1 //===- llvm/ADT/STLExtras.h - Useful STL related functions ------*- C++ -*-===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file contains some templates that are useful if you are working with the
11 // STL at all.
12 //
13 // No library is required when using these functions.
14 //
15 //===----------------------------------------------------------------------===//
16 
17 #ifndef LLVM_ADT_STLEXTRAS_H
18 #define LLVM_ADT_STLEXTRAS_H
19 
20 #include <algorithm> // for std::all_of
21 #include <cassert>
22 #include <cstddef> // for std::size_t
23 #include <cstdlib> // for qsort
24 #include <functional>
25 #include <iterator>
26 #include <memory>
27 #include <utility> // for std::pair
28 
29 #include "llvm/ADT/iterator_range.h"
30 #include "llvm/Support/Compiler.h"
31 
32 namespace llvm {
33 
34 //===----------------------------------------------------------------------===//
35 //     Extra additions to <functional>
36 //===----------------------------------------------------------------------===//
37 
38 template<class Ty>
39 struct identity : public std::unary_function<Ty, Ty> {
operatoridentity40   Ty &operator()(Ty &self) const {
41     return self;
42   }
operatoridentity43   const Ty &operator()(const Ty &self) const {
44     return self;
45   }
46 };
47 
48 template<class Ty>
49 struct less_ptr : public std::binary_function<Ty, Ty, bool> {
operatorless_ptr50   bool operator()(const Ty* left, const Ty* right) const {
51     return *left < *right;
52   }
53 };
54 
55 template<class Ty>
56 struct greater_ptr : public std::binary_function<Ty, Ty, bool> {
operatorgreater_ptr57   bool operator()(const Ty* left, const Ty* right) const {
58     return *right < *left;
59   }
60 };
61 
62 /// An efficient, type-erasing, non-owning reference to a callable. This is
63 /// intended for use as the type of a function parameter that is not used
64 /// after the function in question returns.
65 ///
66 /// This class does not own the callable, so it is not in general safe to store
67 /// a function_ref.
68 template<typename Fn> class function_ref;
69 
70 template<typename Ret, typename ...Params>
71 class function_ref<Ret(Params...)> {
72   Ret (*callback)(intptr_t callable, Params ...params);
73   intptr_t callable;
74 
75   template<typename Callable>
callback_fn(intptr_t callable,Params...params)76   static Ret callback_fn(intptr_t callable, Params ...params) {
77     return (*reinterpret_cast<Callable*>(callable))(
78         std::forward<Params>(params)...);
79   }
80 
81 public:
82   template <typename Callable>
83   function_ref(Callable &&callable,
84                typename std::enable_if<
85                    !std::is_same<typename std::remove_reference<Callable>::type,
86                                  function_ref>::value>::type * = nullptr)
callback(callback_fn<typename std::remove_reference<Callable>::type>)87       : callback(callback_fn<typename std::remove_reference<Callable>::type>),
88         callable(reinterpret_cast<intptr_t>(&callable)) {}
operator()89   Ret operator()(Params ...params) const {
90     return callback(callable, std::forward<Params>(params)...);
91   }
92 };
93 
94 // deleter - Very very very simple method that is used to invoke operator
95 // delete on something.  It is used like this:
96 //
97 //   for_each(V.begin(), B.end(), deleter<Interval>);
98 //
99 template <class T>
deleter(T * Ptr)100 inline void deleter(T *Ptr) {
101   delete Ptr;
102 }
103 
104 
105 
106 //===----------------------------------------------------------------------===//
107 //     Extra additions to <iterator>
108 //===----------------------------------------------------------------------===//
109 
110 // mapped_iterator - This is a simple iterator adapter that causes a function to
111 // be dereferenced whenever operator* is invoked on the iterator.
