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//===- llvm/ADT/STLExtras.h - Useful STL related functions ------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains some templates that are useful if you are working with the
// STL at all.
//
// No library is required when using these functions.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_ADT_STLEXTRAS_H
#define LLVM_ADT_STLEXTRAS_H
#include <algorithm> // for std::all_of
#include <cassert>
#include <cstddef> // for std::size_t
#include <cstdlib> // for qsort
#include <functional>
#include <iterator>
#include <memory>
#include <tuple>
#include <utility> // for std::pair
#include "llvm/ADT/Optional.h"
#include "llvm/ADT/iterator.h"
#include "llvm/ADT/iterator_range.h"
#include "llvm/Support/Compiler.h"
namespace llvm {
// Only used by compiler if both template types are the same. Useful when
// using SFINAE to test for the existence of member functions.
template <typename T, T> struct SameType;
namespace detail {
template <typename RangeT>
using IterOfRange = decltype(std::begin(std::declval<RangeT &>()));
} // End detail namespace
//===----------------------------------------------------------------------===//
// Extra additions to <functional>
//===----------------------------------------------------------------------===//
template<class Ty>
struct identity : public std::unary_function<Ty, Ty> {
Ty &operator()(Ty &self) const {
return self;
}
const Ty &operator()(const Ty &self) const {
return self;
}
};
template<class Ty>
struct less_ptr : public std::binary_function<Ty, Ty, bool> {
bool operator()(const Ty* left, const Ty* right) const {
return *left < *right;
}
};
template<class Ty>
struct greater_ptr : public std::binary_function<Ty, Ty, bool> {
bool operator()(const Ty* left, const Ty* right) const {
return *right < *left;
}
};
/// An efficient, type-erasing, non-owning reference to a callable. This is
/// intended for use as the type of a function parameter that is not used
/// after the function in question returns.
///
/// This class does not own the callable, so it is not in general safe to store
/// a function_ref.
template<typename Fn> class function_ref;
template<typename Ret, typename ...Params>
class function_ref<Ret(Params...)> {
Ret (*callback)(intptr_t callable, Params ...params);
intptr_t callable;
template<typename Callable>
static Ret callback_fn(intptr_t callable, Params ...params) {
return (*reinterpret_cast<Callable*>(callable))(
std::forward<Params>(params)...);
}
public:
template <typename Callable>
function_ref(Callable &&callable,
typename std::enable_if<
!std::is_same<typename std::remove_reference<Callable>::type,
function_ref>::value>::type * = nullptr)
: callback(callback_fn<typename std::remove_reference<Callable>::type>),
callable(reinterpret_cast<intptr_t>(&callable)) {}
Ret operator()(Params ...params) const {
return callback(callable, std::forward<Params>(params)...);
}
};
// deleter - Very very very simple method that is used to invoke operator
// delete on something. It is used like this:
//
// for_each(V.begin(), B.end(), deleter<Interval>);
//
template <class T>
inline void deleter(T *Ptr) {
delete Ptr;
}
//===----------------------------------------------------------------------===//
// Extra additions to <iterator>
//===----------------------------------------------------------------------===//
// mapped_iterator - This is a simple iterator adapter that causes a function to
// be dereferenced whenever operator* is invoked on the iterator.
