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
78 template <class RootIt, class UnaryFunc>
79 class mapped_iterator {
83 typedef typename std::iterator_traits<RootIt>::iterator_category
85 typedef typename std::iterator_traits<RootIt>::difference_type
87 typedef typename UnaryFunc::result_type value_type;
90 //typedef typename UnaryFunc::result_type *pointer;
91 typedef void reference; // Can't modify value returned by fn
93 typedef RootIt iterator_type;
94 typedef mapped_iterator<RootIt, UnaryFunc> _Self;
96 inline RootIt &getCurrent() const { return current; }
98 inline explicit mapped_iterator(const RootIt &I, UnaryFunc F)
99 : current(I), Fn(F) {}
100 inline mapped_iterator(const mapped_iterator &It)
101 : current(It.current), Fn(It.Fn) {}
103 inline value_type operator*() const { // All this work to do this
104 return Fn(*current); // little change
107 _Self& operator++() { ++current; return *this; }
108 _Self& operator--() { --current; return *this; }
109 _Self operator++(int) { _Self __tmp = *this; ++current; return __tmp; }
110 _Self operator--(int) { _Self __tmp = *this; --current; return __tmp; }
111 _Self operator+ (difference_type n) const { return _Self(current + n); }
112 _Self& operator+= (difference_type n) { current += n; return *this; }
113 _Self operator- (difference_type n) const { return _Self(current - n); }
114 _Self& operator-= (difference_type n) { current -= n; return *this; }
115 reference operator[](difference_type n) const { return *(*this + n); }
117 inline bool operator!=(const _Self &X) const { return !operator==(X); }
118 inline bool operator==(const _Self &X) const { return current == X.current; }
119 inline bool operator< (const _Self &X) const { return current < X.current; }
121 inline difference_type operator-(const _Self &X) const {
122 return current - X.current;
126 template <class _Iterator, class Func>
127 inline mapped_iterator<_Iterator, Func>
128 operator+(typename mapped_iterator<_Iterator, Func>::difference_type N,
129 const mapped_iterator<_Iterator, Func>& X) {
130 return mapped_iterator<_Iterator, Func>(X.getCurrent() - N);
134 // map_iterator - Provide a convenient way to create mapped_iterators, just like
135 // make_pair is useful for creating pairs...
137 template <class ItTy, class FuncTy>
138 inline mapped_iterator<ItTy, FuncTy> map_iterator(const ItTy &I, FuncTy F) {
139 return mapped_iterator<ItTy, FuncTy>(I, F);
143 // next/prior - These functions unlike std::advance do not modify the
144 // passed iterator but return a copy.
146 // next(myIt) returns copy of myIt incremented once
147 // next(myIt, n) returns copy of myIt incremented n times
148 // prior(myIt) returns copy of myIt decremented once
149 // prior(myIt, n) returns copy of myIt decremented n times
151 template <typename ItTy, typename Dist>
152 inline ItTy next(ItTy it, Dist n)
158 template <typename ItTy>
159 inline ItTy next(ItTy it)
165 template <typename ItTy, typename Dist>
166 inline ItTy prior(ItTy it, Dist n)
168 std::advance(it, -n);
172 template <typename ItTy>
173 inline ItTy prior(ItTy it)
175 std::advance(it, -1);
180 //===----------------------------------------------------------------------===//
181 // Extra additions to <algorithm>
182 //===----------------------------------------------------------------------===//
184 // apply_until - Apply a functor to a sequence continually, unless the
185 // functor returns true. Return true if the functor returned true, return false
186 // if the functor never returned true.
188 template <class InputIt, class Function>
189 bool apply_until(InputIt First, InputIt Last, Function Func) {
190 for ( ; First != Last; ++First)
191 if (Func(*First)) return true;
196 // reduce - Reduce a sequence values into a single value, given an initial
197 // value and an operator.
199 template <class InputIt, class Function, class ValueType>
200 ValueType reduce(InputIt First, InputIt Last, Function Func, ValueType Value) {
201 for ( ; First != Last; ++First)
202 Value = Func(*First, Value);
206 #if 1 // This is likely to be more efficient
208 // reduce_apply - Reduce the result of applying a function to each value in a
209 // sequence, given an initial value, an operator, a function, and a sequence.
211 template <class InputIt, class Function, class ValueType, class TransFunc>
212 inline ValueType reduce_apply(InputIt First, InputIt Last, Function Func,
213 ValueType Value, TransFunc XForm) {
214 for ( ; First != Last; ++First)
215 Value = Func(XForm(*First), Value);
219 #else // This is arguably more elegant
221 // reduce_apply - Reduce the result of applying a function to each value in a
222 // sequence, given an initial value, an operator, a function, and a sequence.
224 template <class InputIt, class Function, class ValueType, class TransFunc>
225 inline ValueType reduce_apply2(InputIt First, InputIt Last, Function Func,
226 ValueType Value, TransFunc XForm) {
227 return reduce(map_iterator(First, XForm), map_iterator(Last, XForm),
233 // reduce_apply_bool - Reduce the result of applying a (bool returning) function
234 // to each value in a sequence. All of the bools returned by the mapped
235 // function are bitwise or'd together, and the result is returned.
237 template <class InputIt, class Function>
238 inline bool reduce_apply_bool(InputIt First, InputIt Last, Function Func) {
239 return reduce_apply(First, Last, bitwise_or<bool>(), false, Func);
243 // map - This function maps the specified input sequence into the specified
244 // output iterator, applying a unary function in between.
246 template <class InIt, class OutIt, class Functor>
247 inline OutIt mapto(InIt Begin, InIt End, OutIt Dest, Functor F) {
248 return copy(map_iterator(Begin, F), map_iterator(End, F), Dest);
252 //===----------------------------------------------------------------------===//
253 // Extra additions to <utility>
254 //===----------------------------------------------------------------------===//
256 // tie - this function ties two objects and returns a temporary object
257 // that is assignable from a std::pair. This can be used to make code
258 // more readable when using values returned from functions bundled in
259 // a std::pair. Since an example is worth 1000 words:
261 // typedef std::map<int, int> Int2IntMap;
264 // Int2IntMap::iterator where;
266 // tie(where, inserted) = myMap.insert(std::make_pair(123,456));
275 template <typename T1, typename T2>
277 typedef T1 &first_type;
278 typedef T2 &second_type;
283 tier(first_type f, second_type s) : first(f), second(s) { }
284 tier& operator=(const std::pair<T1, T2>& p) {
292 template <typename T1, typename T2>
293 inline tier<T1, T2> tie(T1& f, T2& s) {
294 return tier<T1, T2>(f, s);
297 } // End llvm namespace