[abi] Improve JSON encoding of selectors + layout key (#207)

* Export selector as hex string

To have an unambiguous exported representation.
The previously used `u32` can be interpreted
differently depending on the endianness of the
target system.

* Improve JSON encoding of Key `layout` in Metadata

* Add tests for selector serialization

* Encode selector as [u8; 4]

* Remove unused import

* Satisfy rustfmt check

* Improve messages! macro

* Convert tabs to spaces.
* Replace `DELIMITER` with `@delimiter`.
* Improve comments.

* Improve comment

* Ensure old ABI format stays the same

* Reduce code duplication by introducing selector_to_expr()

* Satisfy rustfmt

abi/Cargo.toml

@@ -19,6 +19,9 @@ derive_more = { version = "0.15", default-features = false, features = ["no_std"
 ink_abi_derive = { version = "0.1.0", path = "derive", default-features = false, optional = true }
 type-metadata = { git = "https://github.com/type-metadata/type-metadata.git", default-features = false, features = ["derive"] }
 
+[dev-dependencies]
+serde_json = "1.0"
+
 [features]
 default = [
     "std",

abi/src/layout.rs

@@ -15,7 +15,11 @@
 // along with ink!.  If not, see <http://www.gnu.org/licenses/>.
 
 use derive_more::From;
-use serde::Serialize;
+use serde::{
+    Serialize,
+    Serializer,
+};
+use std::fmt::Write;
 use type_metadata::{
     form::{
         CompactForm,
@@ -158,7 +162,7 @@ impl IntoCompact for LayoutField {
 #[serde(bound = "F::TypeId: Serialize")]
 pub struct LayoutRange<F: Form = MetaForm> {
     /// The single key for cells or the starting key address for chunks.
-    #[serde(rename = "range.offset")]
+    #[serde(rename = "range.offset", serialize_with = "serialize_key")]
     offset: LayoutKey,
     /// The amount of associated key addresses starting from the offset key.
     #[serde(rename = "range.len")]
@@ -205,3 +209,52 @@ impl LayoutRange {
         }
     }
 }
+
+fn serialize_key<S>(key: &LayoutKey, serializer: S) -> Result<S::Ok, S::Error>
+where
+    S: Serializer,
+{
+    let bytes = key.0;
+    let mut hex = String::with_capacity(bytes.len() * 2 + 2);
+    write!(hex, "0x").expect("failed writing to string");
+    for byte in &bytes {
+        write!(hex, "{:02x}", byte).expect("failed writing to string");
+    }
+
+    serializer.serialize_str(&hex)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use type_metadata::{
+        form::{
+            Form,
+            MetaForm,
+        },
+        IntoCompact,
+        Registry,
+    };
+
+    #[test]
+    fn key_must_serialize_to_hex() {
+        // given
+        let type_id = <MetaForm as Form>::TypeId::new::<u32>();
+        let offset = LayoutKey([1; 32]);
+        let cs: LayoutRange<MetaForm> = LayoutRange {
+            offset,
+            len: 1337,
+            elem_ty: type_id,
+        };
+        let mut registry = Registry::new();
+
+        // when
+        let json = serde_json::to_string(&cs.into_compact(&mut registry)).unwrap();
+
+        // then
+        assert_eq!(
+            json,
+            "{\"range.offset\":\"0x0101010101010101010101010101010101010101010101010101010101010101\",\"range.len\":1337,\"range.elem_type\":1}"
+        );
+    }
+}

abi/src/specs.rs

@@ -15,7 +15,10 @@
 // along with ink!.  If not, see <http://www.gnu.org/licenses/>.
 