//
template <class RootIt, class UnaryFunc>
class mapped_iterator {
RootIt current;
UnaryFunc Fn;
public:
typedef typename std::iterator_traits<RootIt>::iterator_category
iterator_category;
typedef typename std::iterator_traits<RootIt>::difference_type
difference_type;
typedef typename std::result_of<
UnaryFunc(decltype(*std::declval<RootIt>()))>
::type value_type;
typedef void pointer;
//typedef typename UnaryFunc::result_type *pointer;
typedef void reference; // Can't modify value returned by fn
typedef RootIt iterator_type;
inline const RootIt &getCurrent() const { return current; }
inline const UnaryFunc &getFunc() const { return Fn; }
inline explicit mapped_iterator(const RootIt &I, UnaryFunc F)
: current(I), Fn(F) {}
inline value_type operator*() const { // All this work to do this
return Fn(*current); // little change
}
mapped_iterator &operator++() {
++current;
return *this;
}
mapped_iterator &operator--() {
--current;
return *this;
}
mapped_iterator operator++(int) {
mapped_iterator __tmp = *this;
++current;
return __tmp;
}
mapped_iterator operator--(int) {
mapped_iterator __tmp = *this;
--current;
return __tmp;
}
mapped_iterator operator+(difference_type n) const {
return mapped_iterator(current + n, Fn);
}
mapped_iterator &operator+=(difference_type n) {
current += n;
return *this;
}
mapped_iterator operator-(difference_type n) const {
return mapped_iterator(current - n, Fn);
}
mapped_iterator &operator-=(difference_type n) {
current -= n;
return *this;
}
reference operator[](difference_type n) const { return *(*this + n); }
bool operator!=(const mapped_iterator &X) const { return !operator==(X); }
bool operator==(const mapped_iterator &X) const {
return current == X.current;
}
bool operator<(const mapped_iterator &X) const { return current < X.current; }
difference_type operator-(const mapped_iterator &X) const {
return current - X.current;
}
};
template <class Iterator, class Func>
inline mapped_iterator<Iterator, Func>
operator+(typename mapped_iterator<Iterator, Func>::difference_type N,
const mapped_iterator<Iterator, Func> &X) {
return mapped_iterator<Iterator, Func>(X.getCurrent() - N, X.getFunc());
}
// map_iterator - Provide a convenient way to create mapped_iterators, just like
// make_pair is useful for creating pairs...
//
template <class ItTy, class FuncTy>
inline mapped_iterator<ItTy, FuncTy> map_iterator(const ItTy &I, FuncTy F) {
return mapped_iterator<ItTy, FuncTy>(I, F);
}
/// Helper to determine if type T has a member called rbegin().
template <typename Ty> class has_rbegin_impl {
typedef char yes[1];
typedef char no[2];
template <typename Inner>
static yes& test(Inner *I, decltype(I->rbegin()) * = nullptr);
template <typename>
static no& test(...);
public:
static const bool value = sizeof(test<Ty>(nullptr)) == sizeof(yes);
};
/// Metafunction to determine if T& or T has a member called rbegin().
template <typename Ty>
struct has_rbegin : has_rbegin_impl<typename std::remove_reference<Ty>::type> {
};
// Returns an iterator_range over the given container which iterates in reverse.
// Note that the container must have rbegin()/rend() methods for this to work.
template <typename ContainerTy>
auto reverse(ContainerTy &&C,
typename std::enable_if<has_rbegin<ContainerTy>::value>::type * =
nullptr) -> decltype(make_range(C.rbegin(), C.rend())) {
return make_range(C.rbegin(), C.rend());
}
// Returns a std::reverse_iterator wrapped around the given iterator.
template <typename IteratorTy>
std::reverse_iterator<IteratorTy> make_reverse_iterator(IteratorTy It) {
return std::reverse_iterator<IteratorTy>(It);
}
// Returns an iterator_range over the given container which iterates in reverse.
// Note that the container must have begin()/end() methods which return
// bidirectional iterators for this to work.
template <typename ContainerTy>
auto reverse(
ContainerTy &&C,
typename std::enable_if<!has_rbegin<ContainerTy>::value>::type * = nullptr)
-> decltype(make_range(llvm::make_reverse_iterator(std::end(C)),
llvm::make_reverse_iterator(std::begin(C)))) {
return make_range(llvm::make_reverse_iterator(std::end(C)),
llvm::make_reverse_iterator(std::begin(C)));
}
/// An iterator adaptor that filters the elements of given inner iterators.
///
/// The predicate parameter should be a callable object that accepts the wrapped
/// iterator's reference type and returns a bool. When incrementing or
/// decrementing the iterator, it will call the predicate on each element and
/// skip any where it returns false.
