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 identity : public std::unary_function<Ty, Ty> {
34  Ty &operator()(Ty &self) const {
35    return self;
36  }
37  const Ty &operator()(const Ty &self) const {
38    return self;
39  }
40};
41
42template<class Ty>
43struct less_ptr : public std::binary_function<Ty, Ty, bool> {
44  bool operator()(const Ty* left, const Ty* right) const {
45    return *left < *right;
46  }
47};
48
49template<class Ty>
50struct greater_ptr : public std::binary_function<Ty, Ty, bool> {
51  bool operator()(const Ty* left, const Ty* right) const {
52    return *right < *left;
53  }
54};
55
56// deleter - Very very very simple method that is used to invoke operator
57// delete on something.  It is used like this:
58//
59//   for_each(V.begin(), B.end(), deleter<Interval>);
60//
61template <class T>
62inline void deleter(T *Ptr) {
63  delete Ptr;
64}
65
66
67
68//===----------------------------------------------------------------------===//
69//     Extra additions to <iterator>
70//===----------------------------------------------------------------------===//
71
72// mapped_iterator - This is a simple iterator adapter that causes a function to
73// be dereferenced whenever operator* is invoked on the iterator.
74//
75template <class RootIt, class UnaryFunc>
76class mapped_iterator {
77  RootIt current;
78  UnaryFunc Fn;
79public:
80  typedef typename std::iterator_traits<RootIt>::iterator_category
81          iterator_category;
82  typedef typename std::iterator_traits<RootIt>::difference_type
83          difference_type;
84  typedef typename UnaryFunc::result_type value_type;
85
86  typedef void pointer;
87  //typedef typename UnaryFunc::result_type *pointer;
88  typedef void reference;        // Can't modify value returned by fn
89
90  typedef RootIt iterator_type;
91  typedef mapped_iterator<RootIt, UnaryFunc> _Self;
92
93  inline const RootIt &getCurrent() const { return current; }
94  inline const UnaryFunc &getFunc() const { return Fn; }
95
96  inline explicit mapped_iterator(const RootIt &I, UnaryFunc F)
97    : current(I), Fn(F) {}
98  inline mapped_iterator(const mapped_iterator &It)
99    : current(It.current), Fn(It.Fn) {}
100
101  inline value_type operator*() const {   // All this work to do this
102    return Fn(*current);         // little change
103  }
104
105  _Self& operator++() { ++current; return *this; }
106  _Self& operator--() { --current; return *this; }
107  _Self  operator++(int) { _Self __tmp = *this; ++current; return __tmp; }
108  _Self  operator--(int) { _Self __tmp = *this; --current; return __tmp; }
109  _Self  operator+    (difference_type n) const {
110    return _Self(current + n, Fn);
111  }
112  _Self& operator+=   (difference_type n) { current += n; return *this; }
113  _Self  operator-    (difference_type n) const {
114    return _Self(current - n, Fn);
115  }
116  _Self& operator-=   (difference_type n) { current -= n; return *this; }
117  reference operator[](difference_type n) const { return *(*this + n); }
118
119  inline bool operator!=(const _Self &X) const { return !operator==(X); }
120  inline bool operator==(const _Self &X) const { return current == X.current; }
121  inline bool operator< (const _Self &X) const { return current <  X.current; }
122
123  inline difference_type operator-(const _Self &X) const {
124    return current - X.current;
125  }
126};
127
128template <class _Iterator, class Func>
129inline mapped_iterator<_Iterator, Func>
130operator+(typename mapped_iterator<_Iterator, Func>::difference_type N,
131          const mapped_iterator<_Iterator, Func>& X) {
132  return mapped_iterator<_Iterator, Func>(X.getCurrent() - N, X.getFunc());
133}
134
135
136// map_iterator - Provide a convenient way to create mapped_iterators, just like
137// make_pair is useful for creating pairs...
138//
139template <class ItTy, class FuncTy>
140inline mapped_iterator<ItTy, FuncTy> map_iterator(const ItTy &I, FuncTy F) {
141  return mapped_iterator<ItTy, FuncTy>(I, F);
142}
143
144
145// next/prior - These functions unlike std::advance do not modify the
146// passed iterator but return a copy.
