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"
23 //===----------------------------------------------------------------------===//
24 // Extra additions to <functional>
25 //===----------------------------------------------------------------------===//
27 // bind_obj - Often times you want to apply the member function of an object
28 // as a unary functor. This macro is shorthand that makes it happen less
32 // struct Summer { void accumulate(int x); }
33 // vector<int> Numbers;
35 // for_each(Numbers.begin(), Numbers.end(),
36 // bind_obj(&MyS, &Summer::accumulate));
38 // TODO: When I get lots of extra time, convert this from an evil macro
40 #define bind_obj(OBJ, METHOD) std::bind1st(std::mem_fun(METHOD), OBJ)
43 // bitwise_or - This is a simple functor that applys operator| on its two
44 // arguments to get a boolean result.
47 struct bitwise_or : public std::binary_function<Ty, Ty, bool> {
48 bool operator()(const Ty& left, const Ty& right) const {
54 // deleter - Very very very simple method that is used to invoke operator
55 // delete on something. It is used like this:
57 // for_each(V.begin(), B.end(), deleter<Interval>);
60 static inline void deleter(T *Ptr) {
66 //===----------------------------------------------------------------------===//
67 // Extra additions to <iterator>
68 //===----------------------------------------------------------------------===//
70 // mapped_iterator - This is a simple iterator adapter that causes a function to
71 // be dereferenced whenever operator* is invoked on the iterator.
73 // It turns out that this is disturbingly similar to boost::transform_iterator
76 template <class RootIt, class UnaryFunc>
77 class mapped_iterator {
81 typedef typename std::iterator_traits<RootIt>::iterator_category
83 typedef typename std::iterator_traits<RootIt>::difference_type
85 typedef typename UnaryFunc::result_type value_type;
88 //typedef typename UnaryFunc::result_type *pointer;
89 typedef void reference; // Can't modify value returned by fn
91 typedef RootIt iterator_type;
92 typedef mapped_iterator<RootIt, UnaryFunc> _Self;
94 inline RootIt &getCurrent() const { return current; }
96 inline explicit mapped_iterator(const RootIt &I, UnaryFunc F)
97 : current(I), Fn(F) {}
98 inline mapped_iterator(const mapped_iterator &It)
99 : current(It.current), Fn(It.Fn) {}
101 inline value_type operator*() const { // All this work to do this
102 return Fn(*current); // little change
105 _Self& operator++() { ++current; return *this; }
106 _Self& operator--() { --current; return *this; }
107 _Self operator++(int) { _Self __tmp = *this; ++current; return __tmp; }
108 _Self operator--(int) { _Self __tmp = *this; --current; return __tmp; }
109 _Self operator+ (difference_type n) const { return _Self(current + n); }
110 _Self& operator+= (difference_type n) { current += n; return *this; }
111 _Self operator- (difference_type n) const { return _Self(current - n); }
112 _Self& operator-= (difference_type n) { current -= n; return *this; }
113 reference operator[](difference_type n) const { return *(*this + n); }
115 inline bool operator!=(const _Self &X) const { return !operator==(X); }
116 inline bool operator==(const _Self &X) const { return current == X.current; }
117 inline bool operator< (const _Self &X) const { return current < X.current; }
119 inline difference_type operator-(const _Self &X) const {
120 return current - X.current;
124 template <class _Iterator, class Func>
125 inline mapped_iterator<_Iterator, Func>
126 operator+(typename mapped_iterator<_Iterator, Func>::difference_type N,
127 const mapped_iterator<_Iterator, Func>& X) {
128 return mapped_iterator<_Iterator, Func>(X.getCurrent() - N);
133 // This fails to work, because some iterators are not classes, for example
134 // vector iterators are commonly value_type **'s
135 template <class RootIt, class UnaryFunc>
136 class mapped_iterator : public RootIt {
139 typedef typename UnaryFunc::result_type value_type;
140 typedef typename UnaryFunc::result_type *pointer;
141 typedef void reference; // Can't modify value returned by fn
143 typedef mapped_iterator<RootIt, UnaryFunc> _Self;
144 typedef RootIt super;
145 inline explicit mapped_iterator(const RootIt &I) : super(I) {}
146 inline mapped_iterator(const super &It) : super(It) {}
148 inline value_type operator*() const { // All this work to do
149 return Fn(super::operator*()); // this little thing
154 // map_iterator - Provide a convenient way to create mapped_iterators, just like
155 // make_pair is useful for creating pairs...
157 template <class ItTy, class FuncTy>
158 inline mapped_iterator<ItTy, FuncTy> map_iterator(const ItTy &I, FuncTy F) {
159 return mapped_iterator<ItTy, FuncTy>(I, F);
163 //===----------------------------------------------------------------------===//
164 // Extra additions to <algorithm>
165 //===----------------------------------------------------------------------===//
167 // apply_until - Apply a functor to a sequence continually, unless the
168 // functor returns true. Return true if the functor returned true, return false
169 // if the functor never returned true.
171 template <class InputIt, class Function>
172 bool apply_until(InputIt First, InputIt Last, Function Func) {
173 for ( ; First != Last; ++First)
174 if (Func(*First)) return true;
179 // reduce - Reduce a sequence values into a single value, given an initial
180 // value and an operator.
182 template <class InputIt, class Function, class ValueType>
183 ValueType reduce(InputIt First, InputIt Last, Function Func, ValueType Value) {
184 for ( ; First != Last; ++First)
185 Value = Func(*First, Value);
189 #if 1 // This is likely to be more efficient
191 // reduce_apply - Reduce the result of applying a function to each value in a
192 // sequence, given an initial value, an operator, a function, and a sequence.
194 template <class InputIt, class Function, class ValueType, class TransFunc>
195 inline ValueType reduce_apply(InputIt First, InputIt Last, Function Func,
196 ValueType Value, TransFunc XForm) {
197 for ( ; First != Last; ++First)
198 Value = Func(XForm(*First), Value);
202 #else // This is arguably more elegant
204 // reduce_apply - Reduce the result of applying a function to each value in a
205 // sequence, given an initial value, an operator, a function, and a sequence.
207 template <class InputIt, class Function, class ValueType, class TransFunc>
208 inline ValueType reduce_apply2(InputIt First, InputIt Last, Function Func,
209 ValueType Value, TransFunc XForm) {
210 return reduce(map_iterator(First, XForm), map_iterator(Last, XForm),
216 // reduce_apply_bool - Reduce the result of applying a (bool returning) function
217 // to each value in a sequence. All of the bools returned by the mapped
218 // function are bitwise or'd together, and the result is returned.
220 template <class InputIt, class Function>
221 inline bool reduce_apply_bool(InputIt First, InputIt Last, Function Func) {
222 return reduce_apply(First, Last, bitwise_or<bool>(), false, Func);
226 // map - This function maps the specified input sequence into the specified
227 // output iterator, applying a unary function in between.
229 template <class InIt, class OutIt, class Functor>
230 inline OutIt mapto(InIt Begin, InIt End, OutIt Dest, Functor F) {
231 return copy(map_iterator(Begin, F), map_iterator(End, F), Dest);