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 struct less_ptr : public std::binary_function<Ty, Ty, bool> {
58 bool operator()(const Ty* left, const Ty* right) const {
59 return *left < *right;
63 // deleter - Very very very simple method that is used to invoke operator
64 // delete on something. It is used like this:
66 // for_each(V.begin(), B.end(), deleter<Interval>);
69 static inline void deleter(T *Ptr) {
75 //===----------------------------------------------------------------------===//
76 // Extra additions to <iterator>
77 //===----------------------------------------------------------------------===//
79 // mapped_iterator - This is a simple iterator adapter that causes a function to
80 // be dereferenced whenever operator* is invoked on the iterator.
82 template <class RootIt, class UnaryFunc>
83 class mapped_iterator {
87 typedef typename std::iterator_traits<RootIt>::iterator_category
89 typedef typename std::iterator_traits<RootIt>::difference_type
91 typedef typename UnaryFunc::result_type value_type;
94 //typedef typename UnaryFunc::result_type *pointer;
95 typedef void reference; // Can't modify value returned by fn
97 typedef RootIt iterator_type;
98 typedef mapped_iterator<RootIt, UnaryFunc> _Self;
100 inline RootIt &getCurrent() const { return current; }
102 inline explicit mapped_iterator(const RootIt &I, UnaryFunc F)
103 : current(I), Fn(F) {}
104 inline mapped_iterator(const mapped_iterator &It)
105 : current(It.current), Fn(It.Fn) {}
107 inline value_type operator*() const { // All this work to do this
108 return Fn(*current); // little change
111 _Self& operator++() { ++current; return *this; }
112 _Self& operator--() { --current; return *this; }
113 _Self operator++(int) { _Self __tmp = *this; ++current; return __tmp; }
114 _Self operator--(int) { _Self __tmp = *this; --current; return __tmp; }
115 _Self operator+ (difference_type n) const { return _Self(current + n); }
116 _Self& operator+= (difference_type n) { current += n; return *this; }
117 _Self operator- (difference_type n) const { return _Self(current - n); }
118 _Self& operator-= (difference_type n) { current -= n; return *this; }
119 reference operator[](difference_type n) const { return *(*this + n); }
121 inline bool operator!=(const _Self &X) const { return !operator==(X); }
122 inline bool operator==(const _Self &X) const { return current == X.current; }
123 inline bool operator< (const _Self &X) const { return current < X.current; }
125 inline difference_type operator-(const _Self &X) const {
126 return current - X.current;
130 template <class _Iterator, class Func>
131 inline mapped_iterator<_Iterator, Func>
132 operator+(typename mapped_iterator<_Iterator, Func>::difference_type N,
133 const mapped_iterator<_Iterator, Func>& X) {
134 return mapped_iterator<_Iterator, Func>(X.getCurrent() - N);
138 // map_iterator - Provide a convenient way to create mapped_iterators, just like
139 // make_pair is useful for creating pairs...
141 template <class ItTy, class FuncTy>
142 inline mapped_iterator<ItTy, FuncTy> map_iterator(const ItTy &I, FuncTy F) {
143 return mapped_iterator<ItTy, FuncTy>(I, F);
147 // next/prior - These functions unlike std::advance do not modify the
148 // passed iterator but return a copy.
150 // next(myIt) returns copy of myIt incremented once
151 // next(myIt, n) returns copy of myIt incremented n times
152 // prior(myIt) returns copy of myIt decremented once
153 // prior(myIt, n) returns copy of myIt decremented n times
155 template <typename ItTy, typename Dist>
156 inline ItTy next(ItTy it, Dist n)
162 template <typename ItTy>
163 inline ItTy next(ItTy it)
169 template <typename ItTy, typename Dist>
170 inline ItTy prior(ItTy it, Dist n)
172 std::advance(it, -n);
176 template <typename ItTy>
177 inline ItTy prior(ItTy it)
179 std::advance(it, -1);
184 //===----------------------------------------------------------------------===//
185 // Extra additions to <algorithm>
186 //===----------------------------------------------------------------------===//
188 // apply_until - Apply a functor to a sequence continually, unless the
189 // functor returns true. Return true if the functor returned true, return false
190 // if the functor never returned true.
192 template <class InputIt, class Function>
193 bool apply_until(InputIt First, InputIt Last, Function Func) {
194 for ( ; First != Last; ++First)
195 if (Func(*First)) return true;
200 // reduce - Reduce a sequence values into a single value, given an initial
201 // value and an operator.
203 template <class InputIt, class Function, class ValueType>
204 ValueType reduce(InputIt First, InputIt Last, Function Func, ValueType Value) {
205 for ( ; First != Last; ++First)
206 Value = Func(*First, Value);
210 #if 1 // This is likely to be more efficient
212 // reduce_apply - Reduce the result of applying a function to each value in a
213 // sequence, given an initial value, an operator, a function, and a sequence.
215 template <class InputIt, class Function, class ValueType, class TransFunc>
216 inline ValueType reduce_apply(InputIt First, InputIt Last, Function Func,
217 ValueType Value, TransFunc XForm) {
218 for ( ; First != Last; ++First)
219 Value = Func(XForm(*First), Value);
223 #else // This is arguably more elegant
225 // reduce_apply - Reduce the result of applying a function to each value in a
226 // sequence, given an initial value, an operator, a function, and a sequence.
228 template <class InputIt, class Function, class ValueType, class TransFunc>
229 inline ValueType reduce_apply2(InputIt First, InputIt Last, Function Func,
230 ValueType Value, TransFunc XForm) {
231 return reduce(map_iterator(First, XForm), map_iterator(Last, XForm),
237 // reduce_apply_bool - Reduce the result of applying a (bool returning) function
238 // to each value in a sequence. All of the bools returned by the mapped
239 // function are bitwise or'd together, and the result is returned.
241 template <class InputIt, class Function>
242 inline bool reduce_apply_bool(InputIt First, InputIt Last, Function Func) {
243 return reduce_apply(First, Last, bitwise_or<bool>(), false, Func);
247 // map - This function maps the specified input sequence into the specified
248 // output iterator, applying a unary function in between.
250 template <class InIt, class OutIt, class Functor>
251 inline OutIt mapto(InIt Begin, InIt End, OutIt Dest, Functor F) {
252 return copy(map_iterator(Begin, F), map_iterator(End, F), Dest);
256 //===----------------------------------------------------------------------===//
257 // Extra additions to <utility>
258 //===----------------------------------------------------------------------===//
260 // tie - this function ties two objects and returns a temporary object
261 // that is assignable from a std::pair. This can be used to make code
262 // more readable when using values returned from functions bundled in
263 // a std::pair. Since an example is worth 1000 words:
265 // typedef std::map<int, int> Int2IntMap;
268 // Int2IntMap::iterator where;
270 // tie(where, inserted) = myMap.insert(std::make_pair(123,456));
279 template <typename T1, typename T2>
281 typedef T1 &first_type;
282 typedef T2 &second_type;
287 tier(first_type f, second_type s) : first(f), second(s) { }
288 tier& operator=(const std::pair<T1, T2>& p) {
296 template <typename T1, typename T2>
297 inline tier<T1, T2> tie(T1& f, T2& s) {
298 return tier<T1, T2>(f, s);
301 } // End llvm namespace