llvm-project/pstl/test/support/utils.h

// -*- C++ -*-
//===-- utils.h -----------------------------------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//

// File contains common utilities that tests rely on

// Do not #include <algorithm>, because if we do we will not detect accidental dependencies.
#include <atomic>
#include <cstdint>
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <iterator>
#include <memory>
#include <sstream>
#include <vector>

#include "pstl_test_config.h"

namespace TestUtils
{

typedef double float64_t;
typedef float float32_t;

template <class T, std::size_t N>
constexpr size_t
const_size(const T (&)[N]) noexcept
{
    return N;
}

template <typename T>
class Sequence;

// Handy macros for error reporting
#define EXPECT_TRUE(condition, message) ::TestUtils::expect(true, condition, __FILE__, __LINE__, message)
#define EXPECT_FALSE(condition, message) ::TestUtils::expect(false, condition, __FILE__, __LINE__, message)

// Check that expected and actual are equal and have the same type.
#define EXPECT_EQ(expected, actual, message) ::TestUtils::expect_equal(expected, actual, __FILE__, __LINE__, message)

// Check that sequences started with expected and actual and have had size n are equal and have the same type.
#define EXPECT_EQ_N(expected, actual, n, message)                                                                      \
    ::TestUtils::expect_equal(expected, actual, n, __FILE__, __LINE__, message)

// Issue error message from outstr, adding a newline.
// Real purpose of this routine is to have a place to hang a breakpoint.
inline void
issue_error_message(std::stringstream& outstr)
{
    outstr << std::endl;
    std::cerr << outstr.str();
    std::exit(EXIT_FAILURE);
}

inline void
expect(bool expected, bool condition, const char* file, int32_t line, const char* message)
{
    if (condition != expected)
    {
        std::stringstream outstr;
        outstr << "error at " << file << ":" << line << " - " << message;
        issue_error_message(outstr);
    }
}

// Do not change signature to const T&.
// Function must be able to detect const differences between expected and actual.
template <typename T>
void
expect_equal(T& expected, T& actual, const char* file, int32_t line, const char* message)
{
    if (!(expected == actual))
    {
        std::stringstream outstr;
        outstr << "error at " << file << ":" << line << " - " << message << ", expected " << expected << " got "
               << actual;
        issue_error_message(outstr);
    }
}

template <typename T>
void
expect_equal(Sequence<T>& expected, Sequence<T>& actual, const char* file, int32_t line, const char* message)
{
    size_t n = expected.size();
    size_t m = actual.size();
    if (n != m)
    {
        std::stringstream outstr;
        outstr << "error at " << file << ":" << line << " - " << message << ", expected sequence of size " << n
               << " got sequence of size " << m;
        issue_error_message(outstr);
        return;
    }
    size_t error_count = 0;
    for (size_t k = 0; k < n && error_count < 10; ++k)
    {
        if (!(expected[k] == actual[k]))
        {
            std::stringstream outstr;
            outstr << "error at " << file << ":" << line << " - " << message << ", at index " << k << " expected "
                   << expected[k] << " got " << actual[k];
            issue_error_message(outstr);
            ++error_count;
        }
    }
}

template <typename Iterator1, typename Iterator2, typename Size>
void
expect_equal(Iterator1 expected_first, Iterator2 actual_first, Size n, const char* file, int32_t line,
             const char* message)
{
    size_t error_count = 0;
    for (Size k = 0; k < n && error_count < 10; ++k, ++expected_first, ++actual_first)
    {
        if (!(*expected_first == *actual_first))
        {
            std::stringstream outstr;
            outstr << "error at " << file << ":" << line << " - " << message << ", at index " << k;
            issue_error_message(outstr);
            ++error_count;
        }
    }
}

// ForwardIterator is like type Iterator, but restricted to be a forward iterator.
// Only the forward iterator signatures that are necessary for tests are present.
// Post-increment in particular is deliberatly omitted since our templates should avoid using it
// because of efficiency considerations.
template <typename Iterator, typename IteratorTag>
class ForwardIterator
{
  public:
    typedef IteratorTag iterator_category;
    typedef typename std::iterator_traits<Iterator>::value_type value_type;
    typedef typename std::iterator_traits<Iterator>::difference_type difference_type;
    typedef typename std::iterator_traits<Iterator>::pointer pointer;
    typedef typename std::iterator_traits<Iterator>::reference reference;

  protected:
    Iterator my_iterator;
    typedef value_type element_type;

  public:
    ForwardIterator() = default;
    explicit ForwardIterator(Iterator i) : my_iterator(i) {}
    reference operator*() const { return *my_iterator; }
    Iterator operator->() const { return my_iterator; }
    ForwardIterator
    operator++()
    {
        ++my_iterator;
        return *this;
    }
    ForwardIterator operator++(int32_t)
    {
        auto retval = *this;
        my_iterator++;
        return retval;
    }
    friend bool
    operator==(const ForwardIterator& i, const ForwardIterator& j)
    {
        return i.my_iterator == j.my_iterator;
    }
    friend bool
    operator!=(const ForwardIterator& i, const ForwardIterator& j)
    {
        return i.my_iterator != j.my_iterator;
    }

