STLExtras.h revision 545fc87454aabbc8ef8720811ab5dbd5588b537b
1//===- llvm/ADT/STLExtras.h - Useful STL related functions ------*- C++ -*-===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// 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 LLVM_ADT_STLEXTRAS_H 18#define LLVM_ADT_STLEXTRAS_H 19 20#include <functional> 21#include <utility> // for std::pair 22#include <cstring> // for std::size_t 23#include "llvm/ADT/iterator.h" 24 25namespace llvm { 26 27//===----------------------------------------------------------------------===// 28// Extra additions to <functional> 29//===----------------------------------------------------------------------===// 30 31template<class Ty> 32struct greater_ptr : public std::binary_function<Ty, Ty, bool> { 33 bool operator()(const Ty* left, const Ty* right) const { 34 return *right < *left; 35 } 36}; 37 38// deleter - Very very very simple method that is used to invoke operator 39// delete on something. It is used like this: 40// 41// for_each(V.begin(), B.end(), deleter<Interval>); 42// 43template <class T> 44static inline void deleter(T *Ptr) { 45 delete Ptr; 46} 47 48 49 50//===----------------------------------------------------------------------===// 51// Extra additions to <iterator> 52//===----------------------------------------------------------------------===// 53 54// mapped_iterator - This is a simple iterator adapter that causes a function to 55// be dereferenced whenever operator* is invoked on the iterator. 56// 57template <class RootIt, class UnaryFunc> 58class mapped_iterator { 59 RootIt current; 60 UnaryFunc Fn; 61public: 62 typedef typename std::iterator_traits<RootIt>::iterator_category 63 iterator_category; 64 typedef typename std::iterator_traits<RootIt>::difference_type 65 difference_type; 66 typedef typename UnaryFunc::result_type value_type; 67 68 typedef void pointer; 69 //typedef typename UnaryFunc::result_type *pointer; 70 typedef void reference; // Can't modify value returned by fn 71 72 typedef RootIt iterator_type; 73 typedef mapped_iterator<RootIt, UnaryFunc> _Self; 74 75 inline const RootIt &getCurrent() const { return current; } 76 inline const UnaryFunc &getFunc() const { return Fn; } 77 78 inline explicit mapped_iterator(const RootIt &I, UnaryFunc F) 79 : current(I), Fn(F) {} 80 inline mapped_iterator(const mapped_iterator &It) 81 : current(It.current), Fn(It.Fn) {} 82 83 inline value_type operator*() const { // All this work to do this 84 return Fn(*current); // little change 85 } 86 87 _Self& operator++() { ++current; return *this; } 88 _Self& operator--() { --current; return *this; } 89 _Self operator++(int) { _Self __tmp = *this; ++current; return __tmp; } 90 _Self operator--(int) { _Self __tmp = *this; --current; return __tmp; } 91 _Self operator+ (difference_type n) const { 92 return _Self(current + n, Fn); 93 } 94 _Self& operator+= (difference_type n) { current += n; return *this; } 95 _Self operator- (difference_type n) const { 96 return _Self(current - n, Fn); 97 } 98 _Self& operator-= (difference_type n) { current -= n; return *this; } 99 reference operator[](difference_type n) const { return *(*this + n); } 100 101 inline bool operator!=(const _Self &X) const { return !operator==(X); } 102 inline bool operator==(const _Self &X) const { return current == X.current; } 103 inline bool operator< (const _Self &X) const { return current < X.current; } 104 105 inline difference_type operator-(const _Self &X) const { 106 return current - X.current; 107 } 108}; 109 110template <class _Iterator, class Func> 111inline mapped_iterator<_Iterator, Func> 112operator+(typename mapped_iterator<_Iterator, Func>::difference_type N, 113 const mapped_iterator<_Iterator, Func>& X) { 114 return mapped_iterator<_Iterator, Func>(X.getCurrent() - N, X.getFunc()); 115} 116 117 118// map_iterator - Provide a convenient way to create mapped_iterators, just like 119// make_pair is useful for creating pairs... 