]
pub struct Decimal {
// Bits 0-15: unused
// Bits 16-23: Contains "e", a value between 0-28 that indicates the scale
// Bits 24-30: unused
// Bit 31: the sign of the Decimal value, 0 meaning positive and 1 meaning negative.
flags: u32,
// The lo, mid, hi, and flags fields contain the representation of the
// Decimal value as a 96-bit integer.
hi: u32,
lo: u32,
mid: u32,
}
/// `RoundingStrategy` represents the different rounding strategies that can be used by
/// `round_dp_with_strategy`.
#[derive(Clone, Copy, PartialEq, Eq, Debug)]
pub enum RoundingStrategy {
/// When a number is halfway between two others, it is rounded toward the nearest even number.
/// Also known as "Bankers Rounding".
/// e.g.
/// 6.5 -> 6, 7.5 -> 8
MidpointNearestEven,
/// When a number is halfway between two others, it is rounded toward the nearest number that
/// is away from zero. e.g. 6.4 -> 6, 6.5 -> 7, -6.5 -> -7
MidpointAwayFromZero,
/// When a number is halfway between two others, it is rounded toward the nearest number that
/// is toward zero. e.g. 6.4 -> 6, 6.5 -> 6, -6.5 -> -6
MidpointTowardZero,
/// The number is always rounded toward zero. e.g. -6.8 -> -6, 6.8 -> 6
ToZero,
/// The number is always rounded away from zero. e.g. -6.8 -> -7, 6.8 -> 7
AwayFromZero,
/// The number is always rounded towards negative infinity. e.g. 6.8 -> 6, -6.8 -> -7
ToNegativeInfinity,
/// The number is always rounded towards positive infinity. e.g. 6.8 -> 7, -6.8 -> -6
ToPositiveInfinity,
/// When a number is halfway between two others, it is rounded toward the nearest even number.
/// e.g.
/// 6.5 -> 6, 7.5 -> 8
#[deprecated(since = "1.11.0", note = "Please use RoundingStrategy::MidpointNearestEven instead")]
BankersRounding,
/// Rounds up if the value >= 5, otherwise rounds down, e.g. 6.5 -> 7
#[deprecated(since = "1.11.0", note = "Please use RoundingStrategy::MidpointAwayFromZero instead")]
RoundHalfUp,
/// Rounds down if the value =< 5, otherwise rounds up, e.g. 6.5 -> 6, 6.51 -> 7 1.4999999 -> 1
#[deprecated(since = "1.11.0", note = "Please use RoundingStrategy::MidpointTowardZero instead")]
RoundHalfDown,
/// Always round down.
#[deprecated(since = "1.11.0", note = "Please use RoundingStrategy::ToZero instead")]
RoundDown,
/// Always round up.
#[deprecated(since = "1.11.0", note = "Please use RoundingStrategy::AwayFromZero instead")]
RoundUp,
}
#[allow(dead_code)]
impl Decimal {
/// The smallest value that can be represented by this decimal type.
///
/// # Examples
///
/// Basic usage:
/// ```
/// # use rust_decimal::Decimal;
/// # use rust_decimal_macros::dec;
/// assert_eq!(Decimal::MIN, dec!(-79_228_162_514_264_337_593_543_950_335));
/// ```
pub const MIN: Decimal = MIN;
/// The largest value that can be represented by this decimal type.
///
/// # Examples
///
/// Basic usage:
/// ```
/// # use rust_decimal::Decimal;
/// # use rust_decimal_macros::dec;
/// assert_eq!(Decimal::MAX, dec!(79_228_162_514_264_337_593_543_950_335));
/// ```
pub const MAX: Decimal = MAX;
/// A constant representing 0.
///
/// # Examples
///
/// Basic usage:
/// ```
/// # use rust_decimal::Decimal;
/// # use rust_decimal_macros::dec;
/// assert_eq!(Decimal::ZERO, dec!(0));
/// ```
pub const ZERO: Decimal = ZERO;
/// A constant representing 1.
///
/// # Examples
///
/// Basic usage:
/// ```
/// # use rust_decimal::Decimal;
/// # use rust_decimal_macros::dec;
/// assert_eq!(Decimal::ONE, dec!(1));
/// ```
pub const ONE: Decimal = ONE;
/// A constant representing -1.
///
/// # Examples
///
/// Basic usage:
/// ```
/// # use rust_decimal::Decimal;
/// # use rust_decimal_macros::dec;
/// assert_eq!(Decimal::NEGATIVE_ONE, dec!(-1));
/// ```
pub const NEGATIVE_ONE: Decimal = NEGATIVE_ONE;
/// A constant representing 2.
///
/// # Examples
///
/// Basic usage:
/// ```
/// # use rust_decimal::Decimal;
/// # use rust_decimal_macros::dec;
/// assert_eq!(Decimal::TWO, dec!(2));
/// ```
pub const TWO: Decimal = TWO;
/// A constant representing 10.
///
/// # Examples
///
/// Basic usage:
/// ```
/// # use rust_decimal::Decimal;
/// # use rust_decimal_macros::dec;
/// assert_eq!(Decimal::TEN, dec!(10));
/// ```
pub const TEN: Decimal = TEN;
/// A constant representing 100.
///
/// # Examples
///
/// Basic usage:
/// ```
/// # use rust_decimal::Decimal;
/// # use rust_decimal_macros::dec;
/// assert_eq!(Decimal::ONE_HUNDRED, dec!(100));
/// ```
pub const ONE_HUNDRED: Decimal = ONE_HUNDRED;
/// A constant representing 1000.
///
/// # Examples
///
/// Basic usage:
/// ```
/// # use rust_decimal::Decimal;
/// # use rust_decimal_macros::dec;
/// assert_eq!(Decimal::ONE_THOUSAND, dec!(1000));
/// ```
pub const ONE_THOUSAND: Decimal = ONE_THOUSAND;
/// A constant representing π as 3.1415926535897932384626433833
///
/// # Examples
///
/// Basic usage:
/// ```
/// # use rust_decimal::Decimal;
/// # use rust_decimal_macros::dec;
/// assert_eq!(Decimal::PI, dec!(3.1415926535897932384626433833));
/// ```
#[cfg(feature = "maths")]
pub const PI: Decimal = Decimal {
flags: 1835008,
lo: 1102470953,
mid: 185874565,
hi: 1703060790,
};
/// A constant representing π/2 as 1.5707963267948966192313216916
///
/// # Examples
///
/// Basic usage:
/// ```
/// # use rust_decimal::Decimal;
/// # use rust_decimal_macros::dec;
/// assert_eq!(Decimal::HALF_PI, dec!(1.5707963267948966192313216916));
/// ```
#[cfg(feature = "maths")]
pub const HALF_PI: Decimal = Decimal {
flags: 1835008,
lo: 2698719124,
mid: 92937282,
hi: 851530395,
};
/// A constant representing π/4 as 0.7853981633974483096156608458
///
/// # Examples
///
/// Basic usage:
/// ```
/// # use rust_decimal::Decimal;
/// # use rust_decimal_macros::dec;
/// assert_eq!(Decimal::QUARTER_PI, dec!(0.7853981633974483096156608458));
/// ```
#[cfg(feature = "maths")]
pub const QUARTER_PI: Decimal = Decimal {
flags: 1835008,
lo: 1349359562,
mid: 2193952289,
hi: 425765197,
};
/// A constant representing 2π as 6.2831853071795864769252867666
///
/// # Examples
///
/// Basic usage:
/// ```
/// # use rust_decimal::Decimal;
/// # use rust_decimal_macros::dec;
/// assert_eq!(Decimal::TWO_PI, dec!(6.2831853071795864769252867666));
/// ```
#[cfg(feature = "maths")]
pub const TWO_PI: Decimal = Decimal {
flags: 1835008,
lo: 2204941906,
mid: 371749130,
hi: 3406121580,
};
/// A constant representing Euler's number (e) as 2.7182818284590452353602874714
///
/// # Examples
///
/// Basic usage:
/// ```
/// # use rust_decimal::Decimal;
/// # use rust_decimal_macros::dec;
/// assert_eq!(Decimal::E, dec!(2.7182818284590452353602874714));
/// ```
#[cfg(feature = "maths")]
pub const E: Decimal = Decimal {
flags: 1835008,
lo: 2239425882,
mid: 3958169141,
hi: 1473583531,
};
/// A constant representing the inverse of Euler's number (1/e) as 0.3678794411714423215955237702
///
/// # Examples
///
/// Basic usage:
/// ```
/// # use rust_decimal::Decimal;
/// # use rust_decimal_macros::dec;
/// assert_eq!(Decimal::E_INVERSE, dec!(0.3678794411714423215955237702));
/// ```
#[cfg(feature = "maths")]
pub const E_INVERSE: Decimal = Decimal {
flags: 1835008,
lo: 2384059206,
mid: 2857938002,
hi: 199427844,
};
/// Returns a `Decimal` with a 64 bit `m` representation and corresponding `e` scale.