    Iterator
    iterator() const
    {
        return my_iterator;
    }
};

template <typename Iterator, typename IteratorTag>
class BidirectionalIterator : public ForwardIterator<Iterator, IteratorTag>
{
    typedef ForwardIterator<Iterator, IteratorTag> base_type;

  public:
    BidirectionalIterator() = default;
    explicit BidirectionalIterator(Iterator i) : base_type(i) {}
    BidirectionalIterator(const base_type& i) : base_type(i.iterator()) {}

    BidirectionalIterator
    operator++()
    {
        ++base_type::my_iterator;
        return *this;
    }
    BidirectionalIterator
    operator--()
    {
        --base_type::my_iterator;
        return *this;
    }
    BidirectionalIterator operator++(int32_t)
    {
        auto retval = *this;
        base_type::my_iterator++;
        return retval;
    }
    BidirectionalIterator operator--(int32_t)
    {
        auto retval = *this;
        base_type::my_iterator--;
        return retval;
    }
};

template <typename Iterator, typename F>
void
fill_data(Iterator first, Iterator last, F f)
{
    typedef typename std::iterator_traits<Iterator>::value_type T;
    for (std::size_t i = 0; first != last; ++first, ++i)
    {
        *first = T(f(i));
    }
}

struct MemoryChecker {
    // static counters and state tags
    static std::atomic<std::int64_t> alive_object_counter; // initialized outside
    static constexpr std::int64_t alive_state = 0xAAAAAAAAAAAAAAAA;
    static constexpr std::int32_t dead_state = 0; // only used as a set value to cancel alive_state

    std::int32_t _value; // object value used for algorithms
    std::int64_t _state; // state tag used for checks

    // ctors, dtors, assign ops
    explicit MemoryChecker(std::int32_t value = 0) : _value(value) {
        // check for EXPECT_TRUE(state() != alive_state, ...) has not been done since we cannot guarantee that
        // raw memory for object being constructed does not have a bit sequence being equal to alive_state

        // set constructed state and increment counter for living object
        inc_alive_objects();
        _state = alive_state;
    }
    MemoryChecker(MemoryChecker&& other) : _value(other.value()) {
        // check for EXPECT_TRUE(state() != alive_state, ...) has not been done since
        // compiler can optimize out the move ctor call that results in false positive failure
        EXPECT_TRUE(other.state() == alive_state, "wrong effect from MemoryChecker(MemoryChecker&&): attemp to construct an object from non-existing object");
        // set constructed state and increment counter for living object
        inc_alive_objects();
        _state = alive_state;
    }
    MemoryChecker(const MemoryChecker& other) : _value(other.value()) {
        // check for EXPECT_TRUE(state() != alive_state, ...) has not been done since
        // compiler can optimize out the copy ctor call that results in false positive failure
        EXPECT_TRUE(other.state() == alive_state, "wrong effect from MemoryChecker(const MemoryChecker&): attemp to construct an object from non-existing object");
        // set constructed state and increment counter for living object
        inc_alive_objects();
        _state = alive_state;
    }
    MemoryChecker& operator=(MemoryChecker&& other) {
        // check if we do not assign over uninitialized memory
        EXPECT_TRUE(state() == alive_state, "wrong effect from MemoryChecker::operator=(MemoryChecker&& other): attemp to assign to non-existing object");
        EXPECT_TRUE(other.state() == alive_state, "wrong effect from MemoryChecker::operator=(MemoryChecker&& other): attemp to assign from non-existing object");
        // just assign new value, counter is the same, state is the same
        _value = other.value();

        return *this;
    }
    MemoryChecker& operator=(const MemoryChecker& other) {
        // check if we do not assign over uninitialized memory
        EXPECT_TRUE(state() == alive_state, "wrong effect from MemoryChecker::operator=(const MemoryChecker& other): attemp to assign to non-existing object");
        EXPECT_TRUE(other.state() == alive_state, "wrong effect from MemoryChecker::operator=(const MemoryChecker& other): attemp to assign from non-existing object");
        // just assign new value, counter is the same, state is the same
        _value = other.value();

        return *this;
    }
    ~MemoryChecker() {
        // check if we do not double destruct the object
        EXPECT_TRUE(state() == alive_state, "wrong effect from ~MemoryChecker(): attemp to destroy non-existing object");
        // set destructed state and decrement counter for living object
        static_cast<volatile std::int64_t&>(_state) = dead_state;
        dec_alive_objects();
    }

    // getters
    std::int32_t value() const { return _value; }
    std::int64_t state() const { return _state; }
    static std::int32_t alive_objects() { return alive_object_counter.load(); }
private:
    // setters
    void inc_alive_objects() { alive_object_counter.fetch_add(1); }
    void dec_alive_objects() { alive_object_counter.fetch_sub(1); }
};

std::atomic<std::int64_t> MemoryChecker::alive_object_counter{0};

std::ostream& operator<<(std::ostream& os, const MemoryChecker& val) { return (os << val.value()); }
bool operator==(const MemoryChecker& v1, const MemoryChecker& v2) { return v1.value() == v2.value(); }
bool operator<(const MemoryChecker& v1, const MemoryChecker& v2) { return v1.value() < v2.value(); }

