allow static signatures

examples/tictactoe.rs

@@ -176,9 +176,9 @@ impl<'a> ModuleImportResolver for RuntimeModuleImportResolver {
 	) -> Result<FuncRef, InterpreterError> {
 		let func_ref = match field_name {
 			"set" => {
-				FuncInstance::alloc_host(Signature::new(&[ValueType::I32], None), SET_FUNC_INDEX)
+				FuncInstance::alloc_host(Signature::new(&[ValueType::I32][..], None), SET_FUNC_INDEX)
 			},
-			"get" => FuncInstance::alloc_host(Signature::new(&[ValueType::I32], Some(ValueType::I32)), GET_FUNC_INDEX),
+			"get" => FuncInstance::alloc_host(Signature::new(&[ValueType::I32][..], Some(ValueType::I32)), GET_FUNC_INDEX),
 			_ => return Err(
 				InterpreterError::Function(
 					format!("host module doesn't export function with name {}", field_name)

src/tests/host.rs

@@ -657,7 +657,7 @@ fn dynamically_add_host_func() {
 					self.added_funcs += 1;
 
 					let added_func = FuncInstance::alloc_host(
-						Signature::new(&[], Some(ValueType::I32)),
+						Signature::new(&[][..], Some(ValueType::I32)),
 						host_func_index as usize,
 					);
 					self.table.set(table_index, Some(added_func))?;

src/types.rs

@@ -1,3 +1,5 @@
+use std::borrow::Cow;
+
 use parity_wasm::elements::{
 	FunctionType, ValueType as EValueType, GlobalType, TableType, MemoryType};
 
@@ -10,20 +12,23 @@ use parity_wasm::elements::{
 /// [type]: enum.ValueType.html
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct Signature {
-	params: Vec<ValueType>,
+	params: Cow<'static, [ValueType]>,
 	return_type: Option<ValueType>,
 }
 
 impl Signature {
-	pub fn new(params: &[ValueType], return_type: Option<ValueType>) -> Signature {
+	pub fn new<C: Into<Cow<'static, [ValueType]>>>(
+		params: C,
+		return_type: Option<ValueType>
+	) -> Signature {
 		Signature {
-			params: params.to_vec(),
+			params: params.into(),
 			return_type: return_type,
 		}
 	}
 
 	pub fn params(&self) -> &[ValueType] {
-		&self.params
+		&self.params.as_ref()
 	}
 
 	pub fn return_type(&self) -> Option<ValueType> {