Allow to nest structs of arrays

README.md

@@ -138,6 +138,41 @@ for (name, smell, color) in soa_zip!(vec, [name, mut smell, color]) {
 }
 ```
 
+## Nested Struct of Arrays
+
+In order to nest a struct of arrays inside another struct of arrays, one can use the `#[nested_soa]` attribute.
+
+For example, the following code
+
+```rust
+#[derive(StructOfArray)]
+pub struct Point {
+    x: f32,
+    y: f32,
+}
+#[derive(StructOfArray)]
+pub struct Particle {
+    #[nested_soa]
+    point: Point,
+    mass: f32,
+}
+```
+
+will generate structs that looks like this:
+
+```rust
+pub struct PointVec {
+    x: Vec<f32>,
+    y: Vec<f32>,
+}
+pub struct ParticleVec {
+    point: PointVec, // rather than Vec<Point>
+    mass: Vec<f32>
+}
+```
+
+All helper structs will be also nested, for example `PointSlice` will be nested in `ParticleSlice`.
+
 ## Documentation
 
 Please see http://lumol.org/soa-derive/soa_derive_example/ for a small

example/lib.rs

@@ -2,13 +2,14 @@
 //! the code is generated by a single file:
 //!
 //! ```no_run
-//! #[macro_use]
 //! extern crate soa_derive;
-//! # fn main() {
+//! # mod particle {
+//! #[macro_use]
+//! use soa_derive::StructOfArray;
 //!
 //! /// A basic Particle type
 //! #[derive(Debug, PartialEq, StructOfArray)]
-//! #[soa_derive = "Debug, PartialEq"]
+//! #[soa_derive(Debug, PartialEq)]
 //! pub struct Particle {
 //!     /// Mass of the particle
 //!     pub mass: f64,

soa-derive-internal/src/index.rs

@@ -1,19 +1,78 @@
 use proc_macro2::TokenStream;
 use quote::quote;
 
-use crate::input::Input;
+use crate::input::{Input, TokenStreamIterator};
 
 pub fn derive(input: &Input) -> TokenStream {
     let vec_name = &input.vec_name();
-    let slice_name = &input.slice_name();
-    let slice_mut_name = &input.slice_mut_name();
-    let ref_name = &input.ref_name();
-    let ref_mut_name = &input.ref_mut_name();
+    let slice_name = Input::slice_name(&input.name);
+    let slice_mut_name = Input::slice_mut_name(&input.name);
+    let ref_name = Input::ref_name(&input.name);
+    let ref_mut_name = Input::ref_mut_name(&input.name);
     let fields_names = input.fields.iter()
                                    .map(|field| field.ident.clone().unwrap())
                                    .collect::<Vec<_>>();
-    let fields_names_1 = &fields_names;
-    let fields_names_2 = &fields_names;
+
+    let get_unchecked = input.iter_fields().map(
+        |(field_ident, _, is_nested)| {
+            if is_nested {
+                quote! {
+                    #field_ident: self.clone().get_unchecked(slice.#field_ident),
+                }
+            }
+            else {
+                quote! {
+                    #field_ident: slice.#field_ident.get_unchecked(self.clone()),
+                }
+            }
+        },
+    ).concat();
+
+    let get_unchecked_mut = input.iter_fields().map(
+        |(field_ident, _, is_nested)| {
+            if is_nested {
+                quote! {
+                    #field_ident: self.clone().get_unchecked_mut(slice.#field_ident),
+                }
+            }
+            else {
+                quote! {
+                    #field_ident: slice.#field_ident.get_unchecked_mut(self.clone()),
+                }
+            }
+        },
+    ).concat();
+
+    let index = input.iter_fields().map(
+        |(field_ident, _, is_nested)| {
+            if is_nested {
+                quote! {
+                    #field_ident: self.clone().index(slice.#field_ident),
+                }
+            }
+            else {
+                quote! {
+                    #field_ident: & slice.#field_ident[self.clone()],
+                }
+            }
+        },
+    ).concat();
+
+    let index_mut = input.iter_fields().map(
+        |(field_ident, _, is_nested)| {
+            if is_nested {
+                quote! {
+                    #field_ident: self.clone().index_mut(slice.#field_ident),
+                }
+            }
+            else {
+                quote! {
+                    #field_ident: &mut slice.#field_ident[self.clone()],
+                }
+            }
+        },
+    ).concat();
+
     let first_field_name = &fields_names[0];
 
     quote!{
@@ -32,16 +91,12 @@ pub fn derive(input: &Input) -> TokenStream {
 
             #[inline]
             unsafe fn get_unchecked(self, soa: &'a #vec_name) -> Self::RefOutput {
-                #ref_name {
-                    #(#fields_names_1: soa.#fields_names_2.get_unchecked(self),)*
-                }
+                self.get_unchecked(soa.as_slice())
             }
 
             #[inline]
             fn index(self, soa: &'a #vec_name) -> Self::RefOutput {
-                #ref_name {
-                    #(#fields_names_1: & soa.#fields_names_2[self],)*
-                }
