semantics
Collects unresolved semantics in parent-before-child order.
An empty tree returns an empty read-only list. A non-empty tree must be laid out with no pending measurement or layout work. If that precondition fails, the tree is poisoned. A clean node reuses its complete local semantics payload and combines it with current accumulated bounds. Semantics invalidation affects only that node's local payload. Text remains unresolved for the platform adapter. Callback failures poison the tree.
Return
an read-only list of entries with accumulated tree-coordinate bounds.
Throws
when layout is incomplete or geometry remains pending. It is also thrown when the operation is called from another execution owner, re-enters an active operation, or the tree is not active.
when a semantics callback or scope operation throws after pipeline work begins. The exception must escape the callback. The original throwable is propagated unchanged after cleanup attempts.