feat: Add uniswap V2 WETH-USDC swap example (bluealloy#1353)

* Add uniswap V2 WETH-USDC swap example

* Use alloy primitives

* Use revm primitives

* Use alloydb

* Use only necessary pair slots

* typo

* Simplify error handling

* Improve numbers decoding

* Dont use panic for errors

* Remove unused feature

* Use alloydb instead of manually fetching data

crates/revm/Cargo.toml

@@ -46,10 +46,12 @@ alloy-rpc-types = {git = "https://github.com/alloy-rs/alloy.git", optional = tru
 alloy-transport = {git = "https://github.com/alloy-rs/alloy.git", optional = true, default-features = false }
 
 [dev-dependencies]
+alloy-sol-types = { version = "0.7.0", default-features = false, features = ["std"] }
 ethers-contract = { version = "2.0.14", default-features = false }
 anyhow = "1.0.82"
 criterion = "0.5"
 indicatif = "0.17"
+reqwest = { version = "0.12" }
 
 alloy-provider = { git = "https://github.com/alloy-rs/alloy.git", default-features = false, features = ["reqwest"] }
 # needed for enabling TLS to use HTTPS connections when testing alloy DB
@@ -136,6 +138,11 @@ name = "db_by_ref"
 path = "../../examples/db_by_ref.rs"
 required-features = ["std", "serde-json"]
 
+[[example]]
+name = "uniswap_v2_usdc_swap"
+path = "../../examples/uniswap_v2_usdc_swap.rs"
+required-features = ["alloydb"]
+
 [[bench]]
 name = "bench"
 path = "benches/bench.rs"

examples/uniswap_v2_usdc_swap.rs

@@ -0,0 +1,278 @@
+use alloy_provider::{network::Ethereum, ProviderBuilder, RootProvider};
+use alloy_sol_types::{sol, SolCall, SolValue};
+use alloy_transport_http::Http;
+use anyhow::{anyhow, Result};
+use reqwest::Client;
+use revm::{
+    db::{AlloyDB, CacheDB},
+    primitives::{
+        address, keccak256, AccountInfo, Address, Bytes, ExecutionResult, Output, TransactTo, U256,
+    },
+    Evm,
+};
+use std::ops::Div;
+use std::sync::Arc;
+
+type AlloyCacheDB = CacheDB<AlloyDB<Http<Client>, Ethereum, Arc<RootProvider<Http<Client>>>>>;
+
+#[tokio::main]
+async fn main() -> Result<()> {
+    let client = ProviderBuilder::new()
+        .on_reqwest_http(
+            "https://mainnet.infura.io/v3/c60b0bb42f8a4c6481ecd229eddaca27"
+                .parse()
+                .unwrap(),
+        )
+        .unwrap();
+    let client = Arc::new(client);
+    let mut cache_db = CacheDB::new(AlloyDB::new(client, None));
+
+    // Random empty account
+    let account = address!("18B06aaF27d44B756FCF16Ca20C1f183EB49111f");
+
+    let weth = address!("c02aaa39b223fe8d0a0e5c4f27ead9083c756cc2");
+    let usdc = address!("a0b86991c6218b36c1d19d4a2e9eb0ce3606eb48");
+    let usdc_weth_pair = address!("B4e16d0168e52d35CaCD2c6185b44281Ec28C9Dc");
+
+    let weth_balance_slot = U256::from(3);
+
+    // give our test account some fake WETH and ETH
+    let one_ether = U256::from(1_000_000_000_000_000_000u128);
+    let hashed_acc_balance_slot = keccak256((account, weth_balance_slot).abi_encode());
+    cache_db
+        .insert_account_storage(weth, hashed_acc_balance_slot.into(), one_ether)
+        .unwrap();
+
+    let acc_info = AccountInfo {
+        nonce: 0_u64,
+        balance: one_ether,
+        code_hash: keccak256(Bytes::new()),
+        code: None,
+    };
+    cache_db.insert_account_info(account, acc_info);
+
+    let acc_weth_balance_before = balance_of(weth, account, &mut cache_db)?;
+    println!("WETH balance before swap: {}", acc_weth_balance_before);
+    let acc_usdc_balance_before = balance_of(usdc, account, &mut cache_db)?;
+    println!("USDC balance before swap: {}", acc_usdc_balance_before);
+
+    let (reserve0, reserve1) = get_reserves(usdc_weth_pair, &mut cache_db)?;
+
+    let amount_in = one_ether.div(U256::from(10));
+
+    // calculate USDC amount out
+    let amount_out = get_amount_out(amount_in, reserve1, reserve0, &mut cache_db).await?;
+
+    // transfer WETH to USDC-WETH pair
+    transfer(account, usdc_weth_pair, amount_in, weth, &mut cache_db)?;
+
+    // execute low-level swap without using UniswapV2 router
+    swap(
+        account,
+        usdc_weth_pair,
+        account,
+        amount_out,
+        true,
+        &mut cache_db,
+    )?;
+
+    let acc_weth_balance_after = balance_of(weth, account, &mut cache_db)?;
+    println!("WETH balance after swap: {}", acc_weth_balance_after);
+    let acc_usdc_balance_after = balance_of(usdc, account, &mut cache_db)?;
+    println!("USDC balance after swap: {}", acc_usdc_balance_after);
+
+    Ok(())
+}
+
+fn balance_of(token: Address, address: Address, cache_db: &mut AlloyCacheDB) -> Result<U256> {
+    sol! {
+        function balanceOf(address account) public returns (uint256);
+    }
+
+    let encoded = balanceOfCall { account: address }.abi_encode();
+
+    let mut evm = Evm::builder()
+        .with_db(cache_db)
+        .modify_tx_env(|tx| {
+            // 0x1 because calling USDC proxy from zero address fails
+            tx.caller = address!("0000000000000000000000000000000000000001");
+            tx.transact_to = TransactTo::Call(token);
+            tx.data = encoded.into();
+            tx.value = U256::from(0);
+        })
+        .build();
+
+    let ref_tx = evm.transact().unwrap();
+    let result = ref_tx.result;
+
+    let value = match result {
+        ExecutionResult::Success {
+            output: Output::Call(value),
+            ..
+        } => value,
+        result => return Err(anyhow!("'balanceOf' execution failed: {result:?}")),
+    };
+
+    let balance = <U256>::abi_decode(&value, false)?;
+
+    Ok(balance)
+}
+
+async fn get_amount_out(
+    amount_in: U256,
+    reserve_in: U256,
+    reserve_out: U256,
+    cache_db: &mut AlloyCacheDB,
+) -> Result<U256> {
+    let uniswap_v2_router = address!("7a250d5630b4cf539739df2c5dacb4c659f2488d");
+    sol! {
+        function getAmountOut(uint amountIn, uint reserveIn, uint reserveOut) external pure returns (uint amountOut);
+    }
+
+    let encoded = getAmountOutCall {
+        amountIn: amount_in,
+        reserveIn: reserve_in,
+        reserveOut: reserve_out,
+    }
+    .abi_encode();
+
+    let mut evm = Evm::builder()
+        .with_db(cache_db)
+        .modify_tx_env(|tx| {
+            tx.caller = address!("0000000000000000000000000000000000000000");
+            tx.transact_to = TransactTo::Call(uniswap_v2_router);
+            tx.data = encoded.into();
+            tx.value = U256::from(0);
+        })
+        .build();
+
+    let ref_tx = evm.transact().unwrap();
+    let result = ref_tx.result;
+
+    let value = match result {
+        ExecutionResult::Success {
+            output: Output::Call(value),
+            ..
+        } => value,
+        result => return Err(anyhow!("'getAmountOut' execution failed: {result:?}")),
+    };
+
+    let amount_out = <U256>::abi_decode(&value, false)?;
+
+    Ok(amount_out)
+}
+
+fn get_reserves(pair_address: Address, cache_db: &mut AlloyCacheDB) -> Result<(U256, U256)> {
+    sol! {
+        function getReserves() external view returns (uint112 reserve0, uint112 reserve1, uint32 blockTimestampLast);
+    }
+
+    let encoded = getReservesCall {}.abi_encode();
+
+    let mut evm = Evm::builder()
+        .with_db(cache_db)
+        .modify_tx_env(|tx| {
+            tx.caller = address!("0000000000000000000000000000000000000000");
+            tx.transact_to = TransactTo::Call(pair_address);
+            tx.data = encoded.into();
+            tx.value = U256::from(0);
+        })
+        .build();
+
+    let ref_tx = evm.transact().unwrap();
+    let result = ref_tx.result;
+
+    let value = match result {
+        ExecutionResult::Success {
+            output: Output::Call(value),
+            ..
+        } => value,
+        result => return Err(anyhow!("'getReserves' execution failed: {result:?}")),
+    };
+
+    let (reserve0, reserve1, _) = <(U256, U256, u32)>::abi_decode(&value, false)?;
+
+    Ok((reserve0, reserve1))
+}
+
+fn swap(
+    from: Address,
+    pool_address: Address,
+    target: Address,
+    amount_out: U256,
+    is_token0: bool,
+    cache_db: &mut AlloyCacheDB,
+) -> Result<()> {
+    sol! {
+        function swap(uint amount0Out, uint amount1Out, address target, bytes callback) external;
+    }
+
+    let amount0_out = if is_token0 { amount_out } else { U256::from(0) };
+    let amount1_out = if is_token0 { U256::from(0) } else { amount_out };
+
+    let encoded = swapCall {
+        amount0Out: amount0_out,
+        amount1Out: amount1_out,
+        target,
+        callback: Bytes::new(),
+    }
+    .abi_encode();
+
+    let mut evm = Evm::builder()
+        .with_db(cache_db)
+        .modify_tx_env(|tx| {
+            tx.caller = from;
+            tx.transact_to = TransactTo::Call(pool_address);
+            tx.data = encoded.into();
+            tx.value = U256::from(0);
+        })
+        .build();
+
+    let ref_tx = evm.transact_commit().unwrap();
+
+    match ref_tx {
+        ExecutionResult::Success { .. } => {}
+        result => return Err(anyhow!("'swap' execution failed: {result:?}")),
+    };
+
+    Ok(())
+}
+
+fn transfer(
+    from: Address,
+    to: Address,
+    amount: U256,
+    token: Address,
+    cache_db: &mut AlloyCacheDB,
+) -> Result<()> {
+    sol! {
+        function transfer(address to, uint amount) external returns (bool);
+    }
+
+    let encoded = transferCall { to, amount }.abi_encode();
+
+    let mut evm = Evm::builder()
+        .with_db(cache_db)
+        .modify_tx_env(|tx| {
+            tx.caller = from;
+            tx.transact_to = TransactTo::Call(token);
+            tx.data = encoded.into();
+            tx.value = U256::from(0);
+        })
+        .build();
+
+    let ref_tx = evm.transact_commit().unwrap();
+    let success: bool = match ref_tx {
+        ExecutionResult::Success {
+            output: Output::Call(value),
+            ..
+        } => <bool>::abi_decode(&value, false)?,
+        result => return Err(anyhow!("'transfer' execution failed: {result:?}")),
+    };
+
+    if !success {
+        return Err(anyhow!("'transfer' failed"));
+    }
+
+    Ok(())
+}