///
/// # Arguments
///
/// * `num` - An i64 that represents the `m` portion of the decimal number
/// * `scale` - A u32 representing the `e` portion of the decimal number.
///
/// # Panics
///
/// This function panics if `scale` is > 28.
///
/// # Example
///
/// ```
/// # use rust_decimal::Decimal;
/// #
/// let pi = Decimal::new(3141, 3);
/// assert_eq!(pi.to_string(), "3.141");
/// ```
#[must_use]
pub fn new(num: i64, scale: u32) -> Decimal {
match Self::try_new(num, scale) {
Err(e) => panic!("{}", e),
Ok(d) => d,
}
}
/// Checked version of `Decimal::new`. Will return `Err` instead of panicking at run-time.
///
/// # Example
///
/// ```rust
/// # use rust_decimal::Decimal;
/// #
/// let max = Decimal::try_new(i64::MAX, u32::MAX);
/// assert!(max.is_err());
/// ```
pub const fn try_new(num: i64, scale: u32) -> crate::Result<Decimal> {
if scale > MAX_PRECISION_U32 {
return Err(Error::ScaleExceedsMaximumPrecision(scale));
}
let flags: u32 = scale << SCALE_SHIFT;
if num < 0 {
let pos_num = num.wrapping_neg() as u64;
return Ok(Decimal {
flags: flags | SIGN_MASK,
hi: 0,
lo: (pos_num & U32_MASK) as u32,
mid: ((pos_num >> 32) & U32_MASK) as u32,
});
}
Ok(Decimal {
flags,
hi: 0,
lo: (num as u64 & U32_MASK) as u32,
mid: ((num as u64 >> 32) & U32_MASK) as u32,
})
}
/// Creates a `Decimal` using a 128 bit signed `m` representation and corresponding `e` scale.
///
/// # Arguments
///
/// * `num` - An i128 that represents the `m` portion of the decimal number
/// * `scale` - A u32 representing the `e` portion of the decimal number.
///
/// # Panics
///
/// This function panics if `scale` is > 28 or if `num` exceeds the maximum supported 96 bits.
///
/// # Example
///
/// ```rust
/// # use rust_decimal::Decimal;
/// #
/// let pi = Decimal::from_i128_with_scale(3141i128, 3);
/// assert_eq!(pi.to_string(), "3.141");
/// ```
#[must_use]
pub fn from_i128_with_scale(num: i128, scale: u32) -> Decimal {
match Self::try_from_i128_with_scale(num, scale) {
Ok(d) => d,
Err(e) => panic!("{}", e),
}
}
/// Checked version of `Decimal::from_i128_with_scale`. Will return `Err` instead
/// of panicking at run-time.
///
/// # Example
///
/// ```rust
/// # use rust_decimal::Decimal;
/// #
/// let max = Decimal::try_from_i128_with_scale(i128::MAX, u32::MAX);
/// assert!(max.is_err());
/// ```
pub const fn try_from_i128_with_scale(num: i128, scale: u32) -> crate::Result<Decimal> {
if scale > MAX_PRECISION_U32 {
return Err(Error::ScaleExceedsMaximumPrecision(scale));
}
let mut neg = false;
let mut wrapped = num;
if num > MAX_I128_REPR {
return Err(Error::ExceedsMaximumPossibleValue);
} else if num < -MAX_I128_REPR {
return Err(Error::LessThanMinimumPossibleValue);
} else if num < 0 {
neg = true;
wrapped = -num;
}
let flags: u32 = flags(neg, scale);
Ok(Decimal {
flags,
lo: (wrapped as u64 & U32_MASK) as u32,
mid: ((wrapped as u64 >> 32) & U32_MASK) as u32,
hi: ((wrapped as u128 >> 64) as u64 & U32_MASK) as u32,
})
}
/// Returns a `Decimal` using the instances constituent parts.
///
/// # Arguments
///
/// * `lo` - The low 32 bits of a 96-bit integer.
/// * `mid` - The middle 32 bits of a 96-bit integer.
/// * `hi` - The high 32 bits of a 96-bit integer.
/// * `negative` - `true` to indicate a negative number.
/// * `scale` - A power of 10 ranging from 0 to 28.
///
/// # Caution: Undefined behavior
///
/// While a scale greater than 28 can be passed in, it will be automatically capped by this
/// function at the maximum precision. The library opts towards this functionality as opposed
/// to a panic to ensure that the function can be treated as constant. This may lead to
/// undefined behavior in downstream applications and should be treated with caution.
///
/// # Example
///
/// ```
/// # use rust_decimal::Decimal;
/// #
/// let pi = Decimal::from_parts(1102470952, 185874565, 1703060790, false, 28);
/// assert_eq!(pi.to_string(), "3.1415926535897932384626433832");
/// ```
#[must_use]
pub const fn from_parts(lo: u32, mid: u32, hi: u32, negative: bool, scale: u32) -> Decimal {
Decimal {
lo,
mid,
hi,
flags: flags(
if lo == 0 && mid == 0 && hi == 0 {
false
} else {
negative
},
scale % (MAX_PRECISION_U32 + 1),
),
}
}
#[must_use]
pub(crate) const fn from_parts_raw(lo: u32, mid: u32, hi: u32, flags: u32) -> Decimal {
if lo == 0 && mid == 0 && hi == 0 {
Decimal {
lo,
mid,
hi,
flags: flags & SCALE_MASK,
}
} else {
Decimal { flags, hi, lo, mid }
}
}
/// Returns a `Result` which if successful contains the `Decimal` constitution of
/// the scientific notation provided by `value`.
///
/// # Arguments
///
/// * `value` - The scientific notation of the `Decimal`.