// Sequence<T> is a container of a sequence of T with lots of kinds of iterators.
// Prefixes on begin/end mean:
//      c = "const"
//      f = "forward"
// No prefix indicates non-const random-access iterator.
template <typename T>
class Sequence
{
    std::vector<T> m_storage;

  public:
    typedef typename std::vector<T>::iterator iterator;
    typedef typename std::vector<T>::const_iterator const_iterator;
    typedef ForwardIterator<iterator, std::forward_iterator_tag> forward_iterator;
    typedef ForwardIterator<const_iterator, std::forward_iterator_tag> const_forward_iterator;

    typedef BidirectionalIterator<iterator, std::bidirectional_iterator_tag> bidirectional_iterator;
    typedef BidirectionalIterator<const_iterator, std::bidirectional_iterator_tag> const_bidirectional_iterator;

    typedef T value_type;
    explicit Sequence(size_t size) : m_storage(size) {}

    // Construct sequence [f(0), f(1), ... f(size-1)]
    // f can rely on its invocations being sequential from 0 to size-1.
    template <typename Func>
    Sequence(size_t size, Func f)
    {
        m_storage.reserve(size);
        // Use push_back because T might not have a default constructor
        for (size_t k = 0; k < size; ++k)
            m_storage.push_back(T(f(k)));
    }
    Sequence(const std::initializer_list<T>& data) : m_storage(data) {}

    const_iterator
    begin() const
    {
        return m_storage.begin();
    }
    const_iterator
    end() const
    {
        return m_storage.end();
    }
    iterator
    begin()
    {
        return m_storage.begin();
    }
    iterator
    end()
    {
        return m_storage.end();
    }
    const_iterator
    cbegin() const
    {
        return m_storage.cbegin();
    }
    const_iterator
    cend() const
    {
        return m_storage.cend();
    }
    forward_iterator
    fbegin()
    {
        return forward_iterator(m_storage.begin());
    }
    forward_iterator
    fend()
    {
        return forward_iterator(m_storage.end());
    }
    const_forward_iterator
    cfbegin() const
    {
        return const_forward_iterator(m_storage.cbegin());
    }
    const_forward_iterator
    cfend() const
    {
        return const_forward_iterator(m_storage.cend());
    }
    const_forward_iterator
    fbegin() const
    {
        return const_forward_iterator(m_storage.cbegin());
    }
    const_forward_iterator
    fend() const
    {
        return const_forward_iterator(m_storage.cend());
    }

    const_bidirectional_iterator
    cbibegin() const
    {
        return const_bidirectional_iterator(m_storage.cbegin());
    }
    const_bidirectional_iterator
    cbiend() const
    {
        return const_bidirectional_iterator(m_storage.cend());
    }

    bidirectional_iterator
    bibegin()
    {
        return bidirectional_iterator(m_storage.begin());
    }
    bidirectional_iterator
    biend()
    {
        return bidirectional_iterator(m_storage.end());
    }

    std::size_t
    size() const
    {
        return m_storage.size();
    }
    const T*
    data() const
    {
        return m_storage.data();
    }
    typename std::vector<T>::reference operator[](size_t j) { return m_storage[j]; }
    const T& operator[](size_t j) const { return m_storage[j]; }

    // Fill with given value
    void
    fill(const T& value)
    {
        for (size_t i = 0; i < m_storage.size(); i++)
            m_storage[i] = value;
    }

    void
    print() const;

    template <typename Func>
    void
    fill(Func f)
    {
        fill_data(m_storage.begin(), m_storage.end(), f);
    }
};

template <typename T>
void
Sequence<T>::print() const
{
    std::cout << "size = " << size() << ": { ";
    std::copy(begin(), end(), std::ostream_iterator<T>(std::cout, " "));
    std::cout << " } " << std::endl;
}

// Predicates for algorithms
template <typename DataType>
struct is_equal_to
{
    is_equal_to(const DataType& expected) : m_expected(expected) {}
    bool
    operator()(const DataType& actual) const
    {
        return actual == m_expected;
    }

  private:
    DataType m_expected;
};

// Low-quality hash function, returns value between 0 and (1<<bits)-1
// Warning: low-order bits are quite predictable.
inline size_t
HashBits(size_t i, size_t bits)
{
    size_t mask = bits >= 8 * sizeof(size_t) ? ~size_t(0) : (size_t(1) << bits) - 1;
    return (424157 * i ^ 0x24aFa) & mask;
}

// Stateful unary op
template <typename T, typename U>
class Complement
{
    int32_t val;

  public:
    Complement(T v) : val(v) {}
    U
    operator()(const T& x) const
    {
        return U(val - x);
    }
};

// Tag used to prevent accidental use of converting constructor, even if use is explicit.
struct OddTag
{
};

class Sum;

// Type with limited set of operations.  Not default-constructible.
// Only available operator is "==".
// Typically used as value type in tests.
class Number
{
    int32_t value;
    friend class Add;
    friend class Sum;
    friend class IsMultiple;
    friend class Congruent;
    friend Sum
    operator+(const Sum& x, const Sum& y);

  public:
    Number(int32_t val, OddTag) : value(val) {}
    friend bool
    operator==(const Number& x, const Number& y)
    {
        return x.value == y.value;
    }
    friend std::ostream&
    operator<<(std::ostream& o, const Number& d)
    {
        return o << d.value;
    }
};

// Stateful predicate for Number.  Not default-constructible.
class IsMultiple
{
    long modulus;

  public:
    // True if x is multiple of modulus
    bool
    operator()(Number x) const
    {
        return x.value % modulus == 0;
    }
    IsMultiple(long modulus_, OddTag) : modulus(modulus_) {}
};

