Function getHandlerForEvent

packages/db/src/query/effect.ts:1008–1020

(
  event: DeltaEvent<TRow, TKey>,
  config: EffectConfig<TRow, TKey>,
)

// ---------------------------------------------------------------------------

function getHandlerForEvent<TRow extends object, TKey extends string | number>(
  event: DeltaEvent<TRow, TKey>,
  config: EffectConfig<TRow, TKey>,
): EffectEventHandler<TRow, TKey> | undefined {
  switch (event.type) {
    case `enter`:
      return config.onEnter
    case `exit`:
      return config.onExit
    case `update`:
      return config.onUpdate
  }
}

/**
 * Accumulate D2 output multiplicities into per-key effect changes.