/*
 * Copyright (c) Facebook, Inc. and its affiliates.
 *
 * Licensed under the Apache License Version 2.0 with LLVM Exceptions
 * (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 *
 *   https://llvm.org/LICENSE.txt
 *
 * 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.
 */
#pragma once

#include <type_traits>

#include <unifex/config.hpp>
#include <unifex/type_traits.hpp>

#if defined(_MSC_VER) && !defined(__clang__)
#define UNIFEX_WORKAROUND_MSVC_779763 // FATAL_UNREACHABLE calling constexpr function via template parameter
#define UNIFEX_WORKAROUND_MSVC_780775 // Incorrect substitution in function template return type
#endif

#define UNIFEX_PP_CAT_(X, ...)  X ## __VA_ARGS__
#define UNIFEX_PP_CAT(X, ...)   UNIFEX_PP_CAT_(X, __VA_ARGS__)

#define UNIFEX_PP_CAT2_(X, ...)  X ## __VA_ARGS__
#define UNIFEX_PP_CAT2(X, ...)   UNIFEX_PP_CAT2_(X, __VA_ARGS__)

#define UNIFEX_PP_CAT3_(X, ...)  X ## __VA_ARGS__
#define UNIFEX_PP_CAT3(X, ...)   UNIFEX_PP_CAT3_(X, __VA_ARGS__)

#define UNIFEX_PP_CAT4_(X, ...)  X ## __VA_ARGS__
#define UNIFEX_PP_CAT4(X, ...)   UNIFEX_PP_CAT4_(X, __VA_ARGS__)

#define UNIFEX_PP_EVAL_(X, ARGS) X ARGS
#define UNIFEX_PP_EVAL(X, ...) UNIFEX_PP_EVAL_(X, (__VA_ARGS__))

#define UNIFEX_PP_EVAL2_(X, ARGS) X ARGS
#define UNIFEX_PP_EVAL2(X, ...) UNIFEX_PP_EVAL2_(X, (__VA_ARGS__))

#define UNIFEX_PP_EXPAND(...) __VA_ARGS__
#define UNIFEX_PP_EAT(...)

#define UNIFEX_PP_CHECK(...) UNIFEX_PP_EXPAND(UNIFEX_PP_CHECK_N(__VA_ARGS__, 0,))
#define UNIFEX_PP_CHECK_N(x, n, ...) n
#define UNIFEX_PP_PROBE(x) x, 1,
#define UNIFEX_PP_PROBE_N(x, n) x, n,

#define UNIFEX_PP_IS_PAREN(x) UNIFEX_PP_CHECK(UNIFEX_PP_IS_PAREN_PROBE x)
#define UNIFEX_PP_IS_PAREN_PROBE(...) UNIFEX_PP_PROBE(~)

// The final UNIFEX_PP_EXPAND here is to avoid
// https://stackoverflow.com/questions/5134523/msvc-doesnt-expand-va-args-correctly
#define UNIFEX_PP_COUNT(...) \
  UNIFEX_PP_EXPAND(UNIFEX_PP_COUNT_(__VA_ARGS__, \
    50, 49, 48, 47, 46, 45, 44, 43, 42, 41, \
    40, 39, 38, 37, 36, 35, 34, 33, 32, 31, \
    30, 29, 28, 27, 26, 25, 24, 23, 22, 21, \
    20, 19, 18, 17, 16, 15, 14, 13, 12, 11, \
    10, 9, 8, 7, 6, 5, 4, 3, 2, 1,)) \
  /**/
#define UNIFEX_PP_COUNT_( \
  _01, _02, _03, _04, _05, _06, _07, _08, _09, _10, \
  _11, _12, _13, _14, _15, _16, _17, _18, _19, _20, \
  _21, _22, _23, _24, _25, _26, _27, _28, _29, _30, \
  _31, _32, _33, _34, _35, _36, _37, _38, _39, _40, \
  _41, _42, _43, _44, _45, _46, _47, _48, _49, _50, N, ...) \
  N \
  /**/

#define UNIFEX_PP_IIF(BIT) UNIFEX_PP_CAT_(UNIFEX_PP_IIF_, BIT)
#define UNIFEX_PP_IIF_0(TRUE, ...) __VA_ARGS__
#define UNIFEX_PP_IIF_1(TRUE, ...) TRUE

#define UNIFEX_PP_LPAREN (

#define UNIFEX_PP_NOT(BIT) UNIFEX_PP_CAT_(UNIFEX_PP_NOT_, BIT)
#define UNIFEX_PP_NOT_0 1
#define UNIFEX_PP_NOT_1 0

