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
17 #include "llvm/ADT/STLExtras.h"
18 #include "llvm/Support/Compiler.h"
22 /// A simple registry entry which provides only a name, description, and
23 /// no-argument constructor.
25 class SimpleRegistryEntry {
26 const char *Name, *Desc;
27 std::unique_ptr<T> (*Ctor)();
30 SimpleRegistryEntry(const char *N, const char *D, std::unique_ptr<T> (*C)())
31 : Name(N), Desc(D), Ctor(C)
34 const char *getName() const { return Name; }
35 const char *getDesc() const { return Desc; }
36 std::unique_ptr<T> instantiate() const { return Ctor(); }
40 /// Traits for registry entries. If using other than SimpleRegistryEntry, it
41 /// is necessary to define an alternate traits class.
43 class RegistryTraits {
44 RegistryTraits() LLVM_DELETED_FUNCTION;
47 typedef SimpleRegistryEntry<T> entry;
49 /// nameof/descof - Accessors for name and description of entries. These are
50 // used to generate help for command-line options.
51 static const char *nameof(const entry &Entry) { return Entry.getName(); }
52 static const char *descof(const entry &Entry) { return Entry.getDesc(); }
56 /// A global registry used in conjunction with static constructors to make
57 /// pluggable components (like targets or garbage collectors) "just work" when
58 /// linked with an executable.
59 template <typename T, typename U = RegistryTraits<T> >
63 typedef typename U::entry entry;
70 Registry() LLVM_DELETED_FUNCTION;
72 static void Announce(const entry &E) {
73 for (listener *Cur = ListenerHead; Cur; Cur = Cur->Next)
78 static node *Head, *Tail;
80 friend class listener;
81 static listener *ListenerHead, *ListenerTail;
84 /// Node in linked list of entries.
87 friend class iterator;
93 node(const entry& V) : Next(nullptr), Val(V) {
105 /// Iterators for registry entries.
111 explicit iterator(const node *N) : Cur(N) {}
113 bool operator==(const iterator &That) const { return Cur == That.Cur; }
114 bool operator!=(const iterator &That) const { return Cur != That.Cur; }
115 iterator &operator++() { Cur = Cur->Next; return *this; }
116 const entry &operator*() const { return Cur->Val; }
117 const entry *operator->() const { return &Cur->Val; }
120 static iterator begin() { return iterator(Head); }
121 static iterator end() { return iterator(nullptr); }
124 /// Abstract base class for registry listeners, which are informed when new
125 /// entries are added to the registry. Simply subclass and instantiate:
128 /// class CollectorPrinter : public Registry<Collector>::listener {
130 /// void registered(const Registry<Collector>::entry &e) {
131 /// cerr << "collector now available: " << e->getName() << "\n";
135 /// CollectorPrinter() { init(); } // Print those already registered.
138 /// CollectorPrinter Printer;
141 listener *Prev, *Next;
143 friend void Registry::Announce(const entry &E);
146 /// Called when an entry is added to the registry.
148 virtual void registered(const entry &) = 0;
150 /// Calls 'registered' for each pre-existing entry.
153 for (iterator I = begin(), E = end(); I != E; ++I)
158 listener() : Prev(ListenerTail), Next(0) {
166 virtual ~listener() {
179 /// A static registration template. Use like such:
181 /// Registry<Collector>::Add<FancyGC>
182 /// X("fancy-gc", "Newfangled garbage collector.");
184 /// Use of this template requires that:
186 /// 1. The registered subclass has a default constructor.
188 /// 2. The registry entry type has a constructor compatible with this
191 /// entry(const char *Name, const char *ShortDesc, T *(*Ctor)());
193 /// If you have more elaborate requirements, then copy and modify.
195 template <typename V>
200 static std::unique_ptr<T> CtorFn() { return make_unique<V>(); }
203 Add(const char *Name, const char *Desc)
204 : Entry(Name, Desc, CtorFn), Node(Entry) {}
207 /// Registry::Parser now lives in llvm/Support/RegistryParser.h.
211 // Since these are defined in a header file, plugins must be sure to export
214 template <typename T, typename U>
215 typename Registry<T,U>::node *Registry<T,U>::Head;
217 template <typename T, typename U>
218 typename Registry<T,U>::node *Registry<T,U>::Tail;
220 template <typename T, typename U>
221 typename Registry<T,U>::listener *Registry<T,U>::ListenerHead;
223 template <typename T, typename U>
224 typename Registry<T,U>::listener *Registry<T,U>::ListenerTail;