112 //
113 template <class RootIt, class UnaryFunc>
114 class mapped_iterator {
115   RootIt current;
116   UnaryFunc Fn;
117 public:
118   typedef typename std::iterator_traits<RootIt>::iterator_category
119           iterator_category;
120   typedef typename std::iterator_traits<RootIt>::difference_type
121           difference_type;
122   typedef typename std::result_of<
123             UnaryFunc(decltype(*std::declval<RootIt>()))>
124           ::type value_type;
125 
126   typedef void pointer;
127   //typedef typename UnaryFunc::result_type *pointer;
128   typedef void reference;        // Can't modify value returned by fn
129 
130   typedef RootIt iterator_type;
131 
getCurrent()132   inline const RootIt &getCurrent() const { return current; }
getFunc()133   inline const UnaryFunc &getFunc() const { return Fn; }
134 
mapped_iterator(const RootIt & I,UnaryFunc F)135   inline explicit mapped_iterator(const RootIt &I, UnaryFunc F)
136     : current(I), Fn(F) {}
137 
138   inline value_type operator*() const {   // All this work to do this
139     return Fn(*current);         // little change
140   }
141 
142   mapped_iterator &operator++() {
143     ++current;
144     return *this;
145   }
146   mapped_iterator &operator--() {
147     --current;
148     return *this;
149   }
150   mapped_iterator operator++(int) {
151     mapped_iterator __tmp = *this;
152     ++current;
153     return __tmp;
154   }
155   mapped_iterator operator--(int) {
156     mapped_iterator __tmp = *this;
157     --current;
158     return __tmp;
159   }
160   mapped_iterator operator+(difference_type n) const {
161     return mapped_iterator(current + n, Fn);
162   }
163   mapped_iterator &operator+=(difference_type n) {
164     current += n;
165     return *this;
166   }
167   mapped_iterator operator-(difference_type n) const {
168     return mapped_iterator(current - n, Fn);
169   }
170   mapped_iterator &operator-=(difference_type n) {
171     current -= n;
172     return *this;
173   }
174   reference operator[](difference_type n) const { return *(*this + n); }
175 
176   bool operator!=(const mapped_iterator &X) const { return !operator==(X); }
177   bool operator==(const mapped_iterator &X) const {
178     return current == X.current;
179   }
180   bool operator<(const mapped_iterator &X) const { return current < X.current; }
181 
182   difference_type operator-(const mapped_iterator &X) const {
183     return current - X.current;
184   }
185 };
186 
187 template <class Iterator, class Func>
188 inline mapped_iterator<Iterator, Func>
189 operator+(typename mapped_iterator<Iterator, Func>::difference_type N,
190           const mapped_iterator<Iterator, Func> &X) {
191   return mapped_iterator<Iterator, Func>(X.getCurrent() - N, X.getFunc());
192 }
193 
194 
195 // map_iterator - Provide a convenient way to create mapped_iterators, just like
196 // make_pair is useful for creating pairs...
197 //
198 template <class ItTy, class FuncTy>
map_iterator(const ItTy & I,FuncTy F)199 inline mapped_iterator<ItTy, FuncTy> map_iterator(const ItTy &I, FuncTy F) {
200   return mapped_iterator<ItTy, FuncTy>(I, F);
201 }
202 
203 /// \brief Metafunction to determine if type T has a member called rbegin().
204 template <typename T> struct has_rbegin {
205   template <typename U> static char(&f(const U &, decltype(&U::rbegin)))[1];
206   static char(&f(...))[2];
207   const static bool value = sizeof(f(std::declval<T>(), nullptr)) == 1;
208 };
209 
210 // Returns an iterator_range over the given container which iterates in reverse.
211 // Note that the container must have rbegin()/rend() methods for this to work.
212 template <typename ContainerTy>
213 auto reverse(ContainerTy &&C,
214              typename std::enable_if<has_rbegin<ContainerTy>::value>::type * =
215                  nullptr) -> decltype(make_range(C.rbegin(), C.rend())) {
216   return make_range(C.rbegin(), C.rend());
217 }
218 
219 // Returns a std::reverse_iterator wrapped around the given iterator.
220 template <typename IteratorTy>
make_reverse_iterator(IteratorTy It)221 std::reverse_iterator<IteratorTy> make_reverse_iterator(IteratorTy It) {
222   return std::reverse_iterator<IteratorTy>(It);
223 }
224 
225 // Returns an iterator_range over the given container which iterates in reverse.
