Function ExpandOptMapMacro

parser/macro.cc:296–326

}

absl::optional<Expr> ExpandOptMapMacro(MacroExprFactory& factory, Expr& target,
                                       absl::Span<Expr> args) {
  if (args.size() != 2) {
    return factory.ReportError("optMap() requires 2 arguments");
  }
  if (!args[0].has_ident_expr() || args[0].ident_expr().name().empty()) {
    return factory.ReportErrorAt(
        args[0], "optMap() variable name must be a simple identifier");
  }
  if (args[0].ident_expr().name() == kAccumulatorVariableName) {
    return factory.ReportErrorAt(
        args[1], absl::StrCat("optMap() variable name cannot be ",
                              kAccumulatorVariableName));
  }
  auto var_name = args[0].ident_expr().name();

  auto target_copy = factory.Copy(target);
  std::vector<Expr> call_args;
  call_args.reserve(3);
  call_args.push_back(factory.NewMemberCall("hasValue", std::move(target)));
  auto iter_range = factory.NewList();
  auto accu_init = factory.NewMemberCall("value", std::move(target_copy));
  auto condition = factory.NewBoolConst(false);
  auto fold = factory.NewComprehension(
      "#unused", std::move(iter_range), std::move(var_name),
      std::move(accu_init), std::move(condition), std::move(args[0]),
      std::move(args[1]));
  call_args.push_back(factory.NewCall("optional.of", std::move(fold)));
  call_args.push_back(factory.NewCall("optional.none"));
  return factory.NewCall(CelOperator::CONDITIONAL, std::move(call_args));
}

Macro MakeOptMapMacro() {
  auto status_or_macro = Macro::Receiver("optMap", 2, ExpandOptMapMacro);