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/*
* Copyright © 2018 Google, Inc.
* Copyright © 2019 Facebook, Inc.
*
* This is part of HarfBuzz, a text shaping library.
*
* Permission is hereby granted, without written agreement and without
* license or royalty fees, to use, copy, modify, and distribute this
* software and its documentation for any purpose, provided that the
* above copyright notice and the following two paragraphs appear in
* all copies of this software.
*
* IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
* DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
* ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
* IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
* DAMAGE.
*
* THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
* BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
* FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
* ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
* PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
*
* Google Author(s): Behdad Esfahbod
* Facebook Author(s): Behdad Esfahbod
*/
#ifndef HB_ITER_HH
#define HB_ITER_HH
#include "hb.hh"
#include "hb-algs.hh"
#include "hb-meta.hh"
/* Unified iterator object.
*
* The goal of this template is to make the same iterator interface
* available to all types, and make it very easy and compact to use.
* hb_iter_tator objects are small, light-weight, objects that can be
* copied by value. If the collection / object being iterated on
* is writable, then the iterator returns lvalues, otherwise it
* returns rvalues.
*
* TODO Document more.
*
* If iterator implementation implements operator!=, then can be
* used in range-based for loop. That comes free if the iterator
* is random-access. Otherwise, the range-based for loop incurs
* one traversal to find end(), which can be avoided if written
* as a while-style for loop, or if iterator implements a faster
* __end__() method.
* TODO When opting in for C++17, address this by changing return
* type of .end()?
*/
/*
* Base classes for iterators.
*/
/* Base class for all iterators. */
template <typename iter_t, typename Item = typename iter_t::__item_t__>
struct hb_iter_t
{
typedef Item item_t;
static constexpr unsigned item_size = hb_static_size (Item);
static constexpr bool is_iterator = true;
static constexpr bool is_random_access_iterator = false;
static constexpr bool is_sorted_iterator = false;
private:
/* https://en.wikipedia.org/wiki/Curiously_recurring_template_pattern */
const iter_t* thiz () const { return static_cast<const iter_t *> (this); }
iter_t* thiz () { return static_cast< iter_t *> (this); }
public:
/* TODO:
* Port operators below to use hb_enable_if to sniff which method implements
* an operator and use it, and remove hb_iter_fallback_mixin_t completely. */
/* Operators. */
iter_t iter () const { return *thiz(); }
iter_t operator + () const { return *thiz(); }
iter_t begin () const { return *thiz(); }
iter_t end () const { return thiz()->__end__ (); }
explicit operator bool () const { return thiz()->__more__ (); }
unsigned len () const { return thiz()->__len__ (); }
/* The following can only be enabled if item_t is reference type. Otherwise
* it will be returning pointer to temporary rvalue.
* TODO Use a wrapper return type to fix for non-reference type. */
template <typename T = item_t,
hb_enable_if (hb_is_reference (T))>
hb_remove_reference<item_t>* operator -> () const { return hb_addressof (**thiz()); }
item_t operator * () const { return thiz()->__item__ (); }
item_t operator * () { return thiz()->__item__ (); }
item_t operator [] (unsigned i) const { return thiz()->__item_at__ (i); }
item_t operator [] (unsigned i) { return thiz()->__item_at__ (i); }
iter_t& operator += (unsigned count) & { thiz()->__forward__ (count); return *thiz(); }
iter_t operator += (unsigned count) && { thiz()->__forward__ (count); return *thiz(); }
iter_t& operator ++ () & { thiz()->__next__ (); return *thiz(); }
iter_t operator ++ () && { thiz()->__next__ (); return *thiz(); }
iter_t& operator -= (unsigned count) & { thiz()->__rewind__ (count); return *thiz(); }
iter_t operator -= (unsigned count) && { thiz()->__rewind__ (count); return *thiz(); }
iter_t& operator -- () & { thiz()->__prev__ (); return *thiz(); }
iter_t operator -- () && { thiz()->__prev__ (); return *thiz(); }
iter_t operator + (unsigned count) const { auto c = thiz()->iter (); c += count; return c; }
friend iter_t operator + (unsigned count, const iter_t &it) { return it + count; }
iter_t operator ++ (int) { iter_t c (*thiz()); ++*thiz(); return c; }