+                self.index(soa.as_slice())
             }
         }
 
@@ -59,16 +114,12 @@ pub fn derive(input: &Input) -> TokenStream {
 
             #[inline]
             unsafe fn get_unchecked_mut(self, soa: &'a mut #vec_name) -> Self::MutOutput {
-                #ref_mut_name {
-                    #(#fields_names_1: soa.#fields_names_2.get_unchecked_mut(self),)*
-                }
+                self.get_unchecked_mut(soa.as_mut_slice())
             }
 
             #[inline]
             fn index_mut(self, soa: &'a mut #vec_name) -> Self::MutOutput {
-                #ref_mut_name {
-                    #(#fields_names_1: &mut soa.#fields_names_2[self],)*
-                }
+                self.index_mut(soa.as_mut_slice())
             }
         }
 
@@ -89,16 +140,12 @@ pub fn derive(input: &Input) -> TokenStream {
 
             #[inline]
             unsafe fn get_unchecked(self, soa: &'a #vec_name) -> Self::RefOutput {
-                #slice_name {
-                    #(#fields_names_1: soa.#fields_names_2.get_unchecked(self.clone()),)*
-                }
+                self.get_unchecked(soa.as_slice())
             }
 
             #[inline]
             fn index(self, soa: &'a #vec_name) -> Self::RefOutput {
-                #slice_name {
-                    #(#fields_names_1: & soa.#fields_names_2[self.clone()],)*
-                }
+                self.index(soa.as_slice())
             }
         }
 
@@ -116,16 +163,12 @@ pub fn derive(input: &Input) -> TokenStream {
 
             #[inline]
             unsafe fn get_unchecked_mut(self, soa: &'a mut #vec_name) -> Self::MutOutput {
-                #slice_mut_name {
-                    #(#fields_names_1: soa.#fields_names_2.get_unchecked_mut(self.clone()),)*
-                }
+                self.get_unchecked_mut(soa.as_mut_slice())
             }
 
             #[inline]
             fn index_mut(self, soa: &'a mut #vec_name) -> Self::MutOutput {
-                #slice_mut_name {
-                    #(#fields_names_1: &mut soa.#fields_names_2[self.clone()],)*
-                }
+                self.index_mut(soa.as_mut_slice())
             }
         }
 
@@ -354,14 +397,14 @@ pub fn derive(input: &Input) -> TokenStream {
             #[inline]
             unsafe fn get_unchecked(self, slice: #slice_name<'a>) -> Self::RefOutput {
                 #ref_name {
-                    #(#fields_names_1: slice.#fields_names_2.get_unchecked(self),)*
+                    #get_unchecked
                 }
             }
 
             #[inline]
             fn index(self, slice: #slice_name<'a>) -> Self::RefOutput {
                 #ref_name {
-                    #(#fields_names_1: & slice.#fields_names_2[self],)*
+                    #index
                 }
             }
         }
@@ -381,14 +424,14 @@ pub fn derive(input: &Input) -> TokenStream {
             #[inline]
             unsafe fn get_unchecked_mut(self, slice: #slice_mut_name<'a>) -> Self::MutOutput {
                 #ref_mut_name {
-                    #(#fields_names_1: slice.#fields_names_2.get_unchecked_mut(self),)*
+                    #get_unchecked_mut
                 }
             }
 
             #[inline]
             fn index_mut(self, slice: #slice_mut_name<'a>) -> Self::MutOutput {
                 #ref_mut_name {
-                    #(#fields_names_1: &mut slice.#fields_names_2[self],)*
+                    #index_mut
                 }
             }
         }
@@ -411,14 +454,14 @@ pub fn derive(input: &Input) -> TokenStream {
             #[inline]
             unsafe fn get_unchecked(self, slice: #slice_name<'a>) -> Self::RefOutput {
                 #slice_name {
-                    #(#fields_names_1: slice.#fields_names_2.get_unchecked(self.clone()),)*
+                    #get_unchecked
                 }
             }
 
             #[inline]
             fn index(self, slice: #slice_name<'a>) -> Self::RefOutput {
                 #slice_name {
-                    #(#fields_names_1: & slice.#fields_names_2[self.clone()],)*
+                    #index
                 }
             }
         }
@@ -438,14 +481,14 @@ pub fn derive(input: &Input) -> TokenStream {
             #[inline]
             unsafe fn get_unchecked_mut(self, slice: #slice_mut_name<'a>) -> Self::MutOutput {
                 #slice_mut_name {
-                    #(#fields_names_1: slice.#fields_names_2.get_unchecked_mut(self.clone()),)*
+                    #get_unchecked_mut
                 }
             }
 
             #[inline]
             fn index_mut(self, slice: #slice_mut_name<'a>) -> Self::MutOutput {
                 #slice_mut_name {
-                    #(#fields_names_1: &mut slice.#fields_names_2[self.clone()],)*
+                    #index_mut
                 }
             }
         }