1 //===-- STLExtras.h - Useful functions when working with the STL -*- C++ -*--=//
3 // This file contains some templates that are useful if you are working with the
6 // No library is required when using these functinons.
8 //===----------------------------------------------------------------------===//
10 #ifndef LLVM_SUPPORT_STL_EXTRAS_H
11 #define LLVM_SUPPORT_STL_EXTRAS_H
15 //===----------------------------------------------------------------------===//
16 // Extra additions to <functional>
17 //===----------------------------------------------------------------------===//
19 // bind_obj - Often times you want to apply the member function of an object
20 // as a unary functor. This macro is shorthand that makes it happen less
24 // struct Summer { void accumulate(int x); }
25 // vector<int> Numbers;
27 // for_each(Numbers.begin(), Numbers.end(),
28 // bind_obj(&MyS, &Summer::accumulate));
30 // TODO: When I get lots of extra time, convert this from an evil macro
32 #define bind_obj(OBJ, METHOD) std::bind1st(std::mem_fun(METHOD), OBJ)
35 // bitwise_or - This is a simple functor that applys operator| on its two
36 // arguments to get a boolean result.
39 struct bitwise_or : public std::binary_function<Ty, Ty, bool> {
40 bool operator()(const Ty& left, const Ty& right) const {
46 // deleter - Very very very simple method that is used to invoke operator
47 // delete on something. It is used like this:
49 // for_each(V.begin(), B.end(), deleter<Interval>);
52 static inline void deleter(T *Ptr) {
58 //===----------------------------------------------------------------------===//
59 // Extra additions to <iterator>
60 //===----------------------------------------------------------------------===//
62 // mapped_iterator - This is a simple iterator adapter that causes a function to
63 // be dereferenced whenever operator* is invoked on the iterator.
65 // It turns out that this is disturbingly similar to boost::transform_iterator
68 template <class RootIt, class UnaryFunc>
69 class mapped_iterator {
73 typedef typename std::iterator_traits<RootIt>::iterator_category
75 typedef typename std::iterator_traits<RootIt>::difference_type
77 typedef typename UnaryFunc::result_type value_type;
80 //typedef typename UnaryFunc::result_type *pointer;
81 typedef void reference; // Can't modify value returned by fn
83 typedef RootIt iterator_type;
84 typedef mapped_iterator<RootIt, UnaryFunc> _Self;
86 inline RootIt &getCurrent() const { return current; }
88 inline explicit mapped_iterator(const RootIt &I, UnaryFunc F)
89 : current(I), Fn(F) {}
90 inline mapped_iterator(const mapped_iterator &It)
91 : current(It.current), Fn(It.Fn) {}
93 inline value_type operator*() const { // All this work to do this
94 return Fn(*current); // little change
97 _Self& operator++() { ++current; return *this; }
98 _Self& operator--() { --current; return *this; }
99 _Self operator++(int) { _Self __tmp = *this; ++current; return __tmp; }
100 _Self operator--(int) { _Self __tmp = *this; --current; return __tmp; }
101 _Self operator+ (difference_type n) const { return _Self(current + n); }
102 _Self& operator+= (difference_type n) { current += n; return *this; }
103 _Self operator- (difference_type n) const { return _Self(current - n); }
104 _Self& operator-= (difference_type n) { current -= n; return *this; }
105 reference operator[](difference_type n) const { return *(*this + n); }
107 inline bool operator!=(const _Self &X) const { return !operator==(X); }
108 inline bool operator==(const _Self &X) const { return current == X.current; }
109 inline bool operator< (const _Self &X) const { return current < X.current; }
111 inline difference_type operator-(const _Self &X) const {
112 return current - X.current;
116 template <class _Iterator, class Func>
117 inline mapped_iterator<_Iterator, Func>
118 operator+(typename mapped_iterator<_Iterator, Func>::difference_type N,
119 const mapped_iterator<_Iterator, Func>& X) {
120 return mapped_iterator<_Iterator, Func>(X.getCurrent() - N);
125 // This fails to work, because some iterators are not classes, for example
126 // vector iterators are commonly value_type **'s
127 template <class RootIt, class UnaryFunc>
128 class mapped_iterator : public RootIt {
131 typedef typename UnaryFunc::result_type value_type;
132 typedef typename UnaryFunc::result_type *pointer;
133 typedef void reference; // Can't modify value returned by fn
135 typedef mapped_iterator<RootIt, UnaryFunc> _Self;
136 typedef RootIt super;
137 inline explicit mapped_iterator(const RootIt &I) : super(I) {}
138 inline mapped_iterator(const super &It) : super(It) {}
140 inline value_type operator*() const { // All this work to do
141 return Fn(super::operator*()); // this little thing
146 // map_iterator - Provide a convenient way to create mapped_iterators, just like
147 // make_pair is useful for creating pairs...
149 template <class ItTy, class FuncTy>
150 inline mapped_iterator<ItTy, FuncTy> map_iterator(const ItTy &I, FuncTy F) {
151 return mapped_iterator<ItTy, FuncTy>(I, F);
155 //===----------------------------------------------------------------------===//
156 // Extra additions to <algorithm>
157 //===----------------------------------------------------------------------===//
159 // apply_until - Apply a functor to a sequence continually, unless the
160 // functor returns true. Return true if the functor returned true, return false
161 // if the functor never returned true.
163 template <class InputIt, class Function>
164 bool apply_until(InputIt First, InputIt Last, Function Func) {
165 for ( ; First != Last; ++First)
166 if (Func(*First)) return true;
171 // reduce - Reduce a sequence values into a single value, given an initial
172 // value and an operator.
174 template <class InputIt, class Function, class ValueType>
175 ValueType reduce(InputIt First, InputIt Last, Function Func, ValueType Value) {
176 for ( ; First != Last; ++First)
177 Value = Func(*First, Value);
181 #if 1 // This is likely to be more efficient
183 // reduce_apply - Reduce the result of applying a function to each value in a
184 // sequence, given an initial value, an operator, a function, and a sequence.
186 template <class InputIt, class Function, class ValueType, class TransFunc>
187 inline ValueType reduce_apply(InputIt First, InputIt Last, Function Func,
188 ValueType Value, TransFunc XForm) {
189 for ( ; First != Last; ++First)
190 Value = Func(XForm(*First), Value);
194 #else // This is arguably more elegant
196 // reduce_apply - Reduce the result of applying a function to each value in a
197 // sequence, given an initial value, an operator, a function, and a sequence.
199 template <class InputIt, class Function, class ValueType, class TransFunc>
200 inline ValueType reduce_apply2(InputIt First, InputIt Last, Function Func,
201 ValueType Value, TransFunc XForm) {
202 return reduce(map_iterator(First, XForm), map_iterator(Last, XForm),
208 // reduce_apply_bool - Reduce the result of applying a (bool returning) function
209 // to each value in a sequence. All of the bools returned by the mapped
210 // function are bitwise or'd together, and the result is returned.
212 template <class InputIt, class Function>
213 inline bool reduce_apply_bool(InputIt First, InputIt Last, Function Func) {
214 return reduce_apply(First, Last, bitwise_or<bool>(), false, Func);
218 // map - This function maps the specified input sequence into the specified
219 // output iterator, applying a unary function in between.
221 template <class InIt, class OutIt, class Functor>
222 inline OutIt mapto(InIt Begin, InIt End, OutIt Dest, Functor F) {
223 return copy(map_iterator(Begin, F), map_iterator(End, F), Dest);