1 //===-- llvm/ADT/SetOperations.h - Generic Set Operations -------*- 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 defines generic set operations that may be used on set's of 11 // different types, and different element types. 12 // 13 //===----------------------------------------------------------------------===// 14 15 #ifndef LLVM_ADT_SETOPERATIONS_H 16 #define LLVM_ADT_SETOPERATIONS_H 17 18 namespace llvm { 19 20 /// set_union(A, B) - Compute A := A u B, return whether A changed. 21 /// 22 template <class S1Ty, class S2Ty> 23 bool set_union(S1Ty &S1, const S2Ty &S2) { 24 bool Changed = false; 25 26 for (typename S2Ty::const_iterator SI = S2.begin(), SE = S2.end(); 27 SI != SE; ++SI) 28 if (S1.insert(*SI).second) 29 Changed = true; 30 31 return Changed; 32 } 33 34 /// set_intersect(A, B) - Compute A := A ^ B 35 /// Identical to set_intersection, except that it works on set<>'s and 36 /// is nicer to use. Functionally, this iterates through S1, removing 37 /// elements that are not contained in S2. 38 /// 39 template <class S1Ty, class S2Ty> 40 void set_intersect(S1Ty &S1, const S2Ty &S2) { 41 for (typename S1Ty::iterator I = S1.begin(); I != S1.end();) { 42 const auto &E = *I; 43 ++I; 44 if (!S2.count(E)) S1.erase(E); // Erase element if not in S2 45 } 46 } 47 48 /// set_difference(A, B) - Return A - B 49 /// 50 template <class S1Ty, class S2Ty> 51 S1Ty set_difference(const S1Ty &S1, const S2Ty &S2) { 52 S1Ty Result; 53 for (typename S1Ty::const_iterator SI = S1.begin(), SE = S1.end(); 54 SI != SE; ++SI) 55 if (!S2.count(*SI)) // if the element is not in set2 56 Result.insert(*SI); 57 return Result; 58 } 59 60 /// set_subtract(A, B) - Compute A := A - B 61 /// 62 template <class S1Ty, class S2Ty> 63 void set_subtract(S1Ty &S1, const S2Ty &S2) { 64 for (typename S2Ty::const_iterator SI = S2.begin(), SE = S2.end(); 65 SI != SE; ++SI) 66 S1.erase(*SI); 67 } 68 69 } // End llvm namespace 70 71 #endif 72