226 // Note that the container must have begin()/end() methods which return
227 // bidirectional iterators for this to work.
228 template <typename ContainerTy>
229 auto reverse(
230     ContainerTy &&C,
231     typename std::enable_if<!has_rbegin<ContainerTy>::value>::type * = nullptr)
232     -> decltype(make_range(llvm::make_reverse_iterator(std::end(C)),
233                            llvm::make_reverse_iterator(std::begin(C)))) {
234   return make_range(llvm::make_reverse_iterator(std::end(C)),
235                     llvm::make_reverse_iterator(std::begin(C)));
236 }
237 
238 //===----------------------------------------------------------------------===//
239 //     Extra additions to <utility>
240 //===----------------------------------------------------------------------===//
241 
242 /// \brief Function object to check whether the first component of a std::pair
243 /// compares less than the first component of another std::pair.
244 struct less_first {
operatorless_first245   template <typename T> bool operator()(const T &lhs, const T &rhs) const {
246     return lhs.first < rhs.first;
247   }
248 };
249 
250 /// \brief Function object to check whether the second component of a std::pair
251 /// compares less than the second component of another std::pair.
252 struct less_second {
operatorless_second253   template <typename T> bool operator()(const T &lhs, const T &rhs) const {
254     return lhs.second < rhs.second;
255   }
256 };
257 
258 // A subset of N3658. More stuff can be added as-needed.
259 
260 /// \brief Represents a compile-time sequence of integers.
261 template <class T, T... I> struct integer_sequence {
262   typedef T value_type;
263 
sizeinteger_sequence264   static LLVM_CONSTEXPR size_t size() { return sizeof...(I); }
265 };
266 
267 /// \brief Alias for the common case of a sequence of size_ts.
268 template <size_t... I>
269 struct index_sequence : integer_sequence<std::size_t, I...> {};
270 
271 template <std::size_t N, std::size_t... I>
272 struct build_index_impl : build_index_impl<N - 1, N - 1, I...> {};
273 template <std::size_t... I>
274 struct build_index_impl<0, I...> : index_sequence<I...> {};
275 
276 /// \brief Creates a compile-time integer sequence for a parameter pack.
277 template <class... Ts>
278 struct index_sequence_for : build_index_impl<sizeof...(Ts)> {};
279 
280 //===----------------------------------------------------------------------===//
281 //     Extra additions for arrays
282 //===----------------------------------------------------------------------===//
283 
284 /// Find the length of an array.
285 template <class T, std::size_t N>
286 LLVM_CONSTEXPR inline size_t array_lengthof(T (&)[N]) {
287   return N;
288 }
289 
290 /// Adapt std::less<T> for array_pod_sort.
291 template<typename T>
292 inline int array_pod_sort_comparator(const void *P1, const void *P2) {
293   if (std::less<T>()(*reinterpret_cast<const T*>(P1),
294                      *reinterpret_cast<const T*>(P2)))
295     return -1;
296   if (std::less<T>()(*reinterpret_cast<const T*>(P2),
297                      *reinterpret_cast<const T*>(P1)))
298     return 1;
299   return 0;
300 }
301 
302 /// get_array_pod_sort_comparator - This is an internal helper function used to
303 /// get type deduction of T right.
304 template<typename T>
305 inline int (*get_array_pod_sort_comparator(const T &))
306              (const void*, const void*) {
307   return array_pod_sort_comparator<T>;
308 }
309 
310 
311 /// array_pod_sort - This sorts an array with the specified start and end
312 /// extent.  This is just like std::sort, except that it calls qsort instead of
313 /// using an inlined template.  qsort is slightly slower than std::sort, but
314 /// most sorts are not performance critical in LLVM and std::sort has to be
315 /// template instantiated for each type, leading to significant measured code
316 /// bloat.  This function should generally be used instead of std::sort where
317 /// possible.
318 ///
319 /// This function assumes that you have simple POD-like types that can be
320 /// compared with std::less and can be moved with memcpy.  If this isn't true,
321 /// you should use std::sort.
