1------------------------------------------------------------------------------
2--                                                                          --
3--                         GNAT COMPILER COMPONENTS                         --
4--                                                                          --
5--                             S E M _ D I S P                              --
6--                                                                          --
7--                                 S p e c                                  --
8--                                                                          --
9--          Copyright (C) 1992-2002 Free Software Foundation, Inc.          --
10--                                                                          --
11-- GNAT is free software;  you can  redistribute it  and/or modify it under --
12-- terms of the  GNU General Public License as published  by the Free Soft- --
13-- ware  Foundation;  either version 2,  or (at your option) any later ver- --
14-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
15-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
16-- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
17-- for  more details.  You should have  received  a copy of the GNU General --
18-- Public License  distributed with GNAT;  see file COPYING.  If not, write --
19-- to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, --
20-- MA 02111-1307, USA.                                                      --
21--                                                                          --
22-- GNAT was originally developed  by the GNAT team at  New York University. --
23-- Extensive contributions were provided by Ada Core Technologies Inc.      --
24--                                                                          --
25------------------------------------------------------------------------------
26
27--  This package contains routines involved in tagged types and dynamic
28--  dispatching.
29
30with Types; use Types;
31package Sem_Disp is
32
33   procedure Check_Controlling_Formals (Typ : Entity_Id; Subp : Entity_Id);
34   --  Check that all controlling parameters of Subp are of type Typ,
35   --  that defaults for controlling parameters are tag-indeterminate,
36   --  and that the nominal subtype of the parameters and result
37   --  statically match the first subtype of the controlling type.
38
39   procedure Check_Dispatching_Call (N : Node_Id);
40   --  Check if a call is a dispatching call. The subprogram is known to
41   --  be a dispatching operation. The call is dispatching if all the
42   --  controlling actuals are dynamically tagged. This procedure is called
43   --  after overload resolution, so the call is known to be unambiguous.
44
45   procedure Check_Dispatching_Operation (Subp, Old_Subp : Entity_Id);
46   --  Add "Subp" to the list of primitive operations of the corresponding type
47   --  if it has a parameter of this type and is defined at a proper place for
48   --  primitive operations (new primitives are only defined in package spec,
49   --  overridden operation can be defined in any scope). If Old_Subp is not
50   --  Empty we are in the overriding case.
51
52   procedure Check_Operation_From_Incomplete_Type
53     (Subp : Entity_Id;
54      Typ  : Entity_Id);
55   --  If a primitive operation was defined for the incomplete view of the
56   --  type, and the full type declaration is a derived type definition,
57   --  the operation may override an inherited one.
58
59   procedure Check_Operation_From_Private_View (Subp, Old_Subp : Entity_Id);
60   --  Add "Old_Subp" to the list of primitive operations of the corresponding
61   --  tagged type if it is the full view of a private tagged type. The Alias
62   --  of "OldSubp" is adjusted to point to the inherited procedure of the
63   --  full view because it is always this one which has to be called.
64
65   function Find_Controlling_Arg (N : Node_Id) return Node_Id;
66   --  Returns the actual controlling argument if N is dynamically tagged,
67   --  and Empty if it is not dynamically tagged.
68
69   function Find_Dispatching_Type (Subp : Entity_Id) return Entity_Id;
70   --  Check whether a subprogram is dispatching, and find the tagged
71   --  type of the controlling argument or arguments.
72
73   function Is_Dynamically_Tagged (N : Node_Id) return Boolean;
74   --  Used to determine whether a call is dispatching, i.e. if is an
75   --  an expression of a class_Wide type, or a call to a function with
76   --  controlling result where at least one operand is dynamically tagged.
77
78   function Is_Tag_Indeterminate (N : Node_Id) return Boolean;
79   --  An expression is tag-indeterminate if it is a call that dispatches
80   --  on result, and all controlling operands are also indeterminate.
81   --  Such a function call may inherit a tag from an enclosing call.
82
83   procedure Propagate_Tag (Control : Node_Id; Actual : Node_Id);
84   --  If a function call is tag-indeterminate,  its controlling argument is
85   --  found in the context;  either an enclosing call, or the left-hand side
86   --  of the enclosing assignment statement. The tag must be propagated
87   --  recursively to the tag-indeterminate actuals of the call.
88
89end Sem_Disp;
90