STLExtras.h revision 8c42ca937453bd216b68baff1f32b47430d5b374
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 functions. 14// 15//===----------------------------------------------------------------------===// 16 17#ifndef LLVM_ADT_STLEXTRAS_H 18#define LLVM_ADT_STLEXTRAS_H 19 20#include <cstddef> // for std::size_t 21#include <cstdlib> // for qsort 22#include <functional> 23#include <iterator> 24#include <utility> // for std::pair 25 26namespace llvm { 27 28//===----------------------------------------------------------------------===// 29// Extra additions to <functional> 30//===----------------------------------------------------------------------===// 31 32template<class Ty> 33struct less_ptr : public std::binary_function<Ty, Ty, bool> { 34 bool operator()(const Ty* left, const Ty* right) const { 35 return *left < *right; 36 } 37}; 38 39template<class Ty> 40struct greater_ptr : public std::binary_function<Ty, Ty, bool> { 41 bool operator()(const Ty* left, const Ty* right) const { 42 return *right < *left; 43 } 44}; 45 46// deleter - Very very very simple method that is used to invoke operator 47// delete on something. It is used like this: 48// 49// for_each(V.begin(), B.end(), deleter<Interval>); 50// 51template <class T> 52static inline void deleter(T *Ptr) { 53 delete Ptr; 54} 55 56 57 58//===----------------------------------------------------------------------===// 59// Extra additions to <iterator> 60//===----------------------------------------------------------------------===// 61 62// mapped_iterator - This is a simple iterator adapter that causes a function to 63// be dereferenced whenever operator* is invoked on the iterator. 64// 65template <class RootIt, class UnaryFunc> 66class mapped_iterator { 67 RootIt current; 68 UnaryFunc Fn; 69public: 70 typedef typename std::iterator_traits<RootIt>::iterator_category 71 iterator_category; 72 typedef typename std::iterator_traits<RootIt>::difference_type 73 difference_type; 74 typedef typename UnaryFunc::result_type value_type; 75 76 typedef void pointer; 77 //typedef typename UnaryFunc::result_type *pointer; 78 typedef void reference; // Can't modify value returned by fn 79 80 typedef RootIt iterator_type; 81 typedef mapped_iterator<RootIt, UnaryFunc> _Self; 82 83 inline const RootIt &getCurrent() const { return current; } 84 inline const UnaryFunc &getFunc() const { return Fn; } 85 86 inline explicit mapped_iterator(const RootIt &I, UnaryFunc F) 87 : current(I), Fn(F) {} 88 inline mapped_iterator(const mapped_iterator &It) 89 : current(It.current), Fn(It.Fn) {} 90 91 inline value_type operator*() const { // All this work to do this 92 return Fn(*current); // little change 93 } 94 95 _Self& operator++() { ++current; return *this; } 96 _Self& operator--() { --current; return *this; } 97 _Self operator++(int) { _Self __tmp = *this; ++current; return __tmp; } 98 _Self operator--(int) { _Self __tmp = *this; --current; return __tmp; } 99 _Self operator+ (difference_type n) const { 100 return _Self(current + n, Fn); 101 } 102 _Self& operator+= (difference_type n) { current += n; return *this; } 103 _Self operator- (difference_type n) const { 104 return _Self(current - n, Fn); 105 } 106 _Self& operator-= (difference_type n) { current -= n; return *this; } 107 reference operator[](difference_type n) const { return *(*this + n); } 108 109 inline bool operator!=(const _Self &X) const { return !operator==(X); } 110 inline bool operator==(const _Self &X) const { return current == X.current; } 111 inline bool operator< (const _Self &X) const { return current < X.current; } 112 113 inline difference_type operator-(const _Self &X) const { 114 return current - X.current; 115 } 116}; 117 118template <class _Iterator, class Func> 119inline mapped_iterator<_Iterator, Func> 120operator+(typename mapped_iterator<_Iterator, Func>::difference_type N, 121 const mapped_iterator<_Iterator, Func>& X) { 122 return mapped_iterator<_Iterator, Func>(X.getCurrent() - N, X.getFunc()); 123} 124 125 126// map_iterator - Provide a convenient way to create mapped_iterators, just like 127// make_pair is useful for creating pairs... 