#define UNIFEX_PP_EMPTY()
#define UNIFEX_PP_COMMA() ,
#define UNIFEX_PP_LBRACE() {
#define UNIFEX_PP_RBRACE() }
#define UNIFEX_PP_COMMA_IIF(X) \
  UNIFEX_PP_IIF(X)(UNIFEX_PP_EMPTY, UNIFEX_PP_COMMA)() \
  /**/

#define UNIFEX_PP_FOR_EACH(M, ...) \
  UNIFEX_PP_FOR_EACH_N(UNIFEX_PP_COUNT(__VA_ARGS__), M, __VA_ARGS__)
#define UNIFEX_PP_FOR_EACH_N(N, M, ...) \
  UNIFEX_PP_CAT2(UNIFEX_PP_FOR_EACH_, N)(M, __VA_ARGS__)
#define UNIFEX_PP_FOR_EACH_1(M, _1) \
  M(_1)
#define UNIFEX_PP_FOR_EACH_2(M, _1, _2) \
  M(_1) M(_2)
#define UNIFEX_PP_FOR_EACH_3(M, _1, _2, _3) \
  M(_1) M(_2) M(_3)
#define UNIFEX_PP_FOR_EACH_4(M, _1, _2, _3, _4) \
  M(_1) M(_2) M(_3) M(_4)
#define UNIFEX_PP_FOR_EACH_5(M, _1, _2, _3, _4, _5) \
  M(_1) M(_2) M(_3) M(_4) M(_5)
#define UNIFEX_PP_FOR_EACH_6(M, _1, _2, _3, _4, _5, _6) \
  M(_1) M(_2) M(_3) M(_4) M(_5) M(_6)
#define UNIFEX_PP_FOR_EACH_7(M, _1, _2, _3, _4, _5, _6, _7) \
  M(_1) M(_2) M(_3) M(_4) M(_5) M(_6) M(_7)
#define UNIFEX_PP_FOR_EACH_8(M, _1, _2, _3, _4, _5, _6, _7, _8) \
  M(_1) M(_2) M(_3) M(_4) M(_5) M(_6) M(_7) M(_8)

#define UNIFEX_PP_PROBE_EMPTY_PROBE_UNIFEX_PP_PROBE_EMPTY \
  UNIFEX_PP_PROBE(~) \

#define UNIFEX_PP_PROBE_EMPTY()
#define UNIFEX_PP_IS_NOT_EMPTY(...) \
  UNIFEX_PP_EVAL( \
    UNIFEX_PP_CHECK, \
    UNIFEX_PP_CAT( \
      UNIFEX_PP_PROBE_EMPTY_PROBE_, \
      UNIFEX_PP_PROBE_EMPTY __VA_ARGS__ ())) \
  /**/

#define UNIFEX_PP_TAIL(_, ...) __VA_ARGS__

#define UNIFEX_CONCEPT_FRAGMENT_REQS_M0(REQ) \
  UNIFEX_CONCEPT_FRAGMENT_REQS_SELECT_(REQ)(REQ)
#define UNIFEX_CONCEPT_FRAGMENT_REQS_M1(REQ) UNIFEX_PP_EXPAND REQ
#define UNIFEX_CONCEPT_FRAGMENT_REQS_(...) \
  { UNIFEX_PP_FOR_EACH(UNIFEX_CONCEPT_FRAGMENT_REQS_M, __VA_ARGS__) }
#define UNIFEX_CONCEPT_FRAGMENT_REQS_SELECT_(REQ) \
  UNIFEX_PP_CAT3(UNIFEX_CONCEPT_FRAGMENT_REQS_SELECT_, \
    UNIFEX_PP_EVAL(UNIFEX_PP_CHECK, UNIFEX_PP_CAT3( \
      UNIFEX_CONCEPT_FRAGMENT_REQS_SELECT_PROBE_, \
      REQ))) \
  /**/
#define UNIFEX_CONCEPT_FRAGMENT_REQS_SELECT_PROBE_requires UNIFEX_PP_PROBE_N(~, 1)
#define UNIFEX_CONCEPT_FRAGMENT_REQS_SELECT_PROBE_noexcept UNIFEX_PP_PROBE_N(~, 2)
#define UNIFEX_CONCEPT_FRAGMENT_REQS_SELECT_PROBE_typename UNIFEX_PP_PROBE_N(~, 3)