///
/// \code
/// int A[] = { 1, 2, 3, 4 };
/// auto R = make_filter_range(A, [](int N) { return N % 2 == 1; });
/// // R contains { 1, 3 }.
/// \endcode
template <typename WrappedIteratorT, typename PredicateT>
class filter_iterator
: public iterator_adaptor_base<
filter_iterator<WrappedIteratorT, PredicateT>, WrappedIteratorT,
typename std::common_type<
std::forward_iterator_tag,
typename std::iterator_traits<
WrappedIteratorT>::iterator_category>::type> {
using BaseT = iterator_adaptor_base<
filter_iterator<WrappedIteratorT, PredicateT>, WrappedIteratorT,
typename std::common_type<
std::forward_iterator_tag,
typename std::iterator_traits<WrappedIteratorT>::iterator_category>::
type>;
struct PayloadType {
WrappedIteratorT End;
PredicateT Pred;
};
Optional<PayloadType> Payload;
void findNextValid() {
assert(Payload && "Payload should be engaged when findNextValid is called");
while (this->I != Payload->End && !Payload->Pred(*this->I))
BaseT::operator++();
}
// Construct the begin iterator. The begin iterator requires to know where end
// is, so that it can properly stop when it hits end.
filter_iterator(WrappedIteratorT Begin, WrappedIteratorT End, PredicateT Pred)
: BaseT(std::move(Begin)),
Payload(PayloadType{std::move(End), std::move(Pred)}) {
findNextValid();
}
// Construct the end iterator. It's not incrementable, so Payload doesn't
// have to be engaged.
filter_iterator(WrappedIteratorT End) : BaseT(End) {}
public:
using BaseT::operator++;
filter_iterator &operator++() {
BaseT::operator++();
findNextValid();
return *this;
}
template <typename RT, typename PT>
friend iterator_range<filter_iterator<detail::IterOfRange<RT>, PT>>
make_filter_range(RT &&, PT);
};
/// Convenience function that takes a range of elements and a predicate,
/// and return a new filter_iterator range.
///
/// FIXME: Currently if RangeT && is a rvalue reference to a temporary, the
/// lifetime of that temporary is not kept by the returned range object, and the
/// temporary is going to be dropped on the floor after the make_iterator_range
/// full expression that contains this function call.
template <typename RangeT, typename PredicateT>
iterator_range<filter_iterator<detail::IterOfRange<RangeT>, PredicateT>>
make_filter_range(RangeT &&Range, PredicateT Pred) {
using FilterIteratorT =
filter_iterator<detail::IterOfRange<RangeT>, PredicateT>;
return make_range(FilterIteratorT(std::begin(std::forward<RangeT>(Range)),
std::end(std::forward<RangeT>(Range)),
std::move(Pred)),
FilterIteratorT(std::end(std::forward<RangeT>(Range))));
}
// forward declarations required by zip_shortest/zip_first
template <typename R, typename UnaryPredicate>
bool all_of(R &&range, UnaryPredicate P);
template <size_t... I> struct index_sequence;
template <class... Ts> struct index_sequence_for;
namespace detail {
template <typename... Iters> class zip_first {
public:
typedef std::input_iterator_tag iterator_category;
typedef std::tuple<decltype(*std::declval<Iters>())...> value_type;
std::tuple<Iters...> iterators;
private:
template <size_t... Ns> value_type deres(index_sequence<Ns...>) {
return value_type(*std::get<Ns>(iterators)...);
}
template <size_t... Ns> decltype(iterators) tup_inc(index_sequence<Ns...>) {
return std::tuple<Iters...>(std::next(std::get<Ns>(iterators))...);
}
public:
value_type operator*() { return deres(index_sequence_for<Iters...>{}); }
void operator++() { iterators = tup_inc(index_sequence_for<Iters...>{}); }
bool operator!=(const zip_first<Iters...> &other) const {
return std::get<0>(iterators) != std::get<0>(other.iterators);
}
zip_first(Iters &&... ts) : iterators(std::forward<Iters>(ts)...) {}
};
