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/Basic/TokenKinds.h"
#include "clang/Parse/AccessSpecifier.h"

namespace clang {
  // Semantic.
  class DeclSpec;
  class ObjCDeclSpec;
  class Declarator;
  class AttributeList;
  class FieldDeclarator;
  // Parse.
  class Scope;
  class Action;
  class Selector;
  // Lex.
  class Token;

/// 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(), which must be
/// specified in order for the parse to complete accurately.  The EmptyAction
/// 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;
  
  /// 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) {}
    
    const ActionResult &operator=(void *RHS) {
      Val = RHS;
      isInvalid = false;
      return *this;
    }
  };

  /// Expr/Stmt/TypeResult - Provide a unique type to wrap ExprTy/StmtTy/TypeTy,
  /// providing strong typing and allowing for failure.
  typedef ActionResult<0> ExprResult;
  typedef ActionResult<1> StmtResult;
  typedef ActionResult<2> TypeResult;
  
  /// 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.
  virtual DeclTy *isTypeName(const IdentifierInfo &II, Scope *S) = 0;
  
  /// ActOnDeclarator - This callback is invoked when a declarator is parsed and
  /// 'Init' specifies the initializer if any.  This is for things like:
  /// "int X = 4" or "typedef int foo".
  ///
  /// LastInGroup is non-null for cases where one declspec has multiple
  /// declarators on it.  For example in 'int A, B', ActOnDeclarator will be
  /// called with LastInGroup=A when invoked for B.
  virtual DeclTy *ActOnDeclarator(Scope *S, Declarator &D,DeclTy *LastInGroup) {
    return 0;
  }

  /// ActOnParamDeclarator - This callback is invoked when a parameter
  /// declarator is parsed. This callback only occurs for functions
  /// with prototypes. S is the function prototype scope for the
  /// parameters (C++ [basic.scope.proto]).
  virtual DeclTy *ActOnParamDeclarator(Scope *S, Declarator &D) {
    return 0;
  }

  /// AddInitializerToDecl - This action is called immediately after 
  /// ParseDeclarator (when an initializer is present). The code is factored 
  /// this way to make sure we are able to handle the following:
  ///   void func() { int xx = xx; }
  /// This allows ActOnDeclarator to register "xx" prior to parsing the
  /// initializer. The declaration above should still result in a warning, 
  /// since the reference to "xx" is uninitialized.
  virtual void AddInitializerToDecl(DeclTy *Dcl, ExprTy *Init) {
    return;
  }
  /// FinalizeDeclaratorGroup - After a sequence of declarators are parsed, this
  /// gives the actions implementation a chance to process the group as a whole.
  virtual DeclTy *FinalizeDeclaratorGroup(Scope *S, DeclTy *Group) {
    return Group;
  }

  /// ActOnStartNamespaceDef - This is called at the start of a namespace
  /// definition.
  virtual DeclTy *ActOnStartNamespaceDef(Scope *S, SourceLocation IdentLoc,
                                        IdentifierInfo *Ident,
                                        SourceLocation LBrace) {
    return 0;
  }

  /// ActOnFinishNamespaceDef - This callback is called after a namespace is
  /// exited. Decl is the DeclTy returned by ActOnStartNamespaceDef.
  virtual void ActOnFinishNamespaceDef(DeclTy *Dcl,SourceLocation RBrace) {
    return;
  }

  /// ActOnStartOfFunctionDef - This is called at the start of a function
  /// definition, instead of calling ActOnDeclarator.  The Declarator includes
  /// information about formal arguments that are part of this function.
  virtual DeclTy *ActOnStartOfFunctionDef(Scope *FnBodyScope, Declarator &D) {
    // Default to ActOnDeclarator.
    return ActOnDeclarator(FnBodyScope, D, 0);
  }

  virtual void ObjCActOnStartOfMethodDef(Scope *FnBodyScope, DeclTy *D) {
    return;
  }
  
  /// ActOnFunctionDefBody - This is called when a function body has completed
  /// parsing.  Decl is the DeclTy returned by ParseStartOfFunctionDef.
  virtual DeclTy *ActOnFinishFunctionBody(DeclTy *Decl, StmtTy *Body) {
    return Decl;
  }

  virtual DeclTy *ActOnFileScopeAsmDecl(SourceLocation Loc, ExprTy *AsmString) {
    return 0;
  }
  
  /// ActOnPopScope - This callback is called immediately before the specified
  /// scope is popped and deleted.
  virtual void ActOnPopScope(SourceLocation Loc, Scope *S) {}

  /// ActOnTranslationUnitScope - This callback is called once, immediately
  /// after creating the translation unit scope (in Parser::Initialize).
  virtual void ActOnTranslationUnitScope(SourceLocation Loc, Scope *S) {}
    
  /// ParsedFreeStandingDeclSpec - This method is invoked when a declspec with
  /// no declarator (e.g. "struct foo;") is parsed.
  virtual DeclTy *ParsedFreeStandingDeclSpec(Scope *S, DeclSpec &DS) {
    return 0;
  }

  virtual DeclTy *ActOnLinkageSpec(SourceLocation Loc, SourceLocation LBrace,
                                   SourceLocation RBrace, const char *Lang,
                                   unsigned StrSize, DeclTy *D) {
    return 0;
  }
  
  //===--------------------------------------------------------------------===//
  // Type Parsing Callbacks.
  //===--------------------------------------------------------------------===//
  
  virtual TypeResult ActOnTypeName(Scope *S, Declarator &D) {
    return 0;
  }
  
  enum TagKind {
    TK_Reference,   // Reference to a tag:  'struct foo *X;'