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Diffstat (limited to '')
-rw-r--r-- | vendor/ryu/src/buffer/mod.rs | 170 |
1 files changed, 170 insertions, 0 deletions
diff --git a/vendor/ryu/src/buffer/mod.rs b/vendor/ryu/src/buffer/mod.rs new file mode 100644 index 000000000..2ccd9b0a3 --- /dev/null +++ b/vendor/ryu/src/buffer/mod.rs @@ -0,0 +1,170 @@ +use crate::raw; +use core::mem::MaybeUninit; +use core::{slice, str}; +#[cfg(feature = "no-panic")] +use no_panic::no_panic; + +const NAN: &str = "NaN"; +const INFINITY: &str = "inf"; +const NEG_INFINITY: &str = "-inf"; + +/// Safe API for formatting floating point numbers to text. +/// +/// ## Example +/// +/// ``` +/// let mut buffer = ryu::Buffer::new(); +/// let printed = buffer.format_finite(1.234); +/// assert_eq!(printed, "1.234"); +/// ``` +pub struct Buffer { + bytes: [MaybeUninit<u8>; 24], +} + +impl Buffer { + /// This is a cheap operation; you don't need to worry about reusing buffers + /// for efficiency. + #[inline] + #[cfg_attr(feature = "no-panic", no_panic)] + pub fn new() -> Self { + let bytes = [MaybeUninit::<u8>::uninit(); 24]; + Buffer { bytes } + } + + /// Print a floating point number into this buffer and return a reference to + /// its string representation within the buffer. + /// + /// # Special cases + /// + /// This function formats NaN as the string "NaN", positive infinity as + /// "inf", and negative infinity as "-inf" to match std::fmt. + /// + /// If your input is known to be finite, you may get better performance by + /// calling the `format_finite` method instead of `format` to avoid the + /// checks for special cases. + #[cfg_attr(feature = "no-panic", inline)] + #[cfg_attr(feature = "no-panic", no_panic)] + pub fn format<F: Float>(&mut self, f: F) -> &str { + if f.is_nonfinite() { + f.format_nonfinite() + } else { + self.format_finite(f) + } + } + + /// Print a floating point number into this buffer and return a reference to + /// its string representation within the buffer. + /// + /// # Special cases + /// + /// This function **does not** check for NaN or infinity. If the input + /// number is not a finite float, the printed representation will be some + /// correctly formatted but unspecified numerical value. + /// + /// Please check [`is_finite`] yourself before calling this function, or + /// check [`is_nan`] and [`is_infinite`] and handle those cases yourself. + /// + /// [`is_finite`]: https://doc.rust-lang.org/std/primitive.f64.html#method.is_finite + /// [`is_nan`]: https://doc.rust-lang.org/std/primitive.f64.html#method.is_nan + /// [`is_infinite`]: https://doc.rust-lang.org/std/primitive.f64.html#method.is_infinite + #[inline] + #[cfg_attr(feature = "no-panic", no_panic)] + pub fn format_finite<F: Float>(&mut self, f: F) -> &str { + unsafe { + let n = f.write_to_ryu_buffer(self.bytes.as_mut_ptr() as *mut u8); + debug_assert!(n <= self.bytes.len()); + let slice = slice::from_raw_parts(self.bytes.as_ptr() as *const u8, n); + str::from_utf8_unchecked(slice) + } + } +} + +impl Copy for Buffer {} + +impl Clone for Buffer { + #[inline] + fn clone(&self) -> Self { + Buffer::new() + } +} + +impl Default for Buffer { + #[inline] + #[cfg_attr(feature = "no-panic", no_panic)] + fn default() -> Self { + Buffer::new() + } +} + +/// A floating point number, f32 or f64, that can be written into a +/// [`ryu::Buffer`][Buffer]. +/// +/// This trait is sealed and cannot be implemented for types outside of the +/// `ryu` crate. +pub trait Float: Sealed {} +impl Float for f32 {} +impl Float for f64 {} + +pub trait Sealed: Copy { + fn is_nonfinite(self) -> bool; + fn format_nonfinite(self) -> &'static str; + unsafe fn write_to_ryu_buffer(self, result: *mut u8) -> usize; +} + +impl Sealed for f32 { + #[inline] + fn is_nonfinite(self) -> bool { + const EXP_MASK: u32 = 0x7f800000; + let bits = self.to_bits(); + bits & EXP_MASK == EXP_MASK + } + + #[cold] + #[cfg_attr(feature = "no-panic", inline)] + fn format_nonfinite(self) -> &'static str { + const MANTISSA_MASK: u32 = 0x007fffff; + const SIGN_MASK: u32 = 0x80000000; + let bits = self.to_bits(); + if bits & MANTISSA_MASK != 0 { + NAN + } else if bits & SIGN_MASK != 0 { + NEG_INFINITY + } else { + INFINITY + } + } + + #[inline] + unsafe fn write_to_ryu_buffer(self, result: *mut u8) -> usize { + raw::format32(self, result) + } +} + +impl Sealed for f64 { + #[inline] + fn is_nonfinite(self) -> bool { + const EXP_MASK: u64 = 0x7ff0000000000000; + let bits = self.to_bits(); + bits & EXP_MASK == EXP_MASK + } + + #[cold] + #[cfg_attr(feature = "no-panic", inline)] + fn format_nonfinite(self) -> &'static str { + const MANTISSA_MASK: u64 = 0x000fffffffffffff; + const SIGN_MASK: u64 = 0x8000000000000000; + let bits = self.to_bits(); + if bits & MANTISSA_MASK != 0 { + NAN + } else if bits & SIGN_MASK != 0 { + NEG_INFINITY + } else { + INFINITY + } + } + + #[inline] + unsafe fn write_to_ryu_buffer(self, result: *mut u8) -> usize { + raw::format64(self, result) + } +} |