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use crate::primitives::{Address, Bytecode, Env, Log, B256, U256};
mod dummy;
pub use dummy::DummyHost;
/// EVM context host.
pub trait Host {
/// Returns a reference to the environment.
fn env(&self) -> &Env;
/// Returns a mutable reference to the environment.
fn env_mut(&mut self) -> &mut Env;
/// Load an account.
///
/// Returns (is_cold, is_new_account)
fn load_account(&mut self, address: Address) -> Option<LoadAccountResult>;
/// Get the block hash of the given block `number`.
fn block_hash(&mut self, number: U256) -> Option<B256>;
/// Get balance of `address` and if the account is cold.
fn balance(&mut self, address: Address) -> Option<(U256, bool)>;
/// Get code of `address` and if the account is cold.
fn code(&mut self, address: Address) -> Option<(Bytecode, bool)>;
/// Get code hash of `address` and if the account is cold.
fn code_hash(&mut self, address: Address) -> Option<(B256, bool)>;
/// Get storage value of `address` at `index` and if the account is cold.
fn sload(&mut self, address: Address, index: U256) -> Option<(U256, bool)>;
/// Set storage value of account address at index.
///
/// Returns (original, present, new, is_cold).
fn sstore(&mut self, address: Address, index: U256, value: U256) -> Option<SStoreResult>;
/// Get the transient storage value of `address` at `index`.
fn tload(&mut self, address: Address, index: U256) -> U256;
/// Set the transient storage value of `address` at `index`.
fn tstore(&mut self, address: Address, index: U256, value: U256);
/// Emit a log owned by `address` with given `LogData`.
fn log(&mut self, log: Log);
/// Mark `address` to be deleted, with funds transferred to `target`.
fn selfdestruct(&mut self, address: Address, target: Address) -> Option<SelfDestructResult>;
}
/// Represents the result of an `sstore` operation.
#[derive(Debug, Clone, PartialEq, Eq)]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
pub struct SStoreResult {
/// Value of the storage when it is first read
pub original_value: U256,
/// Current value of the storage
pub present_value: U256,
/// New value that is set
pub new_value: U256,
/// Is storage slot loaded from database
pub is_cold: bool,
}
/// Result of the account load from Journal state.
#[derive(Debug, Clone, Default, PartialEq, Eq)]
pub struct LoadAccountResult {
/// Is account cold loaded
pub is_cold: bool,
/// Is account empty, if true account is not created.
pub is_empty: bool,
}
/// Result of a selfdestruct instruction.
#[derive(Default, Clone, Debug, PartialEq, Eq, Hash)]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
pub struct SelfDestructResult {
pub had_value: bool,
pub target_exists: bool,
pub is_cold: bool,
pub previously_destroyed: bool,
}
#[cfg(test)]
mod tests {
use super::*;
fn assert_host<H: Host + ?Sized>() {}
#[test]
fn object_safety() {
assert_host::<DummyHost>();
assert_host::<dyn Host>();
}
}