// Stateful equivalence-class predicate for Number.  Not default-constructible.
class Congruent
{
    long modulus;

  public:
    // True if x and y have same remainder for the given modulus.
    // Note: this is not quite the same as "equivalent modulo modulus" when x and y have different
    // sign, but nonetheless AreCongruent is still an equivalence relationship, which is all
    // we need for testing.
    bool
    operator()(Number x, Number y) const
    {
        return x.value % modulus == y.value % modulus;
    }
    Congruent(long modulus_, OddTag) : modulus(modulus_) {}
};

// Stateful reduction operation for Number
class Add
{
    long bias;

  public:
    explicit Add(OddTag) : bias(1) {}
    Number
    operator()(Number x, const Number& y)
    {
        return Number(x.value + y.value + (bias - 1), OddTag());
    }
};

// Class similar to Number, but has default constructor and +.
class Sum : public Number
{
  public:
    Sum() : Number(0, OddTag()) {}
    Sum(long x, OddTag) : Number(x, OddTag()) {}
    friend Sum
    operator+(const Sum& x, const Sum& y)
    {
        return Sum(x.value + y.value, OddTag());
    }
};

// Type with limited set of operations, which includes an associative but not commutative operation.
// Not default-constructible.
// Typically used as value type in tests involving "GENERALIZED_NONCOMMUTATIVE_SUM".
class MonoidElement
{
    size_t a, b;

  public:
    MonoidElement(size_t a_, size_t b_, OddTag) : a(a_), b(b_) {}
    friend bool
    operator==(const MonoidElement& x, const MonoidElement& y)
    {
        return x.a == y.a && x.b == y.b;
    }
    friend std::ostream&
    operator<<(std::ostream& o, const MonoidElement& x)
    {
        return o << "[" << x.a << ".." << x.b << ")";
    }
    friend class AssocOp;
};

// Stateful associative op for MonoidElement
// It's not really a monoid since the operation is not allowed for any two elements.
// But it's good enough for testing.
class AssocOp
{
    unsigned c;

  public:
    explicit AssocOp(OddTag) : c(5) {}
    MonoidElement
    operator()(const MonoidElement& x, const MonoidElement& y)
    {
        unsigned d = 5;
        EXPECT_EQ(d, c, "state lost");
        EXPECT_EQ(x.b, y.a, "commuted?");

        return MonoidElement(x.a, y.b, OddTag());
    }
};

// Multiplication of matrix is an associative but not commutative operation
// Typically used as value type in tests involving "GENERALIZED_NONCOMMUTATIVE_SUM".
template <typename T>
struct Matrix2x2
{
    T a[2][2];
    Matrix2x2() : a{{1, 0}, {0, 1}} {}
    Matrix2x2(T x, T y) : a{{0, x}, {x, y}} {}
#if !_PSTL_ICL_19_VC14_VC141_TEST_SCAN_RELEASE_BROKEN
    Matrix2x2(const Matrix2x2& m) : a{{m.a[0][0], m.a[0][1]}, {m.a[1][0], m.a[1][1]}} {}
    Matrix2x2&
    operator=(const Matrix2x2& m)
    {
        a[0][0] = m.a[0][0], a[0][1] = m.a[0][1], a[1][0] = m.a[1][0], a[1][1] = m.a[1][1];
        return *this;
    }
#endif
};

template <typename T>
bool
operator==(const Matrix2x2<T>& left, const Matrix2x2<T>& right)
{
    return left.a[0][0] == right.a[0][0] && left.a[0][1] == right.a[0][1] && left.a[1][0] == right.a[1][0] &&
           left.a[1][1] == right.a[1][1];
}

template <typename T>
Matrix2x2<T>
multiply_matrix(const Matrix2x2<T>& left, const Matrix2x2<T>& right)
{
    Matrix2x2<T> result;
    for (int32_t i = 0; i < 2; ++i)
    {
        for (int32_t j = 0; j < 2; ++j)
        {
            result.a[i][j] = left.a[i][0] * right.a[0][j] + left.a[i][1] * right.a[1][j];
        }
    }
    return result;
}

//============================================================================
// Adapters for creating different types of iterators.
//
// In this block we implemented some adapters for creating differnet types of iterators.
// It's needed for extending the unit testing of Parallel STL algorithms.
// We have adapters for iterators with different tags (forward_iterator_tag, bidirectional_iterator_tag), reverse iterators.
// The input iterator should be const or non-const, non-reverse random access iterator.
// Iterator creates in "MakeIterator":
// firstly, iterator is "packed" by "IteratorTypeAdapter" (creating forward or bidirectional iterator)
// then iterator is "packed" by "ReverseAdapter" (if it's possible)
// So, from input iterator we may create, for example, reverse bidirectional iterator.
// "Main" functor for testing iterators is named "invoke_on_all_iterator_types".