#define UNIFEX_CONCEPT_FRAGMENT_REQS_SELECT_0 UNIFEX_PP_EXPAND
#define UNIFEX_CONCEPT_FRAGMENT_REQS_SELECT_1 UNIFEX_CONCEPT_FRAGMENT_REQS_REQUIRES_OR_NOEXCEPT
#define UNIFEX_CONCEPT_FRAGMENT_REQS_SELECT_2 UNIFEX_CONCEPT_FRAGMENT_REQS_REQUIRES_OR_NOEXCEPT
#define UNIFEX_CONCEPT_FRAGMENT_REQS_SELECT_3 UNIFEX_CONCEPT_FRAGMENT_REQS_REQUIRES_OR_NOEXCEPT
#define UNIFEX_CONCEPT_FRAGMENT_REQS_REQUIRES_OR_NOEXCEPT(REQ) \
  UNIFEX_PP_CAT4( \
    UNIFEX_CONCEPT_FRAGMENT_REQS_REQUIRES_, \
    REQ)
#define UNIFEX_PP_EAT_TYPENAME_PROBE_typename UNIFEX_PP_PROBE(~)
#define UNIFEX_PP_EAT_TYPENAME_SELECT_(X,...) \
  UNIFEX_PP_CAT3(UNIFEX_PP_EAT_TYPENAME_SELECT_, \
    UNIFEX_PP_EVAL(UNIFEX_PP_CHECK, UNIFEX_PP_CAT3( \
      UNIFEX_PP_EAT_TYPENAME_PROBE_, \
      X)))
#define UNIFEX_PP_EAT_TYPENAME_(...) \
  UNIFEX_PP_EVAL2(UNIFEX_PP_EAT_TYPENAME_SELECT_, __VA_ARGS__,)(__VA_ARGS__)
#define UNIFEX_PP_EAT_TYPENAME_SELECT_0(...) __VA_ARGS__
#define UNIFEX_PP_EAT_TYPENAME_SELECT_1(...) \
  UNIFEX_PP_CAT3(UNIFEX_PP_EAT_TYPENAME_, __VA_ARGS__)
#define UNIFEX_PP_EAT_TYPENAME_typename

#if UNIFEX_CXX_CONCEPTS || defined(UNIFEX_DOXYGEN_INVOKED)

  #define UNIFEX_CONCEPT concept

  #define UNIFEX_CONCEPT_FRAGMENT(NAME, ...) \
    concept NAME = UNIFEX_PP_CAT(UNIFEX_CONCEPT_FRAGMENT_REQS_, __VA_ARGS__)
  #define UNIFEX_CONCEPT_FRAGMENT_REQS_requires(...) \
    requires(__VA_ARGS__) UNIFEX_CONCEPT_FRAGMENT_REQS_
  #define UNIFEX_CONCEPT_FRAGMENT_REQS_M(REQ) \
    UNIFEX_PP_CAT2(UNIFEX_CONCEPT_FRAGMENT_REQS_M, UNIFEX_PP_IS_PAREN(REQ))(REQ);
  #define UNIFEX_CONCEPT_FRAGMENT_REQS_REQUIRES_requires(...) \
    requires __VA_ARGS__
  #define UNIFEX_CONCEPT_FRAGMENT_REQS_REQUIRES_typename(...) \
    typename UNIFEX_PP_EAT_TYPENAME_(__VA_ARGS__)
  #define UNIFEX_CONCEPT_FRAGMENT_REQS_REQUIRES_noexcept(...) \
    { __VA_ARGS__ } noexcept