template <typename... Iters> class zip_shortest : public zip_first<Iters...> {
template <size_t... Ns>
bool test(const zip_first<Iters...> &other, index_sequence<Ns...>) const {
return all_of(std::initializer_list<bool>{std::get<Ns>(this->iterators) !=
std::get<Ns>(other.iterators)...},
identity<bool>{});
}
public:
bool operator!=(const zip_first<Iters...> &other) const {
return test(other, index_sequence_for<Iters...>{});
}
zip_shortest(Iters &&... ts)
: zip_first<Iters...>(std::forward<Iters>(ts)...) {}
};
template <template <typename...> class ItType, typename... Args> class zippy {
public:
typedef ItType<decltype(std::begin(std::declval<Args>()))...> iterator;
private:
std::tuple<Args...> ts;
template <size_t... Ns> iterator begin_impl(index_sequence<Ns...>) {
return iterator(std::begin(std::get<Ns>(ts))...);
}
template <size_t... Ns> iterator end_impl(index_sequence<Ns...>) {
return iterator(std::end(std::get<Ns>(ts))...);
}
public:
iterator begin() { return begin_impl(index_sequence_for<Args...>{}); }
iterator end() { return end_impl(index_sequence_for<Args...>{}); }
zippy(Args &&... ts_) : ts(std::forward<Args>(ts_)...) {}
};
} // End detail namespace
/// zip iterator for two or more iteratable types.
template <typename T, typename U, typename... Args>
detail::zippy<detail::zip_shortest, T, U, Args...> zip(T &&t, U &&u,
Args &&... args) {
return detail::zippy<detail::zip_shortest, T, U, Args...>(
std::forward<T>(t), std::forward<U>(u), std::forward<Args>(args)...);
}
/// zip iterator that, for the sake of efficiency, assumes the first iteratee to
/// be the shortest.
template <typename T, typename U, typename... Args>
detail::zippy<detail::zip_first, T, U, Args...> zip_first(T &&t, U &&u,
Args &&... args) {
return detail::zippy<detail::zip_first, T, U, Args...>(
std::forward<T>(t), std::forward<U>(u), std::forward<Args>(args)...);
}
//===----------------------------------------------------------------------===//
// Extra additions to <utility>
//===----------------------------------------------------------------------===//
/// \brief Function object to check whether the first component of a std::pair
/// compares less than the first component of another std::pair.
struct less_first {
template <typename T> bool operator()(const T &lhs, const T &rhs) const {
return lhs.first < rhs.first;
}
};
/// \brief Function object to check whether the second component of a std::pair
/// compares less than the second component of another std::pair.
struct less_second {
template <typename T> bool operator()(const T &lhs, const T &rhs) const {
return lhs.second < rhs.second;
}
};
// A subset of N3658. More stuff can be added as-needed.
/// \brief Represents a compile-time sequence of integers.
template <class T, T... I> struct integer_sequence {
typedef T value_type;
static constexpr size_t size() { return sizeof...(I); }
};
/// \brief Alias for the common case of a sequence of size_ts.
template <size_t... I>
struct index_sequence : integer_sequence<std::size_t, I...> {};
template <std::size_t N, std::size_t... I>
struct build_index_impl : build_index_impl<N - 1, N - 1, I...> {};
template <std::size_t... I>
struct build_index_impl<0, I...> : index_sequence<I...> {};
/// \brief Creates a compile-time integer sequence for a parameter pack.
template <class... Ts>
struct index_sequence_for : build_index_impl<sizeof...(Ts)> {};
/// Utility type to build an inheritance chain that makes it easy to rank
/// overload candidates.
template <int N> struct rank : rank<N - 1> {};
template <> struct rank<0> {};
/// \brief traits class for checking whether type T is one of any of the given
/// types in the variadic list.