 use core::marker::PhantomData;
-use serde::Serialize;
+use serde::{
+    Serialize,
+    Serializer,
+};
 use type_metadata::{
     form::{
         CompactForm,
@@ -190,7 +193,8 @@ pub struct ConstructorSpec<F: Form = MetaForm> {
     /// The name of the message.
     name: F::String,
     /// The selector hash of the message.
-    selector: u32,
+    #[serde(serialize_with = "serialize_selector")]
+    selector: [u8; 4],
     /// The parameters of the deploy handler.
     args: Vec<MessageParamSpec<F>>,
     /// The deploy handler documentation.
@@ -234,7 +238,7 @@ impl ConstructorSpec {
         ConstructorSpecBuilder {
             spec: Self {
                 name,
-                selector: 0,
+                selector: [0u8; 4],
                 args: Vec::new(),
                 docs: Vec::new(),
             },
@@ -245,7 +249,7 @@ impl ConstructorSpec {
 
 impl ConstructorSpecBuilder<Missing<state::Selector>> {
     /// Sets the function selector of the message.
-    pub fn selector(self, selector: u32) -> ConstructorSpecBuilder<state::Selector> {
+    pub fn selector(self, selector: [u8; 4]) -> ConstructorSpecBuilder<state::Selector> {
         ConstructorSpecBuilder {
             spec: ConstructorSpec {
                 selector,
@@ -294,7 +298,8 @@ pub struct MessageSpec<F: Form = MetaForm> {
     /// The name of the message.
     name: F::String,
     /// The selector hash of the message.
-    selector: u32,
+    #[serde(serialize_with = "serialize_selector")]
+    selector: [u8; 4],
     /// If the message is allowed to mutate the contract state.
     mutates: bool,
     /// The parameters of the message.
@@ -333,7 +338,7 @@ impl MessageSpec {
         MessageSpecBuilder {
             spec: Self {
                 name,
-                selector: 0,
+                selector: [0u8; 4],
                 mutates: false,
                 args: Vec::new(),
                 return_type: ReturnTypeSpec::new(None),
@@ -358,7 +363,10 @@ pub struct MessageSpecBuilder<Selector, Mutates, Returns> {
 
 impl<M, R> MessageSpecBuilder<Missing<state::Selector>, M, R> {
     /// Sets the function selector of the message.
-    pub fn selector(self, selector: u32) -> MessageSpecBuilder<state::Selector, M, R> {
+    pub fn selector(
+        self,
+        selector: [u8; 4],
+    ) -> MessageSpecBuilder<state::Selector, M, R> {
         MessageSpecBuilder {
             spec: MessageSpec {
                 selector,
@@ -795,3 +803,38 @@ impl MessageParamSpecBuilder {
         self.spec
     }
 }
+
+fn serialize_selector<S>(s: &[u8; 4], serializer: S) -> Result<S::Ok, S::Error>
+where
+    S: Serializer,
+{
+    let hex = format!("0x{:02X}{:02X}{:02X}{:02X}", s[0], s[1], s[2], s[3]);
+    serializer.serialize_str(&hex)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn construct_selector_must_serialize_to_hex() {
+        // given
+        let name = <MetaForm as Form>::String::from("foo");
+        let cs: ConstructorSpec<MetaForm> = ConstructorSpec {
+            name,
+            selector: 123456789u32.to_be_bytes(),
+            args: Vec::new(),
+            docs: Vec::new(),
+        };
+        let mut registry = Registry::new();
+
+        // when
+        let json = serde_json::to_string(&cs.into_compact(&mut registry)).unwrap();
+
+        // then
+        assert_eq!(
+            json,
+            "{\"name\":1,\"selector\":\"0x075BCD15\",\"args\":[],\"docs\":[]}"
+        );
+    }
+}

core/src/env/calls.rs

@@ -40,10 +40,9 @@ struct CallAbi {
 
 impl CallAbi {
     /// Creates new call ABI data for the given selector.
-    pub fn new(selector: u32) -> Self {
-        let bytes = selector.to_le_bytes();
+    pub fn new(selector: [u8; 4]) -> Self {
         Self {
-            raw: vec![bytes[0], bytes[1], bytes[2], bytes[3]],
+            raw: vec![selector[0], selector[1], selector[2], selector[3]],
         }
     }
 