  #define UNIFEX_FRAGMENT(NAME, ...) \
    NAME<__VA_ARGS__>

#else

  #define UNIFEX_CONCEPT inline constexpr bool

  #define UNIFEX_CONCEPT_FRAGMENT(NAME, ...) \
    auto NAME ## UNIFEX_CONCEPT_FRAGMENT_impl_ \
      UNIFEX_CONCEPT_FRAGMENT_REQS_ ## __VA_ARGS__> {} \
    template <typename... As> \
    char NAME ## UNIFEX_CONCEPT_FRAGMENT_( \
      ::unifex::_concept::tag<As...> *, \
      decltype(&NAME ## UNIFEX_CONCEPT_FRAGMENT_impl_<As...>)); \
    char (&NAME ## UNIFEX_CONCEPT_FRAGMENT_(...))[2] \
    /**/
  #if defined(_MSC_VER) && !defined(__clang__)
    #define UNIFEX_CONCEPT_FRAGMENT_TRUE(...) \
      ::unifex::_concept::true_<decltype( \
        UNIFEX_PP_FOR_EACH(UNIFEX_CONCEPT_FRAGMENT_REQS_M, __VA_ARGS__) \
        void())>()
  #else
    #define UNIFEX_CONCEPT_FRAGMENT_TRUE(...) \
      !(decltype(UNIFEX_PP_FOR_EACH(UNIFEX_CONCEPT_FRAGMENT_REQS_M, __VA_ARGS__) \
      void(), \
      false){})
  #endif
  #define UNIFEX_CONCEPT_FRAGMENT_REQS_requires(...) \
    (__VA_ARGS__) -> std::enable_if_t<UNIFEX_CONCEPT_FRAGMENT_REQS_2_
  #define UNIFEX_CONCEPT_FRAGMENT_REQS_2_(...) \
    UNIFEX_CONCEPT_FRAGMENT_TRUE(__VA_ARGS__)
  #define UNIFEX_CONCEPT_FRAGMENT_REQS_M(REQ) \
    UNIFEX_PP_CAT2(UNIFEX_CONCEPT_FRAGMENT_REQS_M, UNIFEX_PP_IS_PAREN(REQ))(REQ),
  #define UNIFEX_CONCEPT_FRAGMENT_REQS_REQUIRES_requires(...) \
    ::unifex::requires_<__VA_ARGS__>
  #define UNIFEX_CONCEPT_FRAGMENT_REQS_REQUIRES_typename(...) \
    static_cast<::unifex::_concept::tag<__VA_ARGS__> *>(nullptr)
  #if defined(__GNUC__) && !defined(__clang__)
    // GCC can't mangle noexcept expressions, so just check that the
    // expression is well-formed.
    // https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70790
    #define UNIFEX_CONCEPT_FRAGMENT_REQS_REQUIRES_noexcept(...) \
      __VA_ARGS__
  #else
    #define UNIFEX_CONCEPT_FRAGMENT_REQS_REQUIRES_noexcept(...) \
      ::unifex::requires_<noexcept(__VA_ARGS__)>
  #endif

  #define UNIFEX_FRAGMENT(NAME, ...) \
    (1u==sizeof(NAME ## UNIFEX_CONCEPT_FRAGMENT_( \
      static_cast<::unifex::_concept::tag<__VA_ARGS__> *>(nullptr), nullptr)))

#endif

////////////////////////////////////////////////////////////////////////////////
// UNIFEX_TEMPLATE
// Usage:
//   UNIFEX_TEMPLATE(typename A, typename B)
//     (requires Concept1<A> UNIFEX_AND Concept2<B>)
//   void foo(A a, B b)
//   {}
#if UNIFEX_CXX_CONCEPTS
  #define UNIFEX_TEMPLATE(...) \
    template <__VA_ARGS__> UNIFEX_PP_EXPAND \
    /**/
  #define UNIFEX_AND && \
    /**/
#else
  #define UNIFEX_TEMPLATE(...) \
    template <__VA_ARGS__ UNIFEX_TEMPLATE_SFINAE_AUX_ \
    /**/
  #define UNIFEX_AND && UNIFEX_true_, int> = 0, std::enable_if_t< \
    /**/
#endif

#define UNIFEX_TEMPLATE_SFINAE(...) \
  template <__VA_ARGS__ UNIFEX_TEMPLATE_SFINAE_AUX_ \
  /**/
#define UNIFEX_TEMPLATE_SFINAE_AUX_(...) , \
  bool UNIFEX_true_ = true, \
  std::enable_if_t< \
    UNIFEX_PP_CAT(UNIFEX_TEMPLATE_SFINAE_AUX_3_, __VA_ARGS__) && UNIFEX_true_, \
    int> = 0> \
  /**/
#define UNIFEX_TEMPLATE_SFINAE_AUX_3_requires

#include <unifex/detail/prologue.hpp>

namespace unifex {
  namespace _concept {
    template <typename...>
    struct tag;
    template <class>
    inline constexpr bool true_() {
      return true;
    }
  } // namespace _concept

#if defined(__clang__) || defined(_MSC_VER)
  template <bool B>
  std::enable_if_t<B> requires_() {}
#else
  template <bool B>
  inline constexpr std::enable_if_t<B, int> requires_ = 0;
#endif

#if UNIFEX_CXX_CONCEPTS
  template <typename Fn, typename... As>
  concept //
    callable = //
      requires (Fn&& fn, As&&... as) {
        ((Fn&&) fn)((As&&) as...);
      };
#else
  template <typename Fn, typename... As>
  UNIFEX_CONCEPT //
    callable = //
      sizeof(decltype(_is_callable::_try_call(static_cast<Fn(*)(As...)>(nullptr)))) ==
      sizeof(_is_callable::yes_type);
#endif

} // namespace unifex

#include <unifex/detail/epilogue.hpp>