Function MakeSelectPathExpr

extensions/select_optimization.cc:107–151

Generates the AST representation of the qualification path for the optimized select branch. I.e., the list-typed second argument of the cel.@attribute call.

// select branch. I.e., the list-typed second argument of the cel.@attribute
// call.
Expr MakeSelectPathExpr(
    const std::vector<QualifierInstruction>& select_instructions) {
  Expr result;
  auto& ast_list = result.mutable_list_expr().mutable_elements();
  ast_list.reserve(select_instructions.size());
  auto visitor = absl::Overload(
      [&](const SelectInstruction& instruction) {
        Expr ast_instruction;
        Expr field_number;
        field_number.mutable_const_expr().set_int64_value(instruction.number);
        Expr field_name;
        field_name.mutable_const_expr().set_string_value(instruction.name);
        auto& field_specifier =
            ast_instruction.mutable_list_expr().mutable_elements();
        field_specifier.emplace_back().set_expr(std::move(field_number));
        field_specifier.emplace_back().set_expr(std::move(field_name));

        ast_list.emplace_back().set_expr(std::move(ast_instruction));
      },
      [&](absl::string_view instruction) {
        Expr const_expr;
        const_expr.mutable_const_expr().set_string_value(instruction);
        ast_list.emplace_back().set_expr(std::move(const_expr));
      },
      [&](int64_t instruction) {
        Expr const_expr;
        const_expr.mutable_const_expr().set_int64_value(instruction);
        ast_list.emplace_back().set_expr(std::move(const_expr));
      },
      [&](uint64_t instruction) {
        Expr const_expr;
        const_expr.mutable_const_expr().set_uint64_value(instruction);
        ast_list.emplace_back().set_expr(std::move(const_expr));
      },
      [&](bool instruction) {
        Expr const_expr;
        const_expr.mutable_const_expr().set_bool_value(instruction);
        ast_list.emplace_back().set_expr(std::move(const_expr));
      });

  for (const auto& instruction : select_instructions) {
    absl::visit(visitor, instruction);
  }
  return result;
}

// Returns a single select operation based on the inferred type of the operand
// and the field name. If the operand type doesn't define the field, returns