iter_t operator - (unsigned count) const { auto c = thiz()->iter (); c -= count; return c; }
iter_t operator -- (int) { iter_t c (*thiz()); --*thiz(); return c; }
template <typename T>
iter_t& operator >> (T &v) & { v = **thiz(); ++*thiz(); return *thiz(); }
template <typename T>
iter_t operator >> (T &v) && { v = **thiz(); ++*thiz(); return *thiz(); }
template <typename T>
iter_t& operator << (const T v) & { **thiz() = v; ++*thiz(); return *thiz(); }
template <typename T>
iter_t operator << (const T v) && { **thiz() = v; ++*thiz(); return *thiz(); }
protected:
hb_iter_t () = default;
hb_iter_t (const hb_iter_t &o HB_UNUSED) = default;
hb_iter_t (hb_iter_t &&o HB_UNUSED) = default;
hb_iter_t& operator = (const hb_iter_t &o HB_UNUSED) = default;
hb_iter_t& operator = (hb_iter_t &&o HB_UNUSED) = default;
};
#define HB_ITER_USING(Name) \
using item_t = typename Name::item_t; \
using Name::begin; \
using Name::end; \
using Name::item_size; \
using Name::is_iterator; \
using Name::iter; \
using Name::operator bool; \
using Name::len; \
using Name::operator ->; \
using Name::operator *; \
using Name::operator []; \
using Name::operator +=; \
using Name::operator ++; \
using Name::operator -=; \
using Name::operator --; \
using Name::operator +; \
using Name::operator -; \
using Name::operator >>; \
using Name::operator <<; \
static_assert (true, "")
/* Returns iterator / item type of a type. */
template <typename Iterable>
using hb_iter_type = decltype (hb_deref (hb_declval (Iterable)).iter ());
template <typename Iterable>
using hb_item_type = decltype (*hb_deref (hb_declval (Iterable)).iter ());
template <typename> struct hb_array_t;
struct
{
template <typename T> hb_iter_type<T>
operator () (T&& c) const
{ return hb_deref (hb_forward<T> (c)).iter (); }
/* Specialization for C arrays. */
template <typename Type> inline hb_array_t<Type>
operator () (Type *array, unsigned int length) const
{ return hb_array_t<Type> (array, length); }
template <typename Type, unsigned int length> hb_array_t<Type>
operator () (Type (&array)[length]) const
{ return hb_array_t<Type> (array, length); }
}
HB_FUNCOBJ (hb_iter);
/* Mixin to fill in what the subclass doesn't provide. */
template <typename iter_t, typename item_t = typename iter_t::__item_t__>
struct hb_iter_fallback_mixin_t
{
private:
/* https://en.wikipedia.org/wiki/Curiously_recurring_template_pattern */
const iter_t* thiz () const { return static_cast<const iter_t *> (this); }
iter_t* thiz () { return static_cast< iter_t *> (this); }
public:
/* Access: Implement __item__(), or __item_at__() if random-access. */
item_t __item__ () const { return (*thiz())[0]; }
item_t __item_at__ (unsigned i) const { return *(*thiz() + i); }
/* Termination: Implement __more__(), or __len__() if random-access. */
bool __more__ () const { return bool (thiz()->len ()); }
unsigned __len__ () const
{ iter_t c (*thiz()); unsigned l = 0; while (c) { c++; l++; } return l; }
/* Advancing: Implement __next__(), or __forward__() if random-access. */
void __next__ () { *thiz() += 1; }
void __forward__ (unsigned n) { while (*thiz() && n--) ++*thiz(); }
/* Rewinding: Implement __prev__() or __rewind__() if bidirectional. */
void __prev__ () { *thiz() -= 1; }
void __rewind__ (unsigned n) { while (*thiz() && n--) --*thiz(); }
/* Range-based for: Implement __end__() if can be done faster,
* and operator!=. */
iter_t __end__ () const
{
if (thiz()->is_random_access_iterator)
return *thiz() + thiz()->len ();
/* Above expression loops twice. Following loops once. */
auto it = *thiz();
while (it) ++it;
return it;
}
protected:
hb_iter_fallback_mixin_t () = default;
hb_iter_fallback_mixin_t (const hb_iter_fallback_mixin_t &o HB_UNUSED) = default;
hb_iter_fallback_mixin_t (hb_iter_fallback_mixin_t &&o HB_UNUSED) = default;
hb_iter_fallback_mixin_t& operator = (const hb_iter_fallback_mixin_t &o HB_UNUSED) = default;
hb_iter_fallback_mixin_t& operator = (hb_iter_fallback_mixin_t &&o HB_UNUSED) = default;
};
template <typename iter_t, typename item_t = typename iter_t::__item_t__>
struct hb_iter_with_fallback_t :
hb_iter_t<iter_t, item_t>,
hb_iter_fallback_mixin_t<iter_t, item_t>
{
protected:
hb_iter_with_fallback_t () = default;
hb_iter_with_fallback_t (const hb_iter_with_fallback_t &o HB_UNUSED) = default;
hb_iter_with_fallback_t (hb_iter_with_fallback_t &&o HB_UNUSED) = default;
hb_iter_with_fallback_t& operator = (const hb_iter_with_fallback_t &o HB_UNUSED) = default;
hb_iter_with_fallback_t& operator = (hb_iter_with_fallback_t &&o HB_UNUSED) = default;
};
/*
* Meta-programming predicates.
