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feat(interpreter): impl Clone for Stack (bluealloy#1820)
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* feat(interpreter): impl Clone for Stack

Signed-off-by: jsvisa <[email protected]>

* apply commits and add test cases

Signed-off-by: jsvisa <[email protected]>

---------

Signed-off-by: jsvisa <[email protected]>
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jsvisa authored Oct 13, 2024
1 parent 021bec5 commit dad766d
Showing 1 changed file with 57 additions and 0 deletions.
57 changes: 57 additions & 0 deletions crates/interpreter/src/interpreter/stack.rs
Original file line number Diff line number Diff line change
Expand Up @@ -34,6 +34,17 @@ impl Default for Stack {
}
}

impl Clone for Stack {
fn clone(&self) -> Self {
// Use `Self::new()` to ensure the cloned Stack maintains the STACK_LIMIT capacity,
// and then copy the data. This preserves the invariant that Stack always has
// STACK_LIMIT capacity, which is crucial for the safety and correctness of other methods.
let mut new_stack = Self::new();
new_stack.data.extend_from_slice(&self.data);
new_stack
}
}

impl Stack {
/// Instantiate a new stack with the [default stack limit][STACK_LIMIT].
#[inline]
Expand Down Expand Up @@ -442,4 +453,50 @@ mod tests {
assert_eq!(stack.data, [U256::ZERO, U256::ZERO, U256::from(n)]);
});
}

#[test]
fn stack_clone() {
// Test cloning an empty stack
let empty_stack = Stack::new();
let cloned_empty = empty_stack.clone();
assert_eq!(empty_stack, cloned_empty);
assert_eq!(cloned_empty.len(), 0);
assert_eq!(cloned_empty.data().capacity(), STACK_LIMIT);

// Test cloning a partially filled stack
let mut partial_stack = Stack::new();
for i in 0..10 {
partial_stack.push(U256::from(i)).unwrap();
}
let mut cloned_partial = partial_stack.clone();
assert_eq!(partial_stack, cloned_partial);
assert_eq!(cloned_partial.len(), 10);
assert_eq!(cloned_partial.data().capacity(), STACK_LIMIT);

// Test that modifying the clone doesn't affect the original
cloned_partial.push(U256::from(100)).unwrap();
assert_ne!(partial_stack, cloned_partial);
assert_eq!(partial_stack.len(), 10);
assert_eq!(cloned_partial.len(), 11);

// Test cloning a full stack
let mut full_stack = Stack::new();
for i in 0..STACK_LIMIT {
full_stack.push(U256::from(i)).unwrap();
}
let mut cloned_full = full_stack.clone();
assert_eq!(full_stack, cloned_full);
assert_eq!(cloned_full.len(), STACK_LIMIT);
assert_eq!(cloned_full.data().capacity(), STACK_LIMIT);

// Test push to the full original or cloned stack should return StackOverflow
assert_eq!(
full_stack.push(U256::from(100)),
Err(InstructionResult::StackOverflow)
);
assert_eq!(
cloned_full.push(U256::from(100)),
Err(InstructionResult::StackOverflow)
);
}
}

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