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https://github.com/denoland/deno.git
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b99c431ac7
This commit enables serializing `v8::BigInt` to `num_bigint::BigInt` in Rust. Pre-requisite for sub upcoming feature work.
76 lines
2.1 KiB
Rust
76 lines
2.1 KiB
Rust
// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
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use smallvec::smallvec;
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use smallvec::SmallVec;
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use super::transl8::FromV8;
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use super::transl8::ToV8;
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use crate::magic::transl8::impl_magic;
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use crate::Error;
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#[derive(
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PartialEq,
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Eq,
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Clone,
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Debug,
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Default,
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derive_more::Deref,
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derive_more::DerefMut,
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derive_more::AsRef,
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derive_more::AsMut,
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)]
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#[as_mut(forward)]
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#[as_ref(forward)]
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pub struct BigInt(num_bigint::BigInt);
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impl_magic!(BigInt);
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impl ToV8 for BigInt {
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fn to_v8<'a>(
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&mut self,
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scope: &mut v8::HandleScope<'a>,
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) -> Result<v8::Local<'a, v8::Value>, crate::Error> {
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let (sign, words) = self.0.to_u64_digits();
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let sign_bit = sign == num_bigint::Sign::Minus;
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let v = v8::BigInt::new_from_words(scope, sign_bit, &words).unwrap();
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Ok(v.into())
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}
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}
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impl FromV8 for BigInt {
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fn from_v8(
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_scope: &mut v8::HandleScope,
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value: v8::Local<v8::Value>,
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) -> Result<Self, crate::Error> {
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let v8bigint = v8::Local::<v8::BigInt>::try_from(value)
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.map_err(|_| Error::ExpectedBigInt)?;
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let word_count = v8bigint.word_count();
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let mut words: SmallVec<[u64; 1]> = smallvec![0u64; word_count];
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let (sign_bit, _words) = v8bigint.to_words_array(&mut words);
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let sign = match sign_bit {
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true => num_bigint::Sign::Minus,
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false => num_bigint::Sign::Plus,
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};
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// SAFETY: Because the alignment of u64 is 8, the alignment of u32 is 4, and
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// the size of u64 is 8, the size of u32 is 4, the alignment of u32 is a
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// factor of the alignment of u64, and the size of u32 is a factor of the
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// size of u64, we can safely transmute the slice of u64 to a slice of u32.
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let (prefix, slice, suffix) = unsafe { words.align_to::<u32>() };
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assert!(prefix.is_empty());
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assert!(suffix.is_empty());
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assert_eq!(slice.len(), words.len() * 2);
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let big_int = num_bigint::BigInt::from_slice(sign, slice);
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Ok(Self(big_int))
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}
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}
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impl From<num_bigint::BigInt> for BigInt {
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fn from(big_int: num_bigint::BigInt) -> Self {
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Self(big_int)
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}
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}
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impl From<BigInt> for num_bigint::BigInt {
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fn from(big_int: BigInt) -> Self {
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big_int.0
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}
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}
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