*/
/* hb_is_iterator() / hb_is_iterator_of() */
template<typename Iter, typename Item>
struct hb_is_iterator_of
{
template <typename Item2 = Item>
static hb_true_type impl (hb_priority<2>, hb_iter_t<Iter, hb_type_identity<Item2>> *);
static hb_false_type impl (hb_priority<0>, const void *);
public:
static constexpr bool value = decltype (impl (hb_prioritize, hb_declval (Iter*)))::value;
};
#define hb_is_iterator_of(Iter, Item) hb_is_iterator_of<Iter, Item>::value
#define hb_is_iterator(Iter) hb_is_iterator_of (Iter, typename Iter::item_t)
/* hb_is_iterable() */
template <typename T>
struct hb_is_iterable
{
private:
template <typename U>
static auto impl (hb_priority<1>) -> decltype (hb_declval (U).iter (), hb_true_type ());
template <typename>
static hb_false_type impl (hb_priority<0>);
public:
static constexpr bool value = decltype (impl<T> (hb_prioritize))::value;
};
#define hb_is_iterable(Iterable) hb_is_iterable<Iterable>::value
/* hb_is_source_of() / hb_is_sink_of() */
template<typename Iter, typename Item>
struct hb_is_source_of
{
private:
template <typename Iter2 = Iter,
hb_enable_if (hb_is_convertible (typename Iter2::item_t, hb_add_lvalue_reference<hb_add_const<Item>>))>
static hb_true_type impl (hb_priority<2>);
template <typename Iter2 = Iter>
static auto impl (hb_priority<1>) -> decltype (hb_declval (Iter2) >> hb_declval (Item &), hb_true_type ());
static hb_false_type impl (hb_priority<0>);
public:
static constexpr bool value = decltype (impl (hb_prioritize))::value;
};
#define hb_is_source_of(Iter, Item) hb_is_source_of<Iter, Item>::value
template<typename Iter, typename Item>
struct hb_is_sink_of
{
private:
template <typename Iter2 = Iter,
hb_enable_if (hb_is_convertible (typename Iter2::item_t, hb_add_lvalue_reference<Item>))>
static hb_true_type impl (hb_priority<2>);
template <typename Iter2 = Iter>
static auto impl (hb_priority<1>) -> decltype (hb_declval (Iter2) << hb_declval (Item), hb_true_type ());
static hb_false_type impl (hb_priority<0>);
public:
static constexpr bool value = decltype (impl (hb_prioritize))::value;
};
#define hb_is_sink_of(Iter, Item) hb_is_sink_of<Iter, Item>::value
/* This is commonly used, so define: */
#define hb_is_sorted_source_of(Iter, Item) \
(hb_is_source_of(Iter, Item) && Iter::is_sorted_iterator)
/* Range-based 'for' for iterables. */
template <typename Iterable,
hb_requires (hb_is_iterable (Iterable))>
static inline auto begin (Iterable&& iterable) HB_AUTO_RETURN (hb_iter (iterable).begin ())
template <typename Iterable,
hb_requires (hb_is_iterable (Iterable))>
static inline auto end (Iterable&& iterable) HB_AUTO_RETURN (hb_iter (iterable).end ())
/* begin()/end() are NOT looked up non-ADL. So each namespace must declare them.
