STLExtras.h revision bc79471be19e412eed4d270908db7ac945be10ca
1//===- STLExtras.h - Useful functions when working with the STL -*- C++ -*-===// 2// 3// The LLVM Compiler Infrastructure 4// 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. 7// 8//===----------------------------------------------------------------------===// 9// 10// This file contains some templates that are useful if you are working with the 11// STL at all. 12// 13// No library is required when using these functinons. 14// 15//===----------------------------------------------------------------------===// 16 17#ifndef SUPPORT_STLEXTRAS_H 18#define SUPPORT_STLEXTRAS_H 19 20#include <functional> 21#include <utility> // for std::pair 22#include "Support/iterator" 23 24namespace llvm { 25 26//===----------------------------------------------------------------------===// 27// Extra additions to <functional> 28//===----------------------------------------------------------------------===// 29 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 32// verbosely. 33// 34// Example: 35// struct Summer { void accumulate(int x); } 36// vector<int> Numbers; 37// Summer MyS; 38// for_each(Numbers.begin(), Numbers.end(), 39// bind_obj(&MyS, &Summer::accumulate)); 40// 41// TODO: When I get lots of extra time, convert this from an evil macro 42// 43#define bind_obj(OBJ, METHOD) std::bind1st(std::mem_fun(METHOD), OBJ) 44 45 46// bitwise_or - This is a simple functor that applys operator| on its two 47// arguments to get a boolean result. 48// 49template<class Ty> 50struct bitwise_or : public std::binary_function<Ty, Ty, bool> { 51 bool operator()(const Ty& left, const Ty& right) const { 52 return left | right; 53 } 54}; 55 56 57// deleter - Very very very simple method that is used to invoke operator 58// delete on something. It is used like this: 59// 60// for_each(V.begin(), B.end(), deleter<Interval>); 61// 62template <class T> 63static inline void deleter(T *Ptr) { 64 delete Ptr; 65} 66 67 68 69//===----------------------------------------------------------------------===// 70// Extra additions to <iterator> 71//===----------------------------------------------------------------------===// 72 73// mapped_iterator - This is a simple iterator adapter that causes a function to 74// be dereferenced whenever operator* is invoked on the iterator. 75// 76// It turns out that this is disturbingly similar to boost::transform_iterator 77// 78template <class RootIt, class UnaryFunc> 79class mapped_iterator { 80 RootIt current; 81 UnaryFunc Fn; 82public: 83 typedef typename std::iterator_traits<RootIt>::iterator_category 84 iterator_category; 85 typedef typename std::iterator_traits<RootIt>::difference_type 86 difference_type; 87 typedef typename UnaryFunc::result_type value_type; 88 89 typedef void pointer; 90 //typedef typename UnaryFunc::result_type *pointer; 91 typedef void reference; // Can't modify value returned by fn 92 93 typedef RootIt iterator_type; 94 typedef mapped_iterator<RootIt, UnaryFunc> _Self; 95 96 inline RootIt &getCurrent() const { return current; } 97 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) {} 102 103 inline value_type operator*() const { // All this work to do this 104 return Fn(*current); // little change 105 } 106 107 _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); } 116 117 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; } 120 121 inline difference_type operator-(const _Self &X) const { 122 return current - X.current; 123 } 124}; 125 126template <class _Iterator, class Func> 127inline mapped_iterator<_Iterator, Func> 128operator+(typename mapped_iterator<_Iterator, Func>::difference_type N, 129 const mapped_iterator<_Iterator, Func>& X) { 130 return mapped_iterator<_Iterator, Func>(X.getCurrent() - N); 131} 132 133 134// map_iterator - Provide a convenient way to create mapped_iterators, just like 135// make_pair is useful for creating pairs... 136// 137template <class ItTy, class FuncTy> 138inline mapped_iterator<ItTy, FuncTy> map_iterator(const ItTy &I, FuncTy F) { 139 return mapped_iterator<ItTy, FuncTy>(I, F); 140} 141 142 143// next/prior - These functions unlike std::advance do not modify the 144// passed iterator but return a copy. 145// 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 150 151template <typename ItTy, typename Dist> 152inline ItTy next(ItTy it, Dist n) 153{ 154 std::advance(it, n); 155 return it; 156} 157 158template <typename ItTy> 159inline ItTy next(ItTy it) 160{ 161 std::advance(it, 1); 162 return it; 163} 164 165template <typename ItTy, typename Dist> 166inline ItTy prior(ItTy it, Dist n) 167{ 168 std::advance(it, -n); 169 return it; 170} 171 172template <typename ItTy> 173inline ItTy prior(ItTy it) 174{ 175 std::advance(it, -1); 176 return it; 177} 178 179 180//===----------------------------------------------------------------------===// 181// Extra additions to <algorithm> 182//===----------------------------------------------------------------------===// 183 184// 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. 187// 188template <class InputIt, class Function> 189bool apply_until(InputIt First, InputIt Last, Function Func) { 190 for ( ; First != Last; ++First) 191 if (Func(*First)) return true; 192 return false; 193} 194 195 196// reduce - Reduce a sequence values into a single value, given an initial 197// value and an operator. 198// 199template <class InputIt, class Function, class ValueType> 200ValueType reduce(InputIt First, InputIt Last, Function Func, ValueType Value) { 201 for ( ; First != Last; ++First) 202 Value = Func(*First, Value); 203 return Value; 204} 205 206#if 1 // This is likely to be more efficient 207 208// 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. 210// 211template <class InputIt, class Function, class ValueType, class TransFunc> 212inline 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); 216 return Value; 217} 218 219#else // This is arguably more elegant 220 221// 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. 223// 224template <class InputIt, class Function, class ValueType, class TransFunc> 225inline 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), 228 Func, Value); 229} 230#endif 231 232 233// 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. 236// 237template <class InputIt, class Function> 238inline bool reduce_apply_bool(InputIt First, InputIt Last, Function Func) { 239 return reduce_apply(First, Last, bitwise_or<bool>(), false, Func); 240} 241 242 243// map - This function maps the specified input sequence into the specified 244// output iterator, applying a unary function in between. 245// 246template <class InIt, class OutIt, class Functor> 247inline OutIt mapto(InIt Begin, InIt End, OutIt Dest, Functor F) { 248 return copy(map_iterator(Begin, F), map_iterator(End, F), Dest); 249} 250 251 252//===----------------------------------------------------------------------===// 253// Extra additions to <utility> 254//===----------------------------------------------------------------------===// 255 256// 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: 260// 261// typedef std::map<int, int> Int2IntMap; 262// 263// Int2IntMap myMap; 264// Int2IntMap::iterator where; 265// bool inserted; 266// tie(where, inserted) = myMap.insert(std::make_pair(123,456)); 267// 268// if (inserted) 269// // do stuff 270// else 271// // do other stuff 272 273namespace 274{ 275 template <typename T1, typename T2> 276 struct tier { 277 typedef T1 &first_type; 278 typedef T2 &second_type; 279 280 first_type first; 281 second_type second; 282 283 tier(first_type f, second_type s) : first(f), second(s) { } 284 tier& operator=(const std::pair<T1, T2>& p) { 285 first = p.first; 286 second = p.second; 287 return *this; 288 } 289 }; 290} 291 292template <typename T1, typename T2> 293inline tier<T1, T2> tie(T1& f, T2& s) { 294 return tier<T1, T2>(f, s); 295} 296 297} // End llvm namespace 298 299#endif 300