Add ContractArgs for building function args

Cargo.toml

@@ -48,10 +48,10 @@ features = ["curr"]
 #git = "https://github.com/stellar/rs-stellar-xdr"
 #rev = "67be5955a15f1d3a4df83fe86e6ae107f687141b"
 
-#[patch."https://github.com/stellar/rs-soroban-env"]
-#soroban-env-common = { path = "../rs-soroban-env/soroban-env-common" }
-#soroban-env-guest = { path = "../rs-soroban-env/soroban-env-guest" }
-#soroban-env-host = { path = "../rs-soroban-env/soroban-env-host" }
+[patch.crates-io]
+soroban-env-common = { path = "../rs-soroban-env/soroban-env-common" }
+soroban-env-guest = { path = "../rs-soroban-env/soroban-env-guest" }
+soroban-env-host = { path = "../rs-soroban-env/soroban-env-host" }
 #[patch."https://github.com/stellar/rs-stellar-xdr"]
 #stellar-xdr = { path = "../rs-stellar-xdr/" }
 

soroban-sdk-macros/src/derive_args.rs

@@ -0,0 +1,92 @@
+use proc_macro2::{Span, TokenStream};
+use quote::{format_ident, quote};
+use syn::{Error, FnArg, Lifetime, Path, Type, TypePath, TypeReference};
+
+use crate::syn_ext;
+
+pub fn derive_args_type(ty: &str, name: &str) -> TokenStream {
+    let ty_str = quote!(#ty).to_string();
+    // Render the Client.
+    let args_doc = format!("{name} is a type for buildings function args defined in {ty_str}.");
+    let args_ident = format_ident!("{}", name);
+    quote! {
+        #[doc = #args_doc]
+        pub struct #args_ident;
+    }
+}
+
+pub fn derive_args_impl(crate_path: &Path, name: &str, fns: &[syn_ext::Fn]) -> TokenStream {
+    // Map the traits methods to methods for the Args.
+    let mut errors = Vec::<Error>::new();
+    let fns: Vec<_> = fns
+        .iter()
+        .map(|f| {
+            let fn_ident = &f.ident;
+
+            // Check for the Env argument.
+            let env_input = f.inputs.first().and_then(|a| match a {
+                FnArg::Typed(pat_type) => {
+                    let mut ty = &*pat_type.ty;
+                    if let Type::Reference(TypeReference { elem, .. }) = ty {
+                        ty = elem;
+                    }
+                    if let Type::Path(TypePath {
+                        path: syn::Path { segments, .. },
+                        ..
+                    }) = ty
+                    {
+                        if segments.last().map_or(false, |s| s.ident == "Env") {
+                            Some(())
+                        } else {
+                            None
+                        }
+                    } else {
+                        None
+                    }
+                }
+                FnArg::Receiver(_) => None,
+            });
+
+            // Map all remaining inputs.
+            let fn_input_lifetime = Lifetime::new("'i", Span::call_site());
+            let (fn_input_names, fn_input_types): (Vec<_>, Vec<_>) = f
+                .inputs
+                .iter()
+                .skip(if env_input.is_some() { 1 } else { 0 })
+                .map(|t| {
+                    let ident = match syn_ext::fn_arg_ident(t) {
+                        Ok(ident) => ident,
+                        Err(e) => {
+                            errors.push(e);
+                            format_ident!("_")
+                        }
+                    };
+                    (ident, syn_ext::fn_arg_make_ref(t, Some(&fn_input_lifetime)))
+                })
+                .unzip();
+
+            quote! {
+                // TODO: Make the fn_input_types an impl Borrow
+                pub fn #fn_ident<#fn_input_lifetime>(#(#fn_input_types),*)
+                    -> impl #crate_path::IntoVal<#crate_path::Env, #crate_path::Vec<#crate_path::Val>> + #fn_input_lifetime
+                {
+                    (#(#fn_input_names,)*)
+                }
+            }
+        })
+        .collect();
+
+    // If errors have occurred, render them instead.
+    if !errors.is_empty() {
+        let compile_errors = errors.iter().map(Error::to_compile_error);
+        return quote! { #(#compile_errors)* };
+    }
+
+    // Render the Client.
+    let args_ident = format_ident!("{}", name);
+    quote! {
+        impl #args_ident {
+            #(#fns)*
+        }
+    }
+}

