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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-19 00:47:55 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-19 00:47:55 +0000 |
commit | 26a029d407be480d791972afb5975cf62c9360a6 (patch) | |
tree | f435a8308119effd964b339f76abb83a57c29483 /third_party/rust/serde_json/src/lexical/num.rs | |
parent | Initial commit. (diff) | |
download | firefox-26a029d407be480d791972afb5975cf62c9360a6.tar.xz firefox-26a029d407be480d791972afb5975cf62c9360a6.zip |
Adding upstream version 124.0.1.upstream/124.0.1
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'third_party/rust/serde_json/src/lexical/num.rs')
-rw-r--r-- | third_party/rust/serde_json/src/lexical/num.rs | 440 |
1 files changed, 440 insertions, 0 deletions
diff --git a/third_party/rust/serde_json/src/lexical/num.rs b/third_party/rust/serde_json/src/lexical/num.rs new file mode 100644 index 0000000000..e47e003419 --- /dev/null +++ b/third_party/rust/serde_json/src/lexical/num.rs @@ -0,0 +1,440 @@ +// Adapted from https://github.com/Alexhuszagh/rust-lexical. + +//! Utilities for Rust numbers. + +use core::ops; + +/// Precalculated values of radix**i for i in range [0, arr.len()-1]. +/// Each value can be **exactly** represented as that type. +const F32_POW10: [f32; 11] = [ + 1.0, + 10.0, + 100.0, + 1000.0, + 10000.0, + 100000.0, + 1000000.0, + 10000000.0, + 100000000.0, + 1000000000.0, + 10000000000.0, +]; + +/// Precalculated values of radix**i for i in range [0, arr.len()-1]. +/// Each value can be **exactly** represented as that type. +const F64_POW10: [f64; 23] = [ + 1.0, + 10.0, + 100.0, + 1000.0, + 10000.0, + 100000.0, + 1000000.0, + 10000000.0, + 100000000.0, + 1000000000.0, + 10000000000.0, + 100000000000.0, + 1000000000000.0, + 10000000000000.0, + 100000000000000.0, + 1000000000000000.0, + 10000000000000000.0, + 100000000000000000.0, + 1000000000000000000.0, + 10000000000000000000.0, + 100000000000000000000.0, + 1000000000000000000000.0, + 10000000000000000000000.0, +]; + +/// Type that can be converted to primitive with `as`. +pub trait AsPrimitive: Sized + Copy + PartialOrd { + fn as_u32(self) -> u32; + fn as_u64(self) -> u64; + fn as_u128(self) -> u128; + fn as_usize(self) -> usize; + fn as_f32(self) -> f32; + fn as_f64(self) -> f64; +} + +macro_rules! as_primitive_impl { + ($($ty:ident)*) => { + $( + impl AsPrimitive for $ty { + #[inline] + fn as_u32(self) -> u32 { + self as u32 + } + + #[inline] + fn as_u64(self) -> u64 { + self as u64 + } + + #[inline] + fn as_u128(self) -> u128 { + self as u128 + } + + #[inline] + fn as_usize(self) -> usize { + self as usize + } + + #[inline] + fn as_f32(self) -> f32 { + self as f32 + } + + #[inline] + fn as_f64(self) -> f64 { + self as f64 + } + } + )* + }; +} + +as_primitive_impl! { u32 u64 u128 usize f32 f64 } + +/// An interface for casting between machine scalars. +pub trait AsCast: AsPrimitive { + /// Creates a number from another value that can be converted into + /// a primitive via the `AsPrimitive` trait. + fn as_cast<N: AsPrimitive>(n: N) -> Self; +} + +macro_rules! as_cast_impl { + ($ty:ident, $method:ident) => { + impl AsCast for $ty { + #[inline] + fn as_cast<N: AsPrimitive>(n: N) -> Self { + n.$method() + } + } + }; +} + +as_cast_impl!(u32, as_u32); +as_cast_impl!(u64, as_u64); +as_cast_impl!(u128, as_u128); +as_cast_impl!(usize, as_usize); +as_cast_impl!(f32, as_f32); +as_cast_impl!