Add support for generics to #[derive(PeekPoke)]

peek-poke-derive/src/peek_poke.rs

@@ -1,12 +1,13 @@
-use crate::{poke_into_expr, peek_from_expr, max_size_expr};
+use crate::{max_size_expr, peek_from_expr, poke_into_expr};
 use proc_macro2::TokenStream;
 use quote::quote;
-use syn::{Data::*, DeriveInput};
+use syn::{parse_quote, Data::*, DeriveInput, GenericParam, Generics};
 
 /// Returns `PeekPoke` trait implementation
 pub fn get_impl(input: DeriveInput) -> TokenStream {
     let name = input.ident;
-
+    let generics = add_peek_poke_trait_bound(input.generics);
+    let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();
     let (max_size, poke_into, peek_from) = match &input.data {
         Struct(ref struct_data) => (
             max_size_expr::for_struct(&struct_data),
@@ -25,12 +26,12 @@ pub fn get_impl(input: DeriveInput) -> TokenStream {
         #[automatically_derived]
         #[allow(unused_qualifications)]
         #[allow(unused)]
-        impl PeekPoke for #name {
+        impl #impl_generics PeekPoke for #name #ty_generics #where_clause {
             #[inline(always)]
             fn max_size() -> usize {
                 #max_size
             }
-            
+
             #[inline(always)]
             fn poke_into(&self, bytes: *mut u8) -> *mut u8 {
                 #poke_into
@@ -43,3 +44,13 @@ pub fn get_impl(input: DeriveInput) -> TokenStream {
         }
     }
 }
+
+// Add a bound `T: PeekPoke` for every type parameter `T`.
+fn add_peek_poke_trait_bound(mut generics: Generics) -> Generics {
+    for param in &mut generics.params {
+        if let GenericParam::Type(ref mut type_param) = *param {
+            type_param.bounds.push(parse_quote!(peek_poke::PeekPoke));
+        }
+    }
+    generics
+}

tests/round_trip.rs

@@ -6,7 +6,9 @@ fn poke_into<V: PeekPoke>(a: &V) -> Vec<u8> {
     let end_ptr = a.poke_into(v.as_mut_ptr());
     let new_size = end_ptr as usize - v.as_ptr() as usize;
     assert!(new_size <= v.capacity());
-    unsafe { v.set_len(new_size); }
+    unsafe {
+        v.set_len(new_size);
+    }
     v
 }
 
@@ -158,6 +160,16 @@ fn test_phantom_data() {
     });
 }
 
+#[test]
+fn test_generic() {
+    #[derive(Debug, PartialEq, Eq, PeekPoke)]
+    struct Foo<T> {
+        x: T,
+        y: T,
+    }
+    the_same(Foo { x: 19.0, y: 42.0 });
+}
+
 #[cfg(feature = "extras")]
 mod extra_tests {
     use super::*;