* Do it for namespace OT. */
namespace OT {
template <typename Iterable,
hb_requires (hb_is_iterable (Iterable))>
static inline auto begin (Iterable&& iterable) HB_AUTO_RETURN (hb_iter (iterable).begin ())
template <typename Iterable,
hb_requires (hb_is_iterable (Iterable))>
static inline auto end (Iterable&& iterable) HB_AUTO_RETURN (hb_iter (iterable).end ())
}
/*
* Adaptors, combiners, etc.
*/
template <typename Lhs, typename Rhs,
hb_requires (hb_is_iterator (Lhs))>
static inline auto
operator | (Lhs&& lhs, Rhs&& rhs) HB_AUTO_RETURN (hb_forward<Rhs> (rhs) (hb_forward<Lhs> (lhs)))
/* hb_map(), hb_filter(), hb_reduce() */
enum class hb_function_sortedness_t {
NOT_SORTED,
RETAINS_SORTING,
SORTED,
};
template <typename Iter, typename Proj, hb_function_sortedness_t Sorted,
hb_requires (hb_is_iterator (Iter))>
struct hb_map_iter_t :
hb_iter_t<hb_map_iter_t<Iter, Proj, Sorted>,
decltype (hb_get (hb_declval (Proj), *hb_declval (Iter)))>
{
hb_map_iter_t (const Iter& it, Proj f_) : it (it), f (f_) {}
typedef decltype (hb_get (hb_declval (Proj), *hb_declval (Iter))) __item_t__;
static constexpr bool is_random_access_iterator = Iter::is_random_access_iterator;
static constexpr bool is_sorted_iterator =
Sorted == hb_function_sortedness_t::SORTED ? true :
Sorted == hb_function_sortedness_t::RETAINS_SORTING ? Iter::is_sorted_iterator :
false;
__item_t__ __item__ () const { return hb_get (f.get (), *it); }
__item_t__ __item_at__ (unsigned i) const { return hb_get (f.get (), it[i]); }
bool __more__ () const { return bool (it); }
unsigned __len__ () const { return it.len (); }
void __next__ () { ++it; }
void __forward__ (unsigned n) { it += n; }
void __prev__ () { --it; }
void __rewind__ (unsigned n) { it -= n; }
hb_map_iter_t __end__ () const { return hb_map_iter_t (it.end (), f); }
bool operator != (const hb_map_iter_t& o) const
{ return it != o.it; }
private:
Iter it;
hb_reference_wrapper<Proj> f;
};
template <typename Proj, hb_function_sortedness_t Sorted>
struct hb_map_iter_factory_t
{
hb_map_iter_factory_t (Proj f) : f (f) {}
template <typename Iter,
hb_requires (hb_is_iterator (Iter))>
hb_map_iter_t<Iter, Proj, Sorted>
operator () (Iter it)
{ return hb_map_iter_t<Iter, Proj, Sorted> (it, f); }
private:
Proj f;
};
struct
{
template <typename Proj>
hb_map_iter_factory_t<Proj, hb_function_sortedness_t::NOT_SORTED>
operator () (Proj&& f) const
{ return hb_map_iter_factory_t<Proj, hb_function_sortedness_t::NOT_SORTED> (f); }
}
HB_FUNCOBJ (hb_map);
struct
{
template <typename Proj>
hb_map_iter_factory_t<Proj, hb_function_sortedness_t::RETAINS_SORTING>
operator () (Proj&& f) const
{ return hb_map_iter_factory_t<Proj, hb_function_sortedness_t::RETAINS_SORTING> (f); }
}
HB_FUNCOBJ (hb_map_retains_sorting);
struct
{
template <typename Proj>
hb_map_iter_factory_t<Proj, hb_function_sortedness_t::SORTED>
operator () (Proj&& f) const
{ return hb_map_iter_factory_t<Proj, hb_function_sortedness_t::SORTED> (f); }
}
HB_FUNCOBJ (hb_map_sorted);
template <typename Iter, typename Pred, typename Proj,
hb_requires (hb_is_iterator (Iter))>
struct hb_filter_iter_t :
hb_iter_with_fallback_t<hb_filter_iter_t<Iter, Pred, Proj>,
typename Iter::item_t>
{
hb_filter_iter_t (const Iter& it_, Pred p_, Proj f_) : it (it_), p (p_), f (f_)
{ while (it && !hb_has (p.get (), hb_get (f.get (), *it))) ++it; }
typedef typename Iter::item_t __item_t__;
static constexpr bool is_sorted_iterator = Iter::is_sorted_iterator;
