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implement bigint serialization #5712

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implement bigint serialization #5712

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9039fe3
implement bigint serialization
arihant2math Apr 18, 2025
35d412b
formatting
arihant2math Apr 18, 2025
9df3c0f
fix some errors
arihant2math Apr 18, 2025
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33 changes: 26 additions & 7 deletions vm/src/py_serde.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -71,14 +71,33 @@ impl serde::Serialize for PyObjectSerializer<'_> {
} else if self.pyobject.fast_isinstance(self.vm.ctx.types.int_type) {
let v = int::get_value(self.pyobject);
let int_too_large = || serde::ser::Error::custom("int too large to serialize");
// TODO: serialize BigInt when it does not fit into i64
// BigInt implements serialization to a tuple of sign and a list of u32s,
// eg. -1 is [-1, [1]], 0 is [0, []], 12345678900000654321 is [1, [2710766577,2874452364]]
// CPython serializes big ints as long decimal integer literals
if v.is_positive() {
serializer.serialize_u64(v.to_u64().ok_or_else(int_too_large)?)

// For backwards-compat
if v.to_u64().is_some() || v.to_i64().is_some() {
if v.is_positive() {
serializer.serialize_u64(v.to_u64().ok_or_else(int_too_large)?)
} else {
serializer.serialize_i64(v.to_i64().ok_or_else(int_too_large)?)
}
} else {
serializer.serialize_i64(v.to_i64().ok_or_else(int_too_large)?)
// BigInt implements serialization to a tuple of sign and a list of u32s,
// eg. -1 is [-1, [1]], 0 is [0, []], 12345678900000654321 is [1, [2710766577,2874452364]]
// CPython serializes big ints as long decimal integer literals

let (sign, mut magnitude) = v.to_bytes_le();
let first = if sign == Sign::Minus { -1 } else { 1 };
let mut u32_list = Vec::new();
for chunk in magnitude.chunks(4) {
let mut n = 0u32;
for (i, byte) in chunk.iter().enumerate() {
n |= (*byte as u32) << (i * 8);
}
u32_list.push(n);
}
let mut seq = serializer.serialize_seq(Some(2))?;
seq.serialize_element(&self.clone_with_object(&self.vm.ctx.new_int(first).into()))?;
seq.serialize_element(&self.clone_with_object(&self.vm.ctx.new_list(u32_list.into_iter().map(|v| &self.vm.ctx.new_int(v).into()).collect())))?;
seq.end()
}
} else if let Some(list) = self.pyobject.payload_if_subclass::<PyList>(self.vm) {
serialize_seq_elements(serializer, &list.borrow_vec())
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