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// Copyright (C) Use Ink (UK) Ltd.
//
// 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.
use super::{
utils::ReturnType,
Selector,
};
use crate::Environment;
/// The input data and the expected return type of a contract execution.
pub struct Execution<Args, Output> {
/// The input data for initiating a contract execution.
pub input: ExecutionInput<Args>,
/// The type of the expected return value of the contract execution.
pub output: ReturnType<Output>,
}
impl<Args, Output> Execution<Args, Output>
where
Args: scale::Encode,
Output: scale::Decode,
{
/// Construct a new contract execution with the given input data.
pub fn new(input: ExecutionInput<Args>) -> Self {
Self {
input,
output: ReturnType::default(),
}
}
/// Perform the execution of the contract with the given executor.
pub fn exec<I, E>(
self,
executor: &I,
) -> Result<ink_primitives::MessageResult<Output>, I::Error>
where
E: Environment,
I: Executor<E>,
{
executor.exec(&self.input)
}
}
/// Implemented in different environments to perform contract execution.
pub trait Executor<E: Environment> {
/// The type of the error that can be returned during execution.
type Error;
/// Perform the contract execution with the given input data, and return the result.
fn exec<Args, Output>(
&self,
input: &ExecutionInput<Args>,
) -> Result<ink_primitives::MessageResult<Output>, Self::Error>
where
Args: scale::Encode,
Output: scale::Decode;
}
/// The input data for a smart contract execution.
#[derive(Clone, Default, Debug)]
pub struct ExecutionInput<Args> {
/// The selector for the smart contract execution.
selector: Selector,
/// The arguments of the smart contract execution.
args: Args,
}
impl ExecutionInput<EmptyArgumentList> {
/// Creates a new execution input with the given selector.
#[inline]
pub fn new(selector: Selector) -> Self {
Self {
selector,
args: ArgumentList::empty(),
}
}
/// Pushes an argument to the execution input.
#[inline]
pub fn push_arg<T>(
self,
arg: T,
) -> ExecutionInput<ArgumentList<Argument<T>, EmptyArgumentList>>
where
T: scale::Encode,
{
ExecutionInput {
selector: self.selector,
args: self.args.push_arg(arg),
}
}
}
impl<Head, Rest> ExecutionInput<ArgumentList<Argument<Head>, Rest>> {
/// Pushes an argument to the execution input.
#[inline]
pub fn push_arg<T>(self, arg: T) -> ExecutionInput<ArgsList<T, ArgsList<Head, Rest>>>
where
T: scale::Encode,
{
ExecutionInput {
selector: self.selector,
args: self.args.push_arg(arg),
}
}
}
impl<Args> ExecutionInput<Args> {
/// Modify the selector.
///
/// Useful when using the [`ExecutionInput`] generated as part of the
/// `ContractRef`, but using a custom selector.
pub fn update_selector(&mut self, selector: Selector) {
self.selector = selector;
}
}
/// An argument list.
///
/// This type is constructed mainly at compile type via type constructions
/// to avoid having to allocate heap memory while constructing the encoded
/// arguments. The potentially heap allocating encoding is done right at the end
/// where we can leverage the static environmental buffer instead of allocating
/// heap memory.
#[derive(Clone, Default, Debug)]
pub struct ArgumentList<Head, Rest> {
/// The first argument of the argument list.
head: Head,
/// All the rest arguments.
rest: Rest,
}
/// Minor simplification of an argument list with a head and rest.
pub type ArgsList<Head, Rest> = ArgumentList<Argument<Head>, Rest>;
/// A single argument and its reference to a known value.
#[derive(Clone, Debug)]
pub struct Argument<T> {
/// The reference to the known value.
///
/// Used for the encoding at the end of the construction.
arg: T,
}
impl<T> Argument<T> {
/// Creates a new argument.
#[inline]
fn new(arg: T) -> Self {
Self { arg }
}
}
/// The end of an argument list.
#[derive(Clone, Default, Debug)]
pub struct ArgumentListEnd;
/// An empty argument list.
pub type EmptyArgumentList = ArgumentList<ArgumentListEnd, ArgumentListEnd>;
impl EmptyArgumentList {
/// Creates a new empty argument list.
