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// Copyright (C) Parity Technologies (UK) Ltd.
// This file is part of Polkadot.
// Substrate 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.
// Substrate 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/>.
//! Version 4 of the Cross-Consensus Message format data structures.
pub use super::v2::GetWeight;
use super::v3::{
Instruction as OldInstruction, PalletInfo as OldPalletInfo,
QueryResponseInfo as OldQueryResponseInfo, Response as OldResponse, Xcm as OldXcm,
};
use crate::DoubleEncoded;
use alloc::{vec, vec::Vec};
use bounded_collections::{parameter_types, BoundedVec};
use core::{
convert::{TryFrom, TryInto},
fmt::Debug,
result,
};
use derivative::Derivative;
use parity_scale_codec::{
self, decode_vec_with_len, Compact, Decode, Encode, Error as CodecError, Input as CodecInput,
MaxEncodedLen,
};
use scale_info::TypeInfo;
mod asset;
mod junction;
pub(crate) mod junctions;
mod location;
mod traits;
pub use asset::{
Asset, AssetFilter, AssetId, AssetInstance, Assets, Fungibility, WildAsset, WildFungibility,
MAX_ITEMS_IN_ASSETS,
};
pub use junction::{BodyId, BodyPart, Junction, NetworkId};
pub use junctions::Junctions;
pub use location::{Ancestor, AncestorThen, InteriorLocation, Location, Parent, ParentThen};
pub use traits::{
send_xcm, validate_send, Error, ExecuteXcm, Outcome, PreparedMessage, Reanchorable, Result,
SendError, SendResult, SendXcm, Weight, XcmHash,
};
// These parts of XCM v3 are unchanged in XCM v4, and are re-imported here.
pub use super::v3::{MaybeErrorCode, OriginKind, WeightLimit};
/// This module's XCM version.
pub const VERSION: super::Version = 4;
/// An identifier for a query.
pub type QueryId = u64;
#[derive(Derivative, Default, Encode, TypeInfo)]
#[derivative(Clone(bound = ""), Eq(bound = ""), PartialEq(bound = ""), Debug(bound = ""))]
#[codec(encode_bound())]
#[codec(decode_bound())]
#[scale_info(bounds(), skip_type_params(Call))]
pub struct Xcm<Call>(pub Vec<Instruction<Call>>);
pub const MAX_INSTRUCTIONS_TO_DECODE: u8 = 100;
environmental::environmental!(instructions_count: u8);
impl<Call> Decode for Xcm<Call> {
fn decode<I: CodecInput>(input: &mut I) -> core::result::Result<Self, CodecError> {
instructions_count::using_once(&mut 0, || {
let number_of_instructions: u32 = <Compact<u32>>::decode(input)?.into();
instructions_count::with(|count| {
*count = count.saturating_add(number_of_instructions as u8);
if *count > MAX_INSTRUCTIONS_TO_DECODE {
return Err(CodecError::from("Max instructions exceeded"))
}
Ok(())
})
.expect("Called in `using` context and thus can not return `None`; qed")?;
let decoded_instructions = decode_vec_with_len(input, number_of_instructions as usize)?;
Ok(Self(decoded_instructions))
})
}
}
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impl<Call> Xcm<Call> {
/// Create an empty instance.
pub fn new() -> Self {
Self(vec![])
}
/// Return `true` if no instructions are held in `self`.
pub fn is_empty(&self) -> bool {
self.0.is_empty()
}
/// Return the number of instructions held in `self`.
pub fn len(&self) -> usize {
self.0.len()
}
/// Return a reference to the inner value.
pub fn inner(&self) -> &[Instruction<Call>] {
&self.0
}
/// Return a mutable reference to the inner value.
pub fn inner_mut(&mut self) -> &mut Vec<Instruction<Call>> {
&mut self.0
}
/// Consume and return the inner value.
pub fn into_inner(self) -> Vec<Instruction<Call>> {
self.0
}
/// Return an iterator over references to the items.
pub fn iter(&self) -> impl Iterator<Item = &Instruction<Call>> {
self.0.iter()
}
/// Return an iterator over mutable references to the items.
pub fn iter_mut(&mut self) -> impl Iterator<Item = &mut Instruction<Call>> {
self.0.iter_mut()
}
/// Consume and return an iterator over the items.
pub fn into_iter(self) -> impl Iterator<Item = Instruction<Call>> {
self.0.into_iter()
}
/// Consume and either return `self` if it contains some instructions, or if it's empty, then
/// instead return the result of `f`.
pub fn or_else(self, f: impl FnOnce() -> Self) -> Self {
if self.0.is_empty() {
f()
} else {
self
}
}
/// Return the first instruction, if any.
pub fn first(&self) -> Option<&Instruction<Call>> {
self.0.first()
}
/// Return the last instruction, if any.
pub fn last(&self) -> Option<&Instruction<Call>> {
self.0.last()
}
/// Return the only instruction, contained in `Self`, iff only one exists (`None` otherwise).
pub fn only(&self) -> Option<&Instruction<Call>> {
if self.0.len() == 1 {
self.0.first()
} else {
None
}
}
/// Return the only instruction, contained in `Self`, iff only one exists (returns `self`
/// otherwise).
pub fn into_only(mut self) -> core::result::Result<Instruction<Call>, Self> {
if self.0.len() == 1 {
self.0.pop().ok_or(self)
} else {
Err(self)
}
}
}
impl<Call> From<Vec<Instruction<Call>>> for Xcm<Call> {
fn from(c: Vec<Instruction<Call>>) -> Self {
Self(c)
}
}
impl<Call> From<Xcm<Call>> for Vec<Instruction<Call>> {
fn from(c: Xcm<Call>) -> Self {
c.0
}
}
/// A prelude for importing all types typically used when interacting with XCM messages.
pub mod prelude {
mod contents {
pub use super::super::{
send_xcm, validate_send, Ancestor, AncestorThen, Asset,
AssetFilter::{self, *},
AssetId,
AssetInstance::{self, *},
Assets, BodyId, BodyPart, Error as XcmError, ExecuteXcm,
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