147//
148// next(myIt) returns copy of myIt incremented once
149// next(myIt, n) returns copy of myIt incremented n times
150// prior(myIt) returns copy of myIt decremented once
151// prior(myIt, n) returns copy of myIt decremented n times
152
153template <typename ItTy, typename Dist>
154inline ItTy next(ItTy it, Dist n)
155{
156  std::advance(it, n);
157  return it;
158}
159
160template <typename ItTy>
161inline ItTy next(ItTy it)
162{
163  return ++it;
164}
165
166template <typename ItTy, typename Dist>
167inline ItTy prior(ItTy it, Dist n)
168{
169  std::advance(it, -n);
170  return it;
171}
172
173template <typename ItTy>
174inline ItTy prior(ItTy it)
175{
176  return --it;
177}
178
179//===----------------------------------------------------------------------===//
180//     Extra additions to <utility>
181//===----------------------------------------------------------------------===//
182
183// tie - this function ties two objects and returns a temporary object
184// that is assignable from a std::pair. This can be used to make code
185// more readable when using values returned from functions bundled in
186// a std::pair. Since an example is worth 1000 words:
187//
188// typedef std::map<int, int> Int2IntMap;
189//
190// Int2IntMap myMap;
191// Int2IntMap::iterator where;
192// bool inserted;
193// tie(where, inserted) = myMap.insert(std::make_pair(123,456));
194//
195// if (inserted)
196//   // do stuff
197// else
198//   // do other stuff
199template <typename T1, typename T2>
200struct tier {
201  typedef T1 &first_type;
202  typedef T2 &second_type;
203
204  first_type first;
205  second_type second;
206
207  tier(first_type f, second_type s) : first(f), second(s) { }
208  tier& operator=(const std::pair<T1, T2>& p) {
209    first = p.first;
210    second = p.second;
211    return *this;
212  }
213};
214
215template <typename T1, typename T2>
216inline tier<T1, T2> tie(T1& f, T2& s) {
217  return tier<T1, T2>(f, s);
218}
219
220//===----------------------------------------------------------------------===//
221//     Extra additions for arrays
222//===----------------------------------------------------------------------===//
223
224/// Find where an array ends (for ending iterators)
225/// This returns a pointer to the byte immediately
226/// after the end of an array.
227template<class T, std::size_t N>
228inline T *array_endof(T (&x)[N]) {
229  return x+N;
230}
231
232/// Find the length of an array.
233template<class T, std::size_t N>
234inline size_t array_lengthof(T (&)[N]) {
235  return N;
236}
237
238/// array_pod_sort_comparator - This is helper function for array_pod_sort,
239/// which just uses operator< on T.
240template<typename T>
241inline int array_pod_sort_comparator(const void *P1, const void *P2) {
242  if (*reinterpret_cast<const T*>(P1) < *reinterpret_cast<const T*>(P2))
243    return -1;
244  if (*reinterpret_cast<const T*>(P2) < *reinterpret_cast<const T*>(P1))
245    return 1;
246  return 0;
247}
248
249/// get_array_pad_sort_comparator - This is an internal helper function used to
250/// get type deduction of T right.
251template<typename T>
252inline int (*get_array_pad_sort_comparator(const T &))
253             (const void*, const void*) {
254  return array_pod_sort_comparator<T>;
255}
256
257
258/// array_pod_sort - This sorts an array with the specified start and end
259/// extent.  This is just like std::sort, except that it calls qsort instead of
260/// using an inlined template.  qsort is slightly slower than std::sort, but
261/// most sorts are not performance critical in LLVM and std::sort has to be
262/// template instantiated for each type, leading to significant measured code
263/// bloat.  This function should generally be used instead of std::sort where
264/// possible.
265///
266/// This function assumes that you have simple POD-like types that can be
267/// compared with operator< and can be moved with memcpy.  If this isn't true,
268/// you should use std::sort.
269///
270/// NOTE: If qsort_r were portable, we could allow a custom comparator and
271/// default to std::less.
272template<class IteratorTy>
273inline void array_pod_sort(IteratorTy Start, IteratorTy End) {
274  // Don't dereference start iterator of empty sequence.
275  if (Start == End) return;
276  qsort(&*Start, End-Start, sizeof(*Start),
277        get_array_pad_sort_comparator(*Start));
278}
279
280template<class IteratorTy>
281inline void array_pod_sort(IteratorTy Start, IteratorTy End,
282                                  int (*Compare)(const void*, const void*)) {
283  // Don't dereference start iterator of empty sequence.
284  if (Start == End) return;
285  qsort(&*Start, End-Start, sizeof(*Start), Compare);
286}
287
288//===----------------------------------------------------------------------===//
289//     Extra additions to <algorithm>
290//===----------------------------------------------------------------------===//
291
292/// For a container of pointers, deletes the pointers and then clears the
293/// container.
294template<typename Container>
295void DeleteContainerPointers(Container &C) {
296  for (typename Container::iterator I = C.begin(), E = C.end(); I != E; ++I)
297    delete *I;
298  C.clear();
299}
300
301/// In a container of pairs (usually a map) whose second element is a pointer,
302/// deletes the second elements and then clears the container.
303template<typename Container>
304void DeleteContainerSeconds(Container &C) {
305  for (typename Container::iterator I = C.begin(), E = C.end(); I != E; ++I)
306    delete I->second;
307  C.clear();
308}
309
310} // End llvm namespace
311
312#endif
313