1 //===- llvm/ADT/STLExtras.h - Useful STL related functions ------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file contains some templates that are useful if you are working with the
13 // No library is required when using these functions.
15 //===----------------------------------------------------------------------===//
17 #ifndef LLVM_ADT_STLEXTRAS_H
18 #define LLVM_ADT_STLEXTRAS_H
20 #include <cstddef> // for std::size_t
23 #include <utility> // for std::pair
27 //===----------------------------------------------------------------------===//
28 // Extra additions to <functional>
29 //===----------------------------------------------------------------------===//
32 struct less_ptr : public std::binary_function<Ty, Ty, bool> {
33 bool operator()(const Ty* left, const Ty* right) const {
34 return *left < *right;
39 struct greater_ptr : public std::binary_function<Ty, Ty, bool> {
40 bool operator()(const Ty* left, const Ty* right) const {
41 return *right < *left;
45 // deleter - Very very very simple method that is used to invoke operator
46 // delete on something. It is used like this:
48 // for_each(V.begin(), B.end(), deleter<Interval>);
51 static inline void deleter(T *Ptr) {
57 //===----------------------------------------------------------------------===//
58 // Extra additions to <iterator>
59 //===----------------------------------------------------------------------===//
61 // mapped_iterator - This is a simple iterator adapter that causes a function to
62 // be dereferenced whenever operator* is invoked on the iterator.
64 template <class RootIt, class UnaryFunc>
65 class mapped_iterator {
69 typedef typename std::iterator_traits<RootIt>::iterator_category
71 typedef typename std::iterator_traits<RootIt>::difference_type
73 typedef typename UnaryFunc::result_type value_type;
76 //typedef typename UnaryFunc::result_type *pointer;
77 typedef void reference; // Can't modify value returned by fn
79 typedef RootIt iterator_type;
80 typedef mapped_iterator<RootIt, UnaryFunc> _Self;
82 inline const RootIt &getCurrent() const { return current; }
83 inline const UnaryFunc &getFunc() const { return Fn; }
85 inline explicit mapped_iterator(const RootIt &I, UnaryFunc F)
86 : current(I), Fn(F) {}
87 inline mapped_iterator(const mapped_iterator &It)
88 : current(It.current), Fn(It.Fn) {}
90 inline value_type operator*() const { // All this work to do this
91 return Fn(*current); // little change
94 _Self& operator++() { ++current; return *this; }
95 _Self& operator--() { --current; return *this; }
96 _Self operator++(int) { _Self __tmp = *this; ++current; return __tmp; }
97 _Self operator--(int) { _Self __tmp = *this; --current; return __tmp; }
98 _Self operator+ (difference_type n) const {
99 return _Self(current + n, Fn);
101 _Self& operator+= (difference_type n) { current += n; return *this; }
102 _Self operator- (difference_type n) const {
103 return _Self(current - n, Fn);
105 _Self& operator-= (difference_type n) { current -= n; return *this; }
106 reference operator[](difference_type n) const { return *(*this + n); }
108 inline bool operator!=(const _Self &X) const { return !operator==(X); }
109 inline bool operator==(const _Self &X) const { return current == X.current; }
110 inline bool operator< (const _Self &X) const { return current < X.current; }
112 inline difference_type operator-(const _Self &X) const {
113 return current - X.current;
117 template <class _Iterator, class Func>
118 inline mapped_iterator<_Iterator, Func>
119 operator+(typename mapped_iterator<_Iterator, Func>::difference_type N,
120 const mapped_iterator<_Iterator, Func>& X) {
121 return mapped_iterator<_Iterator, Func>(X.getCurrent() - N, X.getFunc());
125 // map_iterator - Provide a convenient way to create mapped_iterators, just like
126 // make_pair is useful for creating pairs...
