1 //===- llvm/ADT/STLExtras.h - Useful STL related functions ------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source 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 functinons.
15 //===----------------------------------------------------------------------===//
17 #ifndef LLVM_ADT_STLEXTRAS_H
18 #define LLVM_ADT_STLEXTRAS_H
21 #include <utility> // for std::pair
22 #include "llvm/ADT/iterator"
26 //===----------------------------------------------------------------------===//
27 // Extra additions to <functional>
28 //===----------------------------------------------------------------------===//
30 // bind_obj - Often times you want to apply the member function of an object
31 // as a unary functor. This macro is shorthand that makes it happen less
35 // struct Summer { void accumulate(int x); }
36 // vector<int> Numbers;
38 // for_each(Numbers.begin(), Numbers.end(),
39 // bind_obj(&MyS, &Summer::accumulate));
41 // TODO: When I get lots of extra time, convert this from an evil macro
43 #define bind_obj(OBJ, METHOD) std::bind1st(std::mem_fun(METHOD), OBJ)
46 // bitwise_or - This is a simple functor that applys operator| on its two
47 // arguments to get a boolean result.
50 struct bitwise_or : public std::binary_function<Ty, Ty, bool> {
51 bool operator()(const Ty& left, const Ty& right) const {
57 struct less_ptr : public std::binary_function<Ty, Ty, bool> {
58 bool operator()(const Ty* left, const Ty* right) const {
59 return *left < *right;
64 struct greater_ptr : public std::binary_function<Ty, Ty, bool> {
65 bool operator()(const Ty* left, const Ty* right) const {
66 return *right < *left;
70 // deleter - Very very very simple method that is used to invoke operator
71 // delete on something. It is used like this:
73 // for_each(V.begin(), B.end(), deleter<Interval>);
76 static inline void deleter(T *Ptr) {
82 //===----------------------------------------------------------------------===//
83 // Extra additions to <iterator>
84 //===----------------------------------------------------------------------===//
86 // mapped_iterator - This is a simple iterator adapter that causes a function to
87 // be dereferenced whenever operator* is invoked on the iterator.
89 template <class RootIt, class UnaryFunc>
90 class mapped_iterator {
94 typedef typename std::iterator_traits<RootIt>::iterator_category
96 typedef typename std::iterator_traits<RootIt>::difference_type
98 typedef typename UnaryFunc::result_type value_type;
100 typedef void pointer;
101 //typedef typename UnaryFunc::result_type *pointer;
102 typedef void reference; // Can't modify value returned by fn
104 typedef RootIt iterator_type;
105 typedef mapped_iterator<RootIt, UnaryFunc> _Self;
107 inline RootIt &getCurrent() const { return current; }
109 inline explicit mapped_iterator(const RootIt &I, UnaryFunc F)
110 : current(I), Fn(F) {}
111 inline mapped_iterator(const mapped_iterator &It)
112 : current(It.current), Fn(It.Fn) {}
114 inline value_type operator*() const { // All this work to do this
115 return Fn(*current); // little change
118 _Self& operator++() { ++current; return *this; }
119 _Self& operator--() { --current; return *this; }
120 _Self operator++(int) { _Self __tmp = *this; ++current; return __tmp; }
121 _Self operator--(int) { _Self __tmp = *this; --current; return __tmp; }
122 _Self operator+ (difference_type n) const { return _Self(current + n); }
123 _Self& operator+= (difference_type n) { current += n; return *this; }
124 _Self operator- (difference_type n) const { return _Self(current - n); }
125 _Self& operator-= (difference_type n) { current -= n; return *this; }
126 reference operator[](difference_type n) const { return *(*this + n); }
128 inline bool operator!=(const _Self &X) const { return !operator==(X); }
129 inline bool operator==(const _Self &X) const { return current == X.current; }
130 inline bool operator< (const _Self &X) const { return current < X.current; }
132 inline difference_type operator-(const _Self &X) const {
133 return current - X.current;
137 template <class _Iterator, class Func>
138 inline mapped_iterator<_Iterator, Func>
139 operator+(typename mapped_iterator<_Iterator, Func>::difference_type N,
140 const mapped_iterator<_Iterator, Func>& X) {
141 return mapped_iterator<_Iterator, Func>(X.getCurrent() - N);
145 // map_iterator - Provide a convenient way to create mapped_iterators, just like
146 // make_pair is useful for creating pairs...
