Function toConstant

bolt/expression/ExprToSubfieldFilter.cpp:37–54

namespace bytedance::bolt::exec {
namespace {
VectorPtr toConstant(
    const core::TypedExprPtr& expr,
    core::ExpressionEvaluator* evaluator) {
  auto exprSet = evaluator->compile(expr);
  if (!exprSet->exprs()[0]->isConstant()) {
    return nullptr;
  }
  RowVector input(
      evaluator->pool(), ROW({}, {}), nullptr, 1, std::vector<VectorPtr>{});
  SelectivityVector rows(1);
  VectorPtr result;
  try {
    evaluator->evaluate(exprSet.get(), rows, input, result);
  } catch (const BoltUserError&) {
    return nullptr;
  }
  return result;
}

template <typename T>
T singleValue(const VectorPtr& vector) {