#ifndef THIRD_PARTY_CEL_CPP_EVAL_PUBLIC_BASE_ACTIVATION_H_

#define THIRD_PARTY_CEL_CPP_EVAL_PUBLIC_BASE_ACTIVATION_H_

#include <vector>

#include "google/protobuf/field_mask.pb.h"

#include "absl/base/nullability.h"

#include "absl/strings/string_view.h"

#include "eval/public/cel_attribute.h"

#include "eval/public/cel_function.h"

#include "eval/public/cel_value.h"

#include "runtime/internal/attribute_matcher.h"

namespace cel::runtime_internal {

class ActivationAttributeMatcherAccess;

}

namespace google::api::expr::runtime {

// Base class for an activation.

class BaseActivation {

 public:

  BaseActivation() = default;

  // Non-copyable/non-assignable

  BaseActivation(const BaseActivation&) = delete;

  BaseActivation& operator=(const BaseActivation&) = delete;

  // Move-constructible/move-assignable

  BaseActivation(BaseActivation&& other) = default;

  BaseActivation& operator=(BaseActivation&& other) = default;

  // Return a list of function overloads for the given name.

  virtual std::vector<const CelFunction*> FindFunctionOverloads(

      absl::string_view) const = 0;

  // Provide the value that is bound to the name, if found.

  // arena parameter is provided to support the case when we want to pass the

  // ownership of returned object ( Message/List/Map ) to Evaluator.

  virtual absl::optional<CelValue> FindValue(absl::string_view,

                                             google::protobuf::Arena*) const = 0;

  // Return the collection of attribute patterns that determine missing

  // attributes.

  virtual const std::vector<CelAttributePattern>& missing_attribute_patterns()

      const {

    static const std::vector<CelAttributePattern>* empty =

        new std::vector<CelAttributePattern>({});

    return *empty;

  }

  // Return the collection of attribute patterns that determine "unknown"

  // values.

  virtual const std::vector<CelAttributePattern>& unknown_attribute_patterns()

      const {

    static const std::vector<CelAttributePattern>* empty =

        new std::vector<CelAttributePattern>({});

    return *empty;

  }

  virtual ~BaseActivation() = default;

 private:

  friend class cel::runtime_internal::ActivationAttributeMatcherAccess;

  // Internal getter for overriding the attribute matching behavior.

  virtual const cel::runtime_internal::AttributeMatcher* absl_nullable

  GetAttributeMatcher() const {

    return nullptr;

  }

};

}  // namespace google::api::expr::runtime

#endif  // THIRD_PARTY_CEL_CPP_EVAL_PUBLIC_BASE_ACTIVATION_H_