// Base adapter
template <typename Iterator>
struct BaseAdapter
{
    typedef Iterator iterator_type;
    iterator_type
    operator()(Iterator it)
    {
        return it;
    }
};

// Check if the iterator is reverse iterator
// Note: it works only for iterators that created by std::reverse_iterator
template <typename NotReverseIterator>
struct isReverse : std::false_type
{
};

template <typename Iterator>
struct isReverse<std::reverse_iterator<Iterator>> : std::true_type
{
};

// Reverse adapter
template <typename Iterator, typename IsReverse>
struct ReverseAdapter
{
    typedef std::reverse_iterator<Iterator> iterator_type;
    iterator_type
    operator()(Iterator it)
    {
#if _PSTL_CPP14_MAKE_REVERSE_ITERATOR_PRESENT
        return std::make_reverse_iterator(it);
#else
        return iterator_type(it);
#endif
    }
};

// Non-reverse adapter
template <typename Iterator>
struct ReverseAdapter<Iterator, std::false_type> : BaseAdapter<Iterator>
{
};

// Iterator adapter by type (by default std::random_access_iterator_tag)
template <typename Iterator, typename IteratorTag>
struct IteratorTypeAdapter : BaseAdapter<Iterator>
{
};

// Iterator adapter for forward iterator
template <typename Iterator>
struct IteratorTypeAdapter<Iterator, std::forward_iterator_tag>
{
    typedef ForwardIterator<Iterator, std::forward_iterator_tag> iterator_type;
    iterator_type
    operator()(Iterator it)
    {
        return iterator_type(it);
    }
};

// Iterator adapter for bidirectional iterator
template <typename Iterator>
struct IteratorTypeAdapter<Iterator, std::bidirectional_iterator_tag>
{
    typedef BidirectionalIterator<Iterator, std::bidirectional_iterator_tag> iterator_type;
    iterator_type
    operator()(Iterator it)
    {
        return iterator_type(it);
    }
};

//For creating iterator with new type
template <typename InputIterator, typename IteratorTag, typename IsReverse>
struct MakeIterator
{
    typedef IteratorTypeAdapter<InputIterator, IteratorTag> IterByType;
    typedef ReverseAdapter<typename IterByType::iterator_type, IsReverse> ReverseIter;

    typename ReverseIter::iterator_type
    operator()(InputIterator it)
    {
        return ReverseIter()(IterByType()(it));
    }
};

// Useful constant variables
constexpr std::size_t GuardSize = 5;
constexpr std::ptrdiff_t sizeLimit = 1000;

template <typename Iter, typename Void = void> // local iterator_traits for non-iterators
struct iterator_traits_
{
};

template <typename Iter> // For iterators
struct iterator_traits_<Iter,
                        typename std::enable_if<!std::is_void<typename Iter::iterator_category>::value, void>::type>
{
    typedef typename Iter::iterator_category iterator_category;
};

template <typename T> // For pointers
struct iterator_traits_<T*>
{
    typedef std::random_access_iterator_tag iterator_category;
};

// is iterator Iter has tag Tag
template <typename Iter, typename Tag>
using is_same_iterator_category = std::is_same<typename iterator_traits_<Iter>::iterator_category, Tag>;

// if we run with reverse or const iterators we shouldn't test the large range
template <typename IsReverse, typename IsConst>
struct invoke_if_
{
    template <typename Op, typename... Rest>
    void
    operator()(bool is_allow, Op op, Rest&&... rest)
    {
        if (is_allow)
            op(std::forward<Rest>(rest)...);
    }
};
template <>
struct invoke_if_<std::false_type, std::false_type>
{
    template <typename Op, typename... Rest>
    void
    operator()(bool, Op op, Rest&&... rest)
    {
        op(std::forward<Rest>(rest)...);
    }
};

// Base non_const_wrapper struct. It is used to distinguish non_const testcases
// from a regular one. For non_const testcases only compilation is checked.
struct non_const_wrapper
{
};

// Generic wrapper to specify iterator type to execute callable Op on.
// The condition can be either positive(Op is executed only with IteratorTag)
// or negative(Op is executed with every type of iterators except IteratorTag)
template <typename Op, typename IteratorTag, bool IsPositiveCondition = true>
struct non_const_wrapper_tagged : non_const_wrapper
{
    template <typename Policy, typename Iterator>
    typename std::enable_if<IsPositiveCondition == is_same_iterator_category<Iterator, IteratorTag>::value, void>::type
    operator()(Policy&& exec, Iterator iter)
    {
        Op()(exec, iter);
    }

    template <typename Policy, typename InputIterator, typename OutputIterator>
    typename std::enable_if<IsPositiveCondition == is_same_iterator_category<OutputIterator, IteratorTag>::value,
                            void>::type
    operator()(Policy&& exec, InputIterator input_iter, OutputIterator out_iter)
    {
        Op()(exec, input_iter, out_iter);
    }

    template <typename Policy, typename Iterator>
    typename std::enable_if<IsPositiveCondition != is_same_iterator_category<Iterator, IteratorTag>::value, void>::type
    operator()(Policy&&, Iterator)
    {
    }

    template <typename Policy, typename InputIterator, typename OutputIterator>
    typename std::enable_if<IsPositiveCondition != is_same_iterator_category<OutputIterator, IteratorTag>::value,
                            void>::type
    operator()(Policy&&, InputIterator, OutputIterator)
    {
    }
};

// These run_for_* structures specify with which types of iterators callable object Op
// should be executed.
template <typename Op>
struct run_for_rnd : non_const_wrapper_tagged<Op, std::random_access_iterator_tag>
{
};

template <typename Op>
struct run_for_rnd_bi : non_const_wrapper_tagged<Op, std::forward_iterator_tag, false>
{
};

template <typename Op>
struct run_for_rnd_fw : non_const_wrapper_tagged<Op, std::bidirectional_iterator_tag, false>
{
};