///
/// # Example
///
/// ```
/// # use rust_decimal::Decimal;
/// #
/// # fn main() -> Result<(), rust_decimal::Error> {
/// let value = Decimal::from_scientific("9.7e-7")?;
/// assert_eq!(value.to_string(), "0.00000097");
/// # Ok(())
/// # }
/// ```
pub fn from_scientific(value: &str) -> Result<Decimal, Error> {
const ERROR_MESSAGE: &str = "Failed to parse";
let mut split = value.splitn(2, |c| c == 'e' || c == 'E');
let base = split.next().ok_or_else(|| Error::from(ERROR_MESSAGE))?;
let exp = split.next().ok_or_else(|| Error::from(ERROR_MESSAGE))?;
let mut ret = Decimal::from_str(base)?;
let current_scale = ret.scale();
if let Some(stripped) = exp.strip_prefix('-') {
let exp: u32 = stripped.parse().map_err(|_| Error::from(ERROR_MESSAGE))?;
ret.set_scale(current_scale + exp)?;
} else {
let exp: u32 = exp.parse().map_err(|_| Error::from(ERROR_MESSAGE))?;
if exp <= current_scale {
ret.set_scale(current_scale - exp)?;
} else if exp > 0 {
use crate::constants::BIG_POWERS_10;
// This is a case whereby the mantissa needs to be larger to be correctly
// represented within the decimal type. A good example is 1.2E10. At this point,
// we've parsed 1.2 as the base and 10 as the exponent. To represent this within a
// Decimal type we effectively store the mantissa as 12,000,000,000 and scale as
// zero.
if exp > MAX_PRECISION_U32 {
return Err(Error::ScaleExceedsMaximumPrecision(exp));
}
let mut exp = exp as usize;
// Max two iterations. If exp is 1 then it needs to index position 0 of the array.
while exp > 0 {
let pow;
if exp >= BIG_POWERS_10.len() {
pow = BIG_POWERS_10[BIG_POWERS_10.len() - 1];
exp -= BIG_POWERS_10.len();
} else {
pow = BIG_POWERS_10[exp - 1];
exp = 0;
}
let pow = Decimal {
flags: 0,
lo: pow as u32,
mid: (pow >> 32) as u32,
hi: 0,
};
match ret.checked_mul(pow) {
Some(r) => ret = r,
None => return Err(Error::ExceedsMaximumPossibleValue),
};
}
ret.normalize_assign();
}
}
Ok(ret)
}
/// Converts a string slice in a given base to a decimal.
///
/// The string is expected to be an optional + sign followed by digits.
/// Digits are a subset of these characters, depending on radix, and will return an error if outside
/// the expected range:
///
/// * 0-9
/// * a-z
/// * A-Z
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// # use rust_decimal::prelude::*;
/// #
/// # fn main() -> Result<(), rust_decimal::Error> {
/// assert_eq!(Decimal::from_str_radix("A", 16)?.to_string(), "10");
/// # Ok(())
/// # }
/// ```
pub fn from_str_radix(str: &str, radix: u32) -> Result<Self, crate::Error> {
if radix == 10 {
crate::str::parse_str_radix_10(str)
} else {
crate::str::parse_str_radix_n(str, radix)
}
}
/// Parses a string slice into a decimal. If the value underflows and cannot be represented with the
/// given scale then this will return an error.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// # use rust_decimal::prelude::*;
/// # use rust_decimal::Error;
/// #
/// # fn main() -> Result<(), rust_decimal::Error> {
/// assert_eq!(Decimal::from_str_exact("0.001")?.to_string(), "0.001");
/// assert_eq!(Decimal::from_str_exact("0.00000_00000_00000_00000_00000_001")?.to_string(), "0.0000000000000000000000000001");
/// assert_eq!(Decimal::from_str_exact("0.00000_00000_00000_00000_00000_0001"), Err(Error::Underflow));
/// # Ok(())
/// # }
/// ```
pub fn from_str_exact(str: &str) -> Result<Self, crate::Error> {
crate::str::parse_str_radix_10_exact(str)
}
/// Returns the scale of the decimal number, otherwise known as `e`.
///
/// # Example
///
/// ```
/// # use rust_decimal::Decimal;
/// #
/// let num = Decimal::new(1234, 3);
/// assert_eq!(num.scale(), 3u32);
/// ```
#[inline]
#[must_use]
pub const fn scale(&self) -> u32 {
((self.flags & SCALE_MASK) >> SCALE_SHIFT) as u32
}
/// Returns the mantissa of the decimal number.
///
/// # Example
///
/// ```
/// # use rust_decimal::prelude::*;
/// use rust_decimal_macros::dec;
///
/// let num = dec!(-1.2345678);
/// assert_eq!(num.mantissa(), -12345678i128);
/// assert_eq!(num.scale(), 7);
/// ```
#[must_use]
pub const fn mantissa(&self) -> i128 {
let raw = (self.lo as i128) | ((self.mid as i128) << 32) | ((self.hi as i128) << 64);
if self.is_sign_negative() {
-raw
} else {
raw
}
}
/// Returns true if this Decimal number is equivalent to zero.
///
/// # Example
///
/// ```
/// # use rust_decimal::prelude::*;
/// #
/// let num = Decimal::ZERO;
/// assert!(num.is_zero());
/// ```
#[must_use]
pub const fn is_zero(&self) -> bool {
self.lo == 0 && self.mid == 0 && self.hi == 0
}
/// An optimized method for changing the sign of a decimal number.
///
/// # Arguments
///
/// * `positive`: true if the resulting decimal should be positive.
///
/// # Example
///
/// ```
/// # use rust_decimal::Decimal;
/// #
/// let mut one = Decimal::ONE;
/// one.set_sign(false);
/// assert_eq!(one.to_string(), "-1");
/// ```
#[deprecated(since = "1.4.0", note = "please use `set_sign_positive` instead")]
pub fn set_sign(&mut self, positive: bool) {
self.set_sign_positive(positive);
}
/// An optimized method for changing the sign of a decimal number.
///
/// # Arguments
///
/// * `positive`: true if the resulting decimal should be positive.
///
/// # Example
///
/// ```
/// # use rust_decimal::Decimal;
/// #
/// let mut one = Decimal::ONE;
/// one.set_sign_positive(false);
/// assert_eq!(one.to_string(), "-1");
/// ```
#[inline(always)]
pub fn set_sign_positive(&mut self, positive: bool) {
if positive {
self.flags &= UNSIGN_MASK;
} else {
self.flags |= SIGN_MASK;
}
}
/// An optimized method for changing the sign of a decimal number.
///
/// # Arguments
///
/// * `negative`: true if the resulting decimal should be negative.
///
/// # Example
///
/// ```
/// # use rust_decimal::Decimal;
/// #
/// let mut one = Decimal::ONE;
/// one.set_sign_negative(true);
/// assert_eq!(one.to_string(), "-1");
/// ```
#[inline(always)]
pub fn set_sign_negative(&mut self, negative: bool) {
self.set_sign_positive(!negative);
}
/// An optimized method for changing the scale of a decimal number.
///
/// # Arguments
///
/// * `scale`: the new scale of the number
///
/// # Example
///
/// ```
/// # use rust_decimal::Decimal;
/// #
/// # fn main() -> Result<(), rust_decimal::Error> {
/// let mut one = Decimal::ONE;
/// one.set_scale(5)?;
/// assert_eq!(one.to_string(), "0.00001");
/// # Ok(())
/// # }
/// ```
pub fn set_scale(&mut self, scale: u32) -> Result<(), Error> {
if scale > MAX_PRECISION_U32 {
return Err(Error::ScaleExceedsMaximumPrecision(scale));
}
self.flags = (scale << SCALE_SHIFT) | (self.flags & SIGN_MASK);
Ok(())
}
/// Modifies the `Decimal` towards the desired scale, attempting to do so without changing the
/// underlying number itself.
///
/// Setting the scale to something less then the current `Decimal`s scale will
/// cause the newly created `Decimal` to perform rounding using the `MidpointAwayFromZero` strategy.