soroban-sdk-macros/src/derive_client.rs

@@ -192,7 +192,7 @@ pub fn derive_client_impl(crate_path: &Path, name: &str, fns: &[syn_ext::Fn]) ->
                             format_ident!("_")
                         }
                     };
-                    (ident, syn_ext::fn_arg_make_ref(t))
+                    (ident, syn_ext::fn_arg_make_ref(t, None))
                 })
                 .unzip();
             let fn_output = f.output();

soroban-sdk-macros/src/lib.rs

@@ -1,6 +1,7 @@
 extern crate proc_macro;
 
 mod arbitrary;
+mod derive_args;
 mod derive_client;
 mod derive_enum;
 mod derive_enum_int;
@@ -15,6 +16,7 @@ mod path;
 mod symbol;
 mod syn_ext;
 
+use derive_args::{derive_args_impl, derive_args_type};
 use derive_client::{derive_client_impl, derive_client_type};
 use derive_enum::derive_type_enum;
 use derive_enum_int::derive_type_enum_int;
@@ -136,8 +138,11 @@ pub fn contract(metadata: TokenStream, input: TokenStream) -> TokenStream {
     let fn_set_registry_ident = format_ident!("__{}_fn_set_registry", ty_str.to_lowercase());
     let crate_path = &args.crate_path;
     let client = derive_client_type(&args.crate_path, &ty_str, &client_ident);
+    let args_ident = format!("{ty_str}Args");
+    let contract_args = derive_args_type(&ty_str, &args_ident);
     let mut output = quote! {
         #input2
+        #contract_args
         #client
     };
     if cfg!(feature = "testutils") {
@@ -206,6 +211,18 @@ pub fn contractimpl(metadata: TokenStream, input: TokenStream) -> TokenStream {
     let ty = &imp.self_ty;
     let ty_str = quote!(#ty).to_string();
 
+    // TODO: Use imp.trait_ in generating the args ident, to create a unique
+    // args for each trait impl for a contract, to avoid conflicts.
+    let args_ident = if let Type::Path(path) = &**ty {
+        path.path
+            .segments
+            .last()
+            .map(|name| format!("{}Args", name.ident))
+    } else {
+        None
+    }
+    .unwrap_or_else(|| "Args".to_string());
+
     // TODO: Use imp.trait_ in generating the client ident, to create a unique
     // client for each trait impl for a contract, to avoid conflicts.
     let client_ident = if let Type::Path(path) = &**ty {
@@ -239,6 +256,7 @@ pub fn contractimpl(metadata: TokenStream, input: TokenStream) -> TokenStream {
     match derived {
         Ok(derived_ok) => {
             let mut output = quote! {
+                #[#crate_path::contractargs(crate_path = #crate_path_str, name = #args_ident, impl_only = true)]
                 #[#crate_path::contractclient(crate_path = #crate_path_str, name = #client_ident, impl_only = true)]
                 #[#crate_path::contractspecfn(name = #ty_str)]
                 #imp
@@ -533,6 +551,40 @@ pub fn contractfile(metadata: TokenStream) -> TokenStream {
     quote! { #contents_lit }.into()
 }
 
