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//===- llvm/ADT/STLExtras.h - Useful STL related functions ------*- 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
//
//===----------------------------------------------------------------------===//
///
/// \file
/// 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 "llvm/ADT/Hashing.h"
#include "llvm/ADT/STLForwardCompat.h"
#include "llvm/ADT/STLFunctionalExtras.h"
#include "llvm/ADT/identity.h"
#include "llvm/ADT/iterator.h"
#include "llvm/ADT/iterator_range.h"
#include "llvm/Config/abi-breaking.h"
#include "llvm/Support/ErrorHandling.h"
#include <algorithm>
#include <cassert>
#include <cstddef>
#include <cstdint>
#include <cstdlib>
#include <functional>
#include <initializer_list>
#include <iterator>
#include <limits>
#include <memory>
#include <optional>
#include <tuple>
#include <type_traits>
#include <utility>
#ifdef EXPENSIVE_CHECKS
#include <random> // for std::mt19937
#endif
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 adl_detail {
using std::begin;
template <typename RangeT>
constexpr auto begin_impl(RangeT &&range)
-> decltype(begin(std::forward<RangeT>(range))) {
return begin(std::forward<RangeT>(range));
}
using std::end;
template <typename RangeT>
constexpr auto end_impl(RangeT &&range)
-> decltype(end(std::forward<RangeT>(range))) {
return end(std::forward<RangeT>(range));
}
using std::swap;
template <typename T>
constexpr void swap_impl(T &&lhs,
T &&rhs) noexcept(noexcept(swap(std::declval<T>(),
std::declval<T>()))) {
swap(std::forward<T>(lhs), std::forward<T>(rhs));
}
using std::size;
template <typename RangeT>
constexpr auto size_impl(RangeT &&range)
-> decltype(size(std::forward<RangeT>(range))) {
return size(std::forward<RangeT>(range));
}
} // end namespace adl_detail
/// Returns the begin iterator to \p range using `std::begin` and
/// function found through Argument-Dependent Lookup (ADL).
template <typename RangeT>
constexpr auto adl_begin(RangeT &&range)
-> decltype(adl_detail::begin_impl(std::forward<RangeT>(range))) {
return adl_detail::begin_impl(std::forward<RangeT>(range));
}
/// Returns the end iterator to \p range using `std::end` and
/// functions found through Argument-Dependent Lookup (ADL).
template <typename RangeT>
constexpr auto adl_end(RangeT &&range)
-> decltype(adl_detail::end_impl(std::forward<RangeT>(range))) {
return adl_detail::end_impl(std::forward<RangeT>(range));
}
/// Swaps \p lhs with \p rhs using `std::swap` and functions found through
/// Argument-Dependent Lookup (ADL).
template <typename T>
constexpr void adl_swap(T &&lhs, T &&rhs) noexcept(
noexcept(adl_detail::swap_impl(std::declval<T>(), std::declval<T>()))) {
adl_detail::swap_impl(std::forward<T>(lhs), std::forward<T>(rhs));
}
/// Returns the size of \p range using `std::size` and functions found through
/// Argument-Dependent Lookup (ADL).
template <typename RangeT>
constexpr auto adl_size(RangeT &&range)
-> decltype(adl_detail::size_impl(std::forward<RangeT>(range))) {
return adl_detail::size_impl(std::forward<RangeT>(range));
}
namespace detail {
template <typename RangeT>
using IterOfRange = decltype(adl_begin(std::declval<RangeT &>()));
template <typename RangeT>
using ValueOfRange =
std::remove_reference_t<decltype(*adl_begin(std::declval<RangeT &>()))>;
} // end namespace detail
//===----------------------------------------------------------------------===//
// Extra additions to <type_traits>
//===----------------------------------------------------------------------===//
template <typename T> struct make_const_ptr {
using type = std::add_pointer_t<std::add_const_t<T>>;
};
template <typename T> struct make_const_ref {
using type = std::add_lvalue_reference_t<std::add_const_t<T>>;
};
namespace detail {
template <class, template <class...> class Op, class... Args> struct detector {
using value_t = std::false_type;
};
template <template <class...> class Op, class... Args>
struct detector<std::void_t<Op<Args...>>, Op, Args...> {
using value_t = std::true_type;
};
} // end namespace detail
/// Detects if a given trait holds for some set of arguments 'Args'.
/// For example, the given trait could be used to detect if a given type
/// has a copy assignment operator:
/// template<class T>
/// using has_copy_assign_t = decltype(std::declval<T&>()
/// = std::declval<const T&>());
/// bool fooHasCopyAssign = is_detected<has_copy_assign_t, FooClass>::value;
template <template <class...> class Op, class... Args>
using is_detected = typename detail::detector<void, Op, Args...>::value_t;
/// This class provides various trait information about a callable object.
/// * To access the number of arguments: Traits::num_args
/// * To access the type of an argument: Traits::arg_t<Index>
/// * To access the type of the result: Traits::result_t
template <typename T, bool isClass = std::is_class<T>::value>
struct function_traits : public function_traits<decltype(&T::operator())> {};
/// Overload for class function types.
template <typename ClassType, typename ReturnType, typename... Args>
struct function_traits<ReturnType (ClassType::*)(Args...) const, false> {
/// The number of arguments to this function.
enum { num_args = sizeof...(Args) };
/// The result type of this function.
using result_t = ReturnType;
/// The type of an argument to this function.
template <size_t Index>
using arg_t = std::tuple_element_t<Index, std::tuple<Args...>>;
};
/// Overload for class function types.
template <typename ClassType, typename ReturnType, typename... Args>
struct function_traits<ReturnType (ClassType::*)(Args...), false>
: public function_traits<ReturnType (ClassType::*)(Args...) const> {};
/// Overload for non-class function types.
template <typename ReturnType, typename... Args>
struct function_traits<ReturnType (*)(Args...), false> {
/// The number of arguments to this function.
enum { num_args = sizeof...(Args) };
/// The result type of this function.
using result_t = ReturnType;
/// The type of an argument to this function.
template <size_t i>
using arg_t = std::tuple_element_t<i, std::tuple<Args...>>;
};
template <typename ReturnType, typename... Args>
struct function_traits<ReturnType (*const)(Args...), false>
: public function_traits<ReturnType (*)(Args...)> {};
/// Overload for non-class function type references.
template <typename ReturnType, typename... Args>
struct function_traits<ReturnType (&)(Args...), false>
: public function_traits<ReturnType (*)(Args...)> {};
/// traits class for checking whether type T is one of any of the given
/// types in the variadic list.
template <typename T, typename... Ts>
using is_one_of = std::disjunction<std::is_same<T, Ts>...>;
/// traits class for checking whether type T is a base class for all
/// the given types in the variadic list.
template <typename T, typename... Ts>
using are_base_of = std::conjunction<std::is_base_of<T, Ts>...>;
namespace detail {
template <typename T, typename... Us> struct TypesAreDistinct;
template <typename T, typename... Us>
struct TypesAreDistinct
: std::integral_constant<bool, !is_one_of<T, Us...>::value &&
TypesAreDistinct<Us...>::value> {};
template <typename T> struct TypesAreDistinct<T> : std::true_type {};
} // namespace detail
/// Determine if all types in Ts are distinct.
///
/// Useful to statically assert when Ts is intended to describe a non-multi set
/// of types.
///
/// Expensive (currently quadratic in sizeof(Ts...)), and so should only be
/// asserted once per instantiation of a type which requires it.
template <typename... Ts> struct TypesAreDistinct;
template <> struct TypesAreDistinct<> : std::true_type {};
template <typename... Ts>
struct TypesAreDistinct
: std::integral_constant<bool, detail::TypesAreDistinct<Ts...>::value> {};
/// Find the first index where a type appears in a list of types.
///
/// FirstIndexOfType<T, Us...>::value is the first index of T in Us.
///
/// Typically only meaningful when it is otherwise statically known that the
/// type pack has no duplicate types. This should be guaranteed explicitly with
/// static_assert(TypesAreDistinct<Us...>::value).
///
/// It is a compile-time error to instantiate when T is not present in Us, i.e.
/// if is_one_of<T, Us...>::value is false.
template <typename T, typename... Us> struct FirstIndexOfType;
template <typename T, typename U, typename... Us>
struct FirstIndexOfType<T, U, Us...>
: std::integral_constant<size_t, 1 + FirstIndexOfType<T, Us...>::value> {};
template <typename T, typename... Us>
struct FirstIndexOfType<T, T, Us...> : std::integral_constant<size_t, 0> {};
/// Find the type at a given index in a list of types.
///
/// TypeAtIndex<I, Ts...> is the type at index I in Ts.
template <size_t I, typename... Ts>
using TypeAtIndex = std::tuple_element_t<I, std::tuple<Ts...>>;
/// Helper which adds two underlying types of enumeration type.
/// Implicit conversion to a common type is accepted.
template <typename EnumTy1, typename EnumTy2,
typename UT1 = std::enable_if_t<std::is_enum<EnumTy1>::value,
std::underlying_type_t<EnumTy1>>,
typename UT2 = std::enable_if_t<std::is_enum<EnumTy2>::value,
std::underlying_type_t<EnumTy2>>>
constexpr auto addEnumValues(EnumTy1 LHS, EnumTy2 RHS) {
return static_cast<UT1>(LHS) + static_cast<UT2>(RHS);
}
//===----------------------------------------------------------------------===//
// Extra additions to <iterator>
//===----------------------------------------------------------------------===//
namespace callable_detail {
/// Templated storage wrapper for a callable.
///
/// This class is consistently default constructible, copy / move
/// constructible / assignable.