///
/// Scales greater than the maximum precision that can be represented by `Decimal` will be
/// automatically rounded to either `Decimal::MAX_PRECISION` or the maximum precision that can
/// be represented with the given mantissa.
///
/// # Arguments
/// * `scale`: The desired scale to use for the new `Decimal` number.
///
/// # Example
///
/// ```
/// # use rust_decimal::prelude::*;
/// use rust_decimal_macros::dec;
///
/// // Rescaling to a higher scale preserves the value
/// let mut number = dec!(1.123);
/// assert_eq!(number.scale(), 3);
/// number.rescale(6);
/// assert_eq!(number.to_string(), "1.123000");
/// assert_eq!(number.scale(), 6);
///
/// // Rescaling to a lower scale forces the number to be rounded
/// let mut number = dec!(1.45);
/// assert_eq!(number.scale(), 2);
/// number.rescale(1);
/// assert_eq!(number.to_string(), "1.5");
/// assert_eq!(number.scale(), 1);
///
/// // This function never fails. Consequently, if a scale is provided that is unable to be
/// // represented using the given mantissa, then the maximum possible scale is used.
/// let mut number = dec!(11.76470588235294);
/// assert_eq!(number.scale(), 14);
/// number.rescale(28);
/// // A scale of 28 cannot be represented given this mantissa, however it was able to represent
/// // a number with a scale of 27
/// assert_eq!(number.to_string(), "11.764705882352940000000000000");
/// assert_eq!(number.scale(), 27);
/// ```
pub fn rescale(&mut self, scale: u32) {
let mut array = [self.lo, self.mid, self.hi];
let mut value_scale = self.scale();
ops::array::rescale_internal(&mut array, &mut value_scale, scale);
self.lo = array[0];
self.mid = array[1];
self.hi = array[2];
self.flags = flags(self.is_sign_negative(), value_scale);
}
/// Returns a serialized version of the decimal number.
/// The resulting byte array will have the following representation:
///
/// * Bytes 1-4: flags
/// * Bytes 5-8: lo portion of `m`
/// * Bytes 9-12: mid portion of `m`
/// * Bytes 13-16: high portion of `m`
#[must_use]
pub const fn serialize(&self) -> [u8; 16] {
[
(self.flags & U8_MASK) as u8,
((self.flags >> 8) & U8_MASK) as u8,
((self.flags >> 16) & U8_MASK) as u8,
((self.flags >> 24) & U8_MASK) as u8,
(self.lo & U8_MASK) as u8,
((self.lo >> 8) & U8_MASK) as u8,
((self.lo >> 16) & U8_MASK) as u8,
((self.lo >> 24) & U8_MASK) as u8,
(self.mid & U8_MASK) as u8,
((self.mid >> 8) & U8_MASK) as u8,
((self.mid >> 16) & U8_MASK) as u8,
((self.mid >> 24) & U8_MASK) as u8,
(self.hi & U8_MASK) as u8,
((self.hi >> 8) & U8_MASK) as u8,
((self.hi >> 16) & U8_MASK) as u8,
((self.hi >> 24) & U8_MASK) as u8,
]
}
/// Deserializes the given bytes into a decimal number.
/// The deserialized byte representation must be 16 bytes and adhere to the following convention:
///
/// * Bytes 1-4: flags
/// * Bytes 5-8: lo portion of `m`
/// * Bytes 9-12: mid portion of `m`
/// * Bytes 13-16: high portion of `m`
#[must_use]
pub fn deserialize(bytes: [u8; 16]) -> Decimal {
// We can bound flags by a bitwise mask to correspond to:
// Bits 0-15: unused
// Bits 16-23: Contains "e", a value between 0-28 that indicates the scale
// Bits 24-30: unused
// Bit 31: the sign of the Decimal value, 0 meaning positive and 1 meaning negative.
let mut raw = Decimal {
flags: ((bytes[0] as u32) | (bytes[1] as u32) << 8 | (bytes[2] as u32) << 16 | (bytes[3] as u32) << 24)
& 0x801F_0000,
lo: (bytes[4] as u32) | (bytes[5] as u32) << 8 | (bytes[6] as u32) << 16 | (bytes[7] as u32) << 24,
mid: (bytes[8] as u32) | (bytes[9] as u32) << 8 | (bytes[10] as u32) << 16 | (bytes[11] as u32) << 24,
hi: (bytes[12] as u32) | (bytes[13] as u32) << 8 | (bytes[14] as u32) << 16 | (bytes[15] as u32) << 24,
};
// Scale must be bound to maximum precision. Only two values can be greater than this
if raw.scale() > MAX_PRECISION_U32 {
let mut bits = raw.mantissa_array3();
let remainder = match raw.scale() {
29 => crate::ops::array::div_by_1x(&mut bits, 1),
30 => crate::ops::array::div_by_1x(&mut bits, 2),
31 => crate::ops::array::div_by_1x(&mut bits, 3),
_ => 0,
};
if remainder >= 5 {
ops::array::add_one_internal(&mut bits);
}
raw.lo = bits[0];
raw.mid = bits[1];
raw.hi = bits[2];
raw.flags = flags(raw.is_sign_negative(), MAX_PRECISION_U32);
}
raw
}
/// Returns `true` if the decimal is negative.
#[deprecated(since = "0.6.3", note = "please use `is_sign_negative` instead")]
#[must_use]
pub fn is_negative(&self) -> bool {
self.is_sign_negative()
}
/// Returns `true` if the decimal is positive.
#[deprecated(since = "0.6.3", note = "please use `is_sign_positive` instead")]
#[must_use]
pub fn is_positive(&self) -> bool {
self.is_sign_positive()
}
/// Returns `true` if the sign bit of the decimal is negative.
///
/// # Example
/// ```
/// # use rust_decimal::prelude::*;
/// #
/// assert_eq!(true, Decimal::new(-1, 0).is_sign_negative());
/// assert_eq!(false, Decimal::new(1, 0).is_sign_negative());
/// ```
#[inline(always)]
#[must_use]
pub const fn is_sign_negative(&self) -> bool {
self.flags & SIGN_MASK > 0
}
/// Returns `true` if the sign bit of the decimal is positive.
///
/// # Example
/// ```
/// # use rust_decimal::prelude::*;
/// #
/// assert_eq!(false, Decimal::new(-1, 0).is_sign_positive());
/// assert_eq!(true, Decimal::new(1, 0).is_sign_positive());
/// ```
#[inline(always)]
#[must_use]
pub const fn is_sign_positive(&self) -> bool {
self.flags & SIGN_MASK == 0
}
/// Returns the minimum possible number that `Decimal` can represent.
#[deprecated(since = "1.12.0", note = "Use the associated constant Decimal::MIN")]
#[must_use]
pub const fn min_value() -> Decimal {
MIN
}
/// Returns the maximum possible number that `Decimal` can represent.
#[deprecated(since = "1.12.0", note = "Use the associated constant Decimal::MAX")]
#[must_use]
pub const fn max_value() -> Decimal {
MAX
}
/// Returns a new `Decimal` integral with no fractional portion.
/// This is a true truncation whereby no rounding is performed.
