1 //===- STLExtras.h - Useful functions when working with the STL -*- 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 SUPPORT_STLEXTRAS_H
18 #define SUPPORT_STLEXTRAS_H
21 #include "Support/iterator"
22 #include "boost/type_traits/transform_traits.hpp"
24 //===----------------------------------------------------------------------===//
25 // Extra additions to <functional>
26 //===----------------------------------------------------------------------===//
28 // bind_obj - Often times you want to apply the member function of an object
29 // as a unary functor. This macro is shorthand that makes it happen less
33 // struct Summer { void accumulate(int x); }
34 // vector<int> Numbers;
36 // for_each(Numbers.begin(), Numbers.end(),
37 // bind_obj(&MyS, &Summer::accumulate));
39 // TODO: When I get lots of extra time, convert this from an evil macro
41 #define bind_obj(OBJ, METHOD) std::bind1st(std::mem_fun(METHOD), OBJ)
44 // bitwise_or - This is a simple functor that applys operator| on its two
45 // arguments to get a boolean result.
48 struct bitwise_or : public std::binary_function<Ty, Ty, bool> {
49 bool operator()(const Ty& left, const Ty& right) const {
55 // deleter - Very very very simple method that is used to invoke operator
56 // delete on something. It is used like this:
58 // for_each(V.begin(), B.end(), deleter<Interval>);
61 static inline void deleter(T *Ptr) {
67 //===----------------------------------------------------------------------===//
68 // Extra additions to <iterator>
69 //===----------------------------------------------------------------------===//
71 // mapped_iterator - This is a simple iterator adapter that causes a function to
72 // be dereferenced whenever operator* is invoked on the iterator.
74 // It turns out that this is disturbingly similar to boost::transform_iterator
77 template <class RootIt, class UnaryFunc>
78 class mapped_iterator {
82 typedef typename std::iterator_traits<RootIt>::iterator_category
84 typedef typename std::iterator_traits<RootIt>::difference_type
86 typedef typename UnaryFunc::result_type value_type;
89 //typedef typename UnaryFunc::result_type *pointer;
90 typedef void reference; // Can't modify value returned by fn
92 typedef RootIt iterator_type;
93 typedef mapped_iterator<RootIt, UnaryFunc> _Self;
95 inline RootIt &getCurrent() const { return current; }
97 inline explicit mapped_iterator(const RootIt &I, UnaryFunc F)
98 : current(I), Fn(F) {}
99 inline mapped_iterator(const mapped_iterator &It)
100 : current(It.current), Fn(It.Fn) {}
102 inline value_type operator*() const { // All this work to do this
103 return Fn(*current); // little change
106 _Self& operator++() { ++current; return *this; }
107 _Self& operator--() { --current; return *this; }
108 _Self operator++(int) { _Self __tmp = *this; ++current; return __tmp; }
109 _Self operator--(int) { _Self __tmp = *this; --current; return __tmp; }
110 _Self operator+ (difference_type n) const { return _Self(current + n); }
111 _Self& operator+= (difference_type n) { current += n; return *this; }
112 _Self operator- (difference_type n) const { return _Self(current - n); }
113 _Self& operator-= (difference_type n) { current -= n; return *this; }
114 reference operator[](difference_type n) const { return *(*this + n); }
116 inline bool operator!=(const _Self &X) const { return !operator==(X); }
117 inline bool operator==(const _Self &X) const { return current == X.current; }
118 inline bool operator< (const _Self &X) const { return current < X.current; }
120 inline difference_type operator-(const _Self &X) const {
121 return current - X.current;
125 template <class _Iterator, class Func>
126 inline mapped_iterator<_Iterator, Func>
127 operator+(typename mapped_iterator<_Iterator, Func>::difference_type N,
128 const mapped_iterator<_Iterator, Func>& X) {
129 return mapped_iterator<_Iterator, Func>(X.getCurrent() - N);
134 // This fails to work, because some iterators are not classes, for example
135 // vector iterators are commonly value_type **'s
136 template <class RootIt, class UnaryFunc>
137 class mapped_iterator : public RootIt {
140 typedef typename UnaryFunc::result_type value_type;
141 typedef typename UnaryFunc::result_type *pointer;
142 typedef void reference; // Can't modify value returned by fn
144 typedef mapped_iterator<RootIt, UnaryFunc> _Self;
145 typedef RootIt super;
146 inline explicit mapped_iterator(const RootIt &I) : super(I) {}
147 inline mapped_iterator(const super &It) : super(It) {}
149 inline value_type operator*() const { // All this work to do
150 return Fn(super::operator*()); // this little thing
155 // map_iterator - Provide a convenient way to create mapped_iterators, just like
156 // make_pair is useful for creating pairs...
