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 <cstddef> // for std::size_t
21#include <cstdlib> // for qsort
22#include <functional>
23#include <iterator>
24#include <utility> // for std::pair
25
26namespace llvm {
27
28//===----------------------------------------------------------------------===//
29//     Extra additions to <functional>
30//===----------------------------------------------------------------------===//
31
32template<class Ty>
33struct less_ptr : public std::binary_function<Ty, Ty, bool> {
34  bool operator()(const Ty* left, const Ty* right) const {
35    return *left < *right;
36  }
37};
38
39template<class Ty>
40struct greater_ptr : public std::binary_function<Ty, Ty, bool> {
41  bool operator()(const Ty* left, const Ty* right) const {
42    return *right < *left;
43  }
44};
45
46// deleter - Very very very simple method that is used to invoke operator
47// delete on something.  It is used like this:
48//
49//   for_each(V.begin(), B.end(), deleter<Interval>);
50//
51template <class T>
52static inline void deleter(T *Ptr) {
53  delete Ptr;
54}
55
56
57
58//===----------------------------------------------------------------------===//
59//     Extra additions to <iterator>
60//===----------------------------------------------------------------------===//
61
62// mapped_iterator - This is a simple iterator adapter that causes a function to
63// be dereferenced whenever operator* is invoked on the iterator.
64//
65template <class RootIt, class UnaryFunc>
66class mapped_iterator {
67  RootIt current;
68  UnaryFunc Fn;
69public:
70  typedef typename std::iterator_traits<RootIt>::iterator_category
71          iterator_category;
72  typedef typename std::iterator_traits<RootIt>::difference_type
73          difference_type;
74  typedef typename UnaryFunc::result_type value_type;
75
76  typedef void pointer;
77  //typedef typename UnaryFunc::result_type *pointer;
78  typedef void reference;        // Can't modify value returned by fn
79
80  typedef RootIt iterator_type;
81  typedef mapped_iterator<RootIt, UnaryFunc> _Self;
82
83  inline const RootIt &getCurrent() const { return current; }
84  inline const UnaryFunc &getFunc() const { return Fn; }
85
86  inline explicit mapped_iterator(const RootIt &I, UnaryFunc F)
87    : current(I), Fn(F) {}
88  inline mapped_iterator(const mapped_iterator &It)
89    : current(It.current), Fn(It.Fn) {}
90
91  inline value_type operator*() const {   // All this work to do this
92    return Fn(*current);         // little change
93  }
94
95  _Self& operator++() { ++current; return *this; }
96  _Self& operator--() { --current; return *this; }
97  _Self  operator++(int) { _Self __tmp = *this; ++current; return __tmp; }
98  _Self  operator--(int) { _Self __tmp = *this; --current; return __tmp; }
99  _Self  operator+    (difference_type n) const {
100    return _Self(current + n, Fn);
101  }
102  _Self& operator+=   (difference_type n) { current += n; return *this; }
103  _Self  operator-    (difference_type n) const {
104    return _Self(current - n, Fn);
105  }
106  _Self& operator-=   (difference_type n) { current -= n; return *this; }
107  reference operator[](difference_type n) const { return *(*this + n); }
108
109  inline bool operator!=(const _Self &X) const { return !operator==(X); }
110  inline bool operator==(const _Self &X) const { return current == X.current; }
111  inline bool operator< (const _Self &X) const { return current <  X.current; }
112
113  inline difference_type operator-(const _Self &X) const {
114    return current - X.current;
115  }
116};
117
118template <class _Iterator, class Func>
119inline mapped_iterator<_Iterator, Func>
120operator+(typename mapped_iterator<_Iterator, Func>::difference_type N,
121          const mapped_iterator<_Iterator, Func>& X) {
122  return mapped_iterator<_Iterator, Func>(X.getCurrent() - N, X.getFunc());
123}
124
125
126// map_iterator - Provide a convenient way to create mapped_iterators, just like
127// make_pair is useful for creating pairs...
128//
129template <class ItTy, class FuncTy>
130inline mapped_iterator<ItTy, FuncTy> map_iterator(const ItTy &I, FuncTy F) {
131  return mapped_iterator<ItTy, FuncTy>(I, F);
132}
133
134
135// next/prior - These functions unlike std::advance do not modify the
136// passed iterator but return a copy.