///
/// Supported callable types:
/// - Function pointer
/// - Function reference
/// - Lambda
/// - Function object
template <typename T,
bool = std::is_function_v<std::remove_pointer_t<remove_cvref_t<T>>>>
class Callable {
using value_type = std::remove_reference_t<T>;
using reference = value_type &;
using const_reference = value_type const &;
std::optional<value_type> Obj;
static_assert(!std::is_pointer_v<value_type>,
"Pointers to non-functions are not callable.");
public:
Callable() = default;
Callable(T const &O) : Obj(std::in_place, O) {}
Callable(Callable const &Other) = default;
Callable(Callable &&Other) = default;
Callable &operator=(Callable const &Other) {
Obj = std::nullopt;
if (Other.Obj)
Obj.emplace(*Other.Obj);
return *this;
}
Callable &operator=(Callable &&Other) {
Obj = std::nullopt;
if (Other.Obj)
Obj.emplace(std::move(*Other.Obj));
return *this;
}
template <typename... Pn,
std::enable_if_t<std::is_invocable_v<T, Pn...>, int> = 0>
decltype(auto) operator()(Pn &&...Params) {
return (*Obj)(std::forward<Pn>(Params)...);
}
template <typename... Pn,
std::enable_if_t<std::is_invocable_v<T const, Pn...>, int> = 0>
decltype(auto) operator()(Pn &&...Params) const {
return (*Obj)(std::forward<Pn>(Params)...);
}
bool valid() const { return Obj != std::nullopt; }
bool reset() { return Obj = std::nullopt; }
operator reference() { return *Obj; }
operator const_reference() const { return *Obj; }
};
// Function specialization. No need to waste extra space wrapping with a
// std::optional.
template <typename T> class Callable<T, true> {
static constexpr bool IsPtr = std::is_pointer_v<remove_cvref_t<T>>;
using StorageT = std::conditional_t<IsPtr, T, std::remove_reference_t<T> *>;
using CastT = std::conditional_t<IsPtr, T, T &>;
private:
StorageT Func = nullptr;
private:
template <typename In> static constexpr auto convertIn(In &&I) {
if constexpr (IsPtr) {
// Pointer... just echo it back.
return I;
} else {
// Must be a function reference. Return its address.
return &I;
}
}
public:
Callable() = default;
// Construct from a function pointer or reference.
//
// Disable this constructor for references to 'Callable' so we don't violate
// the rule of 0.
template < // clang-format off
typename FnPtrOrRef,
std::enable_if_t<
!std::is_same_v<remove_cvref_t<FnPtrOrRef>, Callable>, int
> = 0
> // clang-format on
Callable(FnPtrOrRef &&F) : Func(convertIn(F)) {}
template <typename... Pn,
std::enable_if_t<std::is_invocable_v<T, Pn...>, int> = 0>
decltype(auto) operator()(Pn &&...Params) const {
return Func(std::forward<Pn>(Params)...);
}
bool valid() const { return Func != nullptr; }
void reset() { Func = nullptr; }
operator T const &() const {
if constexpr (IsPtr) {
// T is a pointer... just echo it back.
return Func;
} else {
static_assert(std::is_reference_v<T>,
"Expected a reference to a function.");
// T is a function reference... dereference the stored pointer.
return *Func;
}
}
};
} // namespace callable_detail
/// Returns true if the given container only contains a single element.
template <typename ContainerTy> bool hasSingleElement(ContainerTy &&C) {
auto B = std::begin(C), E = std::end(C);
return B != E && std::next(B) == E;
}
/// Return a range covering \p RangeOrContainer with the first N elements
/// excluded.
template <typename T> auto drop_begin(T &&RangeOrContainer, size_t N = 1) {
return make_range(std::next(adl_begin(RangeOrContainer), N),
adl_end(RangeOrContainer));
}
/// Return a range covering \p RangeOrContainer with the last N elements
/// excluded.
template <typename T> auto drop_end(T &&RangeOrContainer, size_t N = 1) {
return make_range(adl_begin(RangeOrContainer),
std::prev(adl_end(RangeOrContainer), N));
}
// mapped_iterator - This is a simple iterator adapter that causes a function to
// be applied whenever operator* is invoked on the iterator.
template <typename ItTy, typename FuncTy,
typename ReferenceTy =
decltype(std::declval<FuncTy>()(*std::declval<ItTy>()))>
class mapped_iterator
: public iterator_adaptor_base<
mapped_iterator<ItTy, FuncTy>, ItTy,
typename std::iterator_traits<ItTy>::iterator_category,
std::remove_reference_t<ReferenceTy>,
typename std::iterator_traits<ItTy>::difference_type,
std::remove_reference_t<ReferenceTy> *, ReferenceTy> {
public:
mapped_iterator() = default;
mapped_iterator(ItTy U, FuncTy F)
: mapped_iterator::iterator_adaptor_base(std::move(U)), F(std::move(F)) {}
ItTy getCurrent() { return this->I; }
const FuncTy &getFunction() const { return F; }
ReferenceTy operator*() const { return F(*this->I); }
private:
callable_detail::Callable<FuncTy> F{};
};
// 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(ItTy I, FuncTy F) {
return mapped_iterator<ItTy, FuncTy>(std::move(I), std::move(F));
}
template <class ContainerTy, class FuncTy>
auto map_range(ContainerTy &&C, FuncTy F) {
return make_range(map_iterator(C.begin(), F), map_iterator(C.end(), F));
}
/// A base type of mapped iterator, that is useful for building derived
/// iterators that do not need/want to store the map function (as in
/// mapped_iterator). These iterators must simply provide a `mapElement` method
/// that defines how to map a value of the iterator to the provided reference
/// type.
template <typename DerivedT, typename ItTy, typename ReferenceTy>
class mapped_iterator_base
: public iterator_adaptor_base<
DerivedT, ItTy,
typename std::iterator_traits<ItTy>::iterator_category,
std::remove_reference_t<ReferenceTy>,
typename std::iterator_traits<ItTy>::difference_type,
std::remove_reference_t<ReferenceTy> *, ReferenceTy> {
public:
using BaseT = mapped_iterator_base;
mapped_iterator_base(ItTy U)
: mapped_iterator_base::iterator_adaptor_base(std::move(U)) {}
ItTy getCurrent() { return this->I; }
ReferenceTy operator*() const {
return static_cast<const DerivedT &>(*this).mapElement(*this->I);
}
};
/// Helper to determine if type T has a member called rbegin().
template <typename Ty> class has_rbegin_impl {
using yes = char[1];
using no = char[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<std::remove_reference_t<Ty>> {};
// Returns an iterator_range over the given container which iterates in reverse.
template <typename ContainerTy> auto reverse(ContainerTy &&C) {
if constexpr (has_rbegin<ContainerTy>::value)
return make_range(C.rbegin(), C.rend());
else
return make_range(std::make_reverse_iterator(std::end(C)),
std::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
///
/// Note: filter_iterator_base implements support for forward iteration.
/// filter_iterator_impl exists to provide support for bidirectional iteration,
/// conditional on whether the wrapped iterator supports it.
template <typename WrappedIteratorT, typename PredicateT, typename IterTag>
class filter_iterator_base
: public iterator_adaptor_base<
filter_iterator_base<WrappedIteratorT, PredicateT, IterTag>,
WrappedIteratorT,
std::common_type_t<IterTag,
typename std::iterator_traits<
WrappedIteratorT>::iterator_category>> {
using BaseT = typename filter_iterator_base::iterator_adaptor_base;
protected:
WrappedIteratorT End;
PredicateT Pred;
void findNextValid() {
while (this->I != End && !Pred(*this->I))
BaseT::operator++();
}
filter_iterator_base() = default;
// Construct the iterator. The begin iterator needs to know where the end
// is, so that it can properly stop when it gets there. The end iterator only
// needs the predicate to support bidirectional iteration.
filter_iterator_base(WrappedIteratorT Begin, WrappedIteratorT End,
PredicateT Pred)
: BaseT(Begin), End(End), Pred(Pred) {
findNextValid();
}
public:
using BaseT::operator++;
filter_iterator_base &operator++() {
BaseT::operator++();
findNextValid();
return *this;
}
decltype(auto) operator*() const {
assert(BaseT::wrapped() != End && "Cannot dereference end iterator!");
return BaseT::operator*();
}
decltype(auto) operator->() const {
assert(BaseT::wrapped() != End && "Cannot dereference end iterator!");
return BaseT::operator->();
}
};
/// Specialization of filter_iterator_base for forward iteration only.
template <typename WrappedIteratorT, typename PredicateT,
typename IterTag = std::forward_iterator_tag>
class filter_iterator_impl
: public filter_iterator_base<WrappedIteratorT, PredicateT, IterTag> {
public:
filter_iterator_impl() = default;
filter_iterator_impl(WrappedIteratorT Begin, WrappedIteratorT End,
PredicateT Pred)
: filter_iterator_impl::filter_iterator_base(Begin, End, Pred) {}
};
/// Specialization of filter_iterator_base for bidirectional iteration.
template <typename WrappedIteratorT, typename PredicateT>
class filter_iterator_impl<WrappedIteratorT, PredicateT,
std::bidirectional_iterator_tag>
: public filter_iterator_base<WrappedIteratorT, PredicateT,
std::bidirectional_iterator_tag> {
using BaseT = typename filter_iterator_impl::filter_iterator_base;
void findPrevValid() {
while (!this->Pred(*this->I))
BaseT::operator--();
}
public:
using BaseT::operator--;
filter_iterator_impl() = default;
filter_iterator_impl(WrappedIteratorT Begin, WrappedIteratorT End,
PredicateT Pred)
: BaseT(Begin, End, Pred) {}
filter_iterator_impl &operator--() {
BaseT::operator--();
findPrevValid();
return *this;
}
};
namespace detail {
template <bool is_bidirectional> struct fwd_or_bidi_tag_impl {
using type = std::forward_iterator_tag;
};
template <> struct fwd_or_bidi_tag_impl<true> {
using type = std::bidirectional_iterator_tag;
};
/// Helper which sets its type member to forward_iterator_tag if the category
/// of \p IterT does not derive from bidirectional_iterator_tag, and to
/// bidirectional_iterator_tag otherwise.
template <typename IterT> struct fwd_or_bidi_tag {
using type = typename fwd_or_bidi_tag_impl<std::is_base_of<
std::bidirectional_iterator_tag,
typename std::iterator_traits<IterT>::iterator_category>::value>::type;
};
} // namespace detail
/// Defines filter_iterator to a suitable specialization of
/// filter_iterator_impl, based on the underlying iterator's category.
template <typename WrappedIteratorT, typename PredicateT>
using filter_iterator = filter_iterator_impl<
WrappedIteratorT, PredicateT,
typename detail::fwd_or_bidi_tag<WrappedIteratorT>::type>;
/// 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)), Pred),
FilterIteratorT(std::end(std::forward<RangeT>(Range)),
std::end(std::forward<RangeT>(Range)), Pred));
}
/// A pseudo-iterator adaptor that is designed to implement "early increment"
/// style loops.
///
/// This is *not a normal iterator* and should almost never be used directly. It
/// is intended primarily to be used with range based for loops and some range
/// algorithms.
///
/// The iterator isn't quite an `OutputIterator` or an `InputIterator` but
/// somewhere between them. The constraints of these iterators are:
///
/// - On construction or after being incremented, it is comparable and
/// dereferencable. It is *not* incrementable.
/// - After being dereferenced, it is neither comparable nor dereferencable, it
/// is only incrementable.