128 template <class ItTy, class FuncTy>
129 inline mapped_iterator<ItTy, FuncTy> map_iterator(const ItTy &I, FuncTy F) {
130 return mapped_iterator<ItTy, FuncTy>(I, F);
134 // next/prior - These functions unlike std::advance do not modify the
135 // passed iterator but return a copy.
137 // next(myIt) returns copy of myIt incremented once
138 // next(myIt, n) returns copy of myIt incremented n times
139 // prior(myIt) returns copy of myIt decremented once
140 // prior(myIt, n) returns copy of myIt decremented n times
142 template <typename ItTy, typename Dist>
143 inline ItTy next(ItTy it, Dist n)
149 template <typename ItTy>
150 inline ItTy next(ItTy it)
155 template <typename ItTy, typename Dist>
156 inline ItTy prior(ItTy it, Dist n)
158 std::advance(it, -n);
162 template <typename ItTy>
163 inline ItTy prior(ItTy it)
168 //===----------------------------------------------------------------------===//
169 // Extra additions to <utility>
170 //===----------------------------------------------------------------------===//
172 // tie - this function ties two objects and returns a temporary object
173 // that is assignable from a std::pair. This can be used to make code
174 // more readable when using values returned from functions bundled in
175 // a std::pair. Since an example is worth 1000 words:
177 // typedef std::map<int, int> Int2IntMap;
180 // Int2IntMap::iterator where;
182 // tie(where, inserted) = myMap.insert(std::make_pair(123,456));
191 template <typename T1, typename T2>
193 typedef T1 &first_type;
194 typedef T2 &second_type;
199 tier(first_type f, second_type s) : first(f), second(s) { }
200 tier& operator=(const std::pair<T1, T2>& p) {
208 template <typename T1, typename T2>
209 inline tier<T1, T2> tie(T1& f, T2& s) {
210 return tier<T1, T2>(f, s);
213 //===----------------------------------------------------------------------===//
214 // Extra additions for arrays
215 //===----------------------------------------------------------------------===//
217 /// Find where an array ends (for ending iterators)
218 /// This returns a pointer to the byte immediately
219 /// after the end of an array.
220 template<class T, std::size_t N>
221 inline T *array_endof(T (&x)[N]) {
225 /// Find the length of an array.
226 template<class T, std::size_t N>
227 inline size_t array_lengthof(T (&x)[N]) {
231 /// array_pod_sort_comparator - This is helper function for array_pod_sort,
232 /// which just uses operator< on T.
234 static inline int array_pod_sort_comparator(const void *P1, const void *P2) {
235 if (*reinterpret_cast<const T*>(P1) < *reinterpret_cast<const T*>(P2))
237 if (*reinterpret_cast<const T*>(P2) < *reinterpret_cast<const T*>(P1))
242 /// get_array_pad_sort_comparator - This is an internal helper function used to
243 /// get type deduction of T right.
245 static int (*get_array_pad_sort_comparator(const T &X))
246 (const void*, const void*) {
247 return array_pod_sort_comparator<T>;
251 /// array_pod_sort - This sorts an array with the specified start and end
252 /// extent. This is just like std::sort, except that it calls qsort instead of
253 /// using an inlined template. qsort is slightly slower than std::sort, but
254 /// most sorts are not performance critical in LLVM and std::sort has to be
255 /// template instantiated for each type, leading to significant measured code
256 /// bloat. This function should generally be used instead of std::sort where
259 /// This function assumes that you have simple POD-like types that can be
260 /// compared with operator< and can be moved with memcpy. If this isn't true,
261 /// you should use std::sort.
263 /// NOTE: If qsort_r were portable, we could allow a custom comparator and
264 /// default to std::less.
265 template<class IteratorTy>
266 static inline void array_pod_sort(IteratorTy Start, IteratorTy End) {
267 // Don't dereference start iterator of empty sequence.
268 if (Start == End) return;
269 qsort(&*Start, End-Start, sizeof(*Start),
270 get_array_pad_sort_comparator(*Start));
273 } // End llvm namespace