------------------------------------------------------------------------------ -- -- -- GNAT COMPILER COMPONENTS -- -- -- -- E X P _ T S S -- -- -- -- S p e c -- -- -- -- Copyright (C) 1992-2005, 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 2, 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 COPYING. If not, write -- -- to the Free Software Foundation, 51 Franklin Street, Fifth Floor, -- -- Boston, MA 02110-1301, USA. -- -- -- -- GNAT was originally developed by the GNAT team at New York University. -- -- Extensive contributions were provided by Ada Core Technologies Inc. -- -- -- ------------------------------------------------------------------------------ -- Type Support Subprogram (TSS) handling with Types; use Types; package Exp_Tss is -- A type support subprogram (TSS) is an internally generated function or -- procedure that is associated with a particular type. Examples are the -- implicit initialization procedure, and subprograms for the Input and -- Output attributes. -- A given TSS is either generated once at the point of the declaration of -- the type, or it is generated as needed in clients, but only one copy is -- required in any one generated object file. The choice between these two -- possibilities is made on a TSS-by-TSS basis depending on the estimation -- of how likely the TSS is to be used. Initialization procedures fall in -- the first category, for example, since it is likely that any declared -- type will be used in a context requiring initialization, but the stream -- attributes use the second approach, since it is more likely that they -- will not be used at all, or will only be used in one client in any case. ------------------------- -- Current Limitations -- ------------------------- -- In the current version of this package, only the case of generating a -- TSS at the point of declaration of the type is accomodated. A clear -- improvement would be to follow through with the full implementation -- as described above, and also accomodate the requirement of generating -- only one copy in a given object file. -- For now, we deal with the local case by generating duplicate versions -- of the TSS routine, which is clearly rather inefficient in space usage. -- This is done by using Make_TSS_Name_Local to generate unique names -- for the different instances of TSS routines in a given scope. ---------------- -- TSS Naming -- ---------------- -- A TSS is identified by its Chars name. The name has the form typXY or -- typ_XY, where typ is the type name, and XY are two characters -- that identify the particular TSS routine. A unique serial number is -- included for the case where several local instances of the same TSS -- must be generated (see discussion under Make_TSS_Name_Local). -- The following codes are used to denote TSSs: -- Note: When making additions to this list, update the list in snames.adb type TSS_Name_Type is new String (1 .. 2); subtype TNT is TSS_Name_Type; TSS_Deep_Adjust : constant TNT := "DA"; -- Deep Adjust TSS_Deep_Finalize : constant TNT := "DF"; -- Deep Finalize TSS_Deep_Initialize : constant TNT := "DI"; -- Deep Initialize TSS_Composite_Equality : constant TNT := "EQ"; -- Composite Equality TSS_From_Any : constant TNT := "FA"; -- PolyORB/DSA From_Any TSS_Init_Proc : constant TNT := "IP"; -- Initialization Procedure TSS_RAS_Access : constant TNT := "RA"; -- RAS type access TSS_RAS_Dereference : constant TNT := "RD"; -- RAS type deference TSS_Rep_To_Pos : constant TNT := "RP"; -- Rep to Pos conversion TSS_Slice_Assign : constant TNT := "SA"; -- Slice assignment TSS_Stream_Input : constant TNT := "SI"; -- Stream Input attribute TSS_Stream_Output : constant TNT := "SO"; -- Stream Output attribute TSS_Stream_Read : constant TNT := "SR"; -- Stream Read attribute TSS_Stream_Write : constant TNT := "SW"; -- Stream Write attribute TSS_To_Any : constant TNT := "TA"; -- PolyORB/DSA To_Any TSS_TypeCode : constant TNT := "TC"; -- PolyORB/DSA TypeCode -- The array below contains all valid TSS names TSS_Names : constant array (Natural range <>) of TSS_Name_Type := (TSS_Deep_Adjust, TSS_Deep_Finalize, TSS_Deep_Initialize, TSS_Composite_Equality, TSS_From_Any, TSS_Init_Proc, TSS_RAS_Access, TSS_RAS_Dereference, TSS_Rep_To_Pos, TSS_Slice_Assign, TSS_Stream_Input, TSS_Stream_Output, TSS_Stream_Read, TSS_Stream_Write, TSS_To_Any, TSS_TypeCode); TSS_Null : constant TNT := " "; -- Dummy entry used to indicated that this is not really a TSS function Get_TSS_Name (E : Entity_Id) return TSS_Name_Type; -- Given an entity, if it is a TSS, then return the corresponding TSS -- name type, otherwise return TSS_Null. function Make_TSS_Name (Typ : Entity_Id; Nam : TSS_Name_Type) return Name_Id; -- Construct the name as described above for the given TSS routine -- identified by Nam for the type identified by Typ. function Make_TSS_Name_Local (Typ : Entity_Id; Nam : TSS_Name_Type) return