test2/source/blender/functions/FN_multi_function_signature.hh

/* SPDX-FileCopyrightText: 2023 Blender Authors
 *
 * SPDX-License-Identifier: GPL-2.0-or-later */

#pragma once

/** \file
 * \ingroup fn
 *
 * The signature of a multi-function contains the functions name and expected parameters. New
 * signatures should be build using the #SignatureBuilder class.
 */

#include "FN_multi_function_param_type.hh"

#include "BLI_enum_flags.hh"
#include "BLI_vector.hh"

namespace blender::fn::multi_function {

enum class ParamFlag {
  None = 0,
  /**
   * If set, the multi-function parameter can be accessed using
   * #Params::uninitialized_single_output_if_required which can result in better performance
   * because the output does not have to be computed when it is not needed.
   */
  SupportsUnusedOutput = 1 << 0,
};
ENUM_OPERATORS(ParamFlag);

struct Signature {
  struct ParamInfo {
    ParamType type;
    const char *name;
    ParamFlag flag = ParamFlag::None;
  };

  /**
   * The name should be statically allocated so that it lives longer than this signature. This is
   * used instead of an #std::string because of the overhead when many functions are created.
   * If the name of the function has to be more dynamic for debugging purposes, override
   * #MultiFunction::debug_name() instead. Then the dynamic name will only be computed when it is
   * actually needed.
   */
  const char *function_name;
  Vector<ParamInfo> params;
};

class SignatureBuilder {
 private:
  Signature &signature_;

 public:
  SignatureBuilder(const char *function_name, Signature &signature_to_build);

  /* Input Parameter Types */

  template<typename T> void single_input(const char *name);
  void single_input(const char *name, const CPPType &type);
  template<typename T> void vector_input(const char *name);
  void vector_input(const char *name, const CPPType &base_type);
  void input(const char *name, DataType data_type);

  /* Output Parameter Types */

  template<typename T>
  void single_output(const char *name, const ParamFlag flag = ParamFlag::None);
  void single_output(const char *name,
                     const CPPType &type,
                     const ParamFlag flag = ParamFlag::None);
  template<typename T>
  void vector_output(const char *name, const ParamFlag flag = ParamFlag::None);
  void vector_output(const char *name,
                     const CPPType &base_type,
                     const ParamFlag flag = ParamFlag::None);
  void output(const char *name, DataType data_type, const ParamFlag flag = ParamFlag::None);

  /* Mutable Parameter Types */

  template<typename T> void single_mutable(const char *name);
  void single_mutable(const char *name, const CPPType &type);
  template<typename T> void vector_mutable(const char *name);
  void vector_mutable(const char *name, const CPPType &base_type);
  void mutable_(const char *name, DataType data_type);

  template<ParamCategory Category, typename T>
  void add(ParamTag<Category, T> /*tag*/, const char *name);
  void add(const char *name, const ParamType &param_type);
};

/* -------------------------------------------------------------------- */
/** \name #SignatureBuilder Inline Methods
 * \{ */

inline SignatureBuilder::SignatureBuilder(const char *function_name, Signature &signature_to_build)
    : signature_(signature_to_build)
{
  signature_.function_name = function_name;
}

template<typename T> inline void SignatureBuilder::single_input(const char *name)
{
  this->single_input(name, CPPType::get<T>());
}

inline void SignatureBuilder::single_input(const char *name, const CPPType &type)
{
  this->input(name, DataType::ForSingle(type));
}

template<typename T> inline void SignatureBuilder::vector_input(const char *name)
{
  this->vector_input(name, CPPType::get<T>());
}

inline void SignatureBuilder::vector_input(const char *name, const CPPType &base_type)
{
  this->input(name, DataType::ForVector(base_type));
}

inline void SignatureBuilder::input(const char *name, DataType data_type)
{
  signature_.params.append({ParamType(ParamType::Input, data_type), name});
}

template<typename T>
inline void SignatureBuilder::single_output(const char *name, const ParamFlag flag)
{
  this->single_output(name, CPPType::get<T>(), flag);
}

inline void SignatureBuilder::single_output(const char *name,
                                            const CPPType &type,
                                            const ParamFlag flag)
{
  this->output(name, DataType::ForSingle(type), flag);
}

template<typename T>
inline void SignatureBuilder::vector_output(const char *name, const ParamFlag flag)
{
  this->vector_output(name, CPPType::get<T>(), flag);
}

inline void SignatureBuilder::vector_output(const char *name,
                                            const CPPType &base_type,
                                            const ParamFlag flag)
{
  this->output(name, DataType::ForVector(base_type), flag);
}

inline void SignatureBuilder::output(const char *name, DataType data_type, const ParamFlag flag)
{
  signature_.params.append({ParamType(ParamType::Output, data_type), name, flag});
}

template<typename T> inline void SignatureBuilder::single_mutable(const char *name)
{
  this->single_mutable(name, CPPType::get<T>());
}

inline void SignatureBuilder::single_mutable(const char *name, const CPPType &type)
{
  this->mutable_(name, DataType::ForSingle(type));
}

template<typename T> inline void SignatureBuilder::vector_mutable(const char *name)
{
  this->vector_mutable(name, CPPType::get<T>());
}

inline void SignatureBuilder::vector_mutable(const char *name, const CPPType &base_type)
{
  this->mutable_(name, DataType::ForVector(base_type));
}

inline void SignatureBuilder::mutable_(const char *name, DataType data_type)
{
  signature_.params.append({ParamType(ParamType::Mutable, data_type), name});
}

inline void SignatureBuilder::add(const char *name, const ParamType &param_type)
{
  switch (param_type.interface_type()) {
    case ParamType::Input:
      this->input(name, param_type.data_type());
      break;
    case ParamType::Mutable:
      this->mutable_(name, param_type.data_type());
      break;
    case ParamType::Output:
      this->output(name, param_type.data_type());
      break;
  }
}

template<ParamCategory Category, typename T>
inline void SignatureBuilder::add(ParamTag<Category, T> /*tag*/, const char *name)
{
  switch (Category) {
    case ParamCategory::SingleInput:
      this->single_input<T>(name);
      return;
    case ParamCategory::VectorInput:
      this->vector_input<T>(name);
      return;
    case ParamCategory::SingleOutput:
      this->single_output<T>(name);
      return;
    case ParamCategory::VectorOutput:
      this->vector_output<T>(name);
      return;
    case ParamCategory::SingleMutable:
      this->single_mutable<T>(name);
      return;
    case ParamCategory::VectorMutable:
      this->vector_mutable<T>(name);
      return;
  }
  BLI_assert_unreachable();
}

/** \} */

}  // namespace blender::fn::multi_function