Use serde for json configuration file

sbp/Cargo.toml

@@ -11,6 +11,7 @@ packed_simd = "0.3.3"
 rayon = { version = "1.3.0", optional = true }
 sprs = { version = "0.7.1", optional = true }
 num-traits = "0.2.11"
+serde = { version = "1.0.115", optional = true, default-features = false, features = ["derive"] }
 
 [features]
 # Use f32 as precision, default is f64

sbp/src/utils.rs

@@ -8,7 +8,11 @@ pub use jacobi::*;
 mod kronecker_product;
 #[cfg(feature = "sparse")]
 pub use kronecker_product::kronecker_product;
+#[cfg(feature = "serde")]
+use serde::{Deserialize, Serialize};
 
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[derive(Clone, Debug)]
 pub struct Direction<T> {
     pub north: T,
     pub south: T,