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#![recursion_limit = "128"]
use inflector::Inflector;
use quote::quote;
use syn::export::{Span, TokenStream2};
use syn::spanned::Spanned;
use syn::{Error, FnArg, Ident, ItemTrait, LitByteStr, LitStr, Pat, TraitItem};
pub fn process_trait(t: &ItemTrait, mod_name: Option<String>) -> syn::Result<TokenStream2> {
let mod_name = mod_name.unwrap_or_else(|| t.ident.to_string().to_snake_case());
let mod_name = Ident::new(&mod_name, Span::call_site());
let mut res = TokenStream2::new();
for item in &t.items {
match item {
TraitItem::Type(_) => {
return Err(Error::new(
item.span(),
"Traits for external contracts do not support associated trait types yet.",
))
}
TraitItem::Method(method) => {
if method.default.is_some() {
return Err(Error::new(
method.span(),
"Traits that are used to describe external contract should not include\
default implementations because this is not a valid use case of traits\
to describe external contracts.",
));
}
let sig = &method.sig;
if sig.unsafety.is_some() {
return Err(Error::new(
method.span(),
"Methods of external contracts are not allowed to be unsafe.",
));
}
if sig.asyncness.is_some() {
return Err(Error::new(
method.span(),
"Methods of external contracts are not allowed to be async.",
));
}
if sig.abi.is_some() {
return Err(Error::new(
method.span(),
"Methods of external contracts are not allowed to have binary interface.",
));
}
if !sig.generics.params.is_empty() {
return Err(Error::new(
method.span(),
"Methods of external contracts are not allowed to have generics.",
));
}
if sig.variadic.is_some() {
return Err(Error::new(
method.span(),
"Methods of external contracts are not allowed to have variadic arguments.",
));
}
let method_name = &sig.ident;
let inputs = &sig.inputs;
let method_name_byte_str =
LitByteStr::new(sig.ident.to_string().as_bytes(), Span::call_site());
let mut arg_to_json = TokenStream2::new();
let mut method_args = TokenStream2::new();
let num_args = inputs.len();
for (i, arg) in inputs.iter().enumerate() {
match arg {
FnArg::Receiver(_) => {}
FnArg::Typed(arg) => {
let arg_name = if let Pat::Ident(arg_name) = arg.pat.as_ref() {
&arg_name.ident
} else {
return Err(Error::new(
arg.span(),
"Unsupported argument name pattern.",
));
};
let arg_name_quoted =
LitStr::new(&arg_name.to_string(), Span::call_site());
arg_to_json.extend(quote! {
#arg_name_quoted: #arg_name
});
method_args.extend(quote! {
#arg ,
});
if i < num_args - 1 {
arg_to_json.extend(quote! {,});
}
}
}
}
if arg_to_json.is_empty() {
arg_to_json = quote! {vec![]};
} else {
arg_to_json = quote! {serde_json::json!({ #arg_to_json }).to_string().as_bytes().to_vec()};
}
res.extend( quote! {
pub fn #method_name<T: ToString>(#method_args __account_id: &T, __balance: Balance, __gas: Gas) -> Promise {
Promise::new(__account_id.to_string())
.function_call(
#method_name_byte_str.to_vec(),
#arg_to_json,
__balance,
__gas,
)
}
});
}
_ => (),
}
}
Ok(quote! {
pub mod #mod_name {
use super::*;
use near_bindgen::{Gas, Balance, AccountId, Promise};
use std::string::ToString;
#res
}
})
}
#[rustfmt::skip]
#[cfg(test)]
mod tests {
use syn::ItemTrait;
use quote::quote;
use crate::process_trait;
#[test]
fn standard() {
let t: ItemTrait = syn::parse2(
quote!{
pub trait ExternalCrossContract {
fn merge_sort(&self, arr: Vec<u8>) -> Vec<u8>;
fn merge(&self) -> Vec<u8>;
}
}
).unwrap();
let actual = process_trait(&t, None).unwrap();
let expected = quote! {
pub mod external_cross_contract {
use super::*;
use near_bindgen::{Gas, Balance, AccountId, Promise};
use std::string::ToString;
pub fn merge_sort<T: ToString>(arr: Vec<u8>, __account_id: &T, __balance: Balance, __gas: Gas) -> Promise {
Promise::new(__account_id.to_string())
.function_call(
b"merge_sort".to_vec(),
serde_json::json!({ "arr": arr }).to_string().as_bytes().to_vec(),
__balance,
__gas,
)
}
pub fn merge<T: ToString>(__account_id: &T, __balance: Balance, __gas: Gas) -> Promise {
Promise::new(__account_id.to_string())
.function_call(
b"merge".to_vec(),
vec![],
__balance,
__gas,
)
}
}
};
assert_eq!(actual.to_string(), expected.to_string());
}
}