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 /// \file
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>
set_union(S1Ty & S1,const S2Ty & S2)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>
set_intersect(S1Ty & S1,const S2Ty & S2)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 template <class S1Ty, class S2Ty>
set_intersection_impl(const S1Ty & S1,const S2Ty & S2)49 S1Ty set_intersection_impl(const S1Ty &S1, const S2Ty &S2) {
50 S1Ty Result;
51 for (typename S1Ty::const_iterator SI = S1.begin(), SE = S1.end(); SI != SE;
52 ++SI)
53 if (S2.count(*SI))
54 Result.insert(*SI);
55 return Result;
56 }
57
58 /// set_intersection(A, B) - Return A ^ B
59 template <class S1Ty, class S2Ty>
set_intersection(const S1Ty & S1,const S2Ty & S2)60 S1Ty set_intersection(const S1Ty &S1, const S2Ty &S2) {
61 if (S1.size() < S2.size())
62 return set_intersection_impl(S1, S2);
63 else
64 return set_intersection_impl(S2, S1);
65 }
66
67 /// set_difference(A, B) - Return A - B
68 ///
69 template <class S1Ty, class S2Ty>
set_difference(const S1Ty & S1,const S2Ty & S2)70 S1Ty set_difference(const S1Ty &S1, const S2Ty &S2) {
71 S1Ty Result;
72 for (typename S1Ty::const_iterator SI = S1.begin(), SE = S1.end();
73 SI != SE; ++SI)
74 if (!S2.count(*SI)) // if the element is not in set2
75 Result.insert(*SI);
76 return Result;
77 }
78
79 /// set_subtract(A, B) - Compute A := A - B
80 ///
81 template <class S1Ty, class S2Ty>
set_subtract(S1Ty & S1,const S2Ty & S2)82 void set_subtract(S1Ty &S1, const S2Ty &S2) {
83 for (typename S2Ty::const_iterator SI = S2.begin(), SE = S2.end();
84 SI != SE; ++SI)
85 S1.erase(*SI);
86 }
87
88 /// set_subtract(A, B, C, D) - Compute A := A - B, set C to the elements of B
89 /// removed from A (A ^ B), and D to the elements of B not found in and removed
90 /// from A (B - A).
91 template <class S1Ty, class S2Ty>
set_subtract(S1Ty & S1,const S2Ty & S2,S1Ty & Removed,S1Ty & Remaining)92 void set_subtract(S1Ty &S1, const S2Ty &S2, S1Ty &Removed, S1Ty &Remaining) {
93 for (typename S2Ty::const_iterator SI = S2.begin(), SE = S2.end(); SI != SE;
94 ++SI)
95 if (S1.erase(*SI))
96 Removed.insert(*SI);
97 else
98 Remaining.insert(*SI);
99 }
100
101 /// set_is_subset(A, B) - Return true iff A in B
102 ///
103 template <class S1Ty, class S2Ty>
set_is_subset(const S1Ty & S1,const S2Ty & S2)104 bool set_is_subset(const S1Ty &S1, const S2Ty &S2) {
105 if (S1.size() > S2.size())
106 return false;
107 for (const auto It : S1)
108 if (!S2.count(It))
109 return false;
110 return true;
111 }
112
113 } // End llvm namespace
114
115 #endif
116