@@ -177,7 +176,7 @@ where
     E::Balance: Default,
 {
     /// Instantiates an evaluatable (returns data) remote smart contract call.
-    pub fn eval(account_id: E::AccountId, selector: u32) -> Self {
+    pub fn eval(account_id: E::AccountId, selector: [u8; 4]) -> Self {
         Self {
             account_id,
             gas_limit: 0,
@@ -194,7 +193,7 @@ where
     E::Balance: Default,
 {
     /// Instantiates a non-evaluatable (returns no data) remote smart contract call.
-    pub fn invoke(account_id: E::AccountId, selector: u32) -> Self {
+    pub fn invoke(account_id: E::AccountId, selector: [u8; 4]) -> Self {
         Self {
             account_id,
             gas_limit: 0,

lang/src/gen/abi.rs

@@ -21,6 +21,7 @@
 
 use crate::{
     ast,
+    gen::selector_to_expr,
     hir,
 };
 use proc_macro2::TokenStream as TokenStream2;
@@ -121,7 +122,7 @@ fn generate_abi_constructor(contract: &hir::Contract) -> TokenStream2 {
 
     quote! {
         ink_abi::ConstructorSpec::new("on_deploy")
-            .selector(0)
+            .selector([0u8; 4])
             .args(vec![
                 #(#args ,)*
             ])
@@ -136,7 +137,7 @@ fn generate_abi_messages<'a>(
     contract: &'a hir::Contract,
 ) -> impl Iterator<Item = TokenStream2> + 'a {
     contract.messages.iter().map(|message| {
-        let selector = message.selector();
+        let selector = selector_to_expr(message.selector());
         let is_mut = message.is_mut();
         let docs = message.docs().map(trim_doc_string);
         let name = message.sig.ident.to_string();

lang/src/gen/as_dependency.rs

@@ -24,6 +24,7 @@
 
 use crate::{
     ast,
+    gen::selector_to_expr,
     hir,
 };
 use proc_macro2::TokenStream as TokenStream2;
@@ -236,7 +237,7 @@ fn generate_call_enhancer_messages<'a>(
                 .map(|ident| quote! { #ident });
             let output = &message.sig.decl.output;
             let (_impl_generics, type_generics, where_clause) = message.sig.decl.generics.split_for_impl();
-            let selector = message.selector();
+            let selector = selector_to_expr(message.selector());
             match output {
                 syn::ReturnType::Default => quote_spanned! { ident.span() =>
                     #(#attrs)*

lang/src/gen/build.rs

@@ -21,11 +21,11 @@
 
 use crate::{
     ast,
+    gen::selector_to_expr,
     hir,
 };
 use proc_macro2::{
     Ident,
-    Span,
     TokenStream as TokenStream2,
 };
 use quote::{
@@ -473,12 +473,7 @@ fn codegen_for_messages(tokens: &mut TokenStream2, contract: &hir::Contract) {
             for attr in &message.attrs {
                 attr.to_tokens(&mut content)
             }
-            let msg_selector = message.selector();
-            let msg_id = syn::LitInt::new(
-                msg_selector.into(),
-                syn::IntSuffix::None,
-                Span::call_site(),
-            );
+            let msg_id = selector_to_expr(message.selector());
             msg_id.to_tokens(&mut content);
             <Token![=>]>::default().to_tokens(&mut content);
             use heck::CamelCase as _;

lang/src/gen/mod.rs

@@ -23,6 +23,10 @@ mod test;
 use crate::hir;
 use proc_macro2::TokenStream as TokenStream2;
 use quote::quote;
+use syn::{
+    parse_str,
+    Expr,
+};
 
