llvm/mlir/include/mlir/Support/InterfaceSupport.h

//===- InterfaceSupport.h - MLIR Interface Support Classes ------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file defines several support classes for defining interfaces.
//
//===----------------------------------------------------------------------===//

#ifndef MLIR_SUPPORT_INTERFACESUPPORT_H
#define MLIR_SUPPORT_INTERFACESUPPORT_H

#include "mlir/Support/TypeID.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/Support/TypeName.h"

namespace mlir {
namespace detail {
//===----------------------------------------------------------------------===//
// Interface
//===----------------------------------------------------------------------===//

/// This class represents an abstract interface. An interface is a simplified
/// mechanism for attaching concept based polymorphism to a class hierarchy. An
/// interface is comprised of two components:
/// * The derived interface class: This is what users interact with, and invoke
///   methods on.
/// * An interface `Trait` class: This is the class that is attached to the
///   object implementing the interface. It is the mechanism with which models
///   are specialized.
///
/// Derived interfaces types must provide the following template types:
/// * ConcreteType: The CRTP derived type.
/// * ValueT: The opaque type the derived interface operates on. For example
///           `Operation*` for operation interfaces, or `Attribute` for
///           attribute interfaces.
/// * Traits: A class that contains definitions for a 'Concept' and a 'Model'
///           class. The 'Concept' class defines an abstract virtual interface,
///           where as the 'Model' class implements this interface for a
///           specific derived T type. Both of these classes *must* not contain
///           non-static data. A simple example is shown below:
///
/// ```c++
///    struct ExampleInterfaceTraits {
///      struct Concept {
///        virtual unsigned getNumInputs(T t) const = 0;
///      };
///      template <typename DerivedT> class Model {
///        unsigned getNumInputs(T t) const final {
///          return cast<DerivedT>(t).getNumInputs();
///        }
///      };
///    };
/// ```
///
/// * BaseType: A desired base type for the interface. This is a class
///             that provides specific functionality for the `ValueT`
///             value. For instance the specific `Op` that will wrap the
///             `Operation*` for an `OpInterface`.
/// * BaseTrait: The base type for the interface trait. This is the base class
///              to use for the interface trait that will be attached to each
///              instance of `ValueT` that implements this interface.
///
template <typename ConcreteType, typename ValueT, typename Traits,
          typename BaseType,
          template <typename, template <typename> class> class BaseTrait>
class Interface : public BaseType { … };

//===----------------------------------------------------------------------===//
// InterfaceMap
//===----------------------------------------------------------------------===//

/// Template utility that computes the number of elements within `T` that
/// satisfy the given predicate.
template <template <class> class Pred, size_t N, typename... Ts>
struct count_if_t_impl : public std::integral_constant<size_t, N> { … };
count_if_t_impl<Pred, N, T, Us...>;
count_if_t;

/// This class provides an efficient mapping between a given `Interface` type,
/// and a particular implementation of its concept.
class InterfaceMap { … };

template <typename ConcreteType, typename ValueT, typename Traits,
          typename BaseType,
          template <typename, template <typename> class> class BaseTrait>
void isInterfaceImpl(
    Interface<ConcreteType, ValueT, Traits, BaseType, BaseTrait> &);

is_interface_t;

IsInterface;

} // namespace detail
} // namespace mlir

namespace llvm {

DenseMapInfo<T, std::enable_if_t<mlir::detail::IsInterface<T>::value>>;

} // namespace llvm

#endif