Function getTargetAtPosition

packages/language-service/src/template_target.ts:273–388

(
  template: TmplAstNode[],
  position: number,
)

 * @param position target cursor position
 */
export function getTargetAtPosition(
  template: TmplAstNode[],
  position: number,
): TemplateTarget | null {
  const path = TemplateTargetVisitor.visitTemplate(template, position);
  if (path.length === 0) {
    return null;
  }

  const candidate = path[path.length - 1];

  // Walk up the result nodes to find the nearest `TmplAstTemplate` which contains the targeted
  // node.
  let context: TmplAstTemplate | null = null;
  for (let i = path.length - 2; i >= 0; i--) {
    const node = path[i];
    if (node instanceof TmplAstTemplate) {
      context = node;
      break;
    }
  }

  // Given the candidate node, determine the full targeted context.
  let nodeInContext: TargetContext;
  if (
    (candidate instanceof Call || candidate instanceof SafeCall) &&
    isWithin(position, candidate.argumentSpan)
  ) {
    nodeInContext = {
      kind: TargetNodeKind.CallExpressionInArgContext,
      node: candidate,
    };
  } else if (candidate instanceof AST) {
    const parents = path.filter((value: AST | TmplAstNode): value is AST => value instanceof AST);
    // Remove the current node from the parents list.
    parents.pop();

    nodeInContext = {
      kind: TargetNodeKind.RawExpression,
      node: candidate,
      parents,
    };
  } else if (candidate instanceof TmplAstElement) {
    // Elements have two contexts: the tag context (position is within the element tag) or the
    // element body context (position is outside of the tag name, but still in the element).
    nodeInContext = {
      kind: isWithinTagBody(position, candidate)
        ? TargetNodeKind.ElementInBodyContext
        : TargetNodeKind.ElementInTagContext,
      node: candidate,
    };
  } else if (candidate instanceof TmplAstComponent) {
    nodeInContext = {
      kind: isWithinTagBody(position, candidate)
        ? TargetNodeKind.ComponentInBodyContext
        : TargetNodeKind.ComponentInTagContext,
      node: candidate,
    };