Function processFor

packages/compiler-core/src/transforms/vFor.ts:253–314

(
  node: ElementNode,
  dir: DirectiveNode,
  context: TransformContext,
  processCodegen?: (forNode: ForNode) => (() => void) | undefined,
)

// target-agnostic transform used for both Client and SSR
export function processFor(
  node: ElementNode,
  dir: DirectiveNode,
  context: TransformContext,
  processCodegen?: (forNode: ForNode) => (() => void) | undefined,
): (() => void) | undefined {
  if (!dir.exp) {
    context.onError(
      createCompilerError(ErrorCodes.X_V_FOR_NO_EXPRESSION, dir.loc),
    )
    return
  }

  const parseResult = dir.forParseResult

  if (!parseResult) {
    context.onError(
      createCompilerError(ErrorCodes.X_V_FOR_MALFORMED_EXPRESSION, dir.loc),
    )
    return
  }

  finalizeForParseResult(parseResult, context)

  const { addIdentifiers, removeIdentifiers, scopes } = context
  const { source, value, key, index } = parseResult

  const forNode: ForNode = {
    type: NodeTypes.FOR,
    loc: dir.loc,
    source,
    valueAlias: value,
    keyAlias: key,
    objectIndexAlias: index,
    parseResult,
    children: isTemplateNode(node) ? node.children : [node],
  }

  context.replaceNode(forNode)

  // bookkeeping
  scopes.vFor++
  if (!__BROWSER__ && context.prefixIdentifiers) {
    // scope management
    // inject identifiers to context
    value && addIdentifiers(value)
    key && addIdentifiers(key)
    index && addIdentifiers(index)
  }

  const onExit = processCodegen && processCodegen(forNode)

  return (): void => {
    scopes.vFor--
    if (!__BROWSER__ && context.prefixIdentifiers) {
      value && removeIdentifiers(value)
      key && removeIdentifiers(key)
      index && removeIdentifiers(index)