(f64, as_f64); + +/// Numerical type trait. +pub trait Number: AsCast + ops::Add<Output = Self> {} + +macro_rules! number_impl { + ($($ty:ident)*) => { + $( + impl Number for $ty {} + )* + }; +} + +number_impl! { u32 u64 u128 usize f32 f64 } + +/// Defines a trait that supports integral operations. +pub trait Integer: Number + ops::BitAnd<Output = Self> + ops::Shr<i32, Output = Self> { + const ZERO: Self; +} + +macro_rules! integer_impl { + ($($ty:tt)*) => { + $( + impl Integer for $ty { + const ZERO: Self = 0; + } + )* + }; +} + +integer_impl! { u32 u64 u128 usize } + +/// Type trait for the mantissa type. +pub trait Mantissa: Integer { + /// Mask to extract the high bits from the integer. + const HIMASK: Self; + /// Mask to extract the low bits from the integer. + const LOMASK: Self; + /// Full size of the integer, in bits. + const FULL: i32; + /// Half size of the integer, in bits. + const HALF: i32 = Self::FULL / 2; +} + +impl Mantissa for u64 { + const HIMASK: u64 = 0xFFFFFFFF00000000; + const LOMASK: u64 = 0x00000000FFFFFFFF; + const FULL: i32 = 64; +} + +/// Get exact exponent limit for radix. +pub trait Float: Number { + /// Unsigned type of the same size. + type Unsigned: Integer; + + /// Literal zero. + const ZERO: Self; + /// Maximum number of digits that can contribute in the mantissa. + /// + /// We can exactly represent a float in radix `b` from radix 2 if + /// `b` is divisible by 2. This function calculates the exact number of + /// digits required to exactly represent that float. + /// + /// According to the "Handbook of Floating Point Arithmetic", + /// for IEEE754, with emin being the min exponent, p2 being the + /// precision, and b being the radix, the number of digits follows as: + /// + /// `−emin + p2 + ⌊(emin + 1) log(2, b) − log(1 − 2^(−p2), b)⌋` + /// + /// For f32, this follows as: + /// emin = -126 + /// p2 = 24 + /// + /// For f64, this follows as: + /// emin = -1022 + /// p2 = 53 + /// + /// In Python: + /// `-emin + p2 + math.floor((emin+1)*math.log(2, b) - math.log(1-2**(-p2), b))` + /// + /// This was used to calculate the maximum number of digits for [2, 36]. + const MAX_DIGITS: usize; + + // MASKS + + /// Bitmask for the sign bit. + const SIGN_MASK: Self::Unsigned; + /// Bitmask for the exponent, including the hidden bit. + const EXPONENT_MASK: Self::Unsigned; + /// Bitmask for the hidden bit in exponent, which is an implicit 1 in the fraction. + const HIDDEN_BIT_MASK: Self::Unsigned; + /// Bitmask for the mantissa (fraction), excluding the hidden bit. + const MANTISSA_MASK: Self::Unsigned; + + // PROPERTIES + + /// Positive infinity as bits. + const INFINITY_BITS: Self::Unsigned; + /// Positive infinity as bits. + const NEGATIVE_INFINITY_BITS: Self::Unsigned; + /// Size of the significand (mantissa) without hidden bit. + const MANTISSA_SIZE: i32; + /// Bias of the exponet + const EXPONENT_BIAS: i32; + /// Exponent portion of a denormal float. + const DENORMAL_EXPONENT: i32; + /// Maximum exponent value in float. + const MAX_EXPONENT: i32; + + // ROUNDING + + /// Default number of bits to shift (or 64 - mantissa size - 1). + const DEFAULT_SHIFT: i32; + /// Mask to determine if a full-carry occurred (1 in bit above hidden bit). + const CARRY_MASK: u64; + + /// Get min and max exponent limits (exact) from radix. + fn exponent_limit() -> (i32, i32); + + /// Get the number of digits that can be shifted from exponent to mantissa. + fn mantissa_limit() -> i32; + + // Re-exported methods from std. + fn pow10(self, n: i32) -> Self; + fn from_bits(u: Self::Unsigned) -> Self; + fn to_bits(self) -> Self::Unsigned; + fn is_sign_positive(self) -> bool; + fn is_sign_negative(self) -> bool; + + /// Returns true if the float is a denormal. + #[inline] + fn is_denormal(self) -> bool { + self.to_bits() & Self::EXPONENT_MASK == Self::Unsigned::ZERO + } + + /// Returns true if the float is a NaN or Infinite. + #[inline] + fn is_special(self) -> bool { + self.to_bits() & Self::EXPONENT_MASK == Self::EXPONENT_MASK + } + + /// Returns true if the float is infinite. + #[inline] + fn is_inf(self) -> bool { + self.is_special() && (self.to_bits() & Self::MANTISSA_MASK) == Self::Unsigned::ZERO + } + + /// Get exponent component from the float. + #[inline] + fn exponent(self) -> i32 { + if self.is_denormal() { + return Self::DENORMAL_EXPONENT; + } + + let bits = self.to_bits(); + let biased_e = ((bits & Self::EXPONENT_MASK) >> Self::MANTISSA_SIZE).as_u32(); + biased_e as i32 - Self::EXPONENT_BIAS + } + + /// Get mantissa (significand) component from float. + #[inline] + fn mantissa(self) -> Self::Unsigned { + let bits = self.to_bits(); + let s = bits & Self::MANTISSA_MASK; + if !self.is_denormal() { + s + Self::HIDDEN_BIT_MASK + } else { + s + } + } + + /// Get next greater float for a positive float. + /// Value must be >= 0.0 and < INFINITY. + #[inline] + fn next_positive(self) -> Self { + debug_assert!(self.is_sign_positive() && !self.is_inf()); + Self::from_bits(self.to_bits() + Self::Unsigned::as_cast(1u32)) + } + + /// Round a positive number to even. + #[inline] + fn round_positive_even(self) -> Self { + if self.mantissa() & Self::Unsigned::as_cast(1u32) == Self::Unsigned::as_cast(1u32) { + self.next_positive() + } else { + self + } + } +} + +impl Float for f32 { + type Unsigned = u32; + + const ZERO: f32 = 0.0; + const MAX_DIGITS: usize = 114; + const SIGN_MASK: u32 = 0x80000000; + const EXPONENT_MASK: u32 = 0x7F800000; + const HIDDEN_BIT_MASK: u32 = 0x00800000; + const MANTISSA_MASK: u32 = 0x007FFFFF; + const INFINITY_BITS: u32 = 0x7F800000; + const NEGATIVE_INFINITY_BITS: u32 = Self::INFINITY_BITS | Self::SIGN_MASK; + const MANTISSA_SIZE: i32 = 23; + const EXPONENT_BIAS: i32 = 127 + Self::MANTISSA_SIZE; + const DENORMAL_EXPONENT: i32 = 1 - Self::EXPONENT_BIAS; + const MAX_EXPONENT: i32 = 0xFF - Self::EXPONENT_BIAS; + const DEFAULT_SHIFT: i32 = u64::FULL - f32::MANTISSA_SIZE - 1; + const CARRY_MASK: u64 = 0x1000000; + + #[inline] + fn exponent_limit() -> (i32, i32) { + (-10, 10) + } + + #[inline] + fn mantissa_limit() -> i32 { + 7 + } + + #[inline] + fn pow10(self, n: i32) -> f32 { + // Check the exponent is within bounds in debug builds. + debug_assert!({ + let (min, max) = Self::exponent_limit(); + n >= min && n <= max + }); + + if n > 0 { + self * F32_POW10[n as usize] + } else { + self / F32_POW10[-n as usize] + } + } + + #[inline] + fn from_bits(u: u32) -> f32 { + f32::from_bits(u) + } + + #[inline] + fn to_bits(self) -> u32 { + f32::to_bits(self) + } + + #[inline] + fn is_sign_positive(self) -> bool { + f32::is_sign_positive(self) + } + + #[inline] + fn is_sign_negative(self) -> bool { + f32::is_sign_negative(self) + } +} + +impl Float for f64 { + type Unsigned = u64; + + const ZERO: f64 = 0.0; + const MAX_DIGITS: usize = 769; + const SIGN_MASK: u64 = 0x8000000000000000; + const EXPONENT_MASK: u64 = 0x7FF0000000000000; + const HIDDEN_BIT_MASK: u64 = 0x0010000000000000; + const MANTISSA_MASK: u64 = 0x000FFFFFFFFFFFFF; + const INFINITY_BITS: u64 = 0x7FF0000000000000; + const NEGATIVE_INFINITY_BITS: u64 = Self::INFINITY_BITS | Self::SIGN_MASK; + const MANTISSA_SIZE: i32 = 52; + const EXPONENT_BIAS: i32 = 1023 + Self::MANTISSA_SIZE; + const DENORMAL_EXPONENT: i32 = 1 - Self::EXPONENT_BIAS; + const MAX_EXPONENT: i32 = 0x7FF - Self::EXPONENT_BIAS; + const DEFAULT_SHIFT: i32 = u64::FULL - f64::MANTISSA_SIZE - 1; + const CARRY_MASK: u64 = 0x20000000000000; + + #[inline] + fn exponent_limit() -> (i32, i32) { + (-22, 22) + } + + #[inline] + fn mantissa_limit() -> i32 { + 15 + } + + #[inline] + fn pow10(self, n: i32) -> f64 { + // Check the exponent is within bounds in debug builds. + debug_assert!({ + let (min, max) = Self::exponent_limit(); + n >= min && n <= max + }); + + if n > 0 { + self * F64_POW10[n as usize] + } else { + self / F64_POW10[-n as usize] + } + } + + #[inline] + fn from_bits(u: u64) -> f64 { + f64::from_bits(u) + } + + #[inline] + fn to_bits(self) -> u64 { + f64::to_bits(self) + } + + #[inline] + fn is_sign_positive(self) -> bool { + f64::is_sign_positive(self) + } + + #[inline] + fn is_sign_negative(self) -> bool { + f64::is_sign_negative(self) + } +} |