__item_t__ __item__ () const { return *it; }
bool __more__ () const { return bool (it); }
void __next__ () { do ++it; while (it && !hb_has (p.get (), hb_get (f.get (), *it))); }
void __prev__ () { do --it; while (it && !hb_has (p.get (), hb_get (f.get (), *it))); }
hb_filter_iter_t __end__ () const { return hb_filter_iter_t (it.end (), p, f); }
bool operator != (const hb_filter_iter_t& o) const
{ return it != o.it; }
private:
Iter it;
hb_reference_wrapper<Pred> p;
hb_reference_wrapper<Proj> f;
};
template <typename Pred, typename Proj>
struct hb_filter_iter_factory_t
{
hb_filter_iter_factory_t (Pred p, Proj f) : p (p), f (f) {}
template <typename Iter,
hb_requires (hb_is_iterator (Iter))>
hb_filter_iter_t<Iter, Pred, Proj>
operator () (Iter it)
{ return hb_filter_iter_t<Iter, Pred, Proj> (it, p, f); }
private:
Pred p;
Proj f;
};
struct
{
template <typename Pred = decltype ((hb_identity)),
typename Proj = decltype ((hb_identity))>
hb_filter_iter_factory_t<Pred, Proj>
operator () (Pred&& p = hb_identity, Proj&& f = hb_identity) const
{ return hb_filter_iter_factory_t<Pred, Proj> (p, f); }
}
HB_FUNCOBJ (hb_filter);
template <typename Redu, typename InitT>
struct hb_reduce_t
{
hb_reduce_t (Redu r, InitT init_value) : r (r), init_value (init_value) {}
template <typename Iter,
hb_requires (hb_is_iterator (Iter)),
typename AccuT = hb_remove_reference<decltype (hb_declval (Redu) (hb_declval (InitT), hb_declval (typename Iter::item_t)))>>
AccuT
operator () (Iter it)
{
AccuT value = init_value;
for (; it; ++it)
value = r (value, *it);
return value;
}
private:
Redu r;
InitT init_value;
};
struct
{
template <typename Redu, typename InitT>
hb_reduce_t<Redu, InitT>
operator () (Redu&& r, InitT init_value) const
{ return hb_reduce_t<Redu, InitT> (r, init_value); }
}
HB_FUNCOBJ (hb_reduce);
/* hb_zip() */
template <typename A, typename B>
struct hb_zip_iter_t :
hb_iter_t<hb_zip_iter_t<A, B>,
hb_pair_t<typename A::item_t, typename B::item_t>>
{
hb_zip_iter_t () {}
hb_zip_iter_t (const A& a, const B& b) : a (a), b (b) {}
typedef hb_pair_t<typename A::item_t, typename B::item_t> __item_t__;
static constexpr bool is_random_access_iterator =
A::is_random_access_iterator &&
B::is_random_access_iterator;
/* Note. The following categorization is only valid if A is strictly sorted,
* ie. does NOT have duplicates. Previously I tried to categorize sortedness
* more granularly, see commits:
*
* 513762849a683914fc266a17ddf38f133cccf072
* 4d3cf2adb669c345cc43832d11689271995e160a
*
* However, that was not enough, since hb_sorted_array_t, hb_sorted_vector_t,
* SortedArrayOf, etc all needed to be updated to add more variants. At that
* point I saw it not worth the effort, and instead we now deem all sorted
* collections as essentially strictly-sorted for the purposes of zip.
*
* The above assumption is not as bad as it sounds. Our "sorted" comes with
* no guarantees. It's just a contract, put in place to help you remember,
* and think about, whether an iterator you receive is expected to be
* sorted or not. As such, it's not perfect by definition, and should not
* be treated so. The inaccuracy here just errs in the direction of being
* more permissive, so your code compiles instead of erring on the side of
* marking your zipped iterator unsorted in which case your code won't
* compile.
*
* This semantical limitation does NOT affect logic in any other place I
* know of as of this writing.
