Implement derive macro for Pixel

proc_macros/src/lib.rs

@@ -0,0 +1,68 @@
+use proc_macro::TokenStream;
+
+#[proc_macro_derive(Pixel)]
+pub fn pixel_derive(input: TokenStream) -> TokenStream {
+    let ast: syn::DeriveInput =
+        syn::parse(input).expect("Invalid structure declaration");
+
+    if let syn::Data::Struct(def) = ast.data {
+        if let syn::Fields::Named(fields) = def.fields {
+            let names =
+                fields.named.into_iter().map(|field| field.ident.unwrap());
+            impl_pixel(ast.ident, names.collect())
+        } else {
+            panic!("Can only derive Pixel for named fields")
+        }
+    } else {
+        panic!("Can only derive Pixel for a struct")
+    }
+}
+
+fn impl_pixel(name: syn::Ident, fields: Vec<syn::Ident>) -> TokenStream {
+    quote::quote! {
+        impl std::ops::AddAssign for #name {
+            fn add_assign(&mut self, other: Self) {
+                #( self.#fields += other.#fields; )*
+            }
+        }
+
+		impl std::ops::MulAssign<f32> for #name {
+			fn mul_assign(&mut self, scalar: f32) {
+				#( self.#fields *= scalar; )*
+			}
+		}
+
+		impl std::ops::DivAssign<f32> for #name {
+			fn div_assign(&mut self, scalar: f32) {
+				#( self.#fields /= scalar; )*
+			}
+		}
+
+		impl std::ops::Mul<f32> for #name {
+			type Output = Self;
+
+			fn mul(mut self, scalar: f32) -> Self {
+				self *= scalar;
+				self
+			}
+		}
+
+		impl std::ops::Div<f32> for #name {
+			type Output = Self;
+
+			fn div(mut self, scalar: f32) -> Self {
+				self /= scalar;
+				self
+			}
+		}
+
+		impl std::default::Default for #name {
+			fn default() -> Self {
+				Self {
+					#( #fields: Default::default(), )*
+				}
+			}
+		}
+    }
+    .into()
+}