// Invoker for different types of iterators.
template <typename IteratorTag, typename IsReverse>
struct iterator_invoker
{
    template <typename Iterator>
    using make_iterator = MakeIterator<Iterator, IteratorTag, IsReverse>;
    template <typename Iterator>
    using IsConst = typename std::is_const<
        typename std::remove_pointer<typename std::iterator_traits<Iterator>::pointer>::type>::type;
    template <typename Iterator>
    using invoke_if = invoke_if_<IsReverse, IsConst<Iterator>>;

    // A single iterator version which is used for non_const testcases
    template <typename Policy, typename Op, typename Iterator>
    typename std::enable_if<is_same_iterator_category<Iterator, std::random_access_iterator_tag>::value &&
                                std::is_base_of<non_const_wrapper, Op>::value,
                            void>::type
    operator()(Policy&& exec, Op op, Iterator iter)
    {
        op(std::forward<Policy>(exec), make_iterator<Iterator>()(iter));
    }

    // A version with 2 iterators which is used for non_const testcases
    template <typename Policy, typename Op, typename InputIterator, typename OutputIterator>
    typename std::enable_if<is_same_iterator_category<OutputIterator, std::random_access_iterator_tag>::value &&
                                std::is_base_of<non_const_wrapper, Op>::value,
                            void>::type
    operator()(Policy&& exec, Op op, InputIterator input_iter, OutputIterator out_iter)
    {
        op(std::forward<Policy>(exec), make_iterator<InputIterator>()(input_iter),
           make_iterator<OutputIterator>()(out_iter));
    }

    template <typename Policy, typename Op, typename Iterator, typename Size, typename... Rest>
    typename std::enable_if<is_same_iterator_category<Iterator, std::random_access_iterator_tag>::value, void>::type
    operator()(Policy&& exec, Op op, Iterator begin, Size n, Rest&&... rest)
    {
        invoke_if<Iterator>()(n <= sizeLimit, op, exec, make_iterator<Iterator>()(begin), n,
                              std::forward<Rest>(rest)...);
    }

    template <typename Policy, typename Op, typename Iterator, typename... Rest>
    typename std::enable_if<is_same_iterator_category<Iterator, std::random_access_iterator_tag>::value &&
                                !std::is_base_of<non_const_wrapper, Op>::value,
                            void>::type
    operator()(Policy&& exec, Op op, Iterator inputBegin, Iterator inputEnd, Rest&&... rest)
    {
        invoke_if<Iterator>()(std::distance(inputBegin, inputEnd) <= sizeLimit, op, exec,
                              make_iterator<Iterator>()(inputBegin), make_iterator<Iterator>()(inputEnd),
                              std::forward<Rest>(rest)...);
    }

    template <typename Policy, typename Op, typename InputIterator, typename OutputIterator, typename... Rest>
    typename std::enable_if<is_same_iterator_category<OutputIterator, std::random_access_iterator_tag>::value,
                            void>::type
    operator()(Policy&& exec, Op op, InputIterator inputBegin, InputIterator inputEnd, OutputIterator outputBegin,
               Rest&&... rest)
    {
        invoke_if<InputIterator>()(std::distance(inputBegin, inputEnd) <= sizeLimit, op, exec,
                                   make_iterator<InputIterator>()(inputBegin), make_iterator<InputIterator>()(inputEnd),
                                   make_iterator<OutputIterator>()(outputBegin), std::forward<Rest>(rest)...);
    }

    template <typename Policy, typename Op, typename InputIterator, typename OutputIterator, typename... Rest>
    typename std::enable_if<is_same_iterator_category<OutputIterator, std::random_access_iterator_tag>::value,
                            void>::type
    operator()(Policy&& exec, Op op, InputIterator inputBegin, InputIterator inputEnd, OutputIterator outputBegin,
               OutputIterator outputEnd, Rest&&... rest)
    {
        invoke_if<InputIterator>()(std::distance(inputBegin, inputEnd) <= sizeLimit, op, exec,
                                   make_iterator<InputIterator>()(inputBegin), make_iterator<InputIterator>()(inputEnd),
                                   make_iterator<OutputIterator>()(outputBegin),
                                   make_iterator<OutputIterator>()(outputEnd), std::forward<Rest>(rest)...);
    }

    template <typename Policy, typename Op, typename InputIterator1, typename InputIterator2, typename OutputIterator,
              typename... Rest>
    typename std::enable_if<is_same_iterator_category<OutputIterator, std::random_access_iterator_tag>::value,
                            void>::type
    operator()(Policy&& exec, Op op, InputIterator1 inputBegin1, InputIterator1 inputEnd1, InputIterator2 inputBegin2,
               InputIterator2 inputEnd2, OutputIterator outputBegin, OutputIterator outputEnd, Rest&&... rest)
    {
        invoke_if<InputIterator1>()(
            std::distance(inputBegin1, inputEnd1) <= sizeLimit, op, exec, make_iterator<InputIterator1>()(inputBegin1),
            make_iterator<InputIterator1>()(inputEnd1), make_iterator<InputIterator2>()(inputBegin2),
            make_iterator<InputIterator2>()(inputEnd2), make_iterator<OutputIterator>()(outputBegin),
            make_iterator<OutputIterator>()(outputEnd), std::forward<Rest>(rest)...);
    }
};

// Invoker for reverse iterators only
// Note: if we run with reverse iterators we shouldn't test the large range
template <typename IteratorTag>
struct iterator_invoker<IteratorTag, /* IsReverse = */ std::true_type>
{

    template <typename Iterator>
    using make_iterator = MakeIterator<Iterator, IteratorTag, std::true_type>;