 /// Generates code for the given contract.
 ///
@@ -39,3 +43,13 @@ pub fn generate_code(contract: &hir::Contract) -> TokenStream2 {
     as_dependency::generate_code(&mut tokens, contract);
     tokens
 }
+
+/// The function is required because syn doesn't provide a
+/// `ToTokens` implementation for `[u8; 4]`.
+fn selector_to_expr(selector: [u8; 4]) -> Expr {
+    let selector = format!(
+        "[{}, {}, {}, {}]",
+        selector[0], selector[1], selector[2], selector[3]
+    );
+    parse_str::<syn::Expr>(&selector).expect("failed to parse selector")
+}

lang/src/hir.rs

@@ -507,14 +507,14 @@ impl Message {
     }
 
     /// Returns the message selector for this message.
-    pub fn selector(&self) -> u32 {
+    pub fn selector(&self) -> [u8; 4] {
         raw_message_selector(self.sig.ident.to_string().as_str())
     }
 }
 
-fn raw_message_selector(name: &str) -> u32 {
+fn raw_message_selector(name: &str) -> [u8; 4] {
     let keccak = ink_utils::hash::keccak256(name.as_bytes());
-    u32::from_le_bytes([keccak[0], keccak[1], keccak[2], keccak[3]])
+    [keccak[3], keccak[2], keccak[1], keccak[0]]
 }
 
 impl From<&ast::ItemImplMethod> for Message {
@@ -570,8 +570,8 @@ mod tests {
 
     #[test]
     fn message_selectors() {
-        assert_eq!(raw_message_selector("inc"), 257544423);
-        assert_eq!(raw_message_selector("get"), 4266279973);
-        assert_eq!(raw_message_selector("compare"), 363906316);
+        assert_eq!(raw_message_selector("inc"), [15, 89, 208, 231]);
+        assert_eq!(raw_message_selector("get"), [254, 74, 68, 37]);
+        assert_eq!(raw_message_selector("compare"), [21, 176, 197, 12]);
     }
 }

lang/src/old_abi.rs

@@ -478,9 +478,11 @@ impl TryFrom<&hir::Message> for MessageDescription {
     type Error = syn::Error;
 
     fn try_from(message: &hir::Message) -> Result<Self> {
+        let s = message.selector();
+        let selector = u32::from_le_bytes([s[3], s[2], s[1], s[0]]).into();
         Ok(Self {
             name: message.sig.ident.to_string(),
-            selector: message.selector().into(),
+            selector,
             mutates: message.is_mut(),
             args: {
                 message

lang/src/tests/events.rs

@@ -115,13 +115,13 @@ fn contract_compiles() {
                         /// # Note
                         ///
                         /// Also emits an event.
-                        257544423 => Inc();
+                        [15, 89, 208, 231] => Inc();
                         /// Decrements the internal counter.
                         ///
                         /// # Note
                         ///
                         /// Also emits an event.
-                        1772705147 => Dec();
+                        [105, 169, 85, 123] => Dec();
                     }
                 }
 
@@ -310,14 +310,14 @@ fn contract_compiles() {
                     ink_abi::ContractSpec::new("CallCounter")
                         .constructors(vec![
                             ink_abi::ConstructorSpec::new("on_deploy")
-                                .selector(0)
+                                .selector([0u8; 4])
                                 .args(vec![])
                                 .docs(vec![])
                                 .done()
                         ])
                         .messages(vec![
                             ink_abi::MessageSpec::new("inc")
-                                .selector(257544423u32)
+                                .selector([15, 89, 208, 231])
                                 .mutates(true)
                                 .args(vec![])
                                 .docs(vec![
@@ -332,7 +332,7 @@ fn contract_compiles() {
                                 )
                                 .done(),
                             ink_abi::MessageSpec::new("dec")
-                                .selector(1772705147u32)
+                                .selector([105, 169, 85, 123])
                                 .mutates(true)
                                 .args(vec![])
                                 .docs(vec![
@@ -496,7 +496,7 @@ fn contract_compiles() {
                     /// Also emits an event.
                     pub fn inc(self,) -> ink_core::env::CallBuilder<Env, ()> {
                         ink_core::env::CallBuilder::<Env, ()>::invoke(
-                            self.contract.account_id.clone(), 257544423u32)
+                            self.contract.account_id.clone(), [15, 89, 208, 231])
                     }
 
