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// Copyright (C) Parity Technologies (UK) Ltd.
// This file is part of Polkadot.
// Polkadot is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// Polkadot is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with Polkadot. If not, see <http://www.gnu.org/licenses/>.
//! Support data structures for `MultiLocation`, primarily the `Junction` datatype.
use super::{BodyId, BodyPart, Junctions, MultiLocation, NetworkId};
use crate::v3::Junction as NewJunction;
use bounded_collections::{ConstU32, WeakBoundedVec};
use codec::{Decode, Encode, MaxEncodedLen};
use scale_info::TypeInfo;
/// A single item in a path to describe the relative location of a consensus system.
///
/// Each item assumes a pre-existing location as its context and is defined in terms of it.
#[derive(Clone, Eq, PartialEq, Ord, PartialOrd, Encode, Decode, Debug, TypeInfo, MaxEncodedLen)]
#[cfg_attr(feature = "std", derive(serde::Serialize, serde::Deserialize))]
#[scale_info(replace_segment("staging_xcm", "xcm"))]
pub enum Junction {
/// An indexed parachain belonging to and operated by the context.
///
/// Generally used when the context is a Polkadot Relay-chain.
Parachain(#[codec(compact)] u32),
/// A 32-byte identifier for an account of a specific network that is respected as a sovereign
/// endpoint within the context.
///
/// Generally used when the context is a Substrate-based chain.
AccountId32 { network: NetworkId, id: [u8; 32] },
/// An 8-byte index for an account of a specific network that is respected as a sovereign
/// endpoint within the context.
///
/// May be used when the context is a Frame-based chain and includes e.g. an indices pallet.
AccountIndex64 {
network: NetworkId,
#[codec(compact)]
index: u64,
},
/// A 20-byte identifier for an account of a specific network that is respected as a sovereign
/// endpoint within the context.
///
/// May be used when the context is an Ethereum or Bitcoin chain or smart-contract.
AccountKey20 { network: NetworkId, key: [u8; 20] },
/// An instanced, indexed pallet that forms a constituent part of the context.
///
/// Generally used when the context is a Frame-based chain.
PalletInstance(u8),
/// A non-descript index within the context location.
///
/// Usage will vary widely owing to its generality.
///
/// NOTE: Try to avoid using this and instead use a more specific item.
GeneralIndex(#[codec(compact)] u128),
/// A nondescript datum acting as a key within the context location.
///
/// Usage will vary widely owing to its generality.
///
/// NOTE: Try to avoid using this and instead use a more specific item.
GeneralKey(WeakBoundedVec<u8, ConstU32<32>>),
/// The unambiguous child.
///
/// Not currently used except as a fallback when deriving ancestry.
OnlyChild,
/// A pluralistic body existing within consensus.
///
/// Typical to be used to represent a governance origin of a chain, but could in principle be
/// used to represent things such as multisigs also.
Plurality { id: BodyId, part: BodyPart },
}
impl TryFrom<NewJunction> for Junction {
type Error = ();
fn try_from(value: NewJunction) -> Result<Self, Self::Error> {
use NewJunction::*;
Ok(match value {
Parachain(id) => Self::Parachain(id),
AccountId32 { network, id } => Self::AccountId32 { network: network.try_into()?, id },
AccountIndex64 { network, index } =>
Self::AccountIndex64 { network: network.try_into()?, index },
AccountKey20 { network, key } =>
Self::AccountKey20 { network: network.try_into()?, key },
PalletInstance(index) => Self::PalletInstance(index),
GeneralIndex(id) => Self::GeneralIndex(id),
GeneralKey { length, data } => Self::GeneralKey(
data[0..data.len().min(length as usize)]
.to_vec()
.try_into()
.expect("key is bounded to 32 and so will never be out of bounds; qed"),
),
OnlyChild => Self::OnlyChild,
Plurality { id, part } => Self::Plurality { id: id.into(), part: part.into() },
_ => return Err(()),
})
}
}
impl Junction {
/// Convert `self` into a `MultiLocation` containing 0 parents.
///
/// Similar to `Into::into`, except that this method can be used in a const evaluation context.
pub const fn into(self) -> MultiLocation {
MultiLocation { parents: 0, interior: Junctions::X1(self) }
}
/// Convert `self` into a `MultiLocation` containing `n` parents.
///
/// Similar to `Self::into`, with the added ability to specify the number of parent junctions.
pub const fn into_exterior(self, n: u8) -> MultiLocation {
MultiLocation { parents: n, interior: Junctions::X1(self) }
}
}