120// 121template <class ItTy, class FuncTy> 122inline mapped_iterator<ItTy, FuncTy> map_iterator(const ItTy &I, FuncTy F) { 123 return mapped_iterator<ItTy, FuncTy>(I, F); 124} 125 126 127// next/prior - These functions unlike std::advance do not modify the 128// passed iterator but return a copy. 129// 130// next(myIt) returns copy of myIt incremented once 131// next(myIt, n) returns copy of myIt incremented n times 132// prior(myIt) returns copy of myIt decremented once 133// prior(myIt, n) returns copy of myIt decremented n times 134 135template <typename ItTy, typename Dist> 136inline ItTy next(ItTy it, Dist n) 137{ 138 std::advance(it, n); 139 return it; 140} 141 142template <typename ItTy> 143inline ItTy next(ItTy it) 144{ 145 return ++it; 146} 147 148template <typename ItTy, typename Dist> 149inline ItTy prior(ItTy it, Dist n) 150{ 151 std::advance(it, -n); 152 return it; 153} 154 155template <typename ItTy> 156inline ItTy prior(ItTy it) 157{ 158 return --it; 159} 160 161//===----------------------------------------------------------------------===// 162// Extra additions to <utility> 163//===----------------------------------------------------------------------===// 164 165// tie - this function ties two objects and returns a temporary object 166// that is assignable from a std::pair. This can be used to make code 167// more readable when using values returned from functions bundled in 168// a std::pair. Since an example is worth 1000 words: 169// 170// typedef std::map<int, int> Int2IntMap; 171// 172// Int2IntMap myMap; 173// Int2IntMap::iterator where; 174// bool inserted; 175// tie(where, inserted) = myMap.insert(std::make_pair(123,456)); 176// 177// if (inserted) 178// // do stuff 179// else 180// // do other stuff 181 182namespace 183{ 184 template <typename T1, typename T2> 185 struct tier { 186 typedef T1 &first_type; 187 typedef T2 &second_type; 188 189 first_type first; 190 second_type second; 191 192 tier(first_type f, second_type s) : first(f), second(s) { } 193 tier& operator=(const std::pair<T1, T2>& p) { 194 first = p.first; 195 second = p.second; 196 return *this; 197 } 198 }; 199} 200 201template <typename T1, typename T2> 202inline tier<T1, T2> tie(T1& f, T2& s) { 203 return tier<T1, T2>(f, s); 204} 205 206//===----------------------------------------------------------------------===// 207// Extra additions for arrays 208//===----------------------------------------------------------------------===// 209 210/// Find where an array ends (for ending iterators) 211/// This returns a pointer to the byte immediately 212/// after the end of an array. 213template<class T, std::size_t N> 214inline T *array_endof(T (&x)[N]) { 215 return x+N; 216} 217 218/// Find the length of an array. 219template<class T, std::size_t N> 220inline size_t array_lengthof(T (&x)[N]) { 221 return N; 222} 223 224/// array_pod_sort_comparator - This is helper function for array_pod_sort, 225/// which just uses operator< on T. 226template<typename T> 227static inline int array_pod_sort_comparator(const void *P1, const void *P2) { 228 if (*reinterpret_cast<const T*>(P1) < *reinterpret_cast<const T*>(P2)) 229 return -1; 230 if (*reinterpret_cast<const T*>(P2) < *reinterpret_cast<const T*>(P1)) 231 return 1; 232 return 0; 233} 234 235/// array_pod_sort - This sorts an array with the specified start and end 236/// extent. This is just like std::sort, except that it calls qsort instead of 237/// using an inlined template. qsort is slightly slower than std::sort, but 238/// most sorts are not performance critical in LLVM and std::sort has to be 239/// template instantiated for each type, leading to significant measured code 240/// bloat. This function should generally be used instead of std::sort where 241/// possible. 242/// 243/// This function assumes that you have simple POD-like types that can be 244/// compared with operator< and can be moved with memcpy. If this isn't true, 245/// you should use std::sort. 246/// 247/// NOTE: If qsort_r were portable, we could allow a custom comparator and 248/// default to std::less. 249template<class IteratorTy> 250static inline void array_pod_sort(IteratorTy Start, IteratorTy End) { 251 // Don't dereference start iterator of empty sequence. 252 if (Start == End) return; 253 qsort(&*Start, End-Start, sizeof(*Start), 254 array_pod_sort_comparator<sizeof(*Start)>); 255} 256 257} // End llvm namespace 258 259#endif 260