1 //=== Registry.h - Linker-supported plugin registries -----------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // Defines a registry template for discovering pluggable modules.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_SUPPORT_REGISTRY_H
15 #define LLVM_SUPPORT_REGISTRY_H
18 /// A simple registry entry which provides only a name, description, and
19 /// no-argument constructor.
21 class SimpleRegistryEntry {
22 const char *Name, *Desc;
26 SimpleRegistryEntry(const char *N, const char *D, T *(*C)())
27 : Name(N), Desc(D), Ctor(C)
30 const char *getName() const { return Name; }
31 const char *getDesc() const { return Desc; }
32 T *instantiate() const { return Ctor(); }
36 /// Traits for registry entries. If using other than SimpleRegistryEntry, it
37 /// is necessary to define an alternate traits class.
39 class RegistryTraits {
40 RegistryTraits(); // Do not implement.
43 typedef SimpleRegistryEntry<T> entry;
45 /// nameof/descof - Accessors for name and description of entries. These are
46 // used to generate help for command-line options.
47 static const char *nameof(const entry &Entry) { return Entry.getName(); }
48 static const char *descof(const entry &Entry) { return Entry.getDesc(); }
52 /// A global registry used in conjunction with static constructors to make
53 /// pluggable components (like targets or garbage collectors) "just work" when
54 /// linked with an executable.
55 template <typename T, typename U = RegistryTraits<T> >
59 typedef typename U::entry entry;
66 Registry(); // Do not implement.
68 static void Announce(const entry &E) {
69 for (listener *Cur = ListenerHead; Cur; Cur = Cur->Next)
74 static node *Head, *Tail;
76 friend class listener;
77 static listener *ListenerHead, *ListenerTail;
83 /// Node in linked list of entries.
86 friend class iterator;
92 node(const entry& V) : Next(0), Val(V) {
104 /// Iterators for registry entries.
110 explicit iterator(const node *N) : Cur(N) {}
112 bool operator==(const iterator &That) const { return Cur == That.Cur; }
113 bool operator!=(const iterator &That) const { return Cur != That.Cur; }
114 iterator &operator++() { Cur = Cur->Next; return *this; }
115 const entry &operator*() const { return Cur->Val; }
116 const entry *operator->() const { return &Cur->Val; }
119 static iterator begin() { return iterator(Head); }
120 static iterator end() { return iterator(0); }
123 /// Abstract base class for registry listeners, which are informed when new
124 /// entries are added to the registry. Simply subclass and instantiate:
126 /// class CollectorPrinter : public Registry<Collector>::listener {
128 /// void registered(const Registry<Collector>::entry &e) {
129 /// cerr << "collector now available: " << e->getName() << "\n";
133 /// CollectorPrinter() { init(); } // Print those already registered.
136 /// CollectorPrinter Printer;
139 listener *Prev, *Next;
141 friend void Registry::Announce(const entry &E);
144 /// Called when an entry is added to the registry.
146 virtual void registered(const entry &) = 0;
148 /// Calls 'registered' for each pre-existing entry.
151 for (iterator I = begin(), E = end(); I != E; ++I)
156 listener() : Prev(ListenerTail), Next(0) {
164 virtual ~listener() {
177 /// A static registration template. Use like such:
179 /// Registry<Collector>::Add<FancyGC>
180 /// X("fancy-gc", "Newfangled garbage collector.");
182 /// Use of this template requires that:
184 /// 1. The registered subclass has a default constructor.
186 /// 2. The registry entry type has a constructor compatible with this
189 /// entry(const char *Name, const char *ShortDesc, T *(*Ctor)());
191 /// If you have more elaborate requirements, then copy and modify.
193 template <typename V>
198 static T *CtorFn() { return new V(); }
201 Add(const char *Name, const char *Desc)
202 : Entry(Name, Desc, CtorFn), Node(Entry) {}
205 /// Registry::Parser now lives in llvm/Support/RegistryParser.h.
210 template <typename T, typename U>
211 typename Registry<T,U>::node *Registry<T,U>::Head;
213 template <typename T, typename U>
214 typename Registry<T,U>::node *Registry<T,U>::Tail;
216 template <typename T, typename U>
217 typename Registry<T,U>::listener *Registry<T,U>::ListenerHead;
219 template <typename T, typename U>
220 typename Registry<T,U>::listener *Registry<T,U>::ListenerTail;