feat: initialize Kurdistan SDK - independent fork of Polkadot SDK

substrate/primitives/runtime-interface/src/host.rs

@@ -0,0 +1,62 @@
+// This file is part of Substrate.
+
+// Copyright (C) Parity Technologies (UK) Ltd.
+// SPDX-License-Identifier: Apache-2.0
+
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// 	http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! Traits required by the runtime interface from the host side.
+
+use crate::RIType;
+
+use sp_wasm_interface::{FunctionContext, Result};
+
+/// A type used as a return value in a host function. Can be turned into an FFI value.
+pub trait IntoFFIValue: RIType {
+	/// Convert `Self::Inner` into an FFI value.
+	fn into_ffi_value(
+		value: Self::Inner,
+		context: &mut dyn FunctionContext,
+	) -> Result<Self::FFIType>;
+}
+
+/// A type used as a parameter in a host function. Can be created from an FFI value.
+///
+/// Implementations are safe to assume that the `arg` given to `from_ffi_value`
+/// is only generated by the corresponding [`wasm::IntoFFIValue`](crate::wasm::IntoFFIValue)
+/// implementation.
+pub trait FromFFIValue<'a>: RIType {
+	/// The owned inner type.
+	type Owned;
+
+	/// Creates `Self::Owned` from the given `arg` received through the FFI boundary from the
+	/// runtime.
+	fn from_ffi_value(context: &mut dyn FunctionContext, arg: Self::FFIType)
+		-> Result<Self::Owned>;
+
+	/// Creates `Self::Inner` from an owned value.
+	fn take_from_owned(owned: &'a mut Self::Owned) -> Self::Inner;
+
+	/// Write back a modified `value` back into the runtime's memory.
+	///
+	/// Only makes sense for parameters like e.g. `&mut [u8]`.
+	#[inline]
+	fn write_back_into_runtime(
+		_value: Self::Owned,
+		_context: &mut dyn FunctionContext,
+		_arg: Self::FFIType,
+	) -> Result<()> {
+		// Default dummy implementation, because the vast majority of impls won't need this.
+		Ok(())
+	}
+}