    // A single iterator version which is used for non_const testcases
    template <typename Policy, typename Op, typename Iterator>
    typename std::enable_if<is_same_iterator_category<Iterator, std::random_access_iterator_tag>::value &&
                                std::is_base_of<non_const_wrapper, Op>::value,
                            void>::type
    operator()(Policy&& exec, Op op, Iterator iter)
    {
        op(std::forward<Policy>(exec), make_iterator<Iterator>()(iter));
    }

    // A version with 2 iterators which is used for non_const testcases
    template <typename Policy, typename Op, typename InputIterator, typename OutputIterator>
    typename std::enable_if<is_same_iterator_category<OutputIterator, std::random_access_iterator_tag>::value &&
                                std::is_base_of<non_const_wrapper, Op>::value,
                            void>::type
    operator()(Policy&& exec, Op op, InputIterator input_iter, OutputIterator out_iter)
    {
        op(std::forward<Policy>(exec), make_iterator<InputIterator>()(input_iter),
           make_iterator<OutputIterator>()(out_iter));
    }

    template <typename Policy, typename Op, typename Iterator, typename Size, typename... Rest>
    typename std::enable_if<is_same_iterator_category<Iterator, std::random_access_iterator_tag>::value, void>::type
    operator()(Policy&& exec, Op op, Iterator begin, Size n, Rest&&... rest)
    {
        if (n <= sizeLimit)
            op(exec, make_iterator<Iterator>()(begin + n), n, std::forward<Rest>(rest)...);
    }

    template <typename Policy, typename Op, typename Iterator, typename... Rest>
    typename std::enable_if<is_same_iterator_category<Iterator, std::random_access_iterator_tag>::value &&
                                !std::is_base_of<non_const_wrapper, Op>::value,
                            void>::type
    operator()(Policy&& exec, Op op, Iterator inputBegin, Iterator inputEnd, Rest&&... rest)
    {
        if (std::distance(inputBegin, inputEnd) <= sizeLimit)
            op(exec, make_iterator<Iterator>()(inputEnd), make_iterator<Iterator>()(inputBegin),
               std::forward<Rest>(rest)...);
    }

    template <typename Policy, typename Op, typename InputIterator, typename OutputIterator, typename... Rest>
    typename std::enable_if<is_same_iterator_category<OutputIterator, std::random_access_iterator_tag>::value,
                            void>::type
    operator()(Policy&& exec, Op op, InputIterator inputBegin, InputIterator inputEnd, OutputIterator outputBegin,
               Rest&&... rest)
    {
        if (std::distance(inputBegin, inputEnd) <= sizeLimit)
            op(exec, make_iterator<InputIterator>()(inputEnd), make_iterator<InputIterator>()(inputBegin),
               make_iterator<OutputIterator>()(outputBegin + (inputEnd - inputBegin)), std::forward<Rest>(rest)...);
    }

    template <typename Policy, typename Op, typename InputIterator, typename OutputIterator, typename... Rest>
    typename std::enable_if<is_same_iterator_category<OutputIterator, std::random_access_iterator_tag>::value,
                            void>::type
    operator()(Policy&& exec, Op op, InputIterator inputBegin, InputIterator inputEnd, OutputIterator outputBegin,
               OutputIterator outputEnd, Rest&&... rest)
    {
        if (std::distance(inputBegin, inputEnd) <= sizeLimit)
            op(exec, make_iterator<InputIterator>()(inputEnd), make_iterator<InputIterator>()(inputBegin),
               make_iterator<OutputIterator>()(outputEnd), make_iterator<OutputIterator>()(outputBegin),
               std::forward<Rest>(rest)...);
    }

    template <typename Policy, typename Op, typename InputIterator1, typename InputIterator2, typename OutputIterator,
              typename... Rest>
    typename std::enable_if<is_same_iterator_category<OutputIterator, std::random_access_iterator_tag>::value,
                            void>::type
    operator()(Policy&& exec, Op op, InputIterator1 inputBegin1, InputIterator1 inputEnd1, InputIterator2 inputBegin2,
               InputIterator2 inputEnd2, OutputIterator outputBegin, OutputIterator outputEnd, Rest&&... rest)
    {
        if (std::distance(inputBegin1, inputEnd1) <= sizeLimit)
            op(exec, make_iterator<InputIterator1>()(inputEnd1), make_iterator<InputIterator1>()(inputBegin1),
               make_iterator<InputIterator2>()(inputEnd2), make_iterator<InputIterator2>()(inputBegin2),
               make_iterator<OutputIterator>()(outputEnd), make_iterator<OutputIterator>()(outputBegin),
               std::forward<Rest>(rest)...);
    }
};

// We can't create reverse iterator from forward iterator
template <>
struct iterator_invoker<std::forward_iterator_tag, /*isReverse=*/std::true_type>
{
    template <typename... Rest>
    void
    operator()(Rest&&...)
    {
    }
};

template <typename IsReverse>
struct reverse_invoker
{
    template <typename... Rest>
    void
    operator()(Rest&&... rest)
    {
        // Random-access iterator
        iterator_invoker<std::random_access_iterator_tag, IsReverse>()(std::forward<Rest>(rest)...);

        // Forward iterator
        iterator_invoker<std::forward_iterator_tag, IsReverse>()(std::forward<Rest>(rest)...);