///
/// This means you can only dereference the iterator once, and you can only
/// increment it once between dereferences.
template <typename WrappedIteratorT>
class early_inc_iterator_impl
: public iterator_adaptor_base<early_inc_iterator_impl<WrappedIteratorT>,
WrappedIteratorT, std::input_iterator_tag> {
using BaseT = typename early_inc_iterator_impl::iterator_adaptor_base;
using PointerT = typename std::iterator_traits<WrappedIteratorT>::pointer;
protected:
#if LLVM_ENABLE_ABI_BREAKING_CHECKS
bool IsEarlyIncremented = false;
#endif
public:
early_inc_iterator_impl(WrappedIteratorT I) : BaseT(I) {}
using BaseT::operator*;
decltype(*std::declval<WrappedIteratorT>()) operator*() {
#if LLVM_ENABLE_ABI_BREAKING_CHECKS
assert(!IsEarlyIncremented && "Cannot dereference twice!");
IsEarlyIncremented = true;
#endif
return *(this->I)++;
}
using BaseT::operator++;
early_inc_iterator_impl &operator++() {
#if LLVM_ENABLE_ABI_BREAKING_CHECKS
assert(IsEarlyIncremented && "Cannot increment before dereferencing!");
IsEarlyIncremented = false;
#endif
return *this;
}
friend bool operator==(const early_inc_iterator_impl &LHS,
const early_inc_iterator_impl &RHS) {
#if LLVM_ENABLE_ABI_BREAKING_CHECKS
assert(!LHS.IsEarlyIncremented && "Cannot compare after dereferencing!");
#endif
return (const BaseT &)LHS == (const BaseT &)RHS;
}
};
/// Make a range that does early increment to allow mutation of the underlying
/// range without disrupting iteration.
///
/// The underlying iterator will be incremented immediately after it is
/// dereferenced, allowing deletion of the current node or insertion of nodes to
/// not disrupt iteration provided they do not invalidate the *next* iterator --
/// the current iterator can be invalidated.
///
/// This requires a very exact pattern of use that is only really suitable to
/// range based for loops and other range algorithms that explicitly guarantee
/// to dereference exactly once each element, and to increment exactly once each
/// element.
template <typename RangeT>
iterator_range<early_inc_iterator_impl<detail::IterOfRange<RangeT>>>
make_early_inc_range(RangeT &&Range) {
using EarlyIncIteratorT =
early_inc_iterator_impl<detail::IterOfRange<RangeT>>;
return make_range(EarlyIncIteratorT(std::begin(std::forward<RangeT>(Range))),
EarlyIncIteratorT(std::end(std::forward<RangeT>(Range))));
}
// Forward declarations required by zip_shortest/zip_equal/zip_first/zip_longest
template <typename R, typename UnaryPredicate>
bool all_of(R &&range, UnaryPredicate P);
template <typename R, typename UnaryPredicate>
bool any_of(R &&range, UnaryPredicate P);
template <typename T> bool all_equal(std::initializer_list<T> Values);
template <typename R> constexpr size_t range_size(R &&Range);
namespace detail {
using std::declval;
// We have to alias this since inlining the actual type at the usage site
// in the parameter list of iterator_facade_base<> below ICEs MSVC 2017.
template<typename... Iters> struct ZipTupleType {
using type = std::tuple<decltype(*declval<Iters>())...>;
};
template <typename ZipType, typename ReferenceTupleType, typename... Iters>
using zip_traits = iterator_facade_base<
ZipType,
std::common_type_t<
std::bidirectional_iterator_tag,
typename std::iterator_traits<Iters>::iterator_category...>,
// ^ TODO: Implement random access methods.
ReferenceTupleType,
typename std::iterator_traits<
std::tuple_element_t<0, std::tuple<Iters...>>>::difference_type,
// ^ FIXME: This follows boost::make_zip_iterator's assumption that all
// inner iterators have the same difference_type. It would fail if, for
// instance, the second field's difference_type were non-numeric while the
// first is.
ReferenceTupleType *, ReferenceTupleType>;
template <typename ZipType, typename ReferenceTupleType, typename... Iters>
struct zip_common : public zip_traits<ZipType, ReferenceTupleType, Iters...> {
using Base = zip_traits<ZipType, ReferenceTupleType, Iters...>;
using IndexSequence = std::index_sequence_for<Iters...>;
using value_type = typename Base::value_type;
std::tuple<Iters...> iterators;
protected:
template <size_t... Ns> value_type deref(std::index_sequence<Ns...>) const {
return value_type(*std::get<Ns>(iterators)...);
}
template <size_t... Ns> void tup_inc(std::index_sequence<Ns...>) {
(++std::get<Ns>(iterators), ...);
}
template <size_t... Ns> void tup_dec(std::index_sequence<Ns...>) {
(--std::get<Ns>(iterators), ...);
}
template <size_t... Ns>
bool test_all_equals(const zip_common &other,
std::index_sequence<Ns...>) const {
return ((std::get<Ns>(this->iterators) == std::get<Ns>(other.iterators)) &&
...);
}
public:
zip_common(Iters &&... ts) : iterators(std::forward<Iters>(ts)...) {}
value_type operator*() const { return deref(IndexSequence{}); }
ZipType &operator++() {
tup_inc(IndexSequence{});
return static_cast<ZipType &>(*this);
}
ZipType &operator--() {
static_assert(Base::IsBidirectional,
"All inner iterators must be at least bidirectional.");
tup_dec(IndexSequence{});
return static_cast<ZipType &>(*this);
}
/// Return true if all the iterator are matching `other`'s iterators.
bool all_equals(zip_common &other) {
return test_all_equals(other, IndexSequence{});
}
};
template <typename... Iters>
struct zip_first : zip_common<zip_first<Iters...>,
typename ZipTupleType<Iters...>::type, Iters...> {
using zip_common<zip_first, typename ZipTupleType<Iters...>::type,
Iters...>::zip_common;
bool operator==(const zip_first &other) const {
return std::get<0>(this->iterators) == std::get<0>(other.iterators);
}
};
template <typename... Iters>
struct zip_shortest
: zip_common<zip_shortest<Iters...>, typename ZipTupleType<Iters...>::type,
Iters...> {
using zip_common<zip_shortest, typename ZipTupleType<Iters...>::type,
Iters...>::zip_common;
bool operator==(const zip_shortest &other) const {
return any_iterator_equals(other, std::index_sequence_for<Iters...>{});
}
private:
template <size_t... Ns>
bool any_iterator_equals(const zip_shortest &other,
std::index_sequence<Ns...>) const {
return ((std::get<Ns>(this->iterators) == std::get<Ns>(other.iterators)) ||
...);
}
};
/// Helper to obtain the iterator types for the tuple storage within `zippy`.
template <template <typename...> class ItType, typename TupleStorageType,
typename IndexSequence>
struct ZippyIteratorTuple;
/// Partial specialization for non-const tuple storage.
template <template <typename...> class ItType, typename... Args,
std::size_t... Ns>
struct ZippyIteratorTuple<ItType, std::tuple<Args...>,
std::index_sequence<Ns...>> {
using type = ItType<decltype(adl_begin(
std::get<Ns>(declval<std::tuple<Args...> &>())))...>;
};
/// Partial specialization for const tuple storage.
template <template <typename...> class ItType, typename... Args,
std::size_t... Ns>
struct ZippyIteratorTuple<ItType, const std::tuple<Args...>,
std::index_sequence<Ns...>> {
using type = ItType<decltype(adl_begin(
std::get<Ns>(declval<const std::tuple<Args...> &>())))...>;
};
template <template <typename...> class ItType, typename... Args> class zippy {
private:
std::tuple<Args...> storage;
using IndexSequence = std::index_sequence_for<Args...>;
public:
using iterator = typename ZippyIteratorTuple<ItType, decltype(storage),
IndexSequence>::type;
using const_iterator =
typename ZippyIteratorTuple<ItType, const decltype(storage),
IndexSequence>::type;
using iterator_category = typename iterator::iterator_category;
using value_type = typename iterator::value_type;
using difference_type = typename iterator::difference_type;
using pointer = typename iterator::pointer;
using reference = typename iterator::reference;
using const_reference = typename const_iterator::reference;
zippy(Args &&...args) : storage(std::forward<Args>(args)...) {}
const_iterator begin() const { return begin_impl(IndexSequence{}); }
iterator begin() { return begin_impl(IndexSequence{}); }
const_iterator end() const { return end_impl(IndexSequence{}); }
iterator end() { return end_impl(IndexSequence{}); }
private:
template <size_t... Ns>
const_iterator begin_impl(std::index_sequence<Ns...>) const {
return const_iterator(adl_begin(std::get<Ns>(storage))...);
}
template <size_t... Ns> iterator begin_impl(std::index_sequence<Ns...>) {
return iterator(adl_begin(std::get<Ns>(storage))...);
}
template <size_t... Ns>
const_iterator end_impl(std::index_sequence<Ns...>) const {
return const_iterator(adl_end(std::get<Ns>(storage))...);
}
template <size_t... Ns> iterator end_impl(std::index_sequence<Ns...>) {
return iterator(adl_end(std::get<Ns>(storage))...);
}
};
} // end namespace detail
/// zip iterator for two or more iteratable types. Iteration continues until the
/// end of the *shortest* iteratee is reached.
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 assumes that all iteratees have the same length.
