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// Copyright 2023 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#ifndef THIRD_PARTY_CEL_CPP_BASE_VALUES_OPTIONAL_VALUE_H_
#define THIRD_PARTY_CEL_CPP_BASE_VALUES_OPTIONAL_VALUE_H_
#include <string>
#include <utility>
#include "absl/log/absl_check.h"
#include "absl/status/statusor.h"
#include "base/handle.h"
#include "base/memory.h"
#include "base/type.h"
#include "base/types/optional_type.h"
#include "base/value.h"
#include "base/values/opaque_value.h"
#include "internal/rtti.h"
namespace cel {
class ValueFactory;
namespace base_internal {
class EmptyOptionalValue;
class FullOptionalValue;
} // namespace base_internal
class OptionalValue : public OpaqueValue {
public:
static bool Is(const Value& value) {
return OpaqueValue::Is(value) &&
OpaqueValue::TypeId(static_cast<const OpaqueValue&>(value)) ==
internal::TypeId<OptionalValue>();
}
using OpaqueValue::Is;
static const OptionalValue& Cast(const Value& value) {
ABSL_DCHECK(Is(value)) << "cannot cast " << value.type()->DebugString()
<< " to optional";
return static_cast<const OptionalValue&>(value);
}
// Create a new optional value which does not have a value. If the type is not
// yet known, use `DynType`.
static absl::StatusOr<Handle<OptionalValue>> None(ValueFactory& value_factory,
Handle<Type> type);
// Create a new optional value which has a value.
static absl::StatusOr<Handle<OptionalValue>> Of(ValueFactory& value_factory,
Handle<Value> value);
const Handle<OptionalType>& type() const {
return OpaqueValue::type().As<OptionalType>();
}
std::string DebugString() const final;
virtual bool has_value() const = 0;
// Requires `OptionalValue::has_value()` be true, otherwise behavior is
// undefined.
virtual const Handle<Value>& value() const = 0;
private:
friend class base_internal::EmptyOptionalValue;
friend class base_internal::FullOptionalValue;
explicit OptionalValue(Handle<OptionalType> type)
: OpaqueValue(std::move(type)) {}
internal::TypeInfo TypeId() const final {
return internal::TypeId<OptionalValue>();
}
};
namespace base_internal {
class EmptyOptionalValue final : public OptionalValue {
public:
bool has_value() const override { return false; }
const Handle<Value>& value() const override;
private:
friend class cel::MemoryManager;
// Called by Arena-based memory managers to determine whether we actually need
// our destructor called.
CEL_INTERNAL_IS_DESTRUCTOR_SKIPPABLE() {
return base_internal::Metadata::IsDestructorSkippable(*type());
}
explicit EmptyOptionalValue(Handle<OptionalType> type)
: OptionalValue(std::move(type)) {}
};
class FullOptionalValue final : public OptionalValue {
public:
bool has_value() const override { return true; }
const Handle<Value>& value() const override { return value_; }
private:
friend class cel::MemoryManager;
// Called by Arena-based memory managers to determine whether we actually need
// our destructor called.
CEL_INTERNAL_IS_DESTRUCTOR_SKIPPABLE() {
return base_internal::Metadata::IsDestructorSkippable(*type()) &&
base_internal::Metadata::IsDestructorSkippable(*value());
}
FullOptionalValue(Handle<OptionalType> type, Handle<Value> value)
: OptionalValue(std::move(type)), value_(std::move(value)) {
ABSL_CHECK(static_cast<bool>(value_)); // Crask OK
}
const Handle<Value> value_;
};
} // namespace base_internal
extern template class Handle<OptionalValue>;
} // namespace cel
#endif // THIRD_PARTY_CEL_CPP_BASE_VALUES_OPTIONAL_VALUE_H_