#![cfg(feature = "serde")]
#![cfg_attr(docsrs, doc(cfg(feature = "serde")))]
use super::{biguint_from_vec, BigUint};
use alloc::vec::Vec;
use core::{cmp, fmt, mem};
use serde::de::{SeqAccess, Visitor};
use serde::{Deserialize, Deserializer, Serialize, Serializer};
fn cautious(hint: Option<usize>) -> usize {
const MAX_PREALLOC_BYTES: usize = 1024 * 1024;
cmp::min(
hint.unwrap_or(0),
MAX_PREALLOC_BYTES / mem::size_of::<u32>(),
)
}
impl Serialize for BigUint {
cfg_digit!(
fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
where
S: Serializer,
{
let data: &[u32] = &self.data;
data.serialize(serializer)
}
fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
where
S: Serializer,
{
use serde::ser::SerializeSeq;
if let Some((&last, data)) = self.data.split_last() {
let last_lo = last as u32;
let last_hi = (last >> 32) as u32;
let u32_len = data.len() * 2 + 1 + (last_hi != 0) as usize;
let mut seq = serializer.serialize_seq(Some(u32_len))?;
for &x in data {
seq.serialize_element(&(x as u32))?;
seq.serialize_element(&((x >> 32) as u32))?;
}
seq.serialize_element(&last_lo)?;
if last_hi != 0 {
seq.serialize_element(&last_hi)?;
}
seq.end()
} else {
let data: &[u32] = &[];
data.serialize(serializer)
}
}
);
}
impl<'de> Deserialize<'de> for BigUint {
fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
where
D: Deserializer<'de>,
{
deserializer.deserialize_seq(U32Visitor)
}
}
struct U32Visitor;
impl<'de> Visitor<'de> for U32Visitor {
type Value = BigUint;
fn expecting(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
formatter.write_str("a sequence of unsigned 32-bit numbers")
}
cfg_digit!(
fn visit_seq<S>(self, mut seq: S) -> Result<Self::Value, S::Error>
where
S: SeqAccess<'de>,
{
let len = cautious(seq.size_hint());
let mut data = Vec::with_capacity(len);
while let Some(value) = seq.next_element::<u32>()? {
data.push(value);
}
Ok(biguint_from_vec(data))
}
fn visit_seq<S>(self, mut seq: S) -> Result<Self::Value, S::Error>
where
S: SeqAccess<'de>,
{
use crate::big_digit::BigDigit;
use num_integer::Integer;
let u32_len = cautious(seq.size_hint());
let len = Integer::div_ceil(&u32_len, &2);
let mut data = Vec::with_capacity(len);
while let Some(lo) = seq.next_element::<u32>()? {
let mut value = BigDigit::from(lo);
if let Some(hi) = seq.next_element::<u32>()? {
value |= BigDigit::from(hi) << 32;
data.push(value);
} else {
data.push(value);
break;
}
}
Ok(biguint_from_vec(data))
}
);
}