322 ///
323 /// NOTE: If qsort_r were portable, we could allow a custom comparator and
324 /// default to std::less.
325 template<class IteratorTy>
326 inline void array_pod_sort(IteratorTy Start, IteratorTy End) {
327   // Don't inefficiently call qsort with one element or trigger undefined
328   // behavior with an empty sequence.
329   auto NElts = End - Start;
330   if (NElts <= 1) return;
331   qsort(&*Start, NElts, sizeof(*Start), get_array_pod_sort_comparator(*Start));
332 }
333 
334 template <class IteratorTy>
335 inline void array_pod_sort(
336     IteratorTy Start, IteratorTy End,
337     int (*Compare)(
338         const typename std::iterator_traits<IteratorTy>::value_type *,
339         const typename std::iterator_traits<IteratorTy>::value_type *)) {
340   // Don't inefficiently call qsort with one element or trigger undefined
341   // behavior with an empty sequence.
342   auto NElts = End - Start;
343   if (NElts <= 1) return;
344   qsort(&*Start, NElts, sizeof(*Start),
345         reinterpret_cast<int (*)(const void *, const void *)>(Compare));
346 }
347 
348 //===----------------------------------------------------------------------===//
349 //     Extra additions to <algorithm>
350 //===----------------------------------------------------------------------===//
351 
352 /// For a container of pointers, deletes the pointers and then clears the
353 /// container.
354 template<typename Container>
355 void DeleteContainerPointers(Container &C) {
356   for (typename Container::iterator I = C.begin(), E = C.end(); I != E; ++I)
357     delete *I;
358   C.clear();
359 }
360 
361 /// In a container of pairs (usually a map) whose second element is a pointer,
362 /// deletes the second elements and then clears the container.
363 template<typename Container>
364 void DeleteContainerSeconds(Container &C) {
365   for (typename Container::iterator I = C.begin(), E = C.end(); I != E; ++I)
366     delete I->second;
367   C.clear();
368 }
369 
370 /// Provide wrappers to std::all_of which take ranges instead of having to pass
371 /// begin/end explicitly.
372 template<typename R, class UnaryPredicate>
373 bool all_of(R &&Range, UnaryPredicate &&P) {
374   return std::all_of(Range.begin(), Range.end(),
375                      std::forward<UnaryPredicate>(P));
376 }
377 
378 /// Provide wrappers to std::any_of which take ranges instead of having to pass
379 /// begin/end explicitly.
380 template <typename R, class UnaryPredicate>
381 bool any_of(R &&Range, UnaryPredicate &&P) {
382   return std::any_of(Range.begin(), Range.end(),
383                      std::forward<UnaryPredicate>(P));
384 }
385 
386 /// Provide wrappers to std::none_of which take ranges instead of having to pass
387 /// begin/end explicitly.
388 template <typename R, class UnaryPredicate>
389 bool none_of(R &&Range, UnaryPredicate &&P) {
390   return std::none_of(Range.begin(), Range.end(),
391                       std::forward<UnaryPredicate>(P));
392 }
393 
394 /// Provide wrappers to std::find which take ranges instead of having to pass
395 /// begin/end explicitly.
396 template<typename R, class T>
397 auto find(R &&Range, const T &val) -> decltype(Range.begin()) {
398   return std::find(Range.begin(), Range.end(), val);
399 }
400 
401 /// Provide wrappers to std::find_if which take ranges instead of having to pass
402 /// begin/end explicitly.
403 template <typename R, class T>
404 auto find_if(R &&Range, const T &Pred) -> decltype(Range.begin()) {
405   return std::find_if(Range.begin(), Range.end(), Pred);
406 }
407 
408 /// Provide wrappers to std::remove_if which take ranges instead of having to
409 /// pass begin/end explicitly.
410 template<typename R, class UnaryPredicate>
411 auto remove_if(R &&Range, UnaryPredicate &&P) -> decltype(Range.begin()) {
412   return std::remove_if(Range.begin(), Range.end(), P);
413 }
414 
415 /// Wrapper function around std::find to detect if an element exists
416 /// in a container.