                     /// Decrements the internal counter.
@@ -506,7 +506,7 @@ fn contract_compiles() {
                     /// Also emits an event.
                     pub fn dec(self,) -> ink_core::env::CallBuilder<Env, ()> {
                         ink_core::env::CallBuilder::<Env, ()>::invoke(
-                            self.contract.account_id.clone(), 1772705147u32)
+                            self.contract.account_id.clone(), [105, 169, 85, 123])
                     }
                 }
             }

lang/src/tests/flipper.rs

@@ -90,9 +90,9 @@ fn contract_compiles() {
 
                     ink_model::messages! {
                         /// Flips the internal boolean.
-                        970692492 => Flip();
+                        [57, 219, 151, 140] => Flip();
                         /// Returns the internal boolean.
-                        4266279973 => Get() -> bool;
+                        [254, 74, 68, 37] => Get() -> bool;
                     }
                 }
 
@@ -208,7 +208,7 @@ fn contract_compiles() {
                     ink_abi::ContractSpec::new("Flipper")
                         .constructors(vec![
                             ink_abi::ConstructorSpec::new("on_deploy")
-                                .selector(0)
+                                .selector([0u8; 4])
                                 .args(vec![])
                                 .docs(vec![
                                     "The internal boolean is initialized with `true`.",
@@ -217,14 +217,14 @@ fn contract_compiles() {
                         ])
                         .messages(vec![
                             ink_abi::MessageSpec::new("flip")
-                                .selector(970692492u32)
+                                .selector([57, 219, 151, 140])
                                 .mutates(true)
                                 .args(vec![])
                                 .docs(vec!["Flips the internal boolean.",])
                                 .returns(ink_abi::ReturnTypeSpec::new(None))
                                 .done(),
                             ink_abi::MessageSpec::new("get")
-                                .selector(4266279973u32)
+                                .selector([254, 74, 68, 37])
                                 .mutates(false)
                                 .args(vec![])
                                 .docs(vec!["Returns the internal boolean.",])
@@ -345,7 +345,7 @@ fn contract_compiles() {
                     /// Returns the internal boolean.
                     pub fn get(self,) -> ink_core::env::CallBuilder<Env, ink_core::env::ReturnType<bool>> {
                         ink_core::env::CallBuilder::eval(
-                            self.contract.account_id.clone(), 4266279973u32
+                            self.contract.account_id.clone(), [254, 74, 68, 37]
                         )
                     }
                 }
@@ -354,7 +354,7 @@ fn contract_compiles() {
                     /// Flips the internal boolean.
                     pub fn flip(self,) -> ink_core::env::CallBuilder<Env, ()> {
                         ink_core::env::CallBuilder::<Env, ()>::invoke(
-                            self.contract.account_id.clone(), 970692492u32)
+                            self.contract.account_id.clone(), [57, 219, 151, 140])
                     }
                 }
             }

lang/src/tests/incrementer.rs

@@ -97,11 +97,11 @@ fn contract_compiles() {
 
                     ink_model::messages! {
                         /// Increments the internal counter.
-                        257544423 => Inc(by: u32);
+                        [15, 89, 208, 231] => Inc(by: u32);
                         /// Returns the internal counter.
-                        4266279973 => Get() -> u32;
+                        [254, 74, 68, 37] => Get() -> u32;
                         /// Returns `true` if `x` is greater than the internal value.
-                        363906316 => Compare(x: u32) -> bool;
+                        [21, 176, 197, 12] => Compare(x: u32) -> bool;
                     }
                 }
 