template <typename T, typename... Ts> struct is_one_of {
static const bool value = false;
};
template <typename T, typename U, typename... Ts>
struct is_one_of<T, U, Ts...> {
static const bool value =
std::is_same<T, U>::value || is_one_of<T, Ts...>::value;
};
//===----------------------------------------------------------------------===//
// Extra additions for arrays
//===----------------------------------------------------------------------===//
/// Find the length of an array.
template <class T, std::size_t N>
constexpr inline size_t array_lengthof(T (&)[N]) {
return N;
}
/// Adapt std::less<T> for array_pod_sort.
template<typename T>
inline int array_pod_sort_comparator(const void *P1, const void *P2) {
if (std::less<T>()(*reinterpret_cast<const T*>(P1),
*reinterpret_cast<const T*>(P2)))
return -1;
if (std::less<T>()(*reinterpret_cast<const T*>(P2),
*reinterpret_cast<const T*>(P1)))
return 1;
return 0;
}
/// get_array_pod_sort_comparator - This is an internal helper function used to
/// get type deduction of T right.
template<typename T>
inline int (*get_array_pod_sort_comparator(const T &))
(const void*, const void*) {
return array_pod_sort_comparator<T>;
}
/// array_pod_sort - This sorts an array with the specified start and end
/// extent. This is just like std::sort, except that it calls qsort instead of
/// using an inlined template. qsort is slightly slower than std::sort, but
/// most sorts are not performance critical in LLVM and std::sort has to be
/// template instantiated for each type, leading to significant measured code
/// bloat. This function should generally be used instead of std::sort where
/// possible.
///
/// This function assumes that you have simple POD-like types that can be
/// compared with std::less and can be moved with memcpy. If this isn't true,
/// you should use std::sort.
///
/// NOTE: If qsort_r were portable, we could allow a custom comparator and
/// default to std::less.
template<class IteratorTy>
inline void array_pod_sort(IteratorTy Start, IteratorTy End) {
// Don't inefficiently call qsort with one element or trigger undefined
// behavior with an empty sequence.
auto NElts = End - Start;
if (NElts <= 1) return;
qsort(&*Start, NElts, sizeof(*Start), get_array_pod_sort_comparator(*Start));
}
template <class IteratorTy>
inline void array_pod_sort(
IteratorTy Start, IteratorTy End,
int (*Compare)(
const typename std::iterator_traits<IteratorTy>::value_type *,
const typename std::iterator_traits<IteratorTy>::value_type *)) {
// Don't inefficiently call qsort with one element or trigger undefined
// behavior with an empty sequence.
auto NElts = End - Start;
if (NElts <= 1) return;
qsort(&*Start, NElts, sizeof(*Start),
reinterpret_cast<int (*)(const void *, const void *)>(Compare));
}
//===----------------------------------------------------------------------===//
// Extra additions to <algorithm>
//===----------------------------------------------------------------------===//
/// For a container of pointers, deletes the pointers and then clears the
/// container.
template<typename Container>
void DeleteContainerPointers(Container &C) {
for (auto V : C)
delete V;
C.clear();
}
/// In a container of pairs (usually a map) whose second element is a pointer,
/// deletes the second elements and then clears the container.
template<typename Container>
void DeleteContainerSeconds(Container &C) {
for (auto &V : C)
delete V.second;
C.clear();
}
/// Provide wrappers to std::all_of which take ranges instead of having to pass
/// begin/end explicitly.
template <typename R, typename UnaryPredicate>
bool all_of(R &&Range, UnaryPredicate P) {
return std::all_of(std::begin(Range), std::end(Range), P);
}
/// Provide wrappers to std::any_of which take ranges instead of having to pass
/// begin/end explicitly.
template <typename R, typename UnaryPredicate>
bool any_of(R &&Range, UnaryPredicate P) {
return std::any_of(std::begin(Range), std::end(Range), P);
}
/// Provide wrappers to std::none_of which take ranges instead of having to pass
/// begin/end explicitly.
