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 --                                                                          --
  10 --          Copyright (C) 1992-1999 Free Software Foundation, Inc.          --
  11 --                                                                          --
  12 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  13 -- terms of the  GNU General Public License as published  by the Free Soft- --
  14 -- ware  Foundation;  either version 2,  or (at your option) any later ver- --
  15 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  16 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  17 -- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
  18 -- for  more details.  You should have  received  a copy of the GNU General --
  19 -- Public License  distributed with GNAT;  see file COPYING.  If not, write --
  20 -- to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, --
  21 -- MA 02111-1307, USA.                                                      --
  22 --                                                                          --
  23 -- GNAT was originally developed  by the GNAT team at  New York University. --
  24 -- It is now maintained by Ada Core Technologies Inc (http://www.gnat.com). --
  25 --                                                                          --
  26 ------------------------------------------------------------------------------
  27
  28 --  This package contains routines involved in tagged types and dynamic
  29 --  dispatching.
  30
  31 with Types; use Types;
  32 package Sem_Disp is
  33
  34    procedure Check_Controlling_Formals (Typ : Entity_Id; Subp : Entity_Id);
  35    --  Check that all controlling parameters of Subp are of type Typ,
  36    --  that defaults for controlling parameters are tag-indeterminate,
  37    --  and that the nominal subtype of the parameters and result
  38    --  statically match the first subtype of the controlling type.
  39
  40    procedure Check_Dispatching_Call (N : Node_Id);
  41    --  Check if a call is a dispatching call. The subprogram is known to
  42    --  be a dispatching operation. The call is dispatching if all the
  43    --  controlling actuals are dynamically tagged. This procedure is called
  44    --  after overload resolution, so the call is known to be unambiguous.
  45
  46    procedure Check_Dispatching_Operation (Subp, Old_Subp : Entity_Id);
  47    --  Add "Subp" to the list of primitive operations of the corresponding type
  48    --  if it has a parameter of this type and is defined at a proper place for
  49    --  primitive operations. (new primitives are only defined in package spec,
  50    --  overridden operation can be defined in any scope). If Old_Subp is not
  51    --  Empty we are in the overriding case.
  52
  53    procedure Check_Operation_From_Incomplete_Type
  54      (Subp : Entity_Id;
  55       Typ  : Entity_Id);
  56    --  If a primitive operation was defined for the incomplete view of the
  57    --  type, and the full type declaration is a derived type definition,
  58    --  the operation may override an inherited one.
  59
  60    procedure Check_Operation_From_Private_View (Subp, Old_Subp : Entity_Id);
  61    --  Add "Old_Subp" to the list of primitive operations of the corresponding
  62    --  tagged type if it is the full view of a private tagged type. The Alias
  63    --  of "OldSubp" is adjusted to point to the inherited procedure of the
  64    --  full view because it is always this one which has to be called.
  65
  66    function Find_Controlling_Arg (N : Node_Id) return Node_Id;
  67    --  Returns the actual controlling argument if N is dynamically tagged,
  68    --  and Empty if it is not dynamically tagged.
  69
  70    function Find_Dispatching_Type (Subp : Entity_Id) return Entity_Id;
  71    --  Check whether a subprogram is dispatching, and find the tagged
  72    --  type of the controlling argument or arguments.
  73
  74    function Is_Dynamically_Tagged (N : Node_Id) return Boolean;
  75    --  Used to determine whether a call is dispatching, i.e. if is an
  76    --  an expression of a class_Wide type, or a call to a function with
  77    --  controlling result where at least one operand is dynamically tagged.
  78
  79    function Is_Tag_Indeterminate (N : Node_Id) return Boolean;
  80    --  An expression is tag-indeterminate if it is a call that dispatches
  81    --  on result, and all controlling operands are also indeterminate.
  82    --  Such a function call may inherit a tag from an enclosing call.
  83
  84    procedure Propagate_Tag (Control : Node_Id; Actual : Node_Id);
  85    --  If a function call is tag-indeterminate,  its controlling argument is
  86    --  found in the context;  either an enclosing call, or the left-hand side
  87    --  of the enclosing assignment statement. The tag must be propagated
  88    --  recursively to the tag-indeterminate actuals of the call.
  89
  90 end Sem_Disp;