Struct CallTree 

pub struct CallTree(/* private fields */);

A cursor-based tree structure for tracking hierarchical contract calls.

The tree maintains a “current position” pointer that moves through the tree as contracts call each other and return. The internal pointer represents:

• None: Empty tree (no calls have been made)
• Some(node): Points to the currently executing contract call

Memory Management

Uses raw pointers with manual allocation (Box::leak) and deallocation (free_tree). The Drop implementation ensures proper cleanup.

Implementations

impl CallTree

pub fn iter(&self) -> impl Iterator<Item = &CallTreeElem>

Returns an iterator over the current node and its descendants.

Traverses in reverse post-order (rightmost leaf first): deepest-rightmost children first, then left siblings, then parents. This matches how contract calls unwind (deepest calls complete first).

Example

Notation:

• -> means “calls”
• [] groups sibling calls (sequential calls made by the same contract)
• , separates siblings (calls made one after another)

For tree A -> B -> [D, E] and A -> C, if positioned at A: A calls B, which calls D then E, then A calls C.

Tree structure:

     A
    / \
   B   C
  / \
 D   E

Iterator yields: C, E, D, B, A (rightmost leaves first)

For tree where TC calls A, which makes two sequential calls to TC and D:

• TC means “Transfer contract”
• A means “Alice contract”
• B means “Bob contract”
• C means “Charlie contract”
• D means “David contract”

Tree structure:

TC (root)
    |
    A
   / \
 TC   D
 /
C

Call sequence: TC -> [A -> [TC -> C], D]

• TC calls A
• A calls TC (which calls C), then A calls D
• TC and D are siblings (both called by A sequentially)

Iterator at root TC yields: D, C, TC (from A), A, TC (root) Iterator at A yields: D, C, TC, A

Trait Implementations

impl Debug for CallTree

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl Default for CallTree

fn default() -> CallTree

Returns the “default value” for a type.

impl Drop for CallTree

fn drop(&mut self)

Executes the destructor for this type.

fn pin_drop(self: Pin<&mut Self>)

🔬This is a nightly-only experimental API. (pin_ergonomics)

Execute the destructor for this type, but different to Drop::drop, it requires self to be pinned.