include/clang/Lex/Pragma.h

//===--- Pragma.h - Pragma registration and handling ------------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines the PragmaHandler and PragmaTable interfaces.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_CLANG_PRAGMA_H
#define LLVM_CLANG_PRAGMA_H

#include <cassert>
#include <vector>

namespace clang {
  class Preprocessor;
  class Token;
  class IdentifierInfo;
  class PragmaNamespace;

/// PragmaHandler - Instances of this interface defined to handle the various
/// pragmas that the language front-end uses.  Each handler optionally has a
/// name (e.g. "pack") and the HandlePragma method is invoked when a pragma with
/// that identifier is found.  If a handler does not match any of the declared
/// pragmas the handler with a null identifier is invoked, if it exists.
///
/// Note that the PragmaNamespace class can be used to subdivide pragmas, e.g.
/// we treat "#pragma STDC" and "#pragma GCC" as namespaces that contain other
/// pragmas.
class PragmaHandler {
  const IdentifierInfo *Name;
public:
  PragmaHandler(const IdentifierInfo *name) : Name(name) {}
  virtual ~PragmaHandler();

  const IdentifierInfo *getName() const { return Name; }
  virtual void HandlePragma(Preprocessor &PP, Token &FirstToken) = 0;

  /// getIfNamespace - If this is a namespace, return it.  This is equivalent to
  /// using a dynamic_cast, but doesn't require RTTI.
  virtual PragmaNamespace *getIfNamespace() { return 0; }
};

/// PragmaNamespace - This PragmaHandler subdivides the namespace of pragmas,
/// allowing hierarchical pragmas to be defined.  Common examples of namespaces
/// are "#pragma GCC", "#pragma STDC", and "#pragma omp", but any namespaces may
/// be (potentially recursively) defined.
class PragmaNamespace : public PragmaHandler {
  /// Handlers - This is the list of handlers in this namespace.
  ///
  std::vector<PragmaHandler*> Handlers;
public:
  PragmaNamespace(const IdentifierInfo *Name) : PragmaHandler(Name) {}
  virtual ~PragmaNamespace();

  /// FindHandler - Check to see if there is already a handler for the
  /// specified name.  If not, return the handler for the null identifier if it
  /// exists, otherwise return null.  If IgnoreNull is true (the default) then
  /// the null handler isn't returned on failure to match.
  PragmaHandler *FindHandler(const IdentifierInfo *Name,
                             bool IgnoreNull = true) const;

  /// AddPragma - Add a pragma to this namespace.
  ///
  void AddPragma(PragmaHandler *Handler) {
    Handlers.push_back(Handler);
  }

  /// RemovePragmaHandler - Remove the given handler from the
  /// namespace.
  void RemovePragmaHandler(PragmaHandler *Handler);

  bool IsEmpty() {
    return Handlers.empty();
  }

  virtual void HandlePragma(Preprocessor &PP, Token &FirstToken);

  virtual PragmaNamespace *getIfNamespace() { return this; }
};


}  // end namespace clang

#endif