Type Alias: TNodeFieldChangeOp#

type TNodeFieldChangeOp = "add" | "delete" | "insert" | "remove" | "length" | "clear";

Defined in: types.ts:90

Structural operation marker on a field-level change record.

Remarks#

previous/new values alone cannot always describe a mutation exactly: assigning undefined to a property and deleting that property produce the same value pair, and array structural methods shift elements without emitting a record per shifted index. The marker carries the missing fact so Retree.applyInverse and Retree.applyChanges can restore state exactly.

• "add" — the key/entry did not exist before this change (object property creation, Map.set of a new key). Inverse: delete the key.
• "delete" — the key/entry was removed (property delete, Map.delete, and the per-entry records emitted by Map.clear). Inverse: restore previous at the key.
• "insert" — an element was inserted by an array structural method (push, unshift, splice); key is the element's index in the post-mutation array. Inverse: splice(index, 1).
• "remove" — an element was removed by an array structural method (pop, shift, splice); key is the element's index in the pre-mutation array. Inverse: splice(index, 0, previous).
• "length" — the length adjustment accompanying an array structural method. It is bookkeeping for the insert/remove records in the same set; applying those already restores the length, so inversion skips it.
• "clear" — the summary record emitted by Map.clear/Set.clear alongside the per-entry "delete" records. The marker separates it from a plain write to a literal "clear" Map key; inversion skips it because the per-entry records restore the contents.

Records without a marker are plain value rewrites (previous -> new at key) and invert by writing previous back. A direct array.length = n assignment emits an unmarked length record; the elements a shrinking assignment discards emit no records, so only the length itself can be restored.