128// 129template <class ItTy, class FuncTy> 130inline mapped_iterator<ItTy, FuncTy> map_iterator(const ItTy &I, FuncTy F) { 131 return mapped_iterator<ItTy, FuncTy>(I, F); 132} 133 134 135// next/prior - These functions unlike std::advance do not modify the 136// passed iterator but return a copy. 137// 138// next(myIt) returns copy of myIt incremented once 139// next(myIt, n) returns copy of myIt incremented n times 140// prior(myIt) returns copy of myIt decremented once 141// prior(myIt, n) returns copy of myIt decremented n times 142 143template <typename ItTy, typename Dist> 144inline ItTy next(ItTy it, Dist n) 145{ 146 std::advance(it, n); 147 return it; 148} 149 150template <typename ItTy> 151inline ItTy next(ItTy it) 152{ 153 return ++it; 154} 155 156template <typename ItTy, typename Dist> 157inline ItTy prior(ItTy it, Dist n) 158{ 159 std::advance(it, -n); 160 return it; 161} 162 163template <typename ItTy> 164inline ItTy prior(ItTy it) 165{ 166 return --it; 167} 168 169//===----------------------------------------------------------------------===// 170// Extra additions to <utility> 171//===----------------------------------------------------------------------===// 172 173// tie - this function ties two objects and returns a temporary object 174// that is assignable from a std::pair. This can be used to make code 175// more readable when using values returned from functions bundled in 176// a std::pair. Since an example is worth 1000 words: 177// 178// typedef std::map<int, int> Int2IntMap; 179// 180// Int2IntMap myMap; 181// Int2IntMap::iterator where; 182// bool inserted; 183// tie(where, inserted) = myMap.insert(std::make_pair(123,456)); 184// 185// if (inserted) 186// // do stuff 187// else 188// // do other stuff 189 190namespace 191{ 192 template <typename T1, typename T2> 193 struct tier { 194 typedef T1 &first_type; 195 typedef T2 &second_type; 196 197 first_type first; 198 second_type second; 199 200 tier(first_type f, second_type s) : first(f), second(s) { } 201 tier& operator=(const std::pair<T1, T2>& p) { 202 first = p.first; 203 second = p.second; 204 return *this; 205 } 206 }; 207} 208 209template <typename T1, typename T2> 210inline tier<T1, T2> tie(T1& f, T2& s) { 211 return tier<T1, T2>(f, s); 212} 213 214//===----------------------------------------------------------------------===// 215// Extra additions for arrays 216//===----------------------------------------------------------------------===// 217 218/// Find where an array ends (for ending iterators) 219/// This returns a pointer to the byte immediately 220/// after the end of an array. 221template<class T, std::size_t N> 222inline T *array_endof(T (&x)[N]) { 223 return x+N; 224} 225 226/// Find the length of an array. 227template<class T, std::size_t N> 228inline size_t array_lengthof(T (&x)[N]) { 229 return N; 230} 231 232/// array_pod_sort_comparator - This is helper function for array_pod_sort, 233/// which just uses operator< on T. 234template<typename T> 235static inline int array_pod_sort_comparator(const void *P1, const void *P2) { 236 if (*reinterpret_cast<const T*>(P1) < *reinterpret_cast<const T*>(P2)) 237 return -1; 238 if (*reinterpret_cast<const T*>(P2) < *reinterpret_cast<const T*>(P1)) 239 return 1; 240 return 0; 241} 242 243/// get_array_pad_sort_comparator - This is an internal helper function used to 244/// get type deduction of T right. 245template<typename T> 246static int (*get_array_pad_sort_comparator(const T &X)) 247 (const void*, const void*) { 248 return array_pod_sort_comparator<T>; 249} 250 251 252/// array_pod_sort - This sorts an array with the specified start and end 253/// extent. This is just like std::sort, except that it calls qsort instead of 254/// using an inlined template. qsort is slightly slower than std::sort, but 255/// most sorts are not performance critical in LLVM and std::sort has to be 256/// template instantiated for each type, leading to significant measured code 257/// bloat. This function should generally be used instead of std::sort where 258/// possible. 259/// 260/// This function assumes that you have simple POD-like types that can be 261/// compared with operator< and can be moved with memcpy. If this isn't true, 262/// you should use std::sort. 263/// 264/// NOTE: If qsort_r were portable, we could allow a custom comparator and 265/// default to std::less. 266template<class IteratorTy> 267static inline void array_pod_sort(IteratorTy Start, IteratorTy End) { 268 // Don't dereference start iterator of empty sequence. 269 if (Start == End) return; 270 qsort(&*Start, End-Start, sizeof(*Start), 271 get_array_pad_sort_comparator(*Start)); 272} 273 274template<class IteratorTy> 275static inline void array_pod_sort(IteratorTy Start, IteratorTy End, 276 int (*Compare)(const void*, const void*)) { 277 // Don't dereference start iterator of empty sequence. 278 if (Start == End) return; 279 qsort(&*Start, End-Start, sizeof(*Start), Compare); 280} 281 282} // End llvm namespace 283 284#endif 285