///
/// # Example
///
/// ```
/// # use rust_decimal::Decimal;
/// #
/// let pi = Decimal::new(3141, 3);
/// let trunc = Decimal::new(3, 0);
/// // note that it returns a decimal
/// assert_eq!(pi.trunc(), trunc);
/// ```
#[must_use]
pub fn trunc(&self) -> Decimal {
let mut scale = self.scale();
if scale == 0 {
// Nothing to do
return *self;
}
let mut working = [self.lo, self.mid, self.hi];
while scale > 0 {
// We're removing precision, so we don't care about overflow
if scale < 10 {
ops::array::div_by_u32(&mut working, POWERS_10[scale as usize]);
break;
} else {
ops::array::div_by_u32(&mut working, POWERS_10[9]);
// Only 9 as this array starts with 1
scale -= 9;
}
}
Decimal {
lo: working[0],
mid: working[1],
hi: working[2],
flags: flags(self.is_sign_negative(), 0),
}
}
/// Returns a new `Decimal` representing the fractional portion of the number.
///
/// # Example
///
/// ```
/// # use rust_decimal::Decimal;
/// #
/// let pi = Decimal::new(3141, 3);
/// let fract = Decimal::new(141, 3);
/// // note that it returns a decimal
/// assert_eq!(pi.fract(), fract);
/// ```
#[must_use]
pub fn fract(&self) -> Decimal {
// This is essentially the original number minus the integral.
// Could possibly be optimized in the future
*self - self.trunc()
}
/// Computes the absolute value of `self`.
///
/// # Example
///
/// ```
/// # use rust_decimal::Decimal;
/// #
/// let num = Decimal::new(-3141, 3);
/// assert_eq!(num.abs().to_string(), "3.141");
/// ```
#[must_use]
pub fn abs(&self) -> Decimal {
let mut me = *self;
me.set_sign_positive(true);
me
}
/// Returns the largest integer less than or equal to a number.
///
/// # Example
///
/// ```
/// # use rust_decimal::Decimal;
/// #
/// let num = Decimal::new(3641, 3);
/// assert_eq!(num.floor().to_string(), "3");
/// ```
#[must_use]
pub fn floor(&self) -> Decimal {
let scale = self.scale();
if scale == 0 {
// Nothing to do
return *self;
}
// Opportunity for optimization here
let floored = self.trunc();
if self.is_sign_negative() && !self.fract().is_zero() {
floored - ONE
} else {
floored
}
}
/// Returns the smallest integer greater than or equal to a number.
///
/// # Example
///
/// ```
/// # use rust_decimal::Decimal;
/// #
/// let num = Decimal::new(3141, 3);
/// assert_eq!(num.ceil().to_string(), "4");
/// let num = Decimal::new(3, 0);
/// assert_eq!(num.ceil().to_string(), "3");
/// ```
#[must_use]
pub fn ceil(&self) -> Decimal {
let scale = self.scale();
if scale == 0 {
// Nothing to do
return *self;
}
// Opportunity for optimization here
if self.is_sign_positive() && !self.fract().is_zero() {
self.trunc() + ONE
} else {
self.trunc()
}
}
/// Returns the maximum of the two numbers.
///
/// ```
/// # use rust_decimal::Decimal;
/// #
/// let x = Decimal::new(1, 0);
/// let y = Decimal::new(2, 0);
/// assert_eq!(y, x.max(y));
/// ```
#[must_use]
pub fn max(self, other: Decimal) -> Decimal {
if self < other {
other
} else {
self
}
}
/// Returns the minimum of the two numbers.
///
/// ```
/// # use rust_decimal::Decimal;
/// #
/// let x = Decimal::new(1, 0);
/// let y = Decimal::new(2, 0);
/// assert_eq!(x, x.min(y));
/// ```
#[must_use]
pub fn min(self, other: Decimal) -> Decimal {
if self > other {
other
} else {
self
}
}
/// Strips any trailing zero's from a `Decimal` and converts -0 to 0.
///
/// # Example
///
/// ```
/// # use rust_decimal::prelude::*;
/// # fn main() -> Result<(), rust_decimal::Error> {
/// let number = Decimal::from_str("3.100")?;
/// assert_eq!(number.normalize().to_string(), "3.1");
/// # Ok(())
/// # }
/// ```
#[must_use]
pub fn normalize(&self) -> Decimal {
let mut result = *self;
result.normalize_assign();
result
}
/// An in place version of `normalize`. Strips any trailing zero's from a `Decimal` and converts -0 to 0.
///
/// # Example
///
/// ```
/// # use rust_decimal::prelude::*;
/// # fn main() -> Result<(), rust_decimal::Error> {
/// let mut number = Decimal::from_str("3.100")?;
/// assert_eq!(number.to_string(), "3.100");
/// number.normalize_assign();
/// assert_eq!(number.to_string(), "3.1");
/// # Ok(())
/// # }
/// ```
pub fn normalize_assign(&mut self) {
if self.is_zero() {
self.flags = 0;
return;
}
let mut scale = self.scale();
if scale == 0 {
return;
}
let mut result = self.mantissa_array3();
let mut working = self.mantissa_array3();
while scale > 0 {
if ops::array::div_by_u32(&mut working, 10) > 0 {
break;
}
scale -= 1;
result.copy_from_slice(&working);
}
self.lo = result[0];
self.mid = result[1];
self.hi = result[2];
self.flags = flags(self.is_sign_negative(), scale);
}
/// Returns a new `Decimal` number with no fractional portion (i.e. an integer).
/// Rounding currently follows "Bankers Rounding" rules. e.g. 6.5 -> 6, 7.5 -> 8
///
/// # Example
///
/// ```
/// # use rust_decimal::Decimal;
/// #
/// // Demonstrating bankers rounding...
/// let number_down = Decimal::new(65, 1);
/// let number_up = Decimal::new(75, 1);
/// assert_eq!(number_down.round().to_string(), "6");
/// assert_eq!(number_up.round().to_string(), "8");
/// ```
#[must_use]
pub fn round(&self) -> Decimal {
self.round_dp(0)
}
/// Returns a new `Decimal` number with the specified number of decimal points for fractional
/// portion.
/// Rounding is performed using the provided [`RoundingStrategy`]
///
/// # Arguments
/// * `dp`: the number of decimal points to round to.
/// * `strategy`: the [`RoundingStrategy`] to use.
///
/// # Example
///
/// ```
/// # use rust_decimal::{Decimal, RoundingStrategy};
/// # use rust_decimal_macros::dec;
/// #
/// let tax = dec!(3.4395);
/// assert_eq!(tax.round_dp_with_strategy(2, RoundingStrategy::MidpointAwayFromZero).to_string(), "3.44");
/// ```
#[must_use]
pub fn round_dp_with_strategy(&self, dp: u32, strategy: RoundingStrategy) -> Decimal {
// Short circuit for zero
if self.is_zero() {
return Decimal {
lo: 0,
mid: 0,
hi: 0,
flags: flags(self.is_sign_negative(), dp),
};
}
let old_scale = self.scale();
// return early if decimal has a smaller number of fractional places than dp
// e.g. 2.51 rounded to 3 decimal places is 2.51
if old_scale <= dp {
return *self;
}
let mut value = [self.lo, self.mid, self.hi];
let mut value_scale = self.scale();
let negative = self.is_sign_negative();
value_scale -= dp;
// Rescale to zero so it's easier to work with
while value_scale > 0 {
if value_scale < 10 {
ops::array::div_by_u32(&mut value, POWERS_10[value_scale as usize]);
value_scale = 0;
} else {
ops::array::div_by_u32(&mut value, POWERS_10[9]);
value_scale -= 9;
}
}
// Do some midpoint rounding checks
// We're actually doing two things here.
// 1. Figuring out midpoint rounding when we're right on the boundary. e.g. 2.50000
// 2. Figuring out whether to add one or not e.g. 2.51
// For this, we need to figure out the fractional portion that is additional to
// the rounded number. e.g. for 0.12345 rounding to 2dp we'd want 345.
