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------------------------------------------------------------------------------
-- --
-- GNAT COMPILER COMPONENTS --
-- --
-- S E M _ D I S P --
-- --
-- S p e c --
-- --
-- Copyright (C) 1992-2010, Free Software Foundation, Inc. --
-- --
-- GNAT is free software; you can redistribute it and/or modify it under --
-- terms of the GNU General Public License as published by the Free Soft- --
-- ware Foundation; either version 3, or (at your option) any later ver- --
-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
-- for more details. You should have received a copy of the GNU General --
-- Public License distributed with GNAT; see file COPYING3. If not, go to --
-- http://www.gnu.org/licenses for a complete copy of the license. --
-- --
-- GNAT was originally developed by the GNAT team at New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc. --
-- --
------------------------------------------------------------------------------
-- This package contains routines involved in tagged types and dynamic
-- dispatching.
with Types; use Types;
package Sem_Disp is
procedure Check_Controlling_Formals (Typ : Entity_Id; Subp : Entity_Id);
-- Check that all controlling parameters of Subp are of type Typ,
-- that defaults for controlling parameters are tag-indeterminate,
-- and that the nominal subtype of the parameters and result
-- statically match the first subtype of the controlling type.
procedure Check_Dispatching_Call (N : Node_Id);
-- Check if a call is a dispatching call. The subprogram is known to
-- be a dispatching operation. The call is dispatching if all the
-- controlling actuals are dynamically tagged. This procedure is called
-- after overload resolution, so the call is known to be unambiguous.
procedure Check_Dispatching_Operation (Subp, Old_Subp : Entity_Id);
-- Add "Subp" to the list of primitive operations of the corresponding type
-- if it has a parameter of this type and is defined at a proper place for
-- primitive operations (new primitives are only defined in package spec,
-- overridden operation can be defined in any scope). If Old_Subp is not
-- Empty we are in the overriding case. If the tagged type associated with
-- Subp is a concurrent type (case that occurs when the type is declared in
-- a generic because the analysis of generics disables generation of the
-- corresponding record) then this routine does does not add "Subp" to the
-- list of primitive operations but leaves Subp decorated as dispatching
-- operation to enable checks associated with the Object.Operation notation
procedure Check_Operation_From_Incomplete_Type
(Subp : Entity_Id;
Typ : Entity_Id);
-- If a primitive operation was defined for the incomplete view of the
-- type, and the full type declaration is a derived type definition,
-- the operation may override an inherited one.
procedure Check_Operation_From_Private_View (Subp, Old_Subp : Entity_Id);
-- Add "Old_Subp" to the list of primitive operations of the corresponding
-- tagged type if it is the full view of a private tagged type. The Alias
-- of "OldSubp" is adjusted to point to the inherited procedure of the
-- full view because it is always this one which has to be called.
function Covers_Some_Interface (Prim : Entity_Id) return Boolean;
-- Returns true if Prim covers some interface primitive of its associated
-- tagged type. The tagged type of Prim must be frozen when this function
-- is invoked.
function Find_Controlling_Arg (N : Node_Id) return Node_Id;
-- Returns the actual controlling argument if N is dynamically tagged,
-- and Empty if it is not dynamically tagged.
function Find_Dispatching_Type (Subp : Entity_Id) return Entity_Id;
-- Check whether a subprogram is dispatching, and find the tagged
-- type of the controlling argument or arguments.
function Find_Primitive_Covering_Interface
(Tagged_Type : Entity_Id;
Iface_Prim : Entity_Id) return Entity_Id;
-- Search in the homonym chain for the primitive of Tagged_Type that covers
-- Iface_Prim. The homonym chain traversal is required to catch primitives
-- associated with the partial view of private types when processing the
-- corresponding full view. If the entity is not found then search for it
-- in the list of primitives of Tagged_Type. This latter search is needed
-- when the interface primitive is covered by a private subprogram. If the
-- primitive has not been covered yet then return the entity that will be
-- overriden when the primitive is covered (that is, return the entity
-- whose alias attribute references the interface primitive). If none of
-- these entities is found then return Empty.
type Subprogram_List is array (Nat range <>) of Entity_Id;
-- Type returned by Inherited_Subprograms function
function Inherited_Subprograms (S : Entity_Id) return Subprogram_List;
-- Given the spec of a subprogram, this function gathers any inherited
-- subprograms from direct inheritance or via interfaces. The list is
-- a list of entity id's of the specs of inherited subprograms. Returns
-- a null array if passed an Empty spec id. Note that the returned array
-- only includes subprograms and generic subprograms (and excludes any
-- other inherited entities, in particular enumeration literals).
function Is_Dynamically_Tagged (N : Node_Id) return Boolean;
-- Used to determine whether a call is dispatching, i.e. if is an
-- an expression of a class_Wide type, or a call to a function with
-- controlling result where at least one operand is dynamically tagged.
function Is_Null_Interface_Primitive (E : Entity_Id) return Boolean;
-- Returns True if E is a null procedure that is an interface primitive
function Is_Tag_Indeterminate (N : Node_Id) return Boolean;
-- An expression is tag-indeterminate if it is a call that dispatches
-- on result, and all controlling operands are also indeterminate.
-- Such a function call may inherit a tag from an enclosing call.
procedure Override_Dispatching_Operation
(Tagged_Type : Entity_Id;
Prev_Op : Entity_Id;
New_Op : Entity_Id);
-- Replace an implicit dispatching operation with an explicit one.
-- Prev_Op is an inherited primitive operation which is overridden
-- by the explicit declaration of New_Op.
procedure Propagate_Tag (Control : Node_Id; Actual : Node_Id);
-- If a function call is tag-indeterminate, its controlling argument is
-- found in the context; either an enclosing call, or the left-hand side
-- of the enclosing assignment statement. The tag must be propagated
-- recursively to the tag-indeterminate actuals of the call.
end Sem_Disp;
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