1//===- llvm/ADT/ilist_base.h - Intrusive List Base --------------*- 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#ifndef LLVM_ADT_ILIST_BASE_H
10#define LLVM_ADT_ILIST_BASE_H
11
12#include "llvm/ADT/ilist_node_base.h"
13#include <cassert>
14
15namespace llvm {
16
17/// Implementations of list algorithms using ilist_node_base.
18template <bool EnableSentinelTracking> class ilist_base {
19public:
20 using node_base_type = ilist_node_base<EnableSentinelTracking>;
21
22 static void insertBeforeImpl(node_base_type &Next, node_base_type &N) {
23 node_base_type &Prev = *Next.getPrev();
24 N.setNext(&Next);
25 N.setPrev(&Prev);
26 Prev.setNext(&N);
27 Next.setPrev(&N);
28 }
29
30 static void removeImpl(node_base_type &N) {
31 node_base_type *Prev = N.getPrev();
32 node_base_type *Next = N.getNext();
33 Next->setPrev(Prev);
34 Prev->setNext(Next);
35
36 // Not strictly necessary, but helps catch a class of bugs.
37 N.setPrev(nullptr);
38 N.setNext(nullptr);
39 }
40
41 static void removeRangeImpl(node_base_type &First, node_base_type &Last) {
42 node_base_type *Prev = First.getPrev();
43 node_base_type *Final = Last.getPrev();
44 Last.setPrev(Prev);
45 Prev->setNext(&Last);
46
47 // Not strictly necessary, but helps catch a class of bugs.
48 First.setPrev(nullptr);
49 Final->setNext(nullptr);
50 }
51
52 static void transferBeforeImpl(node_base_type &Next, node_base_type &First,
53 node_base_type &Last) {
54 if (&Next == &Last || &First == &Last)
55 return;
56
57 // Position cannot be contained in the range to be transferred.
58 assert(&Next != &First &&
59 // Check for the most common mistake.
60 "Insertion point can't be one of the transferred nodes");
61
62 node_base_type &Final = *Last.getPrev();
63
64 // Detach from old list/position.
65 First.getPrev()->setNext(&Last);
66 Last.setPrev(First.getPrev());
67
68 // Splice [First, Final] into its new list/position.
69 node_base_type &Prev = *Next.getPrev();
70 Final.setNext(&Next);
71 First.setPrev(&Prev);
72 Prev.setNext(&First);
73 Next.setPrev(&Final);
74 }
75
76 template <class T> static void insertBefore(T &Next, T &N) {
77 insertBeforeImpl(Next, N);
78 }
79
80 template <class T> static void remove(T &N) { removeImpl(N); }
81 template <class T> static void removeRange(T &First, T &Last) {
82 removeRangeImpl(First, Last);
83 }
84
85 template <class T> static void transferBefore(T &Next, T &First, T &Last) {
86 transferBeforeImpl(Next, First, Last);
87 }
88};
89
90} // end namespace llvm
91
92#endif // LLVM_ADT_ILIST_BASE_H
93