/// In builds with assertions on, this assumption is checked before the
/// iteration starts.
template <typename T, typename U, typename... Args>
detail::zippy<detail::zip_first, T, U, Args...> zip_equal(T &&t, U &&u,
Args &&...args) {
assert(all_equal({range_size(t), range_size(u), range_size(args)...}) &&
"Iteratees do not have equal length");
return detail::zippy<detail::zip_first, 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. Iteration continues until the end of the first iteratee is
/// reached. In builds with assertions on, we check that the assumption about
/// the first iteratee being the shortest holds.
template <typename T, typename U, typename... Args>
detail::zippy<detail::zip_first, T, U, Args...> zip_first(T &&t, U &&u,
Args &&...args) {
assert(range_size(t) <= std::min({range_size(u), range_size(args)...}) &&
"First iteratee is not the shortest");
return detail::zippy<detail::zip_first, T, U, Args...>(
std::forward<T>(t), std::forward<U>(u), std::forward<Args>(args)...);
}
namespace detail {
template <typename Iter>
Iter next_or_end(const Iter &I, const Iter &End) {
if (I == End)
return End;
return std::next(I);
}
template <typename Iter>
auto deref_or_none(const Iter &I, const Iter &End) -> std::optional<
std::remove_const_t<std::remove_reference_t<decltype(*I)>>> {
if (I == End)
return std::nullopt;
return *I;
}
template <typename Iter> struct ZipLongestItemType {
using type = std::optional<std::remove_const_t<
std::remove_reference_t<decltype(*std::declval<Iter>())>>>;
};
template <typename... Iters> struct ZipLongestTupleType {
using type = std::tuple<typename ZipLongestItemType<Iters>::type...>;
};
template <typename... Iters>
class zip_longest_iterator
: public iterator_facade_base<
zip_longest_iterator<Iters...>,
std::common_type_t<
std::forward_iterator_tag,
typename std::iterator_traits<Iters>::iterator_category...>,
typename ZipLongestTupleType<Iters...>::type,
typename std::iterator_traits<
std::tuple_element_t<0, std::tuple<Iters...>>>::difference_type,
typename ZipLongestTupleType<Iters...>::type *,
typename ZipLongestTupleType<Iters...>::type> {
public:
using value_type = typename ZipLongestTupleType<Iters...>::type;
private:
std::tuple<Iters...> iterators;
std::tuple<Iters...> end_iterators;
template <size_t... Ns>
bool test(const zip_longest_iterator<Iters...> &other,
std::index_sequence<Ns...>) const {
return ((std::get<Ns>(this->iterators) != std::get<Ns>(other.iterators)) ||
...);
}
template <size_t... Ns> value_type deref(std::index_sequence<Ns...>) const {
return value_type(
deref_or_none(std::get<Ns>(iterators), std::get<Ns>(end_iterators))...);
}
template <size_t... Ns>
decltype(iterators) tup_inc(std::index_sequence<Ns...>) const {
return std::tuple<Iters...>(
next_or_end(std::get<Ns>(iterators), std::get<Ns>(end_iterators))...);
}
public:
zip_longest_iterator(std::pair<Iters &&, Iters &&>... ts)
: iterators(std::forward<Iters>(ts.first)...),
end_iterators(std::forward<Iters>(ts.second)...) {}
value_type operator*() const {
return deref(std::index_sequence_for<Iters...>{});
}
zip_longest_iterator<Iters...> &operator++() {
iterators = tup_inc(std::index_sequence_for<Iters...>{});
return *this;
}
bool operator==(const zip_longest_iterator<Iters...> &other) const {
return !test(other, std::index_sequence_for<Iters...>{});
}
};
template <typename... Args> class zip_longest_range {
public:
using iterator =
zip_longest_iterator<decltype(adl_begin(std::declval<Args>()))...>;
using iterator_category = typename iterator::iterator_category;
using value_type = typename iterator::value_type;
using difference_type = typename iterator::difference_type;
using pointer = typename iterator::pointer;
using reference = typename iterator::reference;
private:
std::tuple<Args...> ts;
template <size_t... Ns>
iterator begin_impl(std::index_sequence<Ns...>) const {
return iterator(std::make_pair(adl_begin(std::get<Ns>(ts)),
adl_end(std::get<Ns>(ts)))...);
}
template <size_t... Ns> iterator end_impl(std::index_sequence<Ns...>) const {
return iterator(std::make_pair(adl_end(std::get<Ns>(ts)),
adl_end(std::get<Ns>(ts)))...);
}
public:
zip_longest_range(Args &&... ts_) : ts(std::forward<Args>(ts_)...) {}
iterator begin() const {
return begin_impl(std::index_sequence_for<Args...>{});
}
iterator end() const { return end_impl(std::index_sequence_for<Args...>{}); }
};
} // namespace detail
/// Iterate over two or more iterators at the same time. Iteration continues
/// until all iterators reach the end. The std::optional only contains a value
/// if the iterator has not reached the end.
template <typename T, typename U, typename... Args>
detail::zip_longest_range<T, U, Args...> zip_longest(T &&t, U &&u,
Args &&... args) {
return detail::zip_longest_range<T, U, Args...>(
std::forward<T>(t), std::forward<U>(u), std::forward<Args>(args)...);
}
/// Iterator wrapper that concatenates sequences together.
///
/// This can concatenate different iterators, even with different types, into
/// a single iterator provided the value types of all the concatenated
/// iterators expose `reference` and `pointer` types that can be converted to
/// `ValueT &` and `ValueT *` respectively. It doesn't support more
/// interesting/customized pointer or reference types.
///
/// Currently this only supports forward or higher iterator categories as
/// inputs and always exposes a forward iterator interface.
template <typename ValueT, typename... IterTs>
class concat_iterator
: public iterator_facade_base<concat_iterator<ValueT, IterTs...>,
std::forward_iterator_tag, ValueT> {
using BaseT = typename concat_iterator::iterator_facade_base;
/// We store both the current and end iterators for each concatenated
/// sequence in a tuple of pairs.
///
/// Note that something like iterator_range seems nice at first here, but the
/// range properties are of little benefit and end up getting in the way
/// because we need to do mutation on the current iterators.
std::tuple<IterTs...> Begins;
std::tuple<IterTs...> Ends;
/// Attempts to increment a specific iterator.
///
/// Returns true if it was able to increment the iterator. Returns false if
/// the iterator is already at the end iterator.
template <size_t Index> bool incrementHelper() {
auto &Begin = std::get<Index>(Begins);
auto &End = std::get<Index>(Ends);
if (Begin == End)
return false;
++Begin;
return true;
}
/// Increments the first non-end iterator.
///
/// It is an error to call this with all iterators at the end.
template <size_t... Ns> void increment(std::index_sequence<Ns...>) {
// Build a sequence of functions to increment each iterator if possible.
bool (concat_iterator::*IncrementHelperFns[])() = {
&concat_iterator::incrementHelper<Ns>...};
// Loop over them, and stop as soon as we succeed at incrementing one.
for (auto &IncrementHelperFn : IncrementHelperFns)
if ((this->*IncrementHelperFn)())
return;
llvm_unreachable("Attempted to increment an end concat iterator!");
}
/// Returns null if the specified iterator is at the end. Otherwise,
/// dereferences the iterator and returns the address of the resulting
/// reference.
template <size_t Index> ValueT *getHelper() const {
auto &Begin = std::get<Index>(Begins);
auto &End = std::get<Index>(Ends);
if (Begin == End)
return nullptr;
return &*Begin;
}
/// Finds the first non-end iterator, dereferences, and returns the resulting
/// reference.
///
/// It is an error to call this with all iterators at the end.
template <size_t... Ns> ValueT &get(std::index_sequence<Ns...>) const {
// Build a sequence of functions to get from iterator if possible.
ValueT *(concat_iterator::*GetHelperFns[])() const = {
&concat_iterator::getHelper<Ns>...};
// Loop over them, and return the first result we find.
for (auto &GetHelperFn : GetHelperFns)
if (ValueT *P = (this->*GetHelperFn)())
return *P;
llvm_unreachable("Attempted to get a pointer from an end concat iterator!");
}
public:
/// Constructs an iterator from a sequence of ranges.
///
/// We need the full range to know how to switch between each of the
/// iterators.
template <typename... RangeTs>
explicit concat_iterator(RangeTs &&... Ranges)
: Begins(std::begin(Ranges)...), Ends(std::end(Ranges)...) {}
using BaseT::operator++;
concat_iterator &operator++() {
increment(std::index_sequence_for<IterTs...>());
return *this;
}
ValueT &operator*() const {
return get(std::index_sequence_for<IterTs...>());
}
bool operator==(const concat_iterator &RHS) const {
return Begins == RHS.Begins && Ends == RHS.Ends;
}
};
namespace detail {
/// Helper to store a sequence of ranges being concatenated and access them.
///
/// This is designed to facilitate providing actual storage when temporaries
/// are passed into the constructor such that we can use it as part of range
/// based for loops.
template <typename ValueT, typename... RangeTs> class concat_range {
public:
using iterator =
concat_iterator<ValueT,
decltype(std::begin(std::declval<RangeTs &>()))...>;
private:
std::tuple<RangeTs...> Ranges;
template <size_t... Ns>
iterator begin_impl(std::index_sequence<Ns...>) {
return iterator(std::get<Ns>(Ranges)...);
}
template <size_t... Ns>
iterator begin_impl(std::index_sequence<Ns...>) const {
return iterator(std::get<Ns>(Ranges)...);
}
template <size_t... Ns> iterator end_impl(std::index_sequence<Ns...>) {
return iterator(make_range(std::end(std::get<Ns>(Ranges)),
std::end(std::get<Ns>(Ranges)))...);
}
template <size_t... Ns> iterator end_impl(std::index_sequence<Ns...>) const {
return iterator(make_range(std::end(std::get<Ns>(Ranges)),
std::end(std::get<Ns>(Ranges)))...);
}
public:
concat_range(RangeTs &&... Ranges)
: Ranges(std::forward<RangeTs>(Ranges)...) {}
iterator begin() {
return begin_impl(std::index_sequence_for<RangeTs...>{});
}
iterator begin() const {
return begin_impl(std::index_sequence_for<RangeTs...>{});
}
iterator end() {
return end_impl(std::index_sequence_for<RangeTs...>{});
}
iterator end() const {
return end_impl(std::index_sequence_for<RangeTs...>{});
}
};
} // end namespace detail
/// Concatenated range across two or more ranges.
///
/// The desired value type must be explicitly specified.
template <typename ValueT, typename... RangeTs>
detail::concat_range<ValueT, RangeTs...> concat(RangeTs &&... Ranges) {
static_assert(sizeof...(RangeTs) > 1,
"Need more than one range to concatenate!");
return detail::concat_range<ValueT, RangeTs...>(
std::forward<RangeTs>(Ranges)...);
}
/// A utility class used to implement an iterator that contains some base object
/// and an index. The iterator moves the index but keeps the base constant.
template <typename DerivedT, typename BaseT, typename T,
typename PointerT = T *, typename ReferenceT = T &>
class indexed_accessor_iterator
: public llvm::iterator_facade_base<DerivedT,
std::random_access_iterator_tag, T,
std::ptrdiff_t, PointerT, ReferenceT> {
public:
ptrdiff_t operator-(const indexed_accessor_iterator &rhs) const {
assert(base == rhs.base && "incompatible iterators");
return index - rhs.index;
}
bool operator==(const indexed_accessor_iterator &rhs) const {
return base == rhs.base && index == rhs.index;
}
bool operator<(const indexed_accessor_iterator &rhs) const {
assert(base == rhs.base && "incompatible iterators");
return index < rhs.index;
}
DerivedT &operator+=(ptrdiff_t offset) {
this->index += offset;
return static_cast<DerivedT &>(*this);
}
DerivedT &operator-=(ptrdiff_t offset) {
this->index -= offset;
return static_cast<DerivedT &>(*this);
}
/// Returns the current index of the iterator.
ptrdiff_t getIndex() const { return index; }
/// Returns the current base of the iterator.
const BaseT &getBase() const { return base; }
protected:
indexed_accessor_iterator(BaseT base, ptrdiff_t index)
: base(base), index(index) {}
BaseT base;
ptrdiff_t index;
};
namespace detail {
/// The class represents the base of a range of indexed_accessor_iterators. It
/// provides support for many different range functionalities, e.g.
