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
18namespace llvm {
19
20/// set_union(A, B) - Compute A := A u B, return whether A changed.
21///
22template <class S1Ty, class S2Ty>
23bool 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///
39template <class S1Ty, class S2Ty>
40void 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///
50template <class S1Ty, class S2Ty>
51S1Ty 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///
62template <class S1Ty, class S2Ty>
63void 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