158 template <class ItTy, class FuncTy>
159 inline mapped_iterator<ItTy, FuncTy> map_iterator(const ItTy &I, FuncTy F) {
160 return mapped_iterator<ItTy, FuncTy>(I, F);
164 //===----------------------------------------------------------------------===//
165 // Extra additions to <algorithm>
166 //===----------------------------------------------------------------------===//
168 // apply_until - Apply a functor to a sequence continually, unless the
169 // functor returns true. Return true if the functor returned true, return false
170 // if the functor never returned true.
172 template <class InputIt, class Function>
173 bool apply_until(InputIt First, InputIt Last, Function Func) {
174 for ( ; First != Last; ++First)
175 if (Func(*First)) return true;
180 // reduce - Reduce a sequence values into a single value, given an initial
181 // value and an operator.
183 template <class InputIt, class Function, class ValueType>
184 ValueType reduce(InputIt First, InputIt Last, Function Func, ValueType Value) {
185 for ( ; First != Last; ++First)
186 Value = Func(*First, Value);
190 #if 1 // This is likely to be more efficient
192 // reduce_apply - Reduce the result of applying a function to each value in a
193 // sequence, given an initial value, an operator, a function, and a sequence.
195 template <class InputIt, class Function, class ValueType, class TransFunc>
196 inline ValueType reduce_apply(InputIt First, InputIt Last, Function Func,
197 ValueType Value, TransFunc XForm) {
198 for ( ; First != Last; ++First)
199 Value = Func(XForm(*First), Value);
203 #else // This is arguably more elegant
205 // reduce_apply - Reduce the result of applying a function to each value in a
206 // sequence, given an initial value, an operator, a function, and a sequence.
208 template <class InputIt, class Function, class ValueType, class TransFunc>
209 inline ValueType reduce_apply2(InputIt First, InputIt Last, Function Func,
210 ValueType Value, TransFunc XForm) {
211 return reduce(map_iterator(First, XForm), map_iterator(Last, XForm),
217 // reduce_apply_bool - Reduce the result of applying a (bool returning) function
218 // to each value in a sequence. All of the bools returned by the mapped
219 // function are bitwise or'd together, and the result is returned.
221 template <class InputIt, class Function>
222 inline bool reduce_apply_bool(InputIt First, InputIt Last, Function Func) {
223 return reduce_apply(First, Last, bitwise_or<bool>(), false, Func);
227 // map - This function maps the specified input sequence into the specified
228 // output iterator, applying a unary function in between.
230 template <class InIt, class OutIt, class Functor>
231 inline OutIt mapto(InIt Begin, InIt End, OutIt Dest, Functor F) {
232 return copy(map_iterator(Begin, F), map_iterator(End, F), Dest);
236 //===----------------------------------------------------------------------===//
237 // Extra additions to <utility>
238 //===----------------------------------------------------------------------===//
240 // tie - this function ties two objects and returns a temporary object
241 // that is assignable from a std::pair. This can be used to make code
242 // more readable when using values returned from functions bundled in
243 // a std::pair. Since an example is worth 1000 words:
245 // typedef std::map<int, int> Int2IntMap;
248 // Int2IntMap::iterator where;
250 // tie(where, inserted) = myMap.insert(std::make_pair(123,456));
259 template <typename T1, typename T2>
261 typedef typename boost::add_reference<T1>::type first_type;
262 typedef typename boost::add_reference<T2>::type second_type;
267 tier(first_type f, second_type s) : first(f), second(s) { }
268 tier& operator=(const std::pair<T1, T2>& p) {
276 template <typename T1, typename T2>
277 inline tier<T1, T2> tie(T1& f, T2& s) {
278 return tier<T1, T2>(f, s);