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) 1992-2012, 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 29with Types; use Types; 30package 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. If the tagged type associated with 50 -- Subp is a concurrent type (case that occurs when the type is declared in 51 -- a generic because the analysis of generics disables generation of the 52 -- corresponding record) then this routine does does not add "Subp" to the 53 -- list of primitive operations but leaves Subp decorated as dispatching 54 -- operation to enable checks associated with the Object.Operation notation 55 56 procedure Check_Operation_From_Incomplete_Type 57 (Subp : Entity_Id; 58 Typ : Entity_Id); 59 -- If a primitive operation was defined for the incomplete view of the 60 -- type, and the full type declaration is a derived type definition, 61 -- the operation may override an inherited one. 62 63 procedure Check_Operation_From_Private_View (Subp, Old_Subp : Entity_Id); 64 -- Add "Old_Subp" to the list of primitive operations of the corresponding 65 -- tagged type if it is the full view of a private tagged type. The Alias 66 -- of "OldSubp" is adjusted to point to the inherited procedure of the 67 -- full view because it is always this one which has to be called. 68 69 function Covers_Some_Interface (Prim : Entity_Id) return Boolean; 70 -- Returns true if Prim covers some interface primitive of its associated 71 -- tagged type. The tagged type of Prim must be frozen when this function 72 -- is invoked. 73 74 function Find_Controlling_Arg (N : Node_Id) return Node_Id; 75 -- Returns the actual controlling argument if N is dynamically tagged, 76 -- and Empty if it is not dynamically tagged. 77 78 function Find_Dispatching_Type (Subp : Entity_Id) return Entity_Id; 79 -- Check whether a subprogram is dispatching, and find the tagged type of 80 -- the controlling argument or arguments. Returns Empty if Subp is not a 81 -- dispatching operation. 82 83 function Find_Primitive_Covering_Interface 84 (Tagged_Type : Entity_Id; 85 Iface_Prim : Entity_Id) return Entity_Id; 86 -- Search in the homonym chain for the primitive of Tagged_Type that covers 87 -- Iface_Prim. The homonym chain traversal is required to catch primitives 88 -- associated with the partial view of private types when processing the 89 -- corresponding full view. If the entity is not found then search for it 90 -- in the list of primitives of Tagged_Type. This latter search is needed 91 -- when the interface primitive is covered by a private subprogram. If the 92 -- primitive has not been covered yet then return the entity that will be 93 -- overridden when the primitive is covered (that is, return the entity 94 -- whose alias attribute references the interface primitive). If none of 95 -- these entities is found then return Empty. 96 97 type Subprogram_List is array (Nat range <>) of Entity_Id; 98 -- Type returned by Inherited_Subprograms function 99 100 function Inherited_Subprograms (S : Entity_Id) return Subprogram_List; 101 -- Given the spec of a subprogram, this function gathers any inherited 102 -- subprograms from direct inheritance or via interfaces. The list is 103 -- a list of entity id's of the specs of inherited subprograms. Returns 104 -- a null array if passed an Empty spec id. Note that the returned array 105 -- only includes subprograms and generic subprograms (and excludes any 106 -- other inherited entities, in particular enumeration literals). 107 108 function Is_Dynamically_Tagged (N : Node_Id) return Boolean; 109 -- Used to determine whether a call is dispatching, i.e. if is an 110 -- an expression of a class_Wide type, or a call to a function with 111 -- controlling result where at least one operand is dynamically tagged. 112 113 function Is_Null_Interface_Primitive (E : Entity_Id) return Boolean; 114 -- Returns True if E is a null procedure that is an interface primitive 115 116 function Is_Tag_Indeterminate (N : Node_Id) return Boolean; 117 -- An expression is tag-indeterminate if it is a call that dispatches 118 -- on result, and all controlling operands are also indeterminate. 119 -- Such a function call may inherit a tag from an enclosing call. 120 121 procedure Override_Dispatching_Operation 122 (Tagged_Type : Entity_Id; 123 Prev_Op : Entity_Id; 124 New_Op : Entity_Id; 125 Is_Wrapper : Boolean := False); 126 -- Replace an implicit dispatching operation with an explicit one. 127 -- Prev_Op is an inherited primitive operation which is overridden 128 -- by the explicit declaration of New_Op. Is_Wrapper is True when 129 -- New_Op is an internally generated wrapper of a controlling function. 130 131 procedure Propagate_Tag (Control : Node_Id; Actual : Node_Id); 132 -- If a function call is tag-indeterminate, its controlling argument is 133 -- found in the context; either an enclosing call, or the left-hand side 134 -- of the enclosing assignment statement. The tag must be propagated 135 -- recursively to the tag-indeterminate actuals of the call. 136 137end Sem_Disp; 138