/// drop_front/slice/etc.. Derived range classes must implement the following
/// static methods:
/// * ReferenceT dereference_iterator(const BaseT &base, ptrdiff_t index)
/// - Dereference an iterator pointing to the base object at the given
/// index.
/// * BaseT offset_base(const BaseT &base, ptrdiff_t index)
/// - Return a new base that is offset from the provide base by 'index'
/// elements.
template <typename DerivedT, typename BaseT, typename T,
typename PointerT = T *, typename ReferenceT = T &>
class indexed_accessor_range_base {
public:
using RangeBaseT = indexed_accessor_range_base;
/// An iterator element of this range.
class iterator : public indexed_accessor_iterator<iterator, BaseT, T,
PointerT, ReferenceT> {
public:
// Index into this iterator, invoking a static method on the derived type.
ReferenceT operator*() const {
return DerivedT::dereference_iterator(this->getBase(), this->getIndex());
}
private:
iterator(BaseT owner, ptrdiff_t curIndex)
: iterator::indexed_accessor_iterator(owner, curIndex) {}
/// Allow access to the constructor.
friend indexed_accessor_range_base<DerivedT, BaseT, T, PointerT,
ReferenceT>;
};
indexed_accessor_range_base(iterator begin, iterator end)
: base(offset_base(begin.getBase(), begin.getIndex())),
count(end.getIndex() - begin.getIndex()) {}
indexed_accessor_range_base(const iterator_range<iterator> &range)
: indexed_accessor_range_base(range.begin(), range.end()) {}
indexed_accessor_range_base(BaseT base, ptrdiff_t count)
: base(base), count(count) {}
iterator begin() const { return iterator(base, 0); }
iterator end() const { return iterator(base, count); }
ReferenceT operator[](size_t Index) const {
assert(Index < size() && "invalid index for value range");
return DerivedT::dereference_iterator(base, static_cast<ptrdiff_t>(Index));
}
ReferenceT front() const {
assert(!empty() && "expected non-empty range");
return (*this)[0];
}
ReferenceT back() const {
assert(!empty() && "expected non-empty range");
return (*this)[size() - 1];
}
/// Compare this range with another.
template <typename OtherT>
friend bool operator==(const indexed_accessor_range_base &lhs,
const OtherT &rhs) {
return std::equal(lhs.begin(), lhs.end(), rhs.begin(), rhs.end());
}
template <typename OtherT>
friend bool operator!=(const indexed_accessor_range_base &lhs,
const OtherT &rhs) {
return !(lhs == rhs);
}
/// Return the size of this range.
size_t size() const { return count; }
/// Return if the range is empty.
bool empty() const { return size() == 0; }
/// Drop the first N elements, and keep M elements.
DerivedT slice(size_t n, size_t m) const {
assert(n + m <= size() && "invalid size specifiers");
return DerivedT(offset_base(base, n), m);
}
/// Drop the first n elements.
DerivedT drop_front(size_t n = 1) const {
assert(size() >= n && "Dropping more elements than exist");
return slice(n, size() - n);
}
/// Drop the last n elements.
DerivedT drop_back(size_t n = 1) const {
assert(size() >= n && "Dropping more elements than exist");
return DerivedT(base, size() - n);
}
/// Take the first n elements.
DerivedT take_front(size_t n = 1) const {
return n < size() ? drop_back(size() - n)
: static_cast<const DerivedT &>(*this);
}
/// Take the last n elements.
DerivedT take_back(size_t n = 1) const {
return n < size() ? drop_front(size() - n)
: static_cast<const DerivedT &>(*this);
}
/// Allow conversion to any type accepting an iterator_range.
template <typename RangeT, typename = std::enable_if_t<std::is_constructible<
RangeT, iterator_range<iterator>>::value>>
operator RangeT() const {
return RangeT(iterator_range<iterator>(*this));
}
/// Returns the base of this range.
const BaseT &getBase() const { return base; }
private:
/// Offset the given base by the given amount.
static BaseT offset_base(const BaseT &base, size_t n) {
return n == 0 ? base : DerivedT::offset_base(base, n);
}
protected:
indexed_accessor_range_base(const indexed_accessor_range_base &) = default;
indexed_accessor_range_base(indexed_accessor_range_base &&) = default;
indexed_accessor_range_base &
operator=(const indexed_accessor_range_base &) = default;
/// The base that owns the provided range of values.
BaseT base;
/// The size from the owning range.
ptrdiff_t count;
};
} // end namespace detail
/// This class provides an implementation of a range of
/// indexed_accessor_iterators where the base is not indexable. Ranges with
/// bases that are offsetable should derive from indexed_accessor_range_base
/// instead. Derived range classes are expected to implement the following
/// static method:
/// * ReferenceT dereference(const BaseT &base, ptrdiff_t index)
/// - Dereference an iterator pointing to a parent base at the given index.
template <typename DerivedT, typename BaseT, typename T,
typename PointerT = T *, typename ReferenceT = T &>
class indexed_accessor_range
: public detail::indexed_accessor_range_base<
DerivedT, std::pair<BaseT, ptrdiff_t>, T, PointerT, ReferenceT> {
public:
indexed_accessor_range(BaseT base, ptrdiff_t startIndex, ptrdiff_t count)
: detail::indexed_accessor_range_base<
DerivedT, std::pair<BaseT, ptrdiff_t>, T, PointerT, ReferenceT>(
std::make_pair(base, startIndex), count) {}
using detail::indexed_accessor_range_base<
DerivedT, std::pair<BaseT, ptrdiff_t>, T, PointerT,
ReferenceT>::indexed_accessor_range_base;
/// Returns the current base of the range.
const BaseT &getBase() const { return this->base.first; }
/// Returns the current start index of the range.
ptrdiff_t getStartIndex() const { return this->base.second; }
/// See `detail::indexed_accessor_range_base` for details.
static std::pair<BaseT, ptrdiff_t>
offset_base(const std::pair<BaseT, ptrdiff_t> &base, ptrdiff_t index) {
// We encode the internal base as a pair of the derived base and a start
// index into the derived base.
return std::make_pair(base.first, base.second + index);
}
/// See `detail::indexed_accessor_range_base` for details.
static ReferenceT
dereference_iterator(const std::pair<BaseT, ptrdiff_t> &base,
ptrdiff_t index) {
return DerivedT::dereference(base.first, base.second + index);
}
};
namespace detail {
/// Return a reference to the first or second member of a reference. Otherwise,
/// return a copy of the member of a temporary.
///
/// When passing a range whose iterators return values instead of references,
/// the reference must be dropped from `decltype((elt.first))`, which will
/// always be a reference, to avoid returning a reference to a temporary.
template <typename EltTy, typename FirstTy> class first_or_second_type {
public:
using type = std::conditional_t<std::is_reference<EltTy>::value, FirstTy,
std::remove_reference_t<FirstTy>>;
};
} // end namespace detail
/// Given a container of pairs, return a range over the first elements.
template <typename ContainerTy> auto make_first_range(ContainerTy &&c) {
using EltTy = decltype((*std::begin(c)));
return llvm::map_range(std::forward<ContainerTy>(c),
[](EltTy elt) -> typename detail::first_or_second_type<
EltTy, decltype((elt.first))>::type {
return elt.first;
});
}
/// Given a container of pairs, return a range over the second elements.
template <typename ContainerTy> auto make_second_range(ContainerTy &&c) {
using EltTy = decltype((*std::begin(c)));
return llvm::map_range(
std::forward<ContainerTy>(c),
[](EltTy elt) ->
typename detail::first_or_second_type<EltTy,
decltype((elt.second))>::type {
return elt.second;
});
}
//===----------------------------------------------------------------------===//
// Extra additions to <utility>
//===----------------------------------------------------------------------===//
/// Function object to check whether the first component of a container
/// supported by std::get (like std::pair and std::tuple) compares less than the
/// first component of another container.
struct less_first {
template <typename T> bool operator()(const T &lhs, const T &rhs) const {
return std::less<>()(std::get<0>(lhs), std::get<0>(rhs));
}
};
/// Function object to check whether the second component of a container
/// supported by std::get (like std::pair and std::tuple) compares less than the
/// second component of another container.
struct less_second {
template <typename T> bool operator()(const T &lhs, const T &rhs) const {
return std::less<>()(std::get<1>(lhs), std::get<1>(rhs));
}
};
/// \brief Function object to apply a binary function to the first component of
/// a std::pair.
template<typename FuncTy>
struct on_first {
FuncTy func;
template <typename T>
decltype(auto) operator()(const T &lhs, const T &rhs) const {
return func(lhs.first, rhs.first);
}
};
/// 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> {};
/// traits class for checking whether type T is one of any of the given
/// types in the variadic list.
template <typename T, typename... Ts>
using is_one_of = std::disjunction<std::is_same<T, Ts>...>;
/// traits class for checking whether type T is a base class for all
/// the given types in the variadic list.
template <typename T, typename... Ts>
using are_base_of = std::conjunction<std::is_base_of<T, Ts>...>;
namespace detail {
template <typename... Ts> struct Visitor;
template <typename HeadT, typename... TailTs>
struct Visitor<HeadT, TailTs...> : remove_cvref_t<HeadT>, Visitor<TailTs...> {
explicit constexpr Visitor(HeadT &&Head, TailTs &&...Tail)
: remove_cvref_t<HeadT>(std::forward<HeadT>(Head)),
Visitor<TailTs...>(std::forward<TailTs>(Tail)...) {}
using remove_cvref_t<HeadT>::operator();
using Visitor<TailTs...>::operator();
};
template <typename HeadT> struct Visitor<HeadT> : remove_cvref_t<HeadT> {
explicit constexpr Visitor(HeadT &&Head)
: remove_cvref_t<HeadT>(std::forward<HeadT>(Head)) {}
using remove_cvref_t<HeadT>::operator();
};
} // namespace detail
/// Returns an opaquely-typed Callable object whose operator() overload set is
/// the sum of the operator() overload sets of each CallableT in CallableTs.