+#[derive(Debug, FromMeta)]
+struct ContractArgsArgs {
+    #[darling(default = "default_crate_path")]
+    crate_path: Path,
+    name: String,
+    #[darling(default)]
+    impl_only: bool,
+}
+
+#[proc_macro_attribute]
+pub fn contractargs(metadata: TokenStream, input: TokenStream) -> TokenStream {
+    let args = match NestedMeta::parse_meta_list(metadata.into()) {
+        Ok(v) => v,
+        Err(e) => {
+            return TokenStream::from(darling::Error::from(e).write_errors());
+        }
+    };
+    let args = match ContractArgsArgs::from_list(&args) {
+        Ok(v) => v,
+        Err(e) => return e.write_errors().into(),
+    };
+    let input2: TokenStream2 = input.clone().into();
+    let item = parse_macro_input!(input as HasFnsItem);
+    let methods: Vec<_> = item.fns();
+    let args_type = (!args.impl_only).then(|| derive_args_type(&item.name(), &args.name));
+    let args_impl = derive_args_impl(&args.crate_path, &args.name, &methods);
+    quote! {
+        #input2
+        #args_type
+        #args_impl
+    }
+    .into()
+}
+
 #[derive(Debug, FromMeta)]
 struct ContractClientArgs {
     #[darling(default = "default_crate_path")]

soroban-sdk-macros/src/syn_ext.rs

@@ -9,7 +9,7 @@ use syn::{
 };
 use syn::{
     spanned::Spanned, token::And, Error, FnArg, Ident, ImplItem, ImplItemFn, ItemImpl, ItemTrait,
-    Pat, PatType, TraitItem, TraitItemFn, Type, TypeReference, Visibility,
+    Lifetime, Pat, PatType, TraitItem, TraitItemFn, Type, TypeReference, Visibility,
 };
 
 /// Gets methods from the implementation that have public visibility. For
@@ -49,7 +49,7 @@ pub fn fn_arg_ident(arg: &FnArg) -> Result<Ident, Error> {
 
 /// Returns a clone of FnArg with the type as a reference if the arg is a typed
 /// arg and its type is not already a reference.
-pub fn fn_arg_make_ref(arg: &FnArg) -> FnArg {
+pub fn fn_arg_make_ref(arg: &FnArg, lifetime: Option<&Lifetime>) -> FnArg {
     if let FnArg::Typed(pat_type) = arg {
         if !matches!(*pat_type.ty, Type::Reference(_)) {
             return FnArg::Typed(PatType {
@@ -58,7 +58,7 @@ pub fn fn_arg_make_ref(arg: &FnArg) -> FnArg {
                 colon_token: pat_type.colon_token,
                 ty: Box::new(Type::Reference(TypeReference {
                     and_token: And::default(),
-                    lifetime: None,
+                    lifetime: lifetime.cloned(),
                     mutability: None,
                     elem: pat_type.ty.clone(),
                 })),

soroban-sdk/src/lib.rs

@@ -593,6 +593,11 @@ pub use soroban_sdk_macros::contractmeta;
 /// ```
 pub use soroban_sdk_macros::contracttype;
 
+/// Generates a type that helps build function args for a contract trait.
+///
+/// TODO: Docs and examples.
+pub use soroban_sdk_macros::contractargs;
+
 /// Generates a client for a contract trait.
 ///
 /// Can be used to create clients for contracts that live outside the current

soroban-spec-rust/src/lib.rs

@@ -89,6 +89,7 @@ pub fn generate_without_file(specs: &[ScSpecEntry]) -> TokenStream {
     let error_enums = spec_error_enums.iter().map(|s| generate_error_enum(s));
 
     quote! {
+        #[soroban_sdk::contractargs(name = "Args")]
         #[soroban_sdk::contractclient(name = "Client")]
         #trait_
 

tests/constructor/src/lib.rs

@@ -37,7 +37,7 @@ impl Contract {
 #[test]
 fn test_constructor() {
     let env = Env::default();
-    let contract_id = env.register(Contract, (100_u32, 1000_i64));
+    let contract_id = env.register(Contract, ContractArgs::__constructor(100_u32, 1000_i64));
     let client = ContractClient::new(&env, &contract_id);
     assert_eq!(client.get_data(&DataKey::Persistent(100)), Some(1000));
     assert_eq!(client.get_data(&DataKey::Temp(200)), Some(2000));