Name_Id; -- Similar to the above call, but a string of the form _nnn is inserted -- before the TSS code suffix, where nnn is a unique serial number. This -- is used when multiple instances of the same TSS routine may be -- generated in the same scope (see also discussion above of current -- limitations). function Make_Init_Proc_Name (Typ : Entity_Id) return Name_Id; -- Version for init procs, same as Make_TSS_Name (Typ, TSS_Init_Proc) function Is_TSS (E : Entity_Id; Nam : TSS_Name_Type) return Boolean; -- Determines if given entity (E) is the name of a TSS identified by Nam function Is_TSS (N : Name_Id; Nam : TSS_Name_Type) return Boolean; -- Same test applied directly to a Name_Id value function Is_Init_Proc (E : Entity_Id) return Boolean; -- Version for init procs, same as Is_TSS (E, TSS_Init_Proc); ----------------------------------------- -- TSS Data structures and Subprograms -- ----------------------------------------- -- The TSS's for a given type are stored in an element list associated with -- the type, and referenced from the TSS_Elist field of the N_Freeze_Entity -- node associated with the type (all types that need TSS's always need to -- be explicitly frozen, so the N_Freeze_Entity node always exists). function TSS (Typ : Entity_Id; Nam : TSS_Name_Type) return Entity_Id; -- Finds the TSS with the given name associated with the given type -- If no such TSS exists, then Empty is returned; function TSS (Typ : Entity_Id; Nam : Name_Id) return Entity_Id; -- Finds the TSS with the given name associated with the given type. If -- no such TSS exists, then Empty is returned. function Same_TSS (E1, E2 : Entity_Id) return Boolean; -- Returns True if E1 and E2 are the same kind of TSS, even if the names -- are different (i.e. if the names of E1 and E2 end with two upper case -- letters that are the same). procedure Set_TSS (Typ : Entity_Id; TSS : Entity_Id); -- This procedure is used to install a newly created TSS. The second -- argument is the entity for such a new TSS. This entity is placed in -- the TSS list for the type given as the first argument, replacing an -- old entry of the same name if one was present. The tree for the body -- of this TSS, which is not analyzed yet, is placed in the actions field -- of the freeze node for the type. All such bodies are inserted into the -- main tree and analyzed at the point at which the freeze node itself is -- is expanded. procedure Copy_TSS (TSS : Entity_Id; Typ : Entity_Id); -- Given an existing TSS for another type (which is already installed, -- analyzed and expanded), install it as the corresponding TSS for Typ. -- Note that this just copies a reference, not the tree. This can also -- be used to initially install a TSS in the case where the subprogram -- for the TSS has already been created and its declaration processed. function Init_Proc (Typ : Entity_Id) return Entity_Id; pragma Inline (Init_Proc); -- Obtains the _init TSS entry for the given type. This function call is -- equivalent to TSS (Typ, Name_uInit). The _init TSS is the procedure -- used to initialize otherwise uninitialized instances of a type. If -- there is no _init TSS, then the type requires no initialization. Note -- that subtypes and implicit types never have an _init TSS since subtype -- objects are always initialized using the initialization procedure for -- the corresponding base type (see Base_Init_Proc function). A special -- case arises for concurrent types. Such types do not themselves have an -- init proc TSS, but initialization is required. The init proc used is -- the one fot the corresponding record type (see Base_Init_Proc). function Base_Init_Proc (Typ : Entity_Id) return Entity_Id; -- Obtains the _Init TSS entry from the base type of the entity, and also -- deals with going indirect through the Corresponding_Record_Type field -- for concurrent objects (which are initialized with the initialization -- routine for the corresponding record type). Returns Empty if there is -- no _Init TSS entry for the base type. procedure Set_Init_Proc (Typ : Entity_Id; Init : Entity_Id); pragma Inline (Set_Init_Proc); -- The second argument is the _init TSS to be established for the type -- given as the first argument. Equivalent to Set_TSS (Typ, Init). function Has_Non_Null_Base_Init_Proc (Typ : Entity_Id) return Boolean; -- Returns true if the given type has a defined Base_Init_Proc and -- this init proc is not a null init proc (null init procs occur as -- a result of the processing for Initialize_Scalars. This function -- is used to test for the presence of an init proc in cases where -- a null init proc is considered equivalent to no init proc. function Find_Inherited_TSS (Typ : Entity_Id; Nam : TSS_Name_Type) return Entity_Id; -- Returns the TSS of name Nam of Typ, or of its closest ancestor defining -- such a TSS. Empty is returned is neither Typ nor any of its ancestors -- have such a TSS. end Exp_Tss;