///
/// The type of the returned object derives from each CallableT in CallableTs.
/// The returned object is constructed by invoking the appropriate copy or move
/// constructor of each CallableT, as selected by overload resolution on the
/// corresponding argument to makeVisitor.
///
/// Example:
///
/// \code
/// auto visitor = makeVisitor([](auto) { return "unhandled type"; },
/// [](int i) { return "int"; },
/// [](std::string s) { return "str"; });
/// auto a = visitor(42); // `a` is now "int".
/// auto b = visitor("foo"); // `b` is now "str".
/// auto c = visitor(3.14f); // `c` is now "unhandled type".
/// \endcode
///
/// Example of making a visitor with a lambda which captures a move-only type:
///
/// \code
/// std::unique_ptr<FooHandler> FH = /* ... */;
/// auto visitor = makeVisitor(
/// [FH{std::move(FH)}](Foo F) { return FH->handle(F); },
/// [](int i) { return i; },
/// [](std::string s) { return atoi(s); });
/// \endcode
template <typename... CallableTs>
constexpr decltype(auto) makeVisitor(CallableTs &&...Callables) {
return detail::Visitor<CallableTs...>(std::forward<CallableTs>(Callables)...);
}
//===----------------------------------------------------------------------===//
// Extra additions to <algorithm>
//===----------------------------------------------------------------------===//
// We have a copy here so that LLVM behaves the same when using different
// standard libraries.
template <class Iterator, class RNG>
void shuffle(Iterator first, Iterator last, RNG &&g) {
// It would be better to use a std::uniform_int_distribution,
// but that would be stdlib dependent.
typedef
typename std::iterator_traits<Iterator>::difference_type difference_type;
for (auto size = last - first; size > 1; ++first, (void)--size) {
difference_type offset = g() % size;
// Avoid self-assignment due to incorrect assertions in libstdc++
// containers (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85828).
if (offset != difference_type(0))
std::iter_swap(first, first + offset);
}
}
/// 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>;
}
#ifdef EXPENSIVE_CHECKS
namespace detail {
inline unsigned presortShuffleEntropy() {
static unsigned Result(std::random_device{}());
return Result;
}
template <class IteratorTy>
inline void presortShuffle(IteratorTy Start, IteratorTy End) {
std::mt19937 Generator(presortShuffleEntropy());
llvm::shuffle(Start, End, Generator);
}
} // end namespace detail
#endif
/// 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;
#ifdef EXPENSIVE_CHECKS
detail::presortShuffle<IteratorTy>(Start, End);
#endif
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;
#ifdef EXPENSIVE_CHECKS
detail::presortShuffle<IteratorTy>(Start, End);
#endif
qsort(&*Start, NElts, sizeof(*Start),
reinterpret_cast<int (*)(const void *, const void *)>(Compare));
}
namespace detail {
template <typename T>
// We can use qsort if the iterator type is a pointer and the underlying value
// is trivially copyable.
using sort_trivially_copyable = std::conjunction<
std::is_pointer<T>,
std::is_trivially_copyable<typename std::iterator_traits<T>::value_type>>;
} // namespace detail
// Provide wrappers to std::sort which shuffle the elements before sorting
// to help uncover non-deterministic behavior (PR35135).
template <typename IteratorTy>
inline void sort(IteratorTy Start, IteratorTy End) {
if constexpr (detail::sort_trivially_copyable<IteratorTy>::value) {
// Forward trivially copyable types to array_pod_sort. This avoids a large
// amount of code bloat for a minor performance hit.
array_pod_sort(Start, End);
} else {
#ifdef EXPENSIVE_CHECKS
detail::presortShuffle<IteratorTy>(Start, End);
#endif
std::sort(Start, End);
}
}
template <typename Container> inline void sort(Container &&C) {
llvm::sort(adl_begin(C), adl_end(C));
}
template <typename IteratorTy, typename Compare>
inline void sort(IteratorTy Start, IteratorTy End, Compare Comp) {
#ifdef EXPENSIVE_CHECKS
detail::presortShuffle<IteratorTy>(Start, End);
#endif
std::sort(Start, End, Comp);
}
template <typename Container, typename Compare>
inline void sort(Container &&C, Compare Comp) {
llvm::sort(adl_begin(C), adl_end(C), Comp);
}
/// Get the size of a range. This is a wrapper function around std::distance
/// which is only enabled when the operation is O(1).
template <typename R>
auto size(R &&Range,
std::enable_if_t<
std::is_base_of<std::random_access_iterator_tag,
typename std::iterator_traits<decltype(
Range.begin())>::iterator_category>::value,
void> * = nullptr) {
return std::distance(Range.begin(), Range.end());
}
namespace detail {
template <typename Range>
using check_has_free_function_size =
decltype(adl_size(std::declval<Range &>()));
template <typename Range>
static constexpr bool HasFreeFunctionSize =
is_detected<check_has_free_function_size, Range>::value;
} // namespace detail
/// Returns the size of the \p Range, i.e., the number of elements. This
/// implementation takes inspiration from `std::ranges::size` from C++20 and
/// delegates the size check to `adl_size` or `std::distance`, in this order of
/// preference. Unlike `llvm::size`, this function does *not* guarantee O(1)
/// running time, and is intended to be used in generic code that does not know
/// the exact range type.
template <typename R> constexpr size_t range_size(R &&Range) {
if constexpr (detail::HasFreeFunctionSize<R>)
return adl_size(Range);
else
return static_cast<size_t>(std::distance(adl_begin(Range), adl_end(Range)));
}
/// Provide wrappers to std::for_each which take ranges instead of having to
/// pass begin/end explicitly.
template <typename R, typename UnaryFunction>
UnaryFunction for_each(R &&Range, UnaryFunction F) {
return std::for_each(adl_begin(Range), adl_end(Range), F);
}
/// 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(adl_begin(Range), adl_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(adl_begin(Range), adl_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(adl_begin(Range), adl_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) {
return std::find(adl_begin(Range), adl_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) {
return std::find_if(adl_begin(Range), adl_end(Range), P);
}
template <typename R, typename UnaryPredicate>
auto find_if_not(R &&Range, UnaryPredicate P) {
return std::find_if_not(adl_begin(Range), adl_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) {
return std::remove_if(adl_begin(Range), adl_end(Range), P);
}
/// Provide wrappers to std::copy_if which take ranges instead of having to
/// pass begin/end explicitly.
template <typename R, typename OutputIt, typename UnaryPredicate>
OutputIt copy_if(R &&Range, OutputIt Out, UnaryPredicate P) {
return std::copy_if(adl_begin(Range), adl_end(Range), Out, P);
}
/// Return the single value in \p Range that satisfies
/// \p P(<member of \p Range> *, AllowRepeats)->T * returning nullptr
/// when no values or multiple values were found.
/// When \p AllowRepeats is true, multiple values that compare equal
/// are allowed.
template <typename T, typename R, typename Predicate>
T *find_singleton(R &&Range, Predicate P, bool AllowRepeats = false) {
T *RC = nullptr;
for (auto *A : Range) {
if (T *PRC = P(A, AllowRepeats)) {
if (RC) {
if (!AllowRepeats || PRC != RC)
return nullptr;
} else
RC = PRC;
}
}
return RC;
}
/// Return a pair consisting of the single value in \p Range that satisfies
/// \p P(<member of \p Range> *, AllowRepeats)->std::pair<T*, bool> returning
/// nullptr when no values or multiple values were found, and a bool indicating
/// whether multiple values were found to cause the nullptr.
/// When \p AllowRepeats is true, multiple values that compare equal are
/// allowed. The predicate \p P returns a pair<T *, bool> where T is the
/// singleton while the bool indicates whether multiples have already been
/// found. It is expected that first will be nullptr when second is true.
/// This allows using find_singleton_nested within the predicate \P.
template <typename T, typename R, typename Predicate>
std::pair<T *, bool> find_singleton_nested(R &&Range, Predicate P,
bool AllowRepeats = false) {
T *RC = nullptr;
for (auto *A : Range) {
std::pair<T *, bool> PRC = P(A, AllowRepeats);
if (PRC.second) {
assert(PRC.first == nullptr &&
"Inconsistent return values in find_singleton_nested.");
return PRC;
}
if (PRC.first) {
if (RC) {
if (!AllowRepeats || PRC.first != RC)
return {nullptr, true};
} else
RC = PRC.first;
}
}
return {RC, false};
}
template <typename R, typename OutputIt>
OutputIt copy(R &&Range, OutputIt Out) {
return std::copy(adl_begin(Range), adl_end(Range), Out);
}
/// Provide wrappers to std::replace_copy_if which take ranges instead of having
/// to pass begin/end explicitly.
template <typename R, typename OutputIt, typename UnaryPredicate, typename T>
OutputIt replace_copy_if(R &&Range, OutputIt Out, UnaryPredicate P,
const T &NewValue) {
return std::replace_copy_if(adl_begin(Range), adl_end(Range), Out, P,
NewValue);
}
/// Provide wrappers to std::replace_copy which take ranges instead of having to
/// pass begin/end explicitly.
template <typename R, typename OutputIt, typename T>
OutputIt replace_copy(R &&Range, OutputIt Out, const T &OldValue,
const T &NewValue) {
return std::replace_copy(adl_begin(Range), adl_end(Range), Out, OldValue,
NewValue);
}
/// Provide wrappers to std::move which take ranges instead of having to
/// pass begin/end explicitly.
template <typename R, typename OutputIt>
OutputIt move(R &&Range, OutputIt Out) {
return std::move(adl_begin(Range), adl_end(Range), Out);
}
namespace detail {
template <typename Range, typename Element>
using check_has_member_contains_t =
decltype(std::declval<Range &>().contains(std::declval<const Element &>()));
template <typename Range, typename Element>
static constexpr bool HasMemberContains =
is_detected<check_has_member_contains_t, Range, Element>::value;
template <typename Range, typename Element>
using check_has_member_find_t =
decltype(std::declval<Range &>().find(std::declval<const Element &>()) !=
std::declval<Range &>().end());
template <typename Range, typename Element>
static constexpr bool HasMemberFind =
is_detected<check_has_member_find_t, Range, Element>::value;
} // namespace detail
/// Returns true if \p Element is found in \p Range. Delegates the check to
/// either `.contains(Element)`, `.find(Element)`, or `std::find`, in this
/// order of preference. This is intended as the canonical way to check if an
/// element exists in a range in generic code or range type that does not
/// expose a `.contains(Element)` member.
