1 //===-- llvm/ADT/SetOperations.h - Generic Set Operations -------*- C++ -*-===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // This file defines generic set operations that may be used on set's of 10 // different types, and different element types. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #ifndef LLVM_ADT_SETOPERATIONS_H 15 #define LLVM_ADT_SETOPERATIONS_H 16 17 namespace llvm { 18 19 /// set_union(A, B) - Compute A := A u B, return whether A changed. 20 /// 21 template <class S1Ty, class S2Ty> 22 bool set_union(S1Ty &S1, const S2Ty &S2) { 23 bool Changed = false; 24 25 for (typename S2Ty::const_iterator SI = S2.begin(), SE = S2.end(); 26 SI != SE; ++SI) 27 if (S1.insert(*SI).second) 28 Changed = true; 29 30 return Changed; 31 } 32 33 /// set_intersect(A, B) - Compute A := A ^ B 34 /// Identical to set_intersection, except that it works on set<>'s and 35 /// is nicer to use. Functionally, this iterates through S1, removing 36 /// elements that are not contained in S2. 37 /// 38 template <class S1Ty, class S2Ty> 39 void set_intersect(S1Ty &S1, const S2Ty &S2) { 40 for (typename S1Ty::iterator I = S1.begin(); I != S1.end();) { 41 const auto &E = *I; 42 ++I; 43 if (!S2.count(E)) S1.erase(E); // Erase element if not in S2 44 } 45 } 46 47 /// set_difference(A, B) - Return A - B 48 /// 49 template <class S1Ty, class S2Ty> 50 S1Ty set_difference(const S1Ty &S1, const S2Ty &S2) { 51 S1Ty Result; 52 for (typename S1Ty::const_iterator SI = S1.begin(), SE = S1.end(); 53 SI != SE; ++SI) 54 if (!S2.count(*SI)) // if the element is not in set2 55 Result.insert(*SI); 56 return Result; 57 } 58 59 /// set_subtract(A, B) - Compute A := A - B 60 /// 61 template <class S1Ty, class S2Ty> 62 void set_subtract(S1Ty &S1, const S2Ty &S2) { 63 for (typename S2Ty::const_iterator SI = S2.begin(), SE = S2.end(); 64 SI != SE; ++SI) 65 S1.erase(*SI); 66 } 67 68 } // End llvm namespace 69 70 #endif 71