*/
static constexpr bool is_sorted_iterator = A::is_sorted_iterator;
__item_t__ __item__ () const { return __item_t__ (*a, *b); }
__item_t__ __item_at__ (unsigned i) const { return __item_t__ (a[i], b[i]); }
bool __more__ () const { return bool (a) && bool (b); }
unsigned __len__ () const { return hb_min (a.len (), b.len ()); }
void __next__ () { ++a; ++b; }
void __forward__ (unsigned n) { a += n; b += n; }
void __prev__ () { --a; --b; }
void __rewind__ (unsigned n) { a -= n; b -= n; }
hb_zip_iter_t __end__ () const { return hb_zip_iter_t (a.end (), b.end ()); }
/* Note, we should stop if ANY of the iters reaches end. As such two compare
* unequal if both items are unequal, NOT if either is unequal. */
bool operator != (const hb_zip_iter_t& o) const
{ return a != o.a && b != o.b; }
private:
A a;
B b;
};
struct
{
template <typename A, typename B,
hb_requires (hb_is_iterable (A) && hb_is_iterable (B))>
hb_zip_iter_t<hb_iter_type<A>, hb_iter_type<B>>
operator () (A&& a, B&& b) const
{ return hb_zip_iter_t<hb_iter_type<A>, hb_iter_type<B>> (hb_iter (a), hb_iter (b)); }
}
HB_FUNCOBJ (hb_zip);
/* hb_apply() */
template <typename Appl>
struct hb_apply_t
{
hb_apply_t (Appl a) : a (a) {}
template <typename Iter,
hb_requires (hb_is_iterator (Iter))>
void operator () (Iter it)
{
for (; it; ++it)
(void) hb_invoke (a, *it);
}
private:
Appl a;
};
struct
{
template <typename Appl> hb_apply_t<Appl>
operator () (Appl&& a) const
{ return hb_apply_t<Appl> (a); }
template <typename Appl> hb_apply_t<Appl&>
operator () (Appl *a) const
{ return hb_apply_t<Appl&> (*a); }
}
HB_FUNCOBJ (hb_apply);
/* hb_iota()/hb_range() */
template <typename T, typename S>
struct hb_counter_iter_t :
hb_iter_t<hb_counter_iter_t<T, S>, T>
{
hb_counter_iter_t (T start, T end_, S step) : v (start), end_ (end_for (start, end_, step)), step (step) {}
typedef T __item_t__;
static constexpr bool is_random_access_iterator = true;
static constexpr bool is_sorted_iterator = true;
__item_t__ __item__ () const { return +v; }
__item_t__ __item_at__ (unsigned j) const { return v + j * step; }
bool __more__ () const { return v != end_; }
unsigned __len__ () const { return !step ? UINT_MAX : (end_ - v) / step; }
void __next__ () { v += step; }
void __forward__ (unsigned n) { v += n * step; }
void __prev__ () { v -= step; }
void __rewind__ (unsigned n) { v -= n * step; }
hb_counter_iter_t __end__ () const { return hb_counter_iter_t (end_, end_, step); }
bool operator != (const hb_counter_iter_t& o) const
{ return v != o.v; }
private:
static inline T end_for (T start, T end_, S step)
{
if (!step)
return end_;
auto res = (end_ - start) % step;
if (!res)
return end_;
end_ += step - res;
return end_;
}
private:
T v;
T end_;
S step;
};
struct
{
template <typename T = unsigned, typename S = unsigned> hb_counter_iter_t<T, S>
operator () (T start = 0u, S&& step = 1u) const
{ return hb_counter_iter_t<T, S> (start, step >= 0 ? hb_int_max (T) : hb_int_min (T), step); }
}
HB_FUNCOBJ (hb_iota);
struct
{
template <typename T = unsigned> hb_counter_iter_t<T, unsigned>
operator () (T end = (unsigned) -1) const
{ return hb_counter_iter_t<T, unsigned> (0, end, 1u); }
template <typename T, typename S = unsigned> hb_counter_iter_t<T, S>
operator () (T start, T end, S&& step = 1u) const
{ return hb_counter_iter_t<T, S> (start, end, step); }
}