        // Bidirectional iterator
        iterator_invoker<std::bidirectional_iterator_tag, IsReverse>()(std::forward<Rest>(rest)...);
    }
};

struct invoke_on_all_iterator_types
{
    template <typename... Rest>
    void
    operator()(Rest&&... rest)
    {
        reverse_invoker</* IsReverse = */ std::false_type>()(std::forward<Rest>(rest)...);
        reverse_invoker</* IsReverse = */ std::true_type>()(std::forward<Rest>(rest)...);
    }
};
//============================================================================

// Invoke op(policy,rest...) for each possible policy.
template <typename Op, typename... T>
void
invoke_on_all_policies(Op op, T&&... rest)
{
    using namespace __pstl::execution;

    // Try static execution policies
    invoke_on_all_iterator_types()(seq, op, std::forward<T>(rest)...);
    invoke_on_all_iterator_types()(unseq, op, std::forward<T>(rest)...);
    invoke_on_all_iterator_types()(par, op, std::forward<T>(rest)...);
    invoke_on_all_iterator_types()(par_unseq, op, std::forward<T>(rest)...);
}

template <typename F>
struct NonConstAdapter
{
    F my_f;
    NonConstAdapter(const F& f) : my_f(f) {}

    template <typename... Types>
    auto
    operator()(Types&&... args) -> decltype(std::declval<F>().
                                            operator()(std::forward<Types>(args)...))
    {
        return my_f(std::forward<Types>(args)...);
    }
};

template <typename F>
NonConstAdapter<F>
non_const(const F& f)
{
    return NonConstAdapter<F>(f);
}

// Wrapper for types. It's need for counting of constructing and destructing objects
template <typename T>
class Wrapper
{
  public:
    Wrapper()
    {
        my_field = std::shared_ptr<T>(new T());
        ++my_count;
    }
    Wrapper(const T& input)
    {
        my_field = std::shared_ptr<T>(new T(input));
        ++my_count;
    }
    Wrapper(const Wrapper& input)
    {
        my_field = input.my_field;
        ++my_count;
    }
    Wrapper(Wrapper&& input)
    {
        my_field = input.my_field;
        input.my_field = nullptr;
        ++move_count;
    }
    Wrapper&
    operator=(const Wrapper& input)
    {
        my_field = input.my_field;
        return *this;
    }
    Wrapper&
    operator=(Wrapper&& input)
    {
        my_field = input.my_field;
        input.my_field = nullptr;
        ++move_count;
        return *this;
    }
    bool
    operator==(const Wrapper& input) const
    {
        return my_field == input.my_field;
    }
    bool
    operator<(const Wrapper& input) const
    {
        return *my_field < *input.my_field;
    }
    bool
    operator>(const Wrapper& input) const
    {
        return *my_field > *input.my_field;
    }
    friend std::ostream&
    operator<<(std::ostream& stream, const Wrapper& input)
    {
        return stream << *(input.my_field);
    }
    ~Wrapper()
    {
        --my_count;
        if (move_count > 0)
        {
            --move_count;
        }
    }
    T*
    get_my_field() const
    {
        return my_field.get();
    };
    static size_t
    Count()
    {
        return my_count;
    }
    static size_t
    MoveCount()
    {
        return move_count;
    }
    static void
    SetCount(const size_t& n)
    {
        my_count = n;
    }
    static void
    SetMoveCount(const size_t& n)
    {
        move_count = n;
    }

  private:
    static std::atomic<size_t> my_count;
    static std::atomic<size_t> move_count;
    std::shared_ptr<T> my_field;
};

template <typename T>
std::atomic<size_t> Wrapper<T>::my_count = {0};

template <typename T>
std::atomic<size_t> Wrapper<T>::move_count = {0};

template <typename InputIterator, typename T, typename BinaryOperation, typename UnaryOperation>
T
transform_reduce_serial(InputIterator first, InputIterator last, T init, BinaryOperation binary_op,
                        UnaryOperation unary_op) noexcept
{
    for (; first != last; ++first)
    {
        init = binary_op(init, unary_op(*first));
    }
    return init;
}

static const char*
done()
{
#if _PSTL_TEST_SUCCESSFUL_KEYWORD
    return "done";
#else
    return "passed";
#endif
}

// test_algo_basic_* functions are used to execute
// f on a very basic sequence of elements of type T.

// Should be used with unary predicate
template <typename T, typename F>
static void
test_algo_basic_single(F&& f)
{
    size_t N = 10;
    Sequence<T> in(N, [](size_t v) -> T { return T(v); });

    invoke_on_all_policies(f, in.begin());
}

// Should be used with binary predicate
template <typename T, typename F>
static void
test_algo_basic_double(F&& f)
{
    size_t N = 10;
    Sequence<T> in(N, [](size_t v) -> T { return T(v); });
    Sequence<T> out(N, [](size_t v) -> T { return T(v); });

    invoke_on_all_policies(f, in.begin(), out.begin());
}

template <typename Policy, typename F>
static void
invoke_if(Policy&&, F f)
{
#if _PSTL_ICC_16_VC14_TEST_SIMD_LAMBDA_DEBUG_32_BROKEN || _PSTL_ICC_17_VC141_TEST_SIMD_LAMBDA_DEBUG_32_BROKEN
    __pstl::__internal::invoke_if_not(__pstl::__internal::allow_unsequenced<Policy>(), f);
#else
    f();
#endif
}

} /* namespace TestUtils */