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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 "llvm/Support/Compiler.h"
21 : #include <algorithm> // for std::all_of
22 : #include <cassert>
23 : #include <cstddef> // for std::size_t
24 : #include <cstdlib> // for qsort
25 : #include <functional>
26 : #include <iterator>
27 : #include <memory>
28 : #include <utility> // for std::pair
29 :
30 : namespace llvm {
31 :
32 : //===----------------------------------------------------------------------===//
33 : // Extra additions to <functional>
34 : //===----------------------------------------------------------------------===//
35 :
36 : template<class Ty>
37 : struct identity : public std::unary_function<Ty, Ty> {
38 : Ty &operator()(Ty &self) const {
39 : return self;
40 : }
41 : const Ty &operator()(const Ty &self) const {
42 : return self;
43 : }
44 : };
45 :
46 : template<class Ty>
47 : struct less_ptr : public std::binary_function<Ty, Ty, bool> {
48 : bool operator()(const Ty* left, const Ty* right) const {
49 : return *left < *right;
50 : }
51 : };
52 :
53 : template<class Ty>
54 : struct greater_ptr : public std::binary_function<Ty, Ty, bool> {
55 : bool operator()(const Ty* left, const Ty* right) const {
56 : return *right < *left;
57 : }
58 : };
59 :
60 : /// An efficient, type-erasing, non-owning reference to a callable. This is
61 : /// intended for use as the type of a function parameter that is not used
62 : /// after the function in question returns.
63 : ///
64 : /// This class does not own the callable, so it is not in general safe to store
65 : /// a function_ref.
66 : template<typename Fn> class function_ref;
67 :
68 : template<typename Ret, typename ...Params>
69 : class function_ref<Ret(Params...)> {
70 : Ret (*callback)(intptr_t callable, Params ...params);
71 : intptr_t callable;
72 :
73 : template<typename Callable>
74 : static Ret callback_fn(intptr_t callable, Params ...params) {
75 : return (*reinterpret_cast<Callable*>(callable))(
76 : std::forward<Params>(params)...);
77 : }
78 :
79 : public:
80 : template <typename Callable>
81 : function_ref(Callable &&callable,
82 : typename std::enable_if<
83 : !std::is_same<typename std::remove_reference<Callable>::type,
84 : function_ref>::value>::type * = nullptr)
85 : : callback(callback_fn<typename std::remove_reference<Callable>::type>),
86 : callable(reinterpret_cast<intptr_t>(&callable)) {}
87 : Ret operator()(Params ...params) const {
88 : return callback(callable, std::forward<Params>(params)...);
89 : }
90 : };
91 :
92 : // deleter - Very very very simple method that is used to invoke operator
93 : // delete on something. It is used like this:
94 : //
95 : // for_each(V.begin(), B.end(), deleter<Interval>);
96 : //
97 : template <class T>
98 : inline void deleter(T *Ptr) {
99 : delete Ptr;
100 : }
101 :
102 :
103 :
104 : //===----------------------------------------------------------------------===//
105 : // Extra additions to <iterator>
106 : //===----------------------------------------------------------------------===//
107 :
108 : // mapped_iterator - This is a simple iterator adapter that causes a function to
109 : // be dereferenced whenever operator* is invoked on the iterator.
