feat: allow host to be implemented on custom context (#2112)

* allow host to be implemented on custom context

* fix warning

* moved Host default implementation into ContextTr

* add comment in context

* cleanup for inspector Host bound

* remove redundant set_error in contexctTr

Author: theinterestedr1

crates/context/interface/src/context.rs

@@ -1,5 +1,7 @@
-use crate::{Block, Cfg, Database, Journal, Transaction};
+pub use crate::journaled_state::StateLoad;
+use crate::{journaled_state::AccountLoad, Block, Cfg, Database, Journal, Transaction};
 use auto_impl::auto_impl;
+use primitives::{Address, Bytes, Log, B256, BLOCK_HASH_HISTORY, U256};
 
 #[auto_impl(&mut, Box)]
 pub trait ContextTr {
@@ -20,4 +22,189 @@ pub trait ContextTr {
     fn chain(&mut self) -> &mut Self::Chain;
     fn error(&mut self) -> &mut Result<(), <Self::Db as Database>::Error>;
     fn tx_journal(&mut self) -> (&mut Self::Tx, &mut Self::Journal);
+    // default implementationHost calls interface
+
+    /// Gets the block hash of the given block `number`.
+    fn block_hash(&mut self, requested_number: u64) -> Option<B256> {
+        let block_number = self.block().number();
+
+        let Some(diff) = block_number.checked_sub(requested_number) else {
+            return Some(B256::ZERO);
+        };
+
+        // blockhash should push zero if number is same as current block number.
+        if diff == 0 {
+            return Some(B256::ZERO);
+        }
+
+        if diff <= BLOCK_HASH_HISTORY {
+            return self
+                .journal()
+                .db()
+                .block_hash(requested_number)
+                .map_err(|e| {
+                    *self.error() = Err(e);
+                })
+                .ok();
+        }
+
+        Some(B256::ZERO)
+    }
+
+    fn load_account_delegated(&mut self, address: Address) -> Option<StateLoad<AccountLoad>> {
+        self.journal()
+            .load_account_delegated(address)
+            .map_err(|e| {
+                *self.error() = Err(e);
+            })
+            .ok()
+    }
+
+    /// Gets balance of `address` and if the account is cold.
+    fn balance(&mut self, address: Address) -> Option<StateLoad<U256>> {
+        self.journal()
+            .load_account(address)
+            .map(|acc| acc.map(|a| a.info.balance))
+            .map_err(|e| {
+                *self.error() = Err(e);
+            })
+            .ok()
+    }
+
+    /// Gets code of `address` and if the account is cold.
+    fn code(&mut self, address: Address) -> Option<StateLoad<Bytes>> {
+        self.journal()
+            .code(address)
+            .map_err(|e| {
+                *self.error() = Err(e);
+            })
+            .ok()
+    }
+
+    /// Gets code hash of `address` and if the account is cold.
+    fn code_hash(&mut self, address: Address) -> Option<StateLoad<B256>> {
+        self.journal()
+            .code_hash(address)
+            .map_err(|e| {
+                *self.error() = Err(e);
+            })
+            .ok()
+    }
+
+    /// Gets storage value of `address` at `index` and if the account is cold.
+    fn sload(&mut self, address: Address, index: U256) -> Option<StateLoad<U256>> {
+        self.journal()
+            .sload(address, index)
+            .map_err(|e| {
+                *self.error() = Err(e);
+            })
+            .ok()
+    }
+
+    /// Sets storage value of account address at index.
+    ///
+    /// Returns [`StateLoad`] with [`SStoreResult`] that contains original/new/old storage value.
+    fn sstore(
+        &mut self,
+        address: Address,
+        index: U256,
+        value: U256,
+    ) -> Option<StateLoad<SStoreResult>> {
+        self.journal()
+            .sstore(address, index, value)
+            .map_err(|e| {
+                *self.error() = Err(e);
+            })
+            .ok()
+    }
+
+    /// Gets the transient storage value of `address` at `index`.
+    fn tload(&mut self, address: Address, index: U256) -> U256 {
+        self.journal().tload(address, index)
+    }
+
+    /// Sets the transient storage value of `address` at `index`.
+    fn tstore(&mut self, address: Address, index: U256, value: U256) {
+        self.journal().tstore(address, index, value)
+    }
+
+    /// Emits a log owned by `address` with given `LogData`.
+    fn log(&mut self, log: Log) {
+        self.journal().log(log);
+    }
+
+    /// Marks `address` to be deleted, with funds transferred to `target`.
+    fn selfdestruct(
+        &mut self,
+        address: Address,
+        target: Address,
+    ) -> Option<StateLoad<SelfDestructResult>> {
+        self.journal()
+            .selfdestruct(address, target)
+            .map_err(|e| {
+                *self.error() = Err(e);
+            })
+            .ok()
+    }
+}
+
+/// Represents the result of an `sstore` operation.
+#[derive(Clone, Debug, Default, 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,
+}
+
+impl SStoreResult {
+    /// Returns `true` if the new value is equal to the present value.
+    #[inline]
+    pub fn is_new_eq_present(&self) -> bool {
+        self.new_value == self.present_value
+    }
+
+    /// Returns `true` if the original value is equal to the present value.
+    #[inline]
+    pub fn is_original_eq_present(&self) -> bool {
+        self.original_value == self.present_value
+    }
+
+    /// Returns `true` if the original value is equal to the new value.
+    #[inline]
+    pub fn is_original_eq_new(&self) -> bool {
+        self.original_value == self.new_value
+    }
+
+    /// Returns `true` if the original value is zero.
+    #[inline]
+    pub fn is_original_zero(&self) -> bool {
+        self.original_value.is_zero()
+    }
+
+    /// Returns `true` if the present value is zero.
+    #[inline]
+    pub fn is_present_zero(&self) -> bool {
+        self.present_value.is_zero()
+    }
+
+    /// Returns `true` if the new value is zero.
+    #[inline]
+    pub fn is_new_zero(&self) -> bool {
+        self.new_value.is_zero()
+    }
+}
+
+/// Result of a selfdestruct action
+///
+/// Value returned are needed to calculate the gas spent.
+#[derive(Clone, Debug, Default, PartialEq, Eq, Hash)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+pub struct SelfDestructResult {
+    pub had_value: bool,
+    pub target_exists: bool,
+    pub previously_destroyed: bool,
 }

crates/context/interface/src/host.rs

@@ -1,4 +1,4 @@
-use crate::host::{SStoreResult, SelfDestructResult};
+use crate::context::{SStoreResult, SelfDestructResult};
 use core::ops::{Deref, DerefMut};
 use database_interface::Database;
 use primitives::{Address, Bytes, HashSet, Log, B256, U256};

crates/context/interface/src/journaled_state.rs

@@ -8,7 +8,6 @@ extern crate alloc as std;
 pub mod block;
 pub mod cfg;
 pub mod context;
-pub mod host;
 pub mod journaled_state;
 pub mod result;
 pub mod transaction;