1------------------------------------------------------------------------------
2--                                                                          --
3--                         GNAT COMPILER COMPONENTS                         --
4--                                                                          --
5--                              E X P _ T S S                               --
6--                                                                          --
7--                                 S p e c                                  --
8--                                                                          --
9--          Copyright (C) 1992-2011, 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--  Type Support Subprogram (TSS) handling
27
28with Namet; use Namet;
29with Types; use Types;
30
31package Exp_Tss is
32
33   --  A type support subprogram (TSS) is an internally generated function or
34   --  procedure that is associated with a particular type. Examples are the
35   --  implicit initialization procedure, and subprograms for the Input and
36   --  Output attributes.
37
38   --  A given TSS is either generated once at the point of the declaration of
39   --  the type, or it is generated as needed in clients, but only one copy is
40   --  required in any one generated object file. The choice between these two
41   --  possibilities is made on a TSS-by-TSS basis depending on the estimation
42   --  of how likely the TSS is to be used. Initialization procedures fall in
43   --  the first category, for example, since it is likely that any declared
44   --  type will be used in a context requiring initialization, but the stream
45   --  attributes use the second approach, since it is more likely that they
46   --  will not be used at all, or will only be used in one client in any case.
47
48   -------------------------
49   -- Current Limitations --
50   -------------------------
51
52   --  In the current version of this package, only the case of generating a
53   --  TSS at the point of declaration of the type is accommodated. A clear
54   --  improvement would be to follow through with the full implementation
55   --  as described above, and also accommodate the requirement of generating
56   --  only one copy in a given object file.
57
58   --  For now, we deal with the local case by generating duplicate versions
59   --  of the TSS routine, which is clearly rather inefficient in space usage.
60   --  This is done by using Make_TSS_Name_Local to generate unique names
61   --  for the different instances of TSS routines in a given scope.
62
63   ----------------
64   -- TSS Naming --
65   ----------------
66
67   --  A TSS is identified by its Chars name. The name has the form typXY or
68   --  typ_<serial>XY, where typ is the type name, and XY are two characters
69   --  that identify the particular TSS routine. A unique serial number is
70   --  included for the case where several local instances of the same TSS
71   --  must be generated (see discussion under Make_TSS_Name_Local).
72
73   --  The following codes are used to denote TSSs:
74
75   --  Note: When making additions to this list, make the corresponding change
76   --  to the list in snames.adb-tmpl.
77
78   type TSS_Name_Type is new String (1 .. 2);
79   subtype TNT is TSS_Name_Type;
80
81   TSS_Deep_Adjust        : constant TNT := "DA";  -- Deep Adjust
82   TSS_Deep_Finalize      : constant TNT := "DF";  -- Deep Finalize
83   TSS_