137//
138// next(myIt) returns copy of myIt incremented once
139// next(myIt, n) returns copy of myIt incremented n times
140// prior(myIt) returns copy of myIt decremented once
141// prior(myIt, n) returns copy of myIt decremented n times
142
143template <typename ItTy, typename Dist>
144inline ItTy next(ItTy it, Dist n)
145{
146  std::advance(it, n);
147  return it;
148}
149
150template <typename ItTy>
151inline ItTy next(ItTy it)
152{
153  return ++it;
154}
155
156template <typename ItTy, typename Dist>
157inline ItTy prior(ItTy it, Dist n)
158{
159  std::advance(it, -n);
160  return it;
161}
162
163template <typename ItTy>
164inline ItTy prior(ItTy it)
165{
166  return --it;
167}
168
169//===----------------------------------------------------------------------===//
170//     Extra additions to <utility>
171//===----------------------------------------------------------------------===//
172
173// tie - this function ties two objects and returns a temporary object
174// that is assignable from a std::pair. This can be used to make code
175// more readable when using values returned from functions bundled in
176// a std::pair. Since an example is worth 1000 words:
177//
178// typedef std::map<int, int> Int2IntMap;
179//
180// Int2IntMap myMap;
181// Int2IntMap::iterator where;
182// bool inserted;
183// tie(where, inserted) = myMap.insert(std::make_pair(123,456));
184//
185// if (inserted)
186//   // do stuff
187// else
188//   // do other stuff
189template <typename T1, typename T2>
190struct tier {
191  typedef T1 &first_type;
192  typedef T2 &second_type;
193
194  first_type first;
195  second_type second;
196
197  tier(first_type f, second_type s) : first(f), second(s) { }
198  tier& operator=(const std::pair<T1, T2>& p) {
199    first = p.first;
200    second = p.second;
201    return *this;
202  }
203};
204
205template <typename T1, typename T2>
206inline tier<T1, T2> tie(T1& f, T2& s) {
207  return tier<T1, T2>(f, s);
208}
209
210//===----------------------------------------------------------------------===//
211//     Extra additions for arrays
212//===----------------------------------------------------------------------===//
213
214/// Find where an array ends (for ending iterators)
215/// This returns a pointer to the byte immediately
216/// after the end of an array.
217template<class T, std::size_t N>
218inline T *array_endof(T (&x)[N]) {
219  return x+N;
220}
221
222/// Find the length of an array.
223template<class T, std::size_t N>
224inline size_t array_lengthof(T (&)[N]) {
225  return N;
226}
227
228/// array_pod_sort_comparator - This is helper function for array_pod_sort,
229/// which just uses operator< on T.
230template<typename T>
231static inline int array_pod_sort_comparator(const void *P1, const void *P2) {
232  if (*reinterpret_cast<const T*>(P1) < *reinterpret_cast<const T*>(P2))
233    return -1;
234  if (*reinterpret_cast<const T*>(P2) < *reinterpret_cast<const T*>(P1))
235    return 1;
236  return 0;
237}
238
239/// get_array_pad_sort_comparator - This is an internal helper function used to
240/// get type deduction of T right.
241template<typename T>
242static int (*get_array_pad_sort_comparator(const T &))
243             (const void*, const void*) {
244  return array_pod_sort_comparator<T>;
245}
246
247
248/// array_pod_sort - This sorts an array with the specified start and end
249/// extent.  This is just like std::sort, except that it calls qsort instead of
250/// using an inlined template.  qsort is slightly slower than std::sort, but
251/// most sorts are not performance critical in LLVM and std::sort has to be
252/// template instantiated for each type, leading to significant measured code
253/// bloat.  This function should generally be used instead of std::sort where
254/// possible.
255///
256/// This function assumes that you have simple POD-like types that can be
257/// compared with operator< and can be moved with memcpy.  If this isn't true,
258/// you should use std::sort.
259///
260/// NOTE: If qsort_r were portable, we could allow a custom comparator and
261/// default to std::less.
262template<class IteratorTy>
263static inline void array_pod_sort(IteratorTy Start, IteratorTy End) {
264  // Don't dereference start iterator of empty sequence.
265  if (Start == End) return;
266  qsort(&*Start, End-Start, sizeof(*Start),
267        get_array_pad_sort_comparator(*Start));
268}
269
270template<class IteratorTy>
271static inline void array_pod_sort(IteratorTy Start, IteratorTy End,
272                                  int (*Compare)(const void*, const void*)) {
273  // Don't dereference start iterator of empty sequence.
274  if (Start == End) return;
275  qsort(&*Start, End-Start, sizeof(*Start), Compare);
276}
277
278//===----------------------------------------------------------------------===//
279//     Extra additions to <algorithm>
280//===----------------------------------------------------------------------===//
281
282/// For a container of pointers, deletes the pointers and then clears the
283/// container.
284template<typename Container>
285void DeleteContainerPointers(Container &C) {
286  for (typename Container::iterator I = C.begin(), E = C.end(); I != E; ++I)
287    delete *I;
288  C.clear();
289}
290
291/// In a container of pairs (usually a map) whose second element is a pointer,
292/// deletes the second elements and then clears the container.
293template<typename Container>
294void DeleteContainerSeconds(Container &C) {
295  for (typename Container::iterator I = C.begin(), E = C.end(); I != E; ++I)
296    delete I->second;
297  C.clear();
298}
299
300} // End llvm namespace
301
302#endif
303