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) 1992-2008, 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 3,  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 COPYING3.  If not, go to --
  19 -- http://www.gnu.org/licenses for a complete copy of the license.          --
  20 --                                                                          --
  21 -- GNAT was originally developed  by the GNAT team at  New York University. --
  22 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  23 --                                                                          --
  24 ------------------------------------------------------------------------------
  25
  26 --  This package contains routines involved in tagged types and dynamic
  27 --  dispatching.
  28
  29 with Types; use Types;
  30 package Sem_Disp is
  31
  32    procedure Check_Controlling_Formals (Typ : Entity_Id; Subp : Entity_Id);
  33    --  Check that all controlling parameters of Subp are of type Typ,
  34    --  that defaults for controlling parameters are tag-indeterminate,
  35    --  and that the nominal subtype of the parameters and result
  36    --  statically match the first subtype of the controlling type.
  37
  38    procedure Check_Dispatching_Call (N : Node_Id);
  39    --  Check if a call is a dispatching call. The subprogram is known to
  40    --  be a dispatching operation. The call is dispatching if all the
  41    --  controlling actuals are dynamically tagged. This procedure is called
  42    --  after overload resolution, so the call is known to be unambiguous.
  43
  44    procedure Check_Dispatching_Operation (Subp, Old_Subp : Entity_Id);
  45    --  Add "Subp" to the list of primitive operations of the corresponding type
  46    --  if it has a parameter of this type and is defined at a proper place for
  47    --  primitive operations (new primitives are only defined in package spec,
  48    --  overridden operation can be defined in any scope). If Old_Subp is not
  49    --  Empty we are in the overriding case.
  50
  51    procedure Check_Operation_From_Incomplete_Type
  52      (Subp : Entity_Id;
  53       Typ  : Entity_Id);
  54    --  If a primitive operation was defined for the incomplete view of the
  55    --  type, and the full type declaration is a derived type definition,
  56    --  the operation may override an inherited one.
  57
  58    procedure Check_Operation_From_Private_View (Subp, Old_Subp : Entity_Id);
  59    --  Add "Old_Subp" to the list of primitive operations of the corresponding
  60    --  tagged type if it is the full view of a private tagged type. The Alias
  61    --  of "OldSubp" is adjusted to point to the inherited procedure of the
  62    --  full view because it is always this one which has to be called.
  63
  64    function Find_Controlling_Arg (N : Node_Id) return Node_Id;
  65    --  Returns the actual controlling argument if N is dynamically tagged,
  66    --  and Empty if it is not dynamically tagged.
  67
  68    function Find_Dispatching_Type (Subp : Entity_Id) return Entity_Id;
  69    --  Check whether a subprogram is dispatching, and find the tagged
  70    --  type of the controlling argument or arguments.
  71
  72    function Find_Primitive_Covering_Interface
  73      (Tagged_Type : Entity_Id;
  74       Iface_Prim  : Entity_Id) return Entity_Id;
  75    --  Search in the homonym chain for the primitive of Tagged_Type that
  76    --  covers Iface_Prim. The homonym chain traversal is required to catch
  77    --  primitives associated with the partial view of private types when
  78    --  processing the corresponding full view.
  79
  80    function Is_Dynamically_Tagged (N : Node_Id) return Boolean;
  81    --  Used to determine whether a call is dispatching, i.e. if is an
  82    --  an expression of a class_Wide type, or a call to a function with
  83    --  controlling result where at least one operand is dynamically tagged.
  84
  85    function Is_Tag_Indeterminate (N : Node_Id) return Boolean;
  86    --  An expression is tag-indeterminate if it is a call that dispatches
  87    --  on result, and all controlling operands are also indeterminate.
  88    --  Such a function call may inherit a tag from an enclosing call.
  89
  90    procedure Override_Dispatching_Operation
  91      (Tagged_Type : Entity_Id;
  92       Prev_Op     : Entity_Id;
  93       New_Op      : Entity_Id);
  94    --  Replace an implicit dispatching operation with an explicit one.
  95    --  Prev_Op is an inherited primitive operation which is overridden
  96    --  by the explicit declaration of New_Op.
  97
  98    procedure Propagate_Tag (Control : Node_Id; Actual : Node_Id);
  99    --  If a function call is tag-indeterminate,  its controlling argument is
 100    --  found in the context;  either an enclosing call, or the left-hand side
 101    --  of the enclosing assignment statement. The tag must be propagated
 102    --  recursively to the tag-indeterminate actuals of the call.
 103
 104 end Sem_Disp;