Function withCtx

packages/runtime-core/src/componentRenderContext.ts:70–122

(
  fn: Function,
  ctx: ComponentInternalInstance | null = currentRenderingInstance,
  isNonScopedSlot?: boolean, // __COMPAT__ only
)

 * @private compiler helper
 */
export function withCtx(
  fn: Function,
  ctx: ComponentInternalInstance | null = currentRenderingInstance,
  isNonScopedSlot?: boolean, // __COMPAT__ only
): Function {
  if (!ctx) return fn

  // already normalized
  if ((fn as ContextualRenderFn)._n) {
    return fn
  }

  const renderFnWithContext: ContextualRenderFn = (...args: any[]) => {
    // If a user calls a compiled slot inside a template expression (#1745), it
    // can mess up block tracking, so by default we disable block tracking and
    // force bail out when invoking a compiled slot (indicated by the ._d flag).
    // This isn't necessary if rendering a compiled `<slot>`, so we flip the
    // ._d flag off when invoking the wrapped fn inside `renderSlot`.
    if (renderFnWithContext._d) {
      setBlockTracking(-1)
    }
    const prevInstance = setCurrentRenderingInstance(ctx)
    let res
    try {
      res = fn(...args)
    } finally {
      setCurrentRenderingInstance(prevInstance)
      if (renderFnWithContext._d) {
        setBlockTracking(1)
      }
    }

    if (__DEV__ || __FEATURE_PROD_DEVTOOLS__) {
      devtoolsComponentUpdated(ctx)
    }

    return res
  }

  // mark normalized to avoid duplicated wrapping
  renderFnWithContext._n = true
  // mark this as compiled by default
  // this is used in vnode.ts -> normalizeChildren() to set the slot
  // rendering flag.
  renderFnWithContext._c = true
  // disable block tracking by default
  renderFnWithContext._d = true
  // compat build only flag to distinguish scoped slots from non-scoped ones
  if (__COMPAT__ && isNonScopedSlot) {
    renderFnWithContext._ns = true
  }
  return renderFnWithContext
}