path: root/include/clang/Parse/Action.h

//===--- Action.h - Parser Action Interface ---------------------*- 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 Action and EmptyAction interface.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_CLANG_PARSE_ACTION_H
#define LLVM_CLANG_PARSE_ACTION_H

#include "clang/Basic/IdentifierTable.h"
#include "clang/Basic/SourceLocation.h"
#include "clang/Parse/AccessSpecifier.h"

namespace clang {
  // Semantic.
  class DeclSpec;
  class ObjCDeclSpec;
  class CXXScopeSpec;
  class Declarator;
  class AttributeList;
  struct FieldDeclarator;
  // Parse.
  class Scope;
  class Action;
  class Selector;
  class InitListDesignations;
  // Lex.
  class Preprocessor;
  class Token;
  // Basic.
  class DiagnosticBuilder;

/// Action - As the parser reads the input file and recognizes the productions
/// of the grammar, it invokes methods on this class to turn the parsed input
/// into something useful: e.g. a parse tree.
///
/// The callback methods that this class provides are phrased as actions that
/// the parser has just done or is about to do when the method is called.  They
/// are not requests that the actions module do the specified action.
///
/// All of the methods here are optional except isTypeName() and
/// isCurrentClassName(), which must be specified in order for the
/// parse to complete accurately.  The MinimalAction class does this
/// bare-minimum of tracking to implement this functionality.
class Action {
public:
  /// Out-of-line virtual destructor to provide home for this class.
  virtual ~Action();
  
  // Types - Though these don't actually enforce strong typing, they document
  // what types are required to be identical for the actions.
  typedef void ExprTy;
  typedef void StmtTy;
  typedef void DeclTy;
  typedef void TypeTy;
  typedef void AttrTy;
  typedef void BaseTy;
  typedef void MemInitTy;
  typedef void CXXScopeTy;

  /// ActionResult - This structure is used while parsing/acting on expressions,
  /// stmts, etc.  It encapsulates both the object returned by the action, plus
  /// a sense of whether or not it is valid.
  template<unsigned UID>
  struct ActionResult {
    void *Val;
    bool isInvalid;
    
    ActionResult(bool Invalid = false) : Val(0), isInvalid(Invalid) {}
    template<typename ActualExprTy>
    ActionResult(ActualExprTy *val) : Val(val), isInvalid(false) {}
    ActionResult(const DiagnosticBuilder &) : Val(0), isInvalid(true) {}
    
    const ActionResult &operator=(void *RHS) {
      Val = RHS;
      isInvalid = false;
      return *this;
    }
  };

  /// Expr/Stmt/Type/BaseResult - Provide a unique type to wrap
  /// ExprTy/StmtTy/TypeTy/BaseTy, providing strong typing and
  /// allowing for failure.
  typedef ActionResult<0> ExprResult;
  typedef ActionResult<1> StmtResult;
  typedef ActionResult<2> TypeResult;
  typedef ActionResult<3> BaseResult;
  typedef ActionResult<4> MemInitResult;

  /// Deletion callbacks - Since the parser doesn't know the concrete types of
  /// the AST nodes being generated, it must do callbacks to delete objects when
  /// recovering from errors.
  virtual void DeleteExpr(ExprTy *E) {}
  virtual void DeleteStmt(StmtTy *E) {}
  
  /// Statistics.
  virtual void PrintStats() const {}
  //===--------------------------------------------------------------------===//
  // Declaration Tracking Callbacks.
  //===--------------------------------------------------------------------===//
  
  /// isTypeName - Return non-null if the specified identifier is a typedef name
  /// in the current scope.
  /// An optional CXXScopeSpec can be passed to indicate the C++ scope (class or
  /// namespace) that the identifier must be a member of.
  /// i.e. for "foo::bar", 'II' will be "bar" and 'SS' will be "foo::".
  virtual TypeTy *isTypeName(IdentifierInfo &II, Scope *S,
                             const CXXScopeSpec *SS = 0) = 0;

  /// isCurrentClassName - Return true if the specified name is the
  /// name of the innermost C++ class type currently being defined.
  virtual bool isCurrentClassName(const IdentifierInfo &II, Scope *S,
                                  const CXXScopeSpec *SS = 0) = 0;

  /// ActOnCXXGlobalScopeSpecifier - Return the object that represents the
  /// global scope