gcc/ada/sem_disp.ads

   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,  51  Franklin  Street,  Fifth  Floor, --
  20 -- Boston, MA 02110-1301, 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
  30 with Types; use Types;
  31 package 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
  89 end Sem_Disp;