// We're doing the equivalent of losing precision (e.g. to get 0.12)
// then increasing the precision back up to 0.12000
let mut offset = [self.lo, self.mid, self.hi];
let mut diff = old_scale - dp;
while diff > 0 {
if diff < 10 {
ops::array::div_by_u32(&mut offset, POWERS_10[diff as usize]);
break;
} else {
ops::array::div_by_u32(&mut offset, POWERS_10[9]);
// Only 9 as this array starts with 1
diff -= 9;
}
}
let mut diff = old_scale - dp;
while diff > 0 {
if diff < 10 {
ops::array::mul_by_u32(&mut offset, POWERS_10[diff as usize]);
break;
} else {
ops::array::mul_by_u32(&mut offset, POWERS_10[9]);
// Only 9 as this array starts with 1
diff -= 9;
}
}
let mut decimal_portion = [self.lo, self.mid, self.hi];
ops::array::sub_by_internal(&mut decimal_portion, &offset);
// If the decimal_portion is zero then we round based on the other data
let mut cap = [5, 0, 0];
for _ in 0..(old_scale - dp - 1) {
ops::array::mul_by_u32(&mut cap, 10);
}
let order = ops::array::cmp_internal(&decimal_portion, &cap);
#[allow(deprecated)]
match strategy {
RoundingStrategy::BankersRounding | RoundingStrategy::MidpointNearestEven => {
match order {
Ordering::Equal => {
if (value[0] & 1) == 1 {
ops::array::add_one_internal(&mut value);
}
}
Ordering::Greater => {
// Doesn't matter about the decimal portion
ops::array::add_one_internal(&mut value);
}
_ => {}
}
}
RoundingStrategy::RoundHalfDown | RoundingStrategy::MidpointTowardZero => {
if let Ordering::Greater = order {
ops::array::add_one_internal(&mut value);
}
}
RoundingStrategy::RoundHalfUp | RoundingStrategy::MidpointAwayFromZero => {
// when Ordering::Equal, decimal_portion is 0.5 exactly
// when Ordering::Greater, decimal_portion is > 0.5
match order {
Ordering::Equal => {
ops::array::add_one_internal(&mut value);
}
Ordering::Greater => {
// Doesn't matter about the decimal portion
ops::array::add_one_internal(&mut value);
}
_ => {}
}
}
RoundingStrategy::RoundUp | RoundingStrategy::AwayFromZero => {
if !ops::array::is_all_zero(&decimal_portion) {
ops::array::add_one_internal(&mut value);
}
}
RoundingStrategy::ToPositiveInfinity => {
if !negative && !ops::array::is_all_zero(&decimal_portion) {
ops::array::add_one_internal(&mut value);
}
}
RoundingStrategy::ToNegativeInfinity => {
if negative && !ops::array::is_all_zero(&decimal_portion) {
ops::array::add_one_internal(&mut value);
}
}
RoundingStrategy::RoundDown | RoundingStrategy::ToZero => (),
}
Decimal::from_parts(value[0], value[1], value[2], negative, dp)
}
/// Returns a new `Decimal` number with the specified number of decimal points for fractional portion.
/// Rounding currently follows "Bankers Rounding" rules. e.g. 6.5 -> 6, 7.5 -> 8
///
/// # Arguments
/// * `dp`: the number of decimal points to round to.
///
/// # Example
///
/// ```
/// # use rust_decimal::Decimal;
/// # use rust_decimal_macros::dec;
/// #
/// let pi = dec!(3.1415926535897932384626433832);
/// assert_eq!(pi.round_dp(2).to_string(), "3.14");
/// ```
#[must_use]
pub fn round_dp(&self, dp: u32) -> Decimal {
self.round_dp_with_strategy(dp, RoundingStrategy::MidpointNearestEven)
}
/// Returns `Some(Decimal)` number rounded to the specified number of significant digits. If
/// the resulting number is unable to be represented by the `Decimal` number then `None` will
/// be returned.
/// When the number of significant figures of the `Decimal` being rounded is greater than the requested
/// number of significant digits then rounding will be performed using `MidpointNearestEven` strategy.
///
/// # Arguments
/// * `digits`: the number of significant digits to round to.
///
/// # Remarks
/// A significant figure is determined using the following rules:
/// 1. Non-zero digits are always significant.
/// 2. Zeros between non-zero digits are always significant.
/// 3. Leading zeros are never significant.
/// 4. Trailing zeros are only significant if the number contains a decimal point.
///
/// # Example
///
/// ```
/// # use rust_decimal::Decimal;
/// use rust_decimal_macros::dec;
///
/// let value = dec!(305.459);
/// assert_eq!(value.round_sf(0), Some(dec!(0)));
/// assert_eq!(value.round_sf(1), Some(dec!(300)));
/// assert_eq!(value.round_sf(2), Some(dec!(310)));
/// assert_eq!(value.round_sf(3), Some(dec!(305)));
/// assert_eq!(value.round_sf(4), Some(dec!(305.5)));
/// assert_eq!(value.round_sf(5), Some(dec!(305.46)));
/// assert_eq!(value.round_sf(6), Some(dec!(305.459)));
/// assert_eq!(value.round_sf(7), Some(dec!(305.4590)));
/// assert_eq!(Decimal::MAX.round_sf(1), None);
///
/// let value = dec!(0.012301);
/// assert_eq!(value.round_sf(3), Some(dec!(0.0123)));
/// ```
#[must_use]
pub fn round_sf(&self, digits: u32) -> Option<Decimal> {
self.round_sf_with_strategy(digits, RoundingStrategy::MidpointNearestEven)
}
/// Returns `Some(Decimal)` number rounded to the specified number of significant digits. If
/// the resulting number is unable to be represented by the `Decimal` number then `None` will
/// be returned.
/// When the number of significant figures of the `Decimal` being rounded is greater than the requested
/// number of significant digits then rounding will be performed using the provided [RoundingStrategy].
///
/// # Arguments
/// * `digits`: the number of significant digits to round to.
/// * `strategy`: if required, the rounding strategy to use.
///
/// # Remarks
/// A significant figure is determined using the following rules:
/// 1. Non-zero digits are always significant.
/// 2. Zeros between non-zero digits are always significant.
/// 3. Leading zeros are never significant.
/// 4. Trailing zeros are only significant if the number contains a decimal point.