110 : //
111 : template <class RootIt, class UnaryFunc>
112 : class mapped_iterator {
113 : RootIt current;
114 : UnaryFunc Fn;
115 : public:
116 : typedef typename std::iterator_traits<RootIt>::iterator_category
117 : iterator_category;
118 : typedef typename std::iterator_traits<RootIt>::difference_type
119 : difference_type;
120 : typedef typename UnaryFunc::result_type value_type;
121 :
122 : typedef void pointer;
123 : //typedef typename UnaryFunc::result_type *pointer;
124 : typedef void reference; // Can't modify value returned by fn
125 :
126 : typedef RootIt iterator_type;
127 :
128 : inline const RootIt &getCurrent() const { return current; }
129 : inline const UnaryFunc &getFunc() const { return Fn; }
130 :
131 : inline explicit mapped_iterator(const RootIt &I, UnaryFunc F)
132 : : current(I), Fn(F) {}
133 :
134 : inline value_type operator*() const { // All this work to do this
135 : return Fn(*current); // little change
136 : }
137 :
138 : mapped_iterator &operator++() {
139 : ++current;
140 : return *this;
141 : }
142 : mapped_iterator &operator--() {
143 : --current;
144 : return *this;
145 : }
146 : mapped_iterator operator++(int) {
147 : mapped_iterator __tmp = *this;
148 : ++current;
149 : return __tmp;
150 : }
151 : mapped_iterator operator--(int) {
152 : mapped_iterator __tmp = *this;
153 : --current;
154 : return __tmp;
155 : }
156 : mapped_iterator operator+(difference_type n) const {
157 : return mapped_iterator(current + n, Fn);
158 : }
159 : mapped_iterator &operator+=(difference_type n) {
160 : current += n;
161 : return *this;
162 : }
163 : mapped_iterator operator-(difference_type n) const {
164 : return mapped_iterator(current - n, Fn);
165 : }
166 : mapped_iterator &operator-=(difference_type n) {
167 : current -= n;
168 : return *this;
169 : }
170 : reference operator[](difference_type n) const { return *(*this + n); }
171 :
172 : bool operator!=(const mapped_iterator &X) const { return !operator==(X); }
173 : bool operator==(const mapped_iterator &X) const {
174 : return current == X.current;
175 : }
176 : bool operator<(const mapped_iterator &X) const { return current < X.current; }
177 :
178 : difference_type operator-(const mapped_iterator &X) const {
179 : return current - X.current;
180 : }
181 : };
182 :
183 : template <class Iterator, class Func>
184 : inline mapped_iterator<Iterator, Func>
185 : operator+(typename mapped_iterator<Iterator, Func>::difference_type N,
186 : const mapped_iterator<Iterator, Func> &X) {
187 : return mapped_iterator<Iterator, Func>(X.getCurrent() - N, X.getFunc());
188 : }
189 :
190 :
191 : // map_iterator - Provide a convenient way to create mapped_iterators, just like
192 : // make_pair is useful for creating pairs...
193 : //
194 : template <class ItTy, class FuncTy>
195 : inline mapped_iterator<ItTy, FuncTy> map_iterator(const ItTy &I, FuncTy F) {
196 : return mapped_iterator<ItTy, FuncTy>(I, F);
197 : }
198 :
199 : //===----------------------------------------------------------------------===//
200 : // Extra additions to <utility>
201 : //===----------------------------------------------------------------------===//
202 :
203 : /// \brief Function object to check whether the first component of a std::pair
204 : /// compares less than the first component of another std::pair.
205 : struct less_first {
206 : template <typename T> bool operator()(const T &lhs, const T &rhs) const {
207 : return lhs.first < rhs.first;
208 : }
209 : };
210 :
211 : /// \brief Function object to check whether the second component of a std::pair
212 : /// compares less than the second component of another std::pair.
213 : struct less_second {
214 : template <typename T> bool operator()(const T &lhs, const T &rhs) const {
215 : return lhs.second < rhs.second;
216 : }
217 : };
218 :
219 : // A subset of N3658. More stuff can be added as-needed.
220 :
221 : /// \brief Represents a compile-time sequence of integers.
222 : template <class T, T... I> struct integer_sequence {
223 : typedef T value_type;
224 :
225 : static LLVM_CONSTEXPR size_t size() { return sizeof...(I); }
226 : };
227 :
228 : /// \brief Alias for the common case of a sequence of size_ts.
