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//=== Registry.h - Linker-supported plugin registries -----------*- C++ -*-===//
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// The LLVM Compiler Infrastructure
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//===----------------------------------------------------------------------===//
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// Defines a registry template for discovering pluggable modules.
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_SUPPORT_REGISTRY_H
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#define LLVM_SUPPORT_REGISTRY_H
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/// A simple registry entry which provides only a name, description, and
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/// no-argument constructor.
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class SimpleRegistryEntry {
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const char *Name, *Desc;
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SimpleRegistryEntry(const char *N, const char *D, T *(*C)())
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: Name(N), Desc(D), Ctor(C)
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const char *getName() const { return Name; }
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const char *getDesc() const { return Desc; }
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T *instantiate() const { return Ctor(); }
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/// Traits for registry entries. If using other than SimpleRegistryEntry, it
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/// is necessary to define an alternate traits class.
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class RegistryTraits {
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RegistryTraits(); // Do not implement.
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typedef SimpleRegistryEntry<T> entry;
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/// nameof/descof - Accessors for name and description of entries. These are
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// used to generate help for command-line options.
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static const char *nameof(const entry &Entry) { return Entry.getName(); }
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static const char *descof(const entry &Entry) { return Entry.getDesc(); }
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/// A global registry used in conjunction with static constructors to make
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/// pluggable components (like targets or garbage collectors) "just work" when
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/// linked with an executable.
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template <typename T, typename U = RegistryTraits<T> >
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typedef typename U::entry entry;
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Registry(); // Do not implement.
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static void Announce(const entry &E) {
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for (listener *Cur = ListenerHead; Cur; Cur = Cur->Next)
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static node *Head, *Tail;
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friend class listener;
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static listener *ListenerHead, *ListenerTail;
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/// Node in linked list of entries.
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friend class iterator;
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node(const entry& V) : Next(0), Val(V) {
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/// Iterators for registry entries.
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explicit iterator(const node *N) : Cur(N) {}
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bool operator==(const iterator &That) const { return Cur == That.Cur; }
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bool operator!=(const iterator &That) const { return Cur != That.Cur; }
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iterator &operator++() { Cur = Cur->Next; return *this; }
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const entry &operator*() const { return Cur->Val; }
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const entry *operator->() const { return &Cur->Val; }
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static iterator begin() { return iterator(Head); }
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static iterator end() { return iterator(0); }
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/// Abstract base class for registry listeners, which are informed when new
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/// entries are added to the registry. Simply subclass and instantiate:
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/// class CollectorPrinter : public Registry<Collector>::listener {
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/// void registered(const Registry<Collector>::entry &e) {
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/// cerr << "collector now available: " << e->getName() << "\n";
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/// CollectorPrinter() { init(); } // Print those already registered.
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/// CollectorPrinter Printer;
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listener *Prev, *Next;
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friend void Registry::Announce(const entry &E);
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/// Called when an entry is added to the registry.
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virtual void registered(const entry &) = 0;
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/// Calls 'registered' for each pre-existing entry.
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for (iterator I = begin(), E = end(); I != E; ++I)
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listener() : Prev(ListenerTail), Next(0) {
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virtual ~listener() {
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/// A static registration template. Use like such:
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/// Registry<Collector>::Add<FancyGC>
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/// X("fancy-gc", "Newfangled garbage collector.");
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/// Use of this template requires that:
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/// 1. The registered subclass has a default constructor.
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/// 2. The registry entry type has a constructor compatible with this
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/// entry(const char *Name, const char *ShortDesc, T *(*Ctor)());
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/// If you have more elaborate requirements, then copy and modify.
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template <typename V>
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static T *CtorFn() { return new V(); }
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Add(const char *Name, const char *Desc)
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: Entry(Name, Desc, CtorFn), Node(Entry) {}
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/// Registry::Parser now lives in llvm/Support/RegistryParser.h.
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template <typename T, typename U>
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typename Registry<T,U>::node *Registry<T,U>::Head;
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template <typename T, typename U>
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typename Registry<T,U>::node *Registry<T,U>::Tail;
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template <typename T, typename U>
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typename Registry<T,U>::listener *Registry<T,U>::ListenerHead;
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template <typename T, typename U>
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typename Registry<T,U>::listener *Registry<T,U>::ListenerTail;