template <typename R, typename UnaryPredicate>
bool none_of(R &&Range, UnaryPredicate P) {
return std::none_of(std::begin(Range), std::end(Range), P);
}
/// Provide wrappers to std::find which take ranges instead of having to pass
/// begin/end explicitly.
template <typename R, typename T>
auto find(R &&Range, const T &Val) -> decltype(std::begin(Range)) {
return std::find(std::begin(Range), std::end(Range), Val);
}
/// Provide wrappers to std::find_if which take ranges instead of having to pass
/// begin/end explicitly.
template <typename R, typename UnaryPredicate>
auto find_if(R &&Range, UnaryPredicate P) -> decltype(std::begin(Range)) {
return std::find_if(std::begin(Range), std::end(Range), P);
}
template <typename R, typename UnaryPredicate>
auto find_if_not(R &&Range, UnaryPredicate P) -> decltype(std::begin(Range)) {
return std::find_if_not(std::begin(Range), std::end(Range), P);
}
/// Provide wrappers to std::remove_if which take ranges instead of having to
/// pass begin/end explicitly.
template <typename R, typename UnaryPredicate>
auto remove_if(R &&Range, UnaryPredicate P) -> decltype(std::begin(Range)) {
return std::remove_if(std::begin(Range), std::end(Range), P);
}
/// Wrapper function around std::find to detect if an element exists
/// in a container.
template <typename R, typename E>
bool is_contained(R &&Range, const E &Element) {
return std::find(std::begin(Range), std::end(Range), Element) !=
std::end(Range);
}
/// Wrapper function around std::count to count the number of times an element
/// \p Element occurs in the given range \p Range.
template <typename R, typename E>
auto count(R &&Range, const E &Element) -> typename std::iterator_traits<
decltype(std::begin(Range))>::difference_type {
return std::count(std::begin(Range), std::end(Range), Element);
}
/// Wrapper function around std::count_if to count the number of times an
/// element satisfying a given predicate occurs in a range.
template <typename R, typename UnaryPredicate>
auto count_if(R &&Range, UnaryPredicate P) -> typename std::iterator_traits<
decltype(std::begin(Range))>::difference_type {
return std::count_if(std::begin(Range), std::end(Range), P);
}
/// Wrapper function around std::transform to apply a function to a range and
/// store the result elsewhere.
template <typename R, typename OutputIt, typename UnaryPredicate>
OutputIt transform(R &&Range, OutputIt d_first, UnaryPredicate P) {
return std::transform(std::begin(Range), std::end(Range), d_first, P);
}
//===----------------------------------------------------------------------===//
// Extra additions to <memory>
//===----------------------------------------------------------------------===//
// Implement make_unique according to N3656.
/// \brief Constructs a `new T()` with the given args and returns a
/// `unique_ptr<T>` which owns the object.
///
/// Example:
///
/// auto p = make_unique<int>();
/// auto p = make_unique<std::tuple<int, int>>(0, 1);
template <class T, class... Args>
typename std::enable_if<!std::is_array<T>::value, std::unique_ptr<T>>::type
make_unique(Args &&... args) {
return std::unique_ptr<T>(new T(std::forward<Args>(args)...));
}
/// \brief Constructs a `new T[n]` with the given args and returns a
/// `unique_ptr<T[]>` which owns the object.
///
/// \param n size of the new array.
///
/// Example:
///
/// auto p = make_unique<int[]>(2); // value-initializes the array with 0's.
template <class T>
typename std::enable_if<std::is_array<T>::value && std::extent<T>::value == 0,
std::unique_ptr<T>>::type
make_unique(size_t n) {
return std::unique_ptr<T>(new typename std::remove_extent<T>::type[n]());
}
/// This function isn't used and is only here to provide better compile errors.
template <class T, class... Args>
typename std::enable_if<std::extent<T>::value != 0>::type
make_unique(Args &&...) = delete;
struct FreeDeleter {
void operator()(void* v) {
::free(v);
}
};
template<typename First, typename Second>
struct pair_hash {
size_t operator()(const std::pair<First, Second> &P) const {
return std::hash<First>()(P.first) * 31 + std::hash<Second>()(P.second);
}
};
/// A functor like C++14's std::less<void> in its absence.
struct less {
template <typename A, typename B> bool operator()(A &&a, B &&b) const {
return std::forward<A>(a) < std::forward<B>(b);
}
};
/// A functor like C++14's std::equal<void> in its absence.
struct equal {
template <typename A, typename B> bool operator()(A &&a, B &&b) const {
return std::forward<A>(a) == std::forward<B>(b);
}
};
/// Binary functor that adapts to any other binary functor after dereferencing
/// operands.
template <typename T> struct deref {
T func;
// Could be further improved to cope with non-derivable functors and
// non-binary functors (should be a variadic template member function
// operator()).
template <typename A, typename B>
auto operator()(A &lhs, B &rhs) const -> decltype(func(*lhs, *rhs)) {
assert(lhs);
assert(rhs);
return func(*lhs, *rhs);
}
};
namespace detail {
template <typename R> class enumerator_impl {
public:
template <typename X> struct result_pair {
result_pair(std::size_t Index, X Value) : Index(Index), Value(Value) {}
const std::size_t Index;
X Value;
};
class iterator {
typedef
typename std::iterator_traits<IterOfRange<R>>::reference iter_reference;
typedef result_pair<iter_reference> result_type;
public:
iterator(IterOfRange<R> &&Iter, std::size_t Index)
: Iter(Iter), Index(Index) {}
result_type operator*() const { return result_type(Index, *Iter); }
iterator &operator++() {
++Iter;
++Index;
return *this;
}
bool operator!=(const iterator &RHS) const { return Iter != RHS.Iter; }
private:
IterOfRange<R> Iter;
std::size_t Index;
};
public:
explicit enumerator_impl(R &&Range) : Range(std::forward<R>(Range)) {}
iterator begin() { return iterator(std::begin(Range), 0); }
iterator end() { return iterator(std::end(Range), std::size_t(-1)); }
private:
R Range;
};
}
/// Given an input range, returns a new range whose values are are pair (A,B)
/// such that A is the 0-based index of the item in the sequence, and B is
/// the value from the original sequence. Example:
///
/// std::vector<char> Items = {'A', 'B', 'C', 'D'};
/// for (auto X : enumerate(Items)) {
/// printf("Item %d - %c\n", X.Index, X.Value);
/// }
///
/// Output:
/// Item 0 - A
/// Item 1 - B
/// Item 2 - C
/// Item 3 - D
///
template <typename R> detail::enumerator_impl<R> enumerate(R &&Range) {
return detail::enumerator_impl<R>(std::forward<R>(Range));
}
namespace detail {
template <typename F, typename Tuple, std::size_t... I>
auto apply_tuple_impl(F &&f, Tuple &&t, index_sequence<I...>)
-> decltype(std::forward<F>(f)(std::get<I>(std::forward<Tuple>(t))...)) {
return std::forward<F>(f)(std::get<I>(std::forward<Tuple>(t))...);
}
}
/// Given an input tuple (a1, a2, ..., an), pass the arguments of the
/// tuple variadically to f as if by calling f(a1, a2, ..., an) and
/// return the result.
template <typename F, typename Tuple>
auto apply_tuple(F &&f, Tuple &&t) -> decltype(detail::apply_tuple_impl(
std::forward<F>(f), std::forward<Tuple>(t),
build_index_impl<
std::tuple_size<typename std::decay<Tuple>::type>::value>{})) {
using Indices = build_index_impl<
std::tuple_size<typename std::decay<Tuple>::type>::value>;
return detail::apply_tuple_impl(std::forward<F>(f), std::forward<Tuple>(t),
Indices{});
}
} // End llvm namespace
#endif