#[inline]
pub fn empty() -> EmptyArgumentList {
ArgumentList {
head: ArgumentListEnd,
rest: ArgumentListEnd,
}
}
/// Pushes the first argument to the empty argument list.
#[inline]
pub fn push_arg<T>(self, arg: T) -> ArgumentList<Argument<T>, Self>
where
T: scale::Encode,
{
ArgumentList {
head: Argument::new(arg),
rest: self,
}
}
}
impl<Head, Rest> ArgumentList<Argument<Head>, Rest> {
/// Pushes another argument to the argument list.
#[inline]
pub fn push_arg<T>(self, arg: T) -> ArgumentList<Argument<T>, Self>
where
T: scale::Encode,
{
ArgumentList {
head: Argument::new(arg),
rest: self,
}
}
}
impl<T> scale::Encode for Argument<T>
where
T: scale::Encode,
{
#[inline]
fn size_hint(&self) -> usize {
<T as scale::Encode>::size_hint(&self.arg)
}
#[inline]
fn encode_to<O: scale::Output + ?Sized>(&self, output: &mut O) {
<T as scale::Encode>::encode_to(&self.arg, output)
}
}
impl scale::Encode for EmptyArgumentList {
#[inline]
fn size_hint(&self) -> usize {
0
}
#[inline]
fn encode_to<O: scale::Output + ?Sized>(&self, _output: &mut O) {}
}
impl<Head, Rest> scale::Encode for ArgumentList<Argument<Head>, Rest>
where
Head: scale::Encode,
Rest: scale::Encode,
{
#[inline]
fn size_hint(&self) -> usize {
scale::Encode::size_hint(&self.head)
.checked_add(scale::Encode::size_hint(&self.rest))
.unwrap()
}
#[inline]
fn encode_to<O: scale::Output + ?Sized>(&self, output: &mut O) {
// We reverse the order of encoding because we build up the list of
// arguments in reverse order, too. This way we encode the arguments
// in the same order in which they have been pushed to the argument list
// while the argument list itself organizes them in reverse order.
scale::Encode::encode_to(&self.rest, output);
scale::Encode::encode_to(&self.head, output);
}
}
impl<Args> scale::Encode for ExecutionInput<Args>
where
Args: scale::Encode,
{
#[inline]
fn size_hint(&self) -> usize {
scale::Encode::size_hint(&self.selector)
.checked_add(scale::Encode::size_hint(&self.args))
.unwrap()
}
#[inline]
fn encode_to<O: scale::Output + ?Sized>(&self, output: &mut O) {
scale::Encode::encode_to(&self.selector, output);
scale::Encode::encode_to(&self.args, output);
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn empty_exec_input_works() {
let selector = Selector::new([0x01, 0x02, 0x03, 0x04]);
let exec_input = ExecutionInput::new(selector);
let encoded = scale::Encode::encode(&exec_input);
assert!(!encoded.is_empty());
let decoded = <Selector as scale::Decode>::decode(&mut &encoded[..]).unwrap();
assert_eq!(decoded, selector);
}
#[test]
fn empty_args_works() {
let empty_list = ArgumentList::empty();
let encoded = scale::Encode::encode(&empty_list);
assert_eq!(encoded, <Vec<u8>>::new());
}
#[test]
fn single_argument_works() {
let empty_list = ArgumentList::empty().push_arg(&1i32);
let encoded = scale::Encode::encode(&empty_list);
assert!(!encoded.is_empty());
let decoded = <i32 as scale::Decode>::decode(&mut &encoded[..]).unwrap();
assert_eq!(decoded, 1i32);
}
#[test]
fn multiple_arguments_works() {
let empty_list = ArgumentList::empty()
.push_arg(&42i32)
.push_arg(&true)
.push_arg(&[0x66u8; 4]);
let encoded = scale::Encode::encode(&empty_list);
assert!(!encoded.is_empty());
let decoded =
<(i32, bool, [u8; 4]) as scale::Decode>::decode(&mut &encoded[..]).unwrap();
assert_eq!(decoded, (42i32, true, [0x66; 4]));
}
}