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// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
use smallvec::smallvec;
use smallvec::SmallVec;
use super::transl8::FromV8;
use super::transl8::ToV8;
use crate::error::value_to_type_str;
use crate::magic::transl8::impl_magic;
use crate::Error;
#[derive(
PartialEq,
Eq,
Clone,
Debug,
Default,
derive_more::Deref,
derive_more::DerefMut,
derive_more::AsRef,
derive_more::AsMut,
)]
#[as_mut(forward)]
#[as_ref(forward)]
pub struct BigInt(num_bigint::BigInt);
impl_magic!(BigInt);
impl ToV8 for BigInt {
fn to_v8<'a>(
&mut self,
scope: &mut v8::HandleScope<'a>,
) -> Result<v8::Local<'a, v8::Value>, crate::Error> {
let (sign, words) = self.0.to_u64_digits();
let sign_bit = sign == num_bigint::Sign::Minus;
let v = v8::BigInt::new_from_words(scope, sign_bit, &words).unwrap();
Ok(v.into())
}
}
impl FromV8 for BigInt {
fn from_v8(
_scope: &mut v8::HandleScope,
value: v8::Local<v8::Value>,
) -> Result<Self, crate::Error> {
let v8bigint = v8::Local::<v8::BigInt>::try_from(value)
.map_err(|_| Error::ExpectedBigInt(value_to_type_str(value)))?;
let word_count = v8bigint.word_count();
let mut words: SmallVec<[u64; 1]> = smallvec![0u64; word_count];
let (sign_bit, _words) = v8bigint.to_words_array(&mut words);
let sign = match sign_bit {
true => num_bigint::Sign::Minus,
false => num_bigint::Sign::Plus,
};
// SAFETY: Because the alignment of u64 is 8, the alignment of u32 is 4, and
// the size of u64 is 8, the size of u32 is 4, the alignment of u32 is a
// factor of the alignment of u64, and the size of u32 is a factor of the
// size of u64, we can safely transmute the slice of u64 to a slice of u32.
let (prefix, slice, suffix) = unsafe { words.align_to::<u32>() };
assert!(prefix.is_empty());
assert!(suffix.is_empty());
assert_eq!(slice.len(), words.len() * 2);
let big_int = num_bigint::BigInt::from_slice(sign, slice);
Ok(Self(big_int))
}
}
impl From<num_bigint::BigInt> for BigInt {
fn from(big_int: num_bigint::BigInt) -> Self {
Self(big_int)
}
}
impl From<BigInt> for num_bigint::BigInt {
fn from(big_int: BigInt) -> Self {
big_int.0
}
}
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