HB_FUNCOBJ (hb_range);
/* hb_enumerate */
struct
{
template <typename Iterable,
typename Index = unsigned,
hb_requires (hb_is_iterable (Iterable))>
auto operator () (Iterable&& it, Index start = 0u) const HB_AUTO_RETURN
( hb_zip (hb_iota (start), it) )
}
HB_FUNCOBJ (hb_enumerate);
/* hb_sink() */
template <typename Sink>
struct hb_sink_t
{
hb_sink_t (Sink s) : s (s) {}
template <typename Iter,
hb_requires (hb_is_iterator (Iter))>
void operator () (Iter it)
{
for (; it; ++it)
s << *it;
}
private:
Sink s;
};
struct
{
template <typename Sink> hb_sink_t<Sink>
operator () (Sink&& s) const
{ return hb_sink_t<Sink> (s); }
template <typename Sink> hb_sink_t<Sink&>
operator () (Sink *s) const
{ return hb_sink_t<Sink&> (*s); }
}
HB_FUNCOBJ (hb_sink);
/* hb-drain: hb_sink to void / blackhole / /dev/null. */
struct
{
template <typename Iter,
hb_requires (hb_is_iterator (Iter))>
void operator () (Iter it) const
{
for (; it; ++it)
(void) *it;
}
}
HB_FUNCOBJ (hb_drain);
/* hb_unzip(): unzip and sink to two sinks. */
template <typename Sink1, typename Sink2>
struct hb_unzip_t
{
hb_unzip_t (Sink1 s1, Sink2 s2) : s1 (s1), s2 (s2) {}
template <typename Iter,
hb_requires (hb_is_iterator (Iter))>
void operator () (Iter it)
{
for (; it; ++it)
{
const auto &v = *it;
s1 << v.first;
s2 << v.second;
}
}
private:
Sink1 s1;
Sink2 s2;
};
struct
{
template <typename Sink1, typename Sink2> hb_unzip_t<Sink1, Sink2>
operator () (Sink1&& s1, Sink2&& s2) const
{ return hb_unzip_t<Sink1, Sink2> (s1, s2); }
template <typename Sink1, typename Sink2> hb_unzip_t<Sink1&, Sink2&>
operator () (Sink1 *s1, Sink2 *s2) const
{ return hb_unzip_t<Sink1&, Sink2&> (*s1, *s2); }
}
HB_FUNCOBJ (hb_unzip);
/* hb-all, hb-any, hb-none. */
struct
{
template <typename Iterable,
typename Pred = decltype ((hb_identity)),
typename Proj = decltype ((hb_identity)),
hb_requires (hb_is_iterable (Iterable))>
bool operator () (Iterable&& c,
Pred&& p = hb_identity,
Proj&& f = hb_identity) const
{
for (auto it = hb_iter (c); it; ++it)
if (!hb_match (hb_forward<Pred> (p), hb_get (hb_forward<Proj> (f), *it)))
return false;
return true;
}
}
HB_FUNCOBJ (hb_all);
struct
{
template <typename Iterable,
typename Pred = decltype ((hb_identity)),
typename Proj = decltype ((hb_identity)),
hb_requires (hb_is_iterable (Iterable))>
bool operator () (Iterable&& c,
Pred&& p = hb_identity,
Proj&& f = hb_identity) const
{
for (auto it = hb_iter (c); it; ++it)
if (hb_match (hb_forward<Pred> (p), hb_get (hb_forward<Proj> (f), *it)))
return true;
return false;
}
}
HB_FUNCOBJ (hb_any);
struct
{
template <typename Iterable,
typename Pred = decltype ((hb_identity)),
typename Proj = decltype ((hb_identity)),
hb_requires (hb_is_iterable (Iterable))>
bool operator () (Iterable&& c,
Pred&& p = hb_identity,
Proj&& f = hb_identity) const
{
for (auto it = hb_iter (c); it; ++it)
if (hb_match (hb_forward<Pred> (p), hb_get (hb_forward<Proj> (f), *it)))
return false;
return true;
}
}
HB_FUNCOBJ (hb_none);
/*
* Algorithms operating on iterators.
*/
template <typename C, typename V,
hb_requires (hb_is_iterable (C))>
inline void
hb_fill (C& c, const V &v)
{
for (auto i = hb_iter (c); i; i++)
*i = v;
}
template <typename S, typename D>
inline void
hb_copy (S&& is, D&& id)
{
hb_iter (is) | hb_sink (id);
}
#endif /* HB_ITER_HH */
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