@@ -231,7 +231,7 @@ fn contract_compiles() {
                     ink_abi::ContractSpec::new("Incrementer")
                         .constructors(vec![
                             ink_abi::ConstructorSpec::new("on_deploy")
-                                .selector(0)
+                                .selector([0u8; 4])
                                 .args(vec![
                                     ink_abi::MessageParamSpec::new("init_value")
                                         .of_type(
@@ -248,7 +248,7 @@ fn contract_compiles() {
                         ])
                         .messages(vec![
                             ink_abi::MessageSpec::new("inc")
-                                .selector(257544423u32)
+                                .selector([15, 89, 208, 231])
                                 .mutates(true)
                                 .args(vec![
                                     ink_abi::MessageParamSpec::new("by")
@@ -267,7 +267,7 @@ fn contract_compiles() {
                                 )
                                 .done(),
                             ink_abi::MessageSpec::new("get")
-                                .selector(4266279973u32)
+                                .selector([254, 74, 68, 37])
                                 .mutates(false)
                                 .args(vec![])
                                 .docs(vec![
@@ -282,7 +282,7 @@ fn contract_compiles() {
                                 )
                                 .done(),
                             ink_abi::MessageSpec::new("compare")
-                                .selector(363906316u32)
+                                .selector([21, 176, 197, 12])
                                 .mutates(false)
                                 .args(vec![
                                     ink_abi::MessageParamSpec::new("x")
@@ -432,7 +432,7 @@ fn contract_compiles() {
                     /// Returns the internal counter.
                     pub fn get(self,) -> ink_core::env::CallBuilder<Env, ink_core::env::ReturnType<u32>> {
                         ink_core::env::CallBuilder::eval(
-                            self.contract.account_id.clone(), 4266279973u32
+                            self.contract.account_id.clone(), [254, 74, 68, 37]
                         )
                     }
 
@@ -443,7 +443,7 @@ fn contract_compiles() {
                                 .contract
                                 .account_id
                                 .clone(),
-                            363906316u32
+                            [21, 176, 197, 12]
                         ).push_arg(&x)
                     }
                 }
@@ -452,7 +452,7 @@ fn contract_compiles() {
                     /// Increments the internal counter.
                     pub fn inc(self, by: u32,) -> ink_core::env::CallBuilder<Env, ()> {
                         ink_core::env::CallBuilder::<Env, ()>::invoke(
-                            self.contract.account_id.clone(), 257544423u32
+                            self.contract.account_id.clone(), [15, 89, 208, 231]
                         ).push_arg(&by)
                     }
                 }

lang/src/tests/noop.rs

@@ -164,7 +164,7 @@ fn contract_compiles() {
                     ink_abi::ContractSpec::new("Noop")
                         .constructors(vec![
                             ink_abi::ConstructorSpec::new("on_deploy")
-                                .selector(0)
+                                .selector([0u8; 4])
                                 .args(vec![])
                                 .docs(vec![
                                     "Does nothing to initialize itself.",

model/src/msg.rs

@@ -40,44 +40,122 @@ pub trait Message {
 /// Defines messages for contracts with less boilerplate code.
 #[macro_export]
 macro_rules! messages {
-	(
-		$( #[$msg_meta:meta] )*
-		$msg_id:literal => $msg_name:ident (
-			$( $param_name:ident : $param_ty:ty ),*
-		) -> $ret_ty:ty ;
-
-		$($rest:tt)*
-	) => {
-		$( #[$msg_meta] )*
-		#[derive(Copy, Clone)]
-		pub(crate) struct $msg_name;
-
-		impl $crate::Message for $msg_name {
-			type Input = ($($param_ty),*);
-			type Output = $ret_ty;
-
-			const ID: $crate::MessageHandlerSelector = $crate::MessageHandlerSelector::new($msg_id);
-			const NAME: &'static str = stringify!($msg_name);
-		}
-
-		messages!($($rest)*);
-	};
-	(
-		$( #[$msg_meta:meta] )*
-		$msg_id:literal => $msg_name:ident (
-			$( $param_name:ident : $param_ty:ty ),*
-		) ;
-
-		$($rest:tt)*
-	) => {
-		messages!(
-			$( #[$msg_meta] )*
-			$msg_id => $msg_name (
-				$( $param_name : $param_ty ),*
-			) -> ();
-
-			$($rest)*
-		);
-	};
-	() => {};
+    // When parsing the macro with a doc comment Rust cannot decide