229 : template <size_t... I>
230 : struct index_sequence : integer_sequence<std::size_t, I...> {};
231 :
232 : template <std::size_t N, std::size_t... I>
233 : struct build_index_impl : build_index_impl<N - 1, N - 1, I...> {};
234 : template <std::size_t... I>
235 : struct build_index_impl<0, I...> : index_sequence<I...> {};
236 :
237 : /// \brief Creates a compile-time integer sequence for a parameter pack.
238 : template <class... Ts>
239 : struct index_sequence_for : build_index_impl<sizeof...(Ts)> {};
240 :
241 : //===----------------------------------------------------------------------===//
242 : // Extra additions for arrays
243 : //===----------------------------------------------------------------------===//
244 :
245 : /// Find the length of an array.
246 : template <class T, std::size_t N>
247 : LLVM_CONSTEXPR inline size_t array_lengthof(T (&)[N]) {
248 : return N;
249 : }
250 :
251 : /// Adapt std::less<T> for array_pod_sort.
252 : template<typename T>
253 : inline int array_pod_sort_comparator(const void *P1, const void *P2) {
254 : if (std::less<T>()(*reinterpret_cast<const T*>(P1),
255 : *reinterpret_cast<const T*>(P2)))
256 : return -1;
257 : if (std::less<T>()(*reinterpret_cast<const T*>(P2),
258 : *reinterpret_cast<const T*>(P1)))
259 : return 1;
260 : return 0;
261 : }
262 :
263 : /// get_array_pod_sort_comparator - This is an internal helper function used to
264 : /// get type deduction of T right.
265 : template<typename T>
266 : inline int (*get_array_pod_sort_comparator(const T &))
267 : (const void*, const void*) {
268 : return array_pod_sort_comparator<T>;
269 : }
270 :
271 :
272 : /// array_pod_sort - This sorts an array with the specified start and end
273 : /// extent. This is just like std::sort, except that it calls qsort instead of
274 : /// using an inlined template. qsort is slightly slower than std::sort, but
275 : /// most sorts are not performance critical in LLVM and std::sort has to be
276 : /// template instantiated for each type, leading to significant measured code
277 : /// bloat. This function should generally be used instead of std::sort where
278 : /// possible.
279 : ///
280 : /// This function assumes that you have simple POD-like types that can be
281 : /// compared with std::less and can be moved with memcpy. If this isn't true,
282 : /// you should use std::sort.
283 : ///
284 : /// NOTE: If qsort_r were portable, we could allow a custom comparator and
285 : /// default to std::less.
286 : template<class IteratorTy>
287 : inline void array_pod_sort(IteratorTy Start, IteratorTy End) {
288 : // Don't inefficiently call qsort with one element or trigger undefined
289 : // behavior with an empty sequence.
290 : auto NElts = End - Start;
291 : if (NElts <= 1) return;
292 : qsort(&*Start, NElts, sizeof(*Start), get_array_pod_sort_comparator(*Start));
293 : }
294 :
295 : template <class IteratorTy>
296 : inline void array_pod_sort(
297 : IteratorTy Start, IteratorTy End,
298 : int (*Compare)(
299 : const typename std::iterator_traits<IteratorTy>::value_type *,
300 : const typename std::iterator_traits<IteratorTy>::value_type *)) {
301 : // Don't inefficiently call qsort with one element or trigger undefined
302 : // behavior with an empty sequence.
303 : auto NElts = End - Start;
304 : if (NElts <= 1) return;
305 : qsort(&*Start, NElts, sizeof(*Start),
306 : reinterpret_cast<int (*)(const void *, const void *)>(Compare));
307 : }
308 :
309 : //===----------------------------------------------------------------------===//
310 : // Extra additions to <algorithm>
311 : //===----------------------------------------------------------------------===//
312 :
313 : /// For a container of pointers, deletes the pointers and then clears the
314 : /// container.
315 : template<typename Container>
316 : void DeleteContainerPointers(Container &C) {
317 : for (typename Container::iterator I = C.begin(), E = C.end(); I != E; ++I)
318 : delete *I;
319 : C.clear();
320 : }
321 :
322 : /// In a container of pairs (usually a map) whose second element is a pointer,
323 : /// deletes the second elements and then clears the container.