///
/// # Example
///
/// ```
/// # use rust_decimal::{Decimal, RoundingStrategy};
/// use rust_decimal_macros::dec;
///
/// let value = dec!(305.459);
/// assert_eq!(value.round_sf_with_strategy(0, RoundingStrategy::ToZero), Some(dec!(0)));
/// assert_eq!(value.round_sf_with_strategy(1, RoundingStrategy::ToZero), Some(dec!(300)));
/// assert_eq!(value.round_sf_with_strategy(2, RoundingStrategy::ToZero), Some(dec!(300)));
/// assert_eq!(value.round_sf_with_strategy(3, RoundingStrategy::ToZero), Some(dec!(305)));
/// assert_eq!(value.round_sf_with_strategy(4, RoundingStrategy::ToZero), Some(dec!(305.4)));
/// assert_eq!(value.round_sf_with_strategy(5, RoundingStrategy::ToZero), Some(dec!(305.45)));
/// assert_eq!(value.round_sf_with_strategy(6, RoundingStrategy::ToZero), Some(dec!(305.459)));
/// assert_eq!(value.round_sf_with_strategy(7, RoundingStrategy::ToZero), Some(dec!(305.4590)));
/// assert_eq!(Decimal::MAX.round_sf_with_strategy(1, RoundingStrategy::ToZero), Some(dec!(70000000000000000000000000000)));
///
/// let value = dec!(0.012301);
/// assert_eq!(value.round_sf_with_strategy(3, RoundingStrategy::AwayFromZero), Some(dec!(0.0124)));
/// ```
#[must_use]
pub fn round_sf_with_strategy(&self, digits: u32, strategy: RoundingStrategy) -> Option<Decimal> {
if self.is_zero() || digits == 0 {
return Some(Decimal::ZERO);
}
// We start by grabbing the mantissa and figuring out how many significant figures it is
// made up of. We do this by just dividing by 10 and checking remainders - effectively
// we're performing a naive log10.
let mut working = self.mantissa_array3();
let mut mantissa_sf = 0;
while !ops::array::is_all_zero(&working) {
let _remainder = ops::array::div_by_u32(&mut working, 10u32);
mantissa_sf += 1;
if working[2] == 0 && working[1] == 0 && working[0] == 1 {
mantissa_sf += 1;
break;
}
}
let scale = self.scale();
match digits.cmp(&mantissa_sf) {
Ordering::Greater => {
// If we're requesting a higher number of significant figures, we rescale
let mut array = [self.lo, self.mid, self.hi];
let mut value_scale = scale;
ops::array::rescale_internal(&mut array, &mut value_scale, scale + digits - mantissa_sf);
Some(Decimal {
lo: array[0],
mid: array[1],
hi: array[2],
flags: flags(self.is_sign_negative(), value_scale),
})
}
Ordering::Less => {
// We're requesting a lower number of significant digits.
let diff = mantissa_sf - digits;
// If the diff is greater than the scale we're focused on the integral. Otherwise, we can
// just round.
if diff > scale {
use crate::constants::BIG_POWERS_10;
// We need to adjust the integral portion. This also should be rounded, consequently
// we reduce the number down, round it, and then scale back up.
// E.g. If we have 305.459 scaling to a sf of 2 - we first reduce the number
// down to 30.5459, round it to 31 and then scale it back up to 310.
// Likewise, if we have 12301 scaling to a sf of 3 - we first reduce the number
// down to 123.01, round it to 123 and then scale it back up to 12300.
let mut num = *self;
let mut exp = (diff - scale) as usize;
while exp > 0 {
let pow;
if exp >= BIG_POWERS_10.len() {
pow = Decimal::from(BIG_POWERS_10[BIG_POWERS_10.len() - 1]);
exp -= BIG_POWERS_10.len();
} else {
pow = Decimal::from(BIG_POWERS_10[exp - 1]);
exp = 0;
}
num = num.checked_div(pow)?;
}
let mut num = num.round_dp_with_strategy(0, strategy).trunc();
let mut exp = (mantissa_sf - digits - scale) as usize;
while exp > 0 {
let pow;
if exp >= BIG_POWERS_10.len() {
pow = Decimal::from(BIG_POWERS_10[BIG_POWERS_10.len() - 1]);
exp -= BIG_POWERS_10.len();
} else {
pow = Decimal::from(BIG_POWERS_10[exp - 1]);
exp = 0;
}
num = num.checked_mul(pow)?;
}
Some(num)
} else {
Some(self.round_dp_with_strategy(scale - diff, strategy))
}
}
Ordering::Equal => {
// Case where significant figures = requested significant digits.
Some(*self)
}
}
}
/// Convert `Decimal` to an internal representation of the underlying struct. This is useful
/// for debugging the internal state of the object.
///
/// # Important Disclaimer
/// This is primarily intended for library maintainers. The internal representation of a
/// `Decimal` is considered "unstable" for public use.
///
/// # Example
///
/// ```
/// # use rust_decimal::Decimal;
/// use rust_decimal_macros::dec;
///
/// let pi = dec!(3.1415926535897932384626433832);
/// assert_eq!(format!("{:?}", pi), "3.1415926535897932384626433832");
/// assert_eq!(format!("{:?}", pi.unpack()), "UnpackedDecimal { \
/// negative: false, scale: 28, hi: 1703060790, mid: 185874565, lo: 1102470952 \
/// }");
/// ```
#[must_use]
pub const fn unpack(&self) -> UnpackedDecimal {
UnpackedDecimal {
negative: self.is_sign_negative(),
scale: self.scale(),
hi: self.hi,
lo: self.lo,
mid: self.mid,
}
}
#[inline(always)]
pub(crate) const fn lo(&self) -> u32 {
self.lo
}
#[inline(always)]
pub(crate) const fn mid(&self) -> u32 {
self.mid
}
#[inline(always)]
pub(crate) const fn hi(&self) -> u32 {
self.hi
}
#[inline(always)]
pub(crate) const fn flags(&self) -> u32 {
self.flags
}
#[inline(always)]
pub(crate) const fn mantissa_array3(&self) -> [u32; 3] {
[self.lo, self.mid, self.hi]
}
#[inline(always)]
pub(crate) const fn mantissa_array4(&self) -> [u32; 4] {
[self.lo, self.mid, self.hi, 0]
}
/// Parses a 32-bit float into a Decimal number whilst retaining any non-guaranteed precision.
///
/// Typically when a float is parsed in Rust Decimal, any excess bits (after ~7.22 decimal points for
/// f32 as per IEEE-754) are removed due to any digits following this are considered an approximation
/// at best. This function bypasses this additional step and retains these excess bits.
///
/// # Example
///
/// ```
/// # use rust_decimal::prelude::*;
/// #
/// // Usually floats are parsed leveraging float guarantees. i.e. 0.1_f32 => 0.1
/// assert_eq!("0.1", Decimal::from_f32(0.1_f32).unwrap().to_string());
///
/// // Sometimes, we may want to represent the approximation exactly.
/// assert_eq!("0.100000001490116119384765625", Decimal::from_f32_retain(0.1_f32).unwrap().to_string());
/// ```
pub fn from_f32_retain(n: f32) -> Option<Self> {
from_f32(n, false)
}
/// Parses a 64-bit float into a Decimal number whilst retaining any non-guaranteed precision.
///
/// Typically when a float is parsed in Rust Decimal, any excess bits (after ~15.95 decimal points for
/// f64 as per IEEE-754) are removed due to any digits following this are considered an approximation
/// at best. This function bypasses this additional step and retains these excess bits.
///
/// # Example
///
/// ```
/// # use rust_decimal::prelude::*;
/// #
/// // Usually floats are parsed leveraging float guarantees. i.e. 0.1_f64 => 0.1
/// assert_eq!("0.1", Decimal::from_f64(0.1_f64).unwrap().to_string());
///
/// // Sometimes, we may want to represent the approximation exactly.
/// assert_eq!("0.1000000000000000055511151231", Decimal::from_f64_retain(0.1_f64).unwrap().to_string());
/// ```
pub fn from_f64_retain(n: f64) -> Option<Self> {
from_f64(n, false)
}
}
impl Default for Decimal {
/// Returns the default value for a `Decimal` (equivalent to `Decimal::ZERO`). [Read more]
///
/// [Read more]: core::default::Default#tymethod.default
#[inline]
fn default() -> Self {
ZERO
}
}
pub(crate) enum CalculationResult {
Ok(Decimal),
Overflow,
DivByZero,
}
#[inline]
const fn flags(neg: bool, scale: u32) -> u32 {
(scale << SCALE_SHIFT) | ((neg as u32) << SIGN_SHIFT)
}
macro_rules! integer_docs {
( true ) => {
" by truncating and returning the integer component"
};
( false ) => {
""
};
}
// #[doc] attributes are formatted poorly with rustfmt so skip for now.