417 template <typename R, typename E>
418 bool is_contained(R &&Range, const E &Element) {
419   return std::find(Range.begin(), Range.end(), Element) != Range.end();
420 }
421 
422 /// Wrapper function around std::count_if to count the number of times an
423 /// element satisfying a given predicate occurs in a range.
424 template <typename R, typename UnaryPredicate>
425 auto count_if(R &&Range, UnaryPredicate &&P)
426     -> typename std::iterator_traits<decltype(Range.begin())>::difference_type {
427   return std::count_if(Range.begin(), Range.end(), P);
428 }
429 
430 /// Wrapper function around std::transform to apply a function to a range and
431 /// store the result elsewhere.
432 template <typename R, class OutputIt, typename UnaryPredicate>
433 OutputIt transform(R &&Range, OutputIt d_first, UnaryPredicate &&P) {
434   return std::transform(Range.begin(), Range.end(), d_first,
435                         std::forward<UnaryPredicate>(P));
436 }
437 
438 //===----------------------------------------------------------------------===//
439 //     Extra additions to <memory>
440 //===----------------------------------------------------------------------===//
441 
442 // Implement make_unique according to N3656.
443 
444 /// \brief Constructs a `new T()` with the given args and returns a
445 ///        `unique_ptr<T>` which owns the object.
446 ///
447 /// Example:
448 ///
449 ///     auto p = make_unique<int>();
450 ///     auto p = make_unique<std::tuple<int, int>>(0, 1);
451 template <class T, class... Args>
452 typename std::enable_if<!std::is_array<T>::value, std::unique_ptr<T>>::type
453 make_unique(Args &&... args) {
454   return std::unique_ptr<T>(new T(std::forward<Args>(args)...));
455 }
456 
457 /// \brief Constructs a `new T[n]` with the given args and returns a
458 ///        `unique_ptr<T[]>` which owns the object.
459 ///
460 /// \param n size of the new array.
461 ///
462 /// Example:
463 ///
464 ///     auto p = make_unique<int[]>(2); // value-initializes the array with 0's.
465 template <class T>
466 typename std::enable_if<std::is_array<T>::value && std::extent<T>::value == 0,
467                         std::unique_ptr<T>>::type
468 make_unique(size_t n) {
469   return std::unique_ptr<T>(new typename std::remove_extent<T>::type[n]());
470 }
471 
472 /// This function isn't used and is only here to provide better compile errors.
473 template <class T, class... Args>
474 typename std::enable_if<std::extent<T>::value != 0>::type
475 make_unique(Args &&...) = delete;
476 
477 struct FreeDeleter {
478   void operator()(void* v) {
479     ::free(v);
480   }
481 };
482 
483 template<typename First, typename Second>
484 struct pair_hash {
485   size_t operator()(const std::pair<First, Second> &P) const {
486     return std::hash<First>()(P.first) * 31 + std::hash<Second>()(P.second);
487   }
488 };
489 
490 /// A functor like C++14's std::less<void> in its absence.
491 struct less {
492   template <typename A, typename B> bool operator()(A &&a, B &&b) const {
493     return std::forward<A>(a) < std::forward<B>(b);
494   }
495 };
496 
497 /// A functor like C++14's std::equal<void> in its absence.
498 struct equal {
499   template <typename A, typename B> bool operator()(A &&a, B &&b) const {
500     return std::forward<A>(a) == std::forward<B>(b);
501   }
502 };
503 
504 /// Binary functor that adapts to any other binary functor after dereferencing
505 /// operands.
506 template <typename T> struct deref {
507   T func;
508   // Could be further improved to cope with non-derivable functors and
509   // non-binary functors (should be a variadic template member function
510   // operator()).
511   template <typename A, typename B>
512   auto operator()(A &lhs, B &rhs) const -> decltype(func(*lhs, *rhs)) {
513     assert(lhs);
514     assert(rhs);
515     return func(*lhs, *rhs);
516   }
517 };
518 
519 } // End llvm namespace
520 
521 #endif
522