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 <utility> // for std::pair
22 #include "Support/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 // deleter - Very very very simple method that is used to invoke operator
58 // delete on something. It is used like this:
60 // for_each(V.begin(), B.end(), deleter<Interval>);
63 static inline void deleter(T *Ptr) {
69 //===----------------------------------------------------------------------===//
70 // Extra additions to <iterator>
71 //===----------------------------------------------------------------------===//
73 // mapped_iterator - This is a simple iterator adapter that causes a function to
74 // be dereferenced whenever operator* is invoked on the iterator.
76 // It turns out that this is disturbingly similar to boost::transform_iterator
79 template <class RootIt, class UnaryFunc>
80 class mapped_iterator {
84 typedef typename std::iterator_traits<RootIt>::iterator_category
86 typedef typename std::iterator_traits<RootIt>::difference_type
88 typedef typename UnaryFunc::result_type value_type;
91 //typedef typename UnaryFunc::result_type *pointer;
92 typedef void reference; // Can't modify value returned by fn
94 typedef RootIt iterator_type;
95 typedef mapped_iterator<RootIt, UnaryFunc> _Self;
97 inline RootIt &getCurrent() const { return current; }
99 inline explicit mapped_iterator(const RootIt &I, UnaryFunc F)
100 : current(I), Fn(F) {}
101 inline mapped_iterator(const mapped_iterator &It)
102 : current(It.current), Fn(It.Fn) {}
104 inline value_type operator*() const { // All this work to do this
105 return Fn(*current); // little change
108 _Self& operator++() { ++current; return *this; }
109 _Self& operator--() { --current; return *this; }
110 _Self operator++(int) { _Self __tmp = *this; ++current; return __tmp; }
111 _Self operator--(int) { _Self __tmp = *this; --current; return __tmp; }
112 _Self operator+ (difference_type n) const { return _Self(current + n); }
113 _Self& operator+= (difference_type n) { current += n; return *this; }
114 _Self operator- (difference_type n) const { return _Self(current - n); }
115 _Self& operator-= (difference_type n) { current -= n; return *this; }
116 reference operator[](difference_type n) const { return *(*this + n); }
118 inline bool operator!=(const _Self &X) const { return !operator==(X); }
119 inline bool operator==(const _Self &X) const { return current == X.current; }
120 inline bool operator< (const _Self &X) const { return current < X.current; }
122 inline difference_type operator-(const _Self &X) const {
123 return current - X.current;
127 template <class _Iterator, class Func>
128 inline mapped_iterator<_Iterator, Func>
129 operator+(typename mapped_iterator<_Iterator, Func>::difference_type N,
130 const mapped_iterator<_Iterator, Func>& X) {
131 return mapped_iterator<_Iterator, Func>(X.getCurrent() - N);
136 // This fails to work, because some iterators are not classes, for example
137 // vector iterators are commonly value_type **'s
138 template <class RootIt, class UnaryFunc>
139 class mapped_iterator : public RootIt {
142 typedef typename UnaryFunc::result_type value_type;
143 typedef typename UnaryFunc::result_type *pointer;
144 typedef void reference; // Can't modify value returned by fn
146 typedef mapped_iterator<RootIt, UnaryFunc> _Self;
147 typedef RootIt super;
148 inline explicit mapped_iterator(const RootIt &I) : super(I) {}
149 inline mapped_iterator(const super &It) : super(It) {}
151 inline value_type operator*() const { // All this work to do
152 return Fn(super::operator*()); // this little thing
157 // map_iterator - Provide a convenient way to create mapped_iterators, just like
158 // make_pair is useful for creating pairs...
160 template <class ItTy, class FuncTy>
161 inline mapped_iterator<ItTy, FuncTy> map_iterator(const ItTy &I, FuncTy F) {
162 return mapped_iterator<ItTy, FuncTy>(I, F);
166 //===----------------------------------------------------------------------===//
167 // Extra additions to <algorithm>
168 //===----------------------------------------------------------------------===//
170 // apply_until - Apply a functor to a sequence continually, unless the
171 // functor returns true. Return true if the functor returned true, return false
172 // if the functor never returned true.
174 template <class InputIt, class Function>
175 bool apply_until(InputIt First, InputIt Last, Function Func) {
176 for ( ; First != Last; ++First)
177 if (Func(*First)) return true;
182 // reduce - Reduce a sequence values into a single value, given an initial
183 // value and an operator.
185 template <class InputIt, class Function, class ValueType>
186 ValueType reduce(InputIt First, InputIt Last, Function Func, ValueType Value) {
187 for ( ; First != Last; ++First)
188 Value = Func(*First, Value);
192 #if 1 // This is likely to be more efficient
194 // reduce_apply - Reduce the result of applying a function to each value in a
195 // sequence, given an initial value, an operator, a function, and a sequence.
197 template <class InputIt, class Function, class ValueType, class TransFunc>
198 inline ValueType reduce_apply(InputIt First, InputIt Last, Function Func,
199 ValueType Value, TransFunc XForm) {
200 for ( ; First != Last; ++First)
201 Value = Func(XForm(*First), Value);
205 #else // This is arguably more elegant
207 // reduce_apply - Reduce the result of applying a function to each value in a
208 // sequence, given an initial value, an operator, a function, and a sequence.
210 template <class InputIt, class Function, class ValueType, class TransFunc>
211 inline ValueType reduce_apply2(InputIt First, InputIt Last, Function Func,
212 ValueType Value, TransFunc XForm) {
213 return reduce(map_iterator(First, XForm), map_iterator(Last, XForm),
219 // reduce_apply_bool - Reduce the result of applying a (bool returning) function
220 // to each value in a sequence. All of the bools returned by the mapped
221 // function are bitwise or'd together, and the result is returned.
223 template <class InputIt, class Function>
224 inline bool reduce_apply_bool(InputIt First, InputIt Last, Function Func) {
225 return reduce_apply(First, Last, bitwise_or<bool>(), false, Func);
229 // map - This function maps the specified input sequence into the specified
230 // output iterator, applying a unary function in between.
232 template <class InIt, class OutIt, class Functor>
233 inline OutIt mapto(InIt Begin, InIt End, OutIt Dest, Functor F) {
234 return copy(map_iterator(Begin, F), map_iterator(End, F), Dest);
238 //===----------------------------------------------------------------------===//
239 // Extra additions to <utility>
240 //===----------------------------------------------------------------------===//
242 // tie - this function ties two objects and returns a temporary object
243 // that is assignable from a std::pair. This can be used to make code
244 // more readable when using values returned from functions bundled in
245 // a std::pair. Since an example is worth 1000 words:
247 // typedef std::map<int, int> Int2IntMap;
250 // Int2IntMap::iterator where;
252 // tie(where, inserted) = myMap.insert(std::make_pair(123,456));
261 template <typename T1, typename T2>
263 typedef T1 &first_type;
264 typedef T2 &second_type;
269 tier(first_type f, second_type s) : first(f), second(s) { }
270 tier& operator=(const std::pair<T1, T2>& p) {
278 template <typename T1, typename T2>
279 inline tier<T1, T2> tie(T1& f, T2& s) {
280 return tier<T1, T2>(f, s);
283 } // End llvm namespace