148 template <class ItTy, class FuncTy>
149 inline mapped_iterator<ItTy, FuncTy> map_iterator(const ItTy &I, FuncTy F) {
150 return mapped_iterator<ItTy, FuncTy>(I, F);
154 // next/prior - These functions unlike std::advance do not modify the
155 // passed iterator but return a copy.
157 // next(myIt) returns copy of myIt incremented once
158 // next(myIt, n) returns copy of myIt incremented n times
159 // prior(myIt) returns copy of myIt decremented once
160 // prior(myIt, n) returns copy of myIt decremented n times
162 template <typename ItTy, typename Dist>
163 inline ItTy next(ItTy it, Dist n)
169 template <typename ItTy>
170 inline ItTy next(ItTy it)
176 template <typename ItTy, typename Dist>
177 inline ItTy prior(ItTy it, Dist n)
179 std::advance(it, -n);
183 template <typename ItTy>
184 inline ItTy prior(ItTy it)
186 std::advance(it, -1);
191 //===----------------------------------------------------------------------===//
192 // Extra additions to <algorithm>
193 //===----------------------------------------------------------------------===//
195 // apply_until - Apply a functor to a sequence continually, unless the
196 // functor returns true. Return true if the functor returned true, return false
197 // if the functor never returned true.
199 template <class InputIt, class Function>
200 bool apply_until(InputIt First, InputIt Last, Function Func) {
201 for ( ; First != Last; ++First)
202 if (Func(*First)) return true;
207 // reduce - Reduce a sequence values into a single value, given an initial
208 // value and an operator.
210 template <class InputIt, class Function, class ValueType>
211 ValueType reduce(InputIt First, InputIt Last, Function Func, ValueType Value) {
212 for ( ; First != Last; ++First)
213 Value = Func(*First, Value);
217 #if 1 // This is likely to be more efficient
219 // reduce_apply - Reduce the result of applying a function to each value in a
220 // sequence, given an initial value, an operator, a function, and a sequence.
222 template <class InputIt, class Function, class ValueType, class TransFunc>
223 inline ValueType reduce_apply(InputIt First, InputIt Last, Function Func,
224 ValueType Value, TransFunc XForm) {
225 for ( ; First != Last; ++First)
226 Value = Func(XForm(*First), Value);
230 #else // This is arguably more elegant
232 // reduce_apply - Reduce the result of applying a function to each value in a
233 // sequence, given an initial value, an operator, a function, and a sequence.
235 template <class InputIt, class Function, class ValueType, class TransFunc>
236 inline ValueType reduce_apply2(InputIt First, InputIt Last, Function Func,
237 ValueType Value, TransFunc XForm) {
238 return reduce(map_iterator(First, XForm), map_iterator(Last, XForm),
244 // reduce_apply_bool - Reduce the result of applying a (bool returning) function
245 // to each value in a sequence. All of the bools returned by the mapped
246 // function are bitwise or'd together, and the result is returned.
248 template <class InputIt, class Function>
249 inline bool reduce_apply_bool(InputIt First, InputIt Last, Function Func) {
250 return reduce_apply(First, Last, bitwise_or<bool>(), false, Func);
254 // map - This function maps the specified input sequence into the specified
255 // output iterator, applying a unary function in between.
257 template <class InIt, class OutIt, class Functor>
258 inline OutIt mapto(InIt Begin, InIt End, OutIt Dest, Functor F) {
259 return copy(map_iterator(Begin, F), map_iterator(End, F), Dest);
263 //===----------------------------------------------------------------------===//
264 // Extra additions to <utility>
265 //===----------------------------------------------------------------------===//
267 // tie - this function ties two objects and returns a temporary object
268 // that is assignable from a std::pair. This can be used to make code
269 // more readable when using values returned from functions bundled in
270 // a std::pair. Since an example is worth 1000 words:
272 // typedef std::map<int, int> Int2IntMap;
275 // Int2IntMap::iterator where;
277 // tie(where, inserted) = myMap.insert(std::make_pair(123,456));
286 template <typename T1, typename T2>
288 typedef T1 &first_type;
289 typedef T2 &second_type;
294 tier(first_type f, second_type s) : first(f), second(s) { }
295 tier& operator=(const std::pair<T1, T2>& p) {
303 template <typename T1, typename T2>
304 inline tier<T1, T2> tie(T1& f, T2& s) {
305 return tier<T1, T2>(f, s);
308 } // End llvm namespace