template <typename R, typename E>
bool is_contained(R &&Range, const E &Element) {
if constexpr (detail::HasMemberContains<R, E>)
return Range.contains(Element);
else if constexpr (detail::HasMemberFind<R, E>)
return Range.find(Element) != Range.end();
else
return std::find(adl_begin(Range), adl_end(Range), Element) !=
adl_end(Range);
}
/// Returns true iff \p Element exists in \p Set. This overload takes \p Set as
/// an initializer list and is `constexpr`-friendly.
template <typename T, typename E>
constexpr bool is_contained(std::initializer_list<T> Set, const E &Element) {
// TODO: Use std::find when we switch to C++20.
for (const T &V : Set)
if (V == Element)
return true;
return false;
}
/// Wrapper function around std::is_sorted to check if elements in a range \p R
/// are sorted with respect to a comparator \p C.
template <typename R, typename Compare> bool is_sorted(R &&Range, Compare C) {
return std::is_sorted(adl_begin(Range), adl_end(Range), C);
}
/// Wrapper function around std::is_sorted to check if elements in a range \p R
/// are sorted in non-descending order.
template <typename R> bool is_sorted(R &&Range) {
return std::is_sorted(adl_begin(Range), adl_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) {
return std::count(adl_begin(Range), adl_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) {
return std::count_if(adl_begin(Range), adl_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 UnaryFunction>
OutputIt transform(R &&Range, OutputIt d_first, UnaryFunction F) {
return std::transform(adl_begin(Range), adl_end(Range), d_first, F);
}
/// Provide wrappers to std::partition which take ranges instead of having to
/// pass begin/end explicitly.
template <typename R, typename UnaryPredicate>
auto partition(R &&Range, UnaryPredicate P) {
return std::partition(adl_begin(Range), adl_end(Range), P);
}
/// Provide wrappers to std::lower_bound which take ranges instead of having to
/// pass begin/end explicitly.
template <typename R, typename T> auto lower_bound(R &&Range, T &&Value) {
return std::lower_bound(adl_begin(Range), adl_end(Range),
std::forward<T>(Value));
}
template <typename R, typename T, typename Compare>
auto lower_bound(R &&Range, T &&Value, Compare C) {
return std::lower_bound(adl_begin(Range), adl_end(Range),
std::forward<T>(Value), C);
}
/// Provide wrappers to std::upper_bound which take ranges instead of having to
/// pass begin/end explicitly.
template <typename R, typename T> auto upper_bound(R &&Range, T &&Value) {
return std::upper_bound(adl_begin(Range), adl_end(Range),
std::forward<T>(Value));
}
template <typename R, typename T, typename Compare>
auto upper_bound(R &&Range, T &&Value, Compare C) {
return std::upper_bound(adl_begin(Range), adl_end(Range),
std::forward<T>(Value), C);
}
template <typename R>
void stable_sort(R &&Range) {
std::stable_sort(adl_begin(Range), adl_end(Range));
}
template <typename R, typename Compare>
void stable_sort(R &&Range, Compare C) {
std::stable_sort(adl_begin(Range), adl_end(Range), C);
}
/// Binary search for the first iterator in a range where a predicate is false.
/// Requires that C is always true below some limit, and always false above it.
template <typename R, typename Predicate,
typename Val = decltype(*adl_begin(std::declval<R>()))>
auto partition_point(R &&Range, Predicate P) {
return std::partition_point(adl_begin(Range), adl_end(Range), P);
}
template<typename Range, typename Predicate>
auto unique(Range &&R, Predicate P) {
return std::unique(adl_begin(R), adl_end(R), P);
}
/// Wrapper function around std::equal to detect if pair-wise elements between
/// two ranges are the same.
template <typename L, typename R> bool equal(L &&LRange, R &&RRange) {
return std::equal(adl_begin(LRange), adl_end(LRange), adl_begin(RRange),
adl_end(RRange));
}
/// Returns true if all elements in Range are equal or when the Range is empty.
template <typename R> bool all_equal(R &&Range) {
auto Begin = adl_begin(Range);
auto End = adl_end(Range);
return Begin == End || std::equal(Begin + 1, End, Begin);
}
/// Returns true if all Values in the initializer lists are equal or the list
// is empty.
template <typename T> bool all_equal(std::initializer_list<T> Values) {
return all_equal<std::initializer_list<T>>(std::move(Values));
}
/// Provide a container algorithm similar to C++ Library Fundamentals v2's
/// `erase_if` which is equivalent to:
///
/// C.erase(remove_if(C, pred), C.end());
///
/// This version works for any container with an erase method call accepting
/// two iterators.
template <typename Container, typename UnaryPredicate>
void erase_if(Container &C, UnaryPredicate P) {
C.erase(remove_if(C, P), C.end());
}
/// Wrapper function to remove a value from a container:
///
/// C.erase(remove(C.begin(), C.end(), V), C.end());
template <typename Container, typename ValueType>
void erase_value(Container &C, ValueType V) {
C.erase(std::remove(C.begin(), C.end(), V), C.end());
}
/// Wrapper function to append a range to a container.
///
/// C.insert(C.end(), R.begin(), R.end());
template <typename Container, typename Range>
inline void append_range(Container &C, Range &&R) {
C.insert(C.end(), adl_begin(R), adl_end(R));
}
/// Given a sequence container Cont, replace the range [ContIt, ContEnd) with
/// the range [ValIt, ValEnd) (which is not from the same container).
template<typename Container, typename RandomAccessIterator>
void replace(Container &Cont, typename Container::iterator ContIt,
typename Container::iterator ContEnd, RandomAccessIterator ValIt,
RandomAccessIterator ValEnd) {
while (true) {
if (ValIt == ValEnd) {
Cont.erase(ContIt, ContEnd);
return;
} else if (ContIt == ContEnd) {
Cont.insert(ContIt, ValIt, ValEnd);
return;
}
*ContIt++ = *ValIt++;
}
}
/// Given a sequence container Cont, replace the range [ContIt, ContEnd) with
/// the range R.
template<typename Container, typename Range = std::initializer_list<
typename Container::value_type>>
void replace(Container &Cont, typename Container::iterator ContIt,
typename Container::iterator ContEnd, Range R) {
replace(Cont, ContIt, ContEnd, R.begin(), R.end());
}
/// An STL-style algorithm similar to std::for_each that applies a second
/// functor between every pair of elements.
///
/// This provides the control flow logic to, for example, print a
/// comma-separated list:
/// \code
/// interleave(names.begin(), names.end(),
/// [&](StringRef name) { os << name; },
/// [&] { os << ", "; });
/// \endcode
template <typename ForwardIterator, typename UnaryFunctor,
typename NullaryFunctor,
typename = std::enable_if_t<
!std::is_constructible<StringRef, UnaryFunctor>::value &&
!std::is_constructible<StringRef, NullaryFunctor>::value>>
inline void interleave(ForwardIterator begin, ForwardIterator end,
UnaryFunctor each_fn, NullaryFunctor between_fn) {
if (begin == end)
return;
each_fn(*begin);
++begin;
for (; begin != end; ++begin) {
between_fn();
each_fn(*begin);
}
}
template <typename Container, typename UnaryFunctor, typename NullaryFunctor,
typename = std::enable_if_t<
!std::is_constructible<StringRef, UnaryFunctor>::value &&
!std::is_constructible<StringRef, NullaryFunctor>::value>>
inline void interleave(const Container &c, UnaryFunctor each_fn,
NullaryFunctor between_fn) {
interleave(c.begin(), c.end(), each_fn, between_fn);
}
/// Overload of interleave for the common case of string separator.
template <typename Container, typename UnaryFunctor, typename StreamT,
typename T = detail::ValueOfRange<Container>>
inline void interleave(const Container &c, StreamT &os, UnaryFunctor each_fn,
const StringRef &separator) {
interleave(c.begin(), c.end(), each_fn, [&] { os << separator; });
}
template <typename Container, typename StreamT,
typename T = detail::ValueOfRange<Container>>
inline void interleave(const Container &c, StreamT &os,
const StringRef &separator) {
interleave(
c, os, [&](const T &a) { os << a; }, separator);
}
template <typename Container, typename UnaryFunctor, typename StreamT,
typename T = detail::ValueOfRange<Container>>
inline void interleaveComma(const Container &c, StreamT &os,
UnaryFunctor each_fn) {
interleave(c, os, each_fn, ", ");
}
template <typename Container, typename StreamT,
typename T = detail::ValueOfRange<Container>>
inline void interleaveComma(const Container &c, StreamT &os) {
interleaveComma(c, os, [&](const T &a) { os << a; });
}
//===----------------------------------------------------------------------===//
// Extra additions to <memory>
//===----------------------------------------------------------------------===//
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);
}
};
/// 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 {
assert(lhs);
assert(rhs);
return func(*lhs, *rhs);
}
};
namespace detail {
/// Tuple-like type for `zip_enumerator` dereference.
template <typename... Refs> struct enumerator_result;
template <typename... Iters>
using EnumeratorTupleType = enumerator_result<decltype(*declval<Iters>())...>;
/// Zippy iterator that uses the second iterator for comparisons. For the
/// increment to be safe, the second range has to be the shortest.
/// Returns `enumerator_result` on dereference to provide `.index()` and
/// `.value()` member functions.
/// Note: Because the dereference operator returns `enumerator_result` as a
/// value instead of a reference and does not strictly conform to the C++17's
/// definition of forward iterator. However, it satisfies all the
/// forward_iterator requirements that the `zip_common` and `zippy` depend on
/// and fully conforms to the C++20 definition of forward iterator.