324 : template<typename Container>
325 : void DeleteContainerSeconds(Container &C) {
326 : for (typename Container::iterator I = C.begin(), E = C.end(); I != E; ++I)
327 : delete I->second;
328 : C.clear();
329 : }
330 :
331 : /// Provide wrappers to std::all_of which take ranges instead of having to pass
332 : /// being/end explicitly.
333 : template<typename R, class UnaryPredicate>
334 : bool all_of(R &&Range, UnaryPredicate &&P) {
335 : return std::all_of(Range.begin(), Range.end(),
336 : std::forward<UnaryPredicate>(P));
337 : }
338 :
339 : //===----------------------------------------------------------------------===//
340 : // Extra additions to <memory>
341 : //===----------------------------------------------------------------------===//
342 :
343 : // Implement make_unique according to N3656.
344 :
345 : /// \brief Constructs a `new T()` with the given args and returns a
346 : /// `unique_ptr<T>` which owns the object.
347 : ///
348 : /// Example:
349 : ///
350 : /// auto p = make_unique<int>();
351 : /// auto p = make_unique<std::tuple<int, int>>(0, 1);
352 : template <class T, class... Args>
353 : typename std::enable_if<!std::is_array<T>::value, std::unique_ptr<T>>::type
354 : make_unique(Args &&... args) {
355 24 : return std::unique_ptr<T>(new T(std::forward<Args>(args)...));
356 0 : }
357 :
358 : /// \brief Constructs a `new T[n]` with the given args and returns a
359 : /// `unique_ptr<T[]>` which owns the object.
360 : ///
361 : /// \param n size of the new array.
362 : ///
363 : /// Example:
364 : ///
365 : /// auto p = make_unique<int[]>(2); // value-initializes the array with 0's.
366 : template <class T>
367 : typename std::enable_if<std::is_array<T>::value && std::extent<T>::value == 0,
368 : std::unique_ptr<T>>::type
369 : make_unique(size_t n) {
370 : return std::unique_ptr<T>(new typename std::remove_extent<T>::type[n]());
371 : }
372 :
373 : /// This function isn't used and is only here to provide better compile errors.
374 : template <class T, class... Args>
375 : typename std::enable_if<std::extent<T>::value != 0>::type
376 : make_unique(Args &&...) = delete;
377 :
378 : struct FreeDeleter {
379 : void operator()(void* v) {
380 : ::free(v);
381 : }
382 : };
383 :
384 : template<typename First, typename Second>
385 : struct pair_hash {
386 : size_t operator()(const std::pair<First, Second> &P) const {
387 : return std::hash<First>()(P.first) * 31 + std::hash<Second>()(P.second);
388 : }
389 : };
390 :
391 : /// A functor like C++14's std::less<void> in its absence.
392 : struct less {
393 : template <typename A, typename B> bool operator()(A &&a, B &&b) const {
394 : return std::forward<A>(a) < std::forward<B>(b);
395 : }
396 : };
397 :
398 : /// A functor like C++14's std::equal<void> in its absence.
399 : struct equal {
400 : template <typename A, typename B> bool operator()(A &&a, B &&b) const {
401 : return std::forward<A>(a) == std::forward<B>(b);
402 : }
403 : };
404 :
405 : /// Binary functor that adapts to any other binary functor after dereferencing
406 : /// operands.
407 : template <typename T> struct deref {
408 : T func;
409 : // Could be further improved to cope with non-derivable functors and
410 : // non-binary functors (should be a variadic template member function
411 : // operator()).
412 : template <typename A, typename B>
413 : auto operator()(A &lhs, B &rhs) const -> decltype(func(*lhs, *rhs)) {
414 : assert(lhs);
415 : assert(rhs);
416 : return func(*lhs, *rhs);
417 : }
418 : };
419 :
420 : } // End llvm namespace
421 :
422 : #endif
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