// See https://github.com/rust-lang/rustfmt/issues/5062 for more information.
#[rustfmt::skip]
macro_rules! impl_try_from_decimal {
($TInto:ty, $conversion_fn:path, $additional_docs:expr) => {
#[doc = concat!(
"Try to convert a `Decimal` to `",
stringify!($TInto),
"`",
$additional_docs,
".\n\nCan fail if the `Decimal` is out of range for `",
stringify!($TInto),
"`.",
)]
impl TryFrom<Decimal> for $TInto {
type Error = crate::Error;
#[inline]
fn try_from(t: Decimal) -> Result<Self, Error> {
$conversion_fn(&t).ok_or_else(|| Error::ConversionTo(stringify!($TInto).into()))
}
}
};
}
impl_try_from_decimal!(f32, Decimal::to_f32, integer_docs!(false));
impl_try_from_decimal!(f64, Decimal::to_f64, integer_docs!(false));
impl_try_from_decimal!(isize, Decimal::to_isize, integer_docs!(true));
impl_try_from_decimal!(i8, Decimal::to_i8, integer_docs!(true));
impl_try_from_decimal!(i16, Decimal::to_i16, integer_docs!(true));
impl_try_from_decimal!(i32, Decimal::to_i32, integer_docs!(true));
impl_try_from_decimal!(i64, Decimal::to_i64, integer_docs!(true));
impl_try_from_decimal!(i128, Decimal::to_i128, integer_docs!(true));
impl_try_from_decimal!(usize, Decimal::to_usize, integer_docs!(true));
impl_try_from_decimal!(u8, Decimal::to_u8, integer_docs!(true));
impl_try_from_decimal!(u16, Decimal::to_u16, integer_docs!(true));
impl_try_from_decimal!(u32, Decimal::to_u32, integer_docs!(true));
impl_try_from_decimal!(u64, Decimal::to_u64, integer_docs!(true));
impl_try_from_decimal!(u128, Decimal::to_u128, integer_docs!(true));
// #[doc] attributes are formatted poorly with rustfmt so skip for now.
// See https://github.com/rust-lang/rustfmt/issues/5062 for more information.
#[rustfmt::skip]
macro_rules! impl_try_from_primitive {
($TFrom:ty, $conversion_fn:path $(, $err:expr)?) => {
#[doc = concat!(
"Try to convert a `",
stringify!($TFrom),
"` into a `Decimal`.\n\nCan fail if the value is out of range for `Decimal`."
)]
impl TryFrom<$TFrom> for Decimal {
type Error = crate::Error;
#[inline]
fn try_from(t: $TFrom) -> Result<Self, Error> {
$conversion_fn(t) $( .ok_or_else(|| $err) )?
}
}
};
}
impl_try_from_primitive!(f32, Self::from_f32, Error::ConversionTo("Decimal".into()));
impl_try_from_primitive!(f64, Self::from_f64, Error::ConversionTo("Decimal".into()));
impl_try_from_primitive!(&str, core::str::FromStr::from_str);
macro_rules! impl_from {
($T:ty, $from_ty:path) => {
///
/// Conversion to `Decimal`.
///
impl core::convert::From<$T> for Decimal {
#[inline]
fn from(t: $T) -> Self {
$from_ty(t).unwrap()
}
}
};
}
impl_from!(isize, FromPrimitive::from_isize);
impl_from!(i8, FromPrimitive::from_i8);
impl_from!(i16, FromPrimitive::from_i16);
impl_from!(i32, FromPrimitive::from_i32);
impl_from!(i64, FromPrimitive::from_i64);
impl_from!(usize, FromPrimitive::from_usize);
impl_from!(u8, FromPrimitive::from_u8);
impl_from!(u16, FromPrimitive::from_u16);
impl_from!(u32, FromPrimitive::from_u32);
impl_from!(u64, FromPrimitive::from_u64);
impl_from!(i128, FromPrimitive::from_i128);
impl_from!(u128, FromPrimitive::from_u128);
impl Zero for Decimal {
fn zero() -> Decimal {
ZERO
}
fn is_zero(&self) -> bool {
self.is_zero()
}
}
impl One for Decimal {
fn one() -> Decimal {
ONE
}
}
impl Signed for Decimal {
fn abs(&self) -> Self {
self.abs()
}
fn abs_sub(&self, other: &Self) -> Self {
if self <= other {
ZERO
} else {
self.abs()
}
}
fn signum(&self) -> Self {
if self.is_zero() {
ZERO
} else {
let mut value = ONE;
if self.is_sign_negative() {
value.set_sign_negative(true);
}
value
}
}
fn is_positive(&self) -> bool {
self.is_sign_positive()
}
fn is_negative(&self) -> bool {
self.is_sign_negative()
}
}
impl Num for Decimal {
type FromStrRadixErr = Error;
fn from_str_radix(str: &str, radix: u32) -> Result<Self, Self::FromStrRadixErr> {
Decimal::from_str_radix(str, radix)
}
}
impl FromStr for Decimal {
type Err = Error;
fn from_str(value: &str) -> Result<Decimal, Self::Err> {
crate::str::parse_str_radix_10(value)
}
}
impl FromPrimitive for Decimal {
fn from_i32(n: i32) -> Option<Decimal> {
let flags: u32;
let value_copy: i64;
if n >= 0 {
flags = 0;
value_copy = n as i64;
} else {
flags = SIGN_MASK;
value_copy = -(n as i64);
}
Some(Decimal {
flags,
lo: value_copy as u32,
mid: 0,
hi: 0,
})
}
fn from_i64(n: i64) -> Option<Decimal> {
let flags: u32;
let value_copy: i128;
if n >= 0 {
flags = 0;
value_copy = n as i128;
} else {
flags = SIGN_MASK;
value_copy = -(n as i128);
}
Some(Decimal {
flags,
lo: value_copy as u32,
mid: (value_copy >> 32) as u32,
hi: 0,
})
}
fn from_i128(n: i128) -> Option<Decimal> {
let flags;
let unsigned;
if n >= 0 {
unsigned = n as u128;
flags = 0;
} else {
unsigned = -n as u128;
flags = SIGN_MASK;
};
// Check if we overflow
if unsigned >> 96 != 0 {
return None;
}
Some(Decimal {
flags,
lo: unsigned as u32,
mid: (unsigned >> 32) as u32,
hi: (unsigned >> 64) as u32,
})
}
fn from_u32(n: u32) -> Option<Decimal> {
Some(Decimal {
flags: 0,
lo: n,
mid: 0,
hi: 0,
})
}
fn from_u64(n: u64) -> Option<Decimal> {
Some(Decimal {
flags: 0,
lo: n as u32,
mid: (n >> 32) as u32,
hi: 0,
})
}
fn from_u128(n: u128) -> Option<Decimal> {
// Check if we overflow
if n >> 96 != 0 {
return None;
}
Some(Decimal {
flags: 0,
lo: n as u32,
mid: (n >> 32) as u32,
hi: (n >> 64) as u32,
})
}
fn from_f32(n: f32) -> Option<Decimal> {
// By default, we remove excess bits. This allows 0.1_f64 == dec!(0.1).
from_f32(n, true)
}
fn from_f64(n: f64) -> Option<Decimal> {
// By default, we remove excess bits. This allows 0.1_f64 == dec!(0.1).
from_f64(n, true)
}
}
#[inline]
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