/// This is similar to `std::vector<bool>::iterator` that returns bit reference
/// wrappers on dereference.
template <typename... Iters>
struct zip_enumerator : zip_common<zip_enumerator<Iters...>,
EnumeratorTupleType<Iters...>, Iters...> {
static_assert(sizeof...(Iters) >= 2, "Expected at least two iteratees");
using zip_common<zip_enumerator<Iters...>, EnumeratorTupleType<Iters...>,
Iters...>::zip_common;
bool operator==(const zip_enumerator &Other) const {
return std::get<1>(this->iterators) == std::get<1>(Other.iterators);
}
};
template <typename... Refs> struct enumerator_result<std::size_t, Refs...> {
static constexpr std::size_t NumRefs = sizeof...(Refs);
static_assert(NumRefs != 0);
// `NumValues` includes the index.
static constexpr std::size_t NumValues = NumRefs + 1;
// Tuple type whose element types are references for each `Ref`.
using range_reference_tuple = std::tuple<Refs...>;
// Tuple type who elements are references to all values, including both
// the index and `Refs` reference types.
using value_reference_tuple = std::tuple<std::size_t, Refs...>;
enumerator_result(std::size_t Index, Refs &&...Rs)
: Idx(Index), Storage(std::forward<Refs>(Rs)...) {}
/// Returns the 0-based index of the current position within the original
/// input range(s).
std::size_t index() const { return Idx; }
/// Returns the value(s) for the current iterator. This does not include the
/// index.
decltype(auto) value() const {
if constexpr (NumRefs == 1)
return std::get<0>(Storage);
else
return Storage;
}
/// Returns the value at index `I`. This case covers the index.
template <std::size_t I, typename = std::enable_if_t<I == 0>>
friend std::size_t get(const enumerator_result &Result) {
return Result.Idx;
}
/// Returns the value at index `I`. This case covers references to the
/// iteratees.
template <std::size_t I, typename = std::enable_if_t<I != 0>>
friend decltype(auto) get(const enumerator_result &Result) {
// Note: This is a separate function from the other `get`, instead of an
// `if constexpr` case, to work around an MSVC 19.31.31XXX compiler
// (Visual Studio 2022 17.1) return type deduction bug.
return std::get<I - 1>(Result.Storage);
}
template <typename... Ts>
friend bool operator==(const enumerator_result &Result,
const std::tuple<std::size_t, Ts...> &Other) {
static_assert(NumRefs == sizeof...(Ts), "Size mismatch");
if (Result.Idx != std::get<0>(Other))
return false;
return Result.is_value_equal(Other, std::make_index_sequence<NumRefs>{});
}
private:
template <typename Tuple, std::size_t... Idx>
bool is_value_equal(const Tuple &Other, std::index_sequence<Idx...>) const {
return ((std::get<Idx>(Storage) == std::get<Idx + 1>(Other)) && ...);
}
std::size_t Idx;
// Make this tuple mutable to avoid casts that obfuscate const-correctness
// issues. Const-correctness of references is taken care of by `zippy` that
// defines const-non and const iterator types that will propagate down to
// `enumerator_result`'s `Refs`.
// Note that unlike the results of `zip*` functions, `enumerate`'s result are
// supposed to be modifiable even when defined as
// `const`.
mutable range_reference_tuple Storage;
};
/// Infinite stream of increasing 0-based `size_t` indices.
struct index_stream {
struct iterator : iterator_facade_base<iterator, std::forward_iterator_tag,
const iterator> {
iterator &operator++() {
assert(Index != std::numeric_limits<std::size_t>::max() &&
"Attempting to increment end iterator");
++Index;
return *this;
}
// Note: This dereference operator returns a value instead of a reference
// and does not strictly conform to the C++17's definition of forward
// iterator. However, it satisfies all the forward_iterator requirements
// that the `zip_common` depends on and fully conforms to the C++20
// definition of forward iterator.
std::size_t operator*() const { return Index; }
friend bool operator==(const iterator &Lhs, const iterator &Rhs) {
return Lhs.Index == Rhs.Index;
}
std::size_t Index = 0;
};
iterator begin() const { return {}; }
iterator end() const {
// We approximate 'infinity' with the max size_t value, which should be good
// enough to index over any container.
iterator It;
It.Index = std::numeric_limits<std::size_t>::max();
return It;
}
};
} // end namespace detail
/// Given two or more input ranges, returns a new range whose values are are
/// tuples (A, B, C, ...), such that A is the 0-based index of the item in the
/// sequence, and B, C, ..., are the values from the original input ranges. All
/// input ranges are required to have equal lengths. Note that the returned
/// iterator allows for the values (B, C, ...) to be modified. Example:
///
/// ```c++
/// std::vector<char> Letters = {'A', 'B', 'C', 'D'};
/// std::vector<int> Vals = {10, 11, 12, 13};
///
/// for (auto [Index, Letter, Value] : enumerate(Letters, Vals)) {
/// printf("Item %zu - %c: %d\n", Index, Letter, Value);
/// Value -= 10;
/// }
/// ```
///
/// Output:
/// Item 0 - A: 10
/// Item 1 - B: 11
/// Item 2 - C: 12
/// Item 3 - D: 13
///
/// or using an iterator:
/// ```c++
/// for (auto it : enumerate(Vals)) {
/// it.value() += 10;
/// printf("Item %zu: %d\n", it.index(), it.value());
/// }
/// ```
///
/// Output:
/// Item 0: 20
/// Item 1: 21
/// Item 2: 22
/// Item 3: 23
///
template <typename FirstRange, typename... RestRanges>
auto enumerate(FirstRange &&First, RestRanges &&...Rest) {
if constexpr (sizeof...(Rest) != 0) {
#ifndef NDEBUG
// Note: Create an array instead of an initializer list to work around an
// Apple clang 14 compiler bug.
size_t sizes[] = {range_size(First), range_size(Rest)...};
assert(all_equal(sizes) && "Ranges have different length");
#endif
}
using enumerator = detail::zippy<detail::zip_enumerator, detail::index_stream,
FirstRange, RestRanges...>;
return enumerator(detail::index_stream{}, std::forward<FirstRange>(First),
std::forward<RestRanges>(Rest)...);
}
namespace detail {
template <typename Predicate, typename... Args>
bool all_of_zip_predicate_first(Predicate &&P, Args &&...args) {
auto z = zip(args...);
auto it = z.begin();
auto end = z.end();
while (it != end) {
if (!std::apply([&](auto &&...args) { return P(args...); }, *it))
return false;
++it;
}
return it.all_equals(end);
}
// Just an adaptor to switch the order of argument and have the predicate before
// the zipped inputs.
template <typename... ArgsThenPredicate, size_t... InputIndexes>
bool all_of_zip_predicate_last(
std::tuple<ArgsThenPredicate...> argsThenPredicate,
std::index_sequence<InputIndexes...>) {
auto constexpr OutputIndex =
std::tuple_size<decltype(argsThenPredicate)>::value - 1;
return all_of_zip_predicate_first(std::get<OutputIndex>(argsThenPredicate),
std::get<InputIndexes>(argsThenPredicate)...);
}
} // end namespace detail
/// Compare two zipped ranges using the provided predicate (as last argument).
/// Return true if all elements satisfy the predicate and false otherwise.
// Return false if the zipped iterator aren't all at end (size mismatch).
template <typename... ArgsAndPredicate>
bool all_of_zip(ArgsAndPredicate &&...argsAndPredicate) {
return detail::all_of_zip_predicate_last(
std::forward_as_tuple(argsAndPredicate...),
std::make_index_sequence<sizeof...(argsAndPredicate) - 1>{});
}
/// Return true if the sequence [Begin, End) has exactly N items. Runs in O(N)
/// time. Not meant for use with random-access iterators.
/// Can optionally take a predicate to filter lazily some items.
template <typename IterTy,
typename Pred = bool (*)(const decltype(*std::declval<IterTy>()) &)>
bool hasNItems(
IterTy &&Begin, IterTy &&End, unsigned N,
Pred &&ShouldBeCounted =
[](const decltype(*std::declval<IterTy>()) &) { return true; },
std::enable_if_t<
!std::is_base_of<std::random_access_iterator_tag,
typename std::iterator_traits<std::remove_reference_t<
decltype(Begin)>>::iterator_category>::value,
void> * = nullptr) {
for (; N; ++Begin) {
if (Begin == End)
return false; // Too few.
N -= ShouldBeCounted(*Begin);
}
for (; Begin != End; ++Begin)
if (ShouldBeCounted(*Begin))
return false; // Too many.
return true;
}
/// Return true if the sequence [Begin, End) has N or more items. Runs in O(N)
/// time. Not meant for use with random-access iterators.
/// Can optionally take a predicate to lazily filter some items.
template <typename IterTy,
typename Pred = bool (*)(const decltype(*std::declval<IterTy>()) &)>
bool hasNItemsOrMore(
IterTy &&Begin, IterTy &&End, unsigned N,
Pred &&ShouldBeCounted =
[](const decltype(*std::declval<IterTy>()) &) { return true; },
std::enable_if_t<
!std::is_base_of<std::random_access_iterator_tag,
typename std::iterator_traits<std::remove_reference_t<
decltype(Begin)>>::iterator_category>::value,
void> * = nullptr) {
for (; N; ++Begin) {
if (Begin == End)
return false; // Too few.
N -= ShouldBeCounted(*Begin);
}
return true;
}
/// Returns true if the sequence [Begin, End) has N or less items. Can
/// optionally take a predicate to lazily filter some items.
template <typename IterTy,
typename Pred = bool (*)(const decltype(*std::declval<IterTy>()) &)>
bool hasNItemsOrLess(
IterTy &&Begin, IterTy &&End, unsigned N,
Pred &&ShouldBeCounted = [](const decltype(*std::declval<IterTy>()) &) {
return true;
}) {
assert(N != std::numeric_limits<unsigned>::max());
return !hasNItemsOrMore(Begin, End, N + 1, ShouldBeCounted);
}
/// Returns true if the given container has exactly N items
template <typename ContainerTy> bool hasNItems(ContainerTy &&C, unsigned N) {
return hasNItems(std::begin(C), std::end(C), N);
}
/// Returns true if the given container has N or more items
template <typename ContainerTy>
bool hasNItemsOrMore(ContainerTy &&C, unsigned N) {
return hasNItemsOrMore(std::begin(C), std::end(C), N);
}
/// Returns true if the given container has N or less items
template <typename ContainerTy>
bool hasNItemsOrLess(ContainerTy &&C, unsigned N) {
return hasNItemsOrLess(std::begin(C), std::end(C), N);
}
/// Returns a raw pointer that represents the same address as the argument.
///
/// This implementation can be removed once we move to C++20 where it's defined
/// as std::to_address().
///
/// The std::pointer_traits<>::to_address(p) variations of these overloads has
/// not been implemented.
template <class Ptr> auto to_address(const Ptr &P) { return P.operator->(); }
template <class T> constexpr T *to_address(T *P) { return P; }
} // end namespace llvm
namespace std {
template <typename... Refs>
struct tuple_size<llvm::detail::enumerator_result<Refs...>>
: std::integral_constant<std::size_t, sizeof...(Refs)> {};
template <std::size_t I, typename... Refs>
struct tuple_element<I, llvm::detail::enumerator_result<Refs...>>
: std::tuple_element<I, std::tuple<Refs...>> {};
template <std::size_t I, typename... Refs>
struct tuple_element<I, const llvm::detail::enumerator_result<Refs...>>
: std::tuple_element<I, std::tuple<Refs...>> {};
} // namespace std
#endif // LLVM_ADT_STLEXTRAS_H