Struct MappingWalker 

pub struct MappingWalker { /* private fields */ }

Walks mapped-item nesting, detecting cycles and excessive depth.

Separate from the views because the views are stateless borrows while a safe walk needs to remember where it has been.

Implementations

impl MappingWalker

pub fn new() -> Self

A walker with no history.

pub fn depth(&self) -> usize

Current nesting depth.

pub fn enter(&mut self, item: EntityId) -> GeometryResult<()>

Enter a mapped item, or fail if that would revisit or go too deep.

Call Self::exit when done with the item, so sibling instances of the same map do not look like a cycle. A map legitimately appears many times; what is illegal is a map containing itself.

pub fn exit(&mut self)

Leave the most recently entered item.

pub fn resolve( &mut self, model: &Model, item_id: EntityId, ) -> GeometryResult<MappedInstance>

Resolve the source map and target operator of a mapped item.

Returns both ids so a caller can compose MappingOrigin with MappingTarget. Composing only the target is the bug this signature is shaped to prevent.

Trait Implementations

impl Debug for MappingWalker

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

Formats the value using the given formatter.

impl Default for MappingWalker

fn default() -> Self

Returns the “default value” for a type.