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 17namespace llvm { 18 19/// set_union(A, B) - Compute A := A u B, return whether A changed. 20/// 21template <class S1Ty, class S2Ty> 22bool 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/// 38template <class S1Ty, class S2Ty> 39void 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/// 49template <class S1Ty, class S2Ty> 50S1Ty 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/// 61template <class S1Ty, class S2Ty> 62void 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