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
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+++ 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)
+    }
+}