Function getSwitchVarName

book/tiny-ts-parser.ts:561–566

(node: p.TSESTree.Expression)

}

function getSwitchVarName(node: p.TSESTree.Expression) {
  if (node.type !== "MemberExpression" || node.computed || getIdentifier(node.property) !== "tag") {
    error(`switch statement must be switch(VAR.tag) { ... }`, node);
  }
  return getIdentifier(node.object);
}

function getParam(node: p.TSESTree.Parameter): Param {
  if (node.type !== "Identifier") error("parameter must be a variable", node);