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// Copyright (c) The Diem Core Contributors
// SPDX-License-Identifier: Apache-2.0
use crate::{
account_address::AccountAddress,
language_storage::{ModuleId, StructTag},
};
use std::fmt::Debug;
/// Traits for resolving Move modules and resources from persistent storage
/// A persistent storage backend that can resolve modules by address + name.
/// Storage backends should return
/// - Ok(Some(..)) if the data exists
/// - Ok(None) if the data does not exist
/// - Err(..) only when something really wrong happens, for example
/// - invariants are broken and observable from the storage side
/// (this is not currently possible as ModuleId and StructTag
/// are always structurally valid)
/// - storage encounters internal error
pub trait ModuleResolver {
type Error: Debug;
fn get_module(&self, id: &ModuleId) -> Result<Option<Vec<u8>>, Self::Error>;
}
/// A persistent storage backend that can resolve resources by address + type
/// Storage backends should return
/// - Ok(Some(..)) if the data exists
/// - Ok(None) if the data does not exist
/// - Err(..) only when something really wrong happens, for example
/// - invariants are broken and observable from the storage side
/// (this is not currently possible as ModuleId and StructTag
/// are always structurally valid)
/// - storage encounters internal error
pub trait ResourceResolver {
type Error: Debug;
fn get_resource(
&self,
address: &AccountAddress,
typ: &StructTag,
) -> Result<Option<Vec<u8>>, Self::Error>;
}
/// A persistent storage implementation that can resolve both resources and modules
pub trait MoveResolver:
ModuleResolver<Error = Self::Err> + ResourceResolver<Error = Self::Err>
{
type Err: Debug;
}
impl<E: Debug, T: ModuleResolver<Error = E> + ResourceResolver<Error = E> + ?Sized> MoveResolver
for T
{
type Err = E;
}
impl<T: ResourceResolver + ?Sized> ResourceResolver for &T {
type Error = T::Error;
fn get_resource(
&self,
address: &AccountAddress,
tag: &StructTag,
) -> Result<Option<Vec<u8>>, Self::Error> {
(**self).get_resource(address, tag)
}
}
impl<T: ModuleResolver + ?Sized> ModuleResolver for &T {
type Error = T::Error;
fn get_module(&self, module_id: &ModuleId) -> Result<Option<Vec<u8>>, Self::Error> {
(**self).get_module(module_id)
}
}