chore(zink): introduce interface for contract storage

zink/codegen/src/contract.rs

@@ -0,0 +1,9 @@
+//! derive macro for contract storage
+
+use proc_macro::TokenStream;
+use syn::ItemStruct;
+
+/// Parse the input struct and generate the contract storage
+pub fn parse(input: ItemStruct) -> TokenStream {
+    todo!()
+}

zink/codegen/src/lib.rs

@@ -8,6 +8,7 @@ use proc_macro2::Span;
 use quote::ToTokens;
 use syn::{parse_macro_input, Attribute, DeriveInput, Expr, ItemFn, ItemStruct, LitStr};
 
+mod contract;
 mod event;
 mod revert;
 mod selector;
@@ -33,6 +34,13 @@ pub fn assert(input: TokenStream) -> TokenStream {
     revert::parse_assert(input)
 }
 
+/// Declare contract storage
+#[proc_macro_derive(Contract)]
+pub fn contract(input: TokenStream) -> TokenStream {
+    let input = parse_macro_input!(input as ItemStruct);
+    contract::parse(input)
+}
+
 /// Event logging interface
 ///
 /// ```ignore