Allow account allocations (#161)

* Support repetitions in the tool

* Add support for account allocations

* Update the JSON schema

crates/common/src/types/mod.rs

@@ -1,7 +1,9 @@
 mod identifiers;
 mod mode;
+mod private_key_allocator;
 mod version_or_requirement;
 
 pub use identifiers::*;
 pub use mode::*;
+pub use private_key_allocator::*;
 pub use version_or_requirement::*;

crates/common/src/types/private_key_allocator.rs

@@ -0,0 +1,35 @@
+use alloy::signers::local::PrivateKeySigner;
+use alloy_primitives::U256;
+use anyhow::{Result, bail};
+
+/// This is a sequential private key allocator. When instantiated, it allocated private keys in
+/// sequentially and in order until the maximum private key specified is reached.
+#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct PrivateKeyAllocator {
+    /// The next private key to be returned by the allocator when requested.
+    next_private_key: U256,
+
+    /// The highest private key (exclusive) that can be returned by this allocator.
+    highest_private_key_exclusive: U256,
+}
+
+impl PrivateKeyAllocator {
+    /// Creates a new instance of the private key allocator.
+    pub fn new(highest_private_key_exclusive: U256) -> Self {
+        Self {
+            next_private_key: U256::ZERO,
+            highest_private_key_exclusive,
+        }
+    }
+
+    /// Allocates a new private key and errors out if the maximum private key has been reached.
+    pub fn allocate(&mut self) -> Result<PrivateKeySigner> {
+        if self.next_private_key >= self.highest_private_key_exclusive {
+            bail!("Attempted to allocate a private key but failed since all have been allocated");
+        };
+        let private_key =
+            PrivateKeySigner::from_slice(self.next_private_key.to_be_bytes::<32>().as_slice())?;
+        self.next_private_key += U256::ONE;
+        Ok(private_key)
+    }
+}