nalgebra/nalgebra-sparse/src/csr/csr_serde.rs

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use crate::CsrMatrix;
use serde::{de, Deserialize, Deserializer, Serialize, Serializer};
/// This is an intermediate type for (de)serializing `CsrMatrix`.
///
/// Deserialization requires using a `try_from_*` function for validation. We could have used
/// the `remote = "Self"` trick (https://github.com/serde-rs/serde/issues/1220) which allows
/// to directly serialize/deserialize the original fields and combine it with validation.
/// However, this would lead to nested serialization of the `CsMatrix` and `SparsityPattern`
/// types. Instead, we decided that we want a more human-readable serialization format using
/// field names like `row_offsets` and `cal_indices`. The easiest way to achieve this is to
/// introduce an intermediate type. It also allows the serialization format to stay constant
/// even if the internal layout in `nalgebra` changes.
///
/// We want to avoid unnecessary copies when serializing (i.e. cloning slices into owned
/// storage). Therefore, we use generic arguments to allow using slices during serialization and
/// owned storage (i.e. `Vec`) during deserialization. Without a major update of serde, slices
/// and `Vec`s should always (de)serialize identically.
#[derive(Serialize, Deserialize)]
struct CsrMatrixSerializationData<Indices, Values> {
nrows: usize,
ncols: usize,
row_offsets: Indices,
col_indices: Indices,
values: Values,
}
impl<T> Serialize for CsrMatrix<T>
where
T: Serialize + Clone,
{
fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
where
S: Serializer,
{
CsrMatrixSerializationData::<&[usize], &[T]> {
nrows: self.nrows(),
ncols: self.ncols(),
row_offsets: self.row_offsets(),
col_indices: self.col_indices(),
values: self.values(),
}
.serialize(serializer)
}
}
impl<'de, T> Deserialize<'de> for CsrMatrix<T>
where
T: Deserialize<'de> + Clone,
{
fn deserialize<D>(deserializer: D) -> Result<CsrMatrix<T>, D::Error>
where
D: Deserializer<'de>,
{
let de = CsrMatrixSerializationData::<Vec<usize>, Vec<T>>::deserialize(deserializer)?;
CsrMatrix::try_from_csr_data(
de.nrows,
de.ncols,
de.row_offsets,
de.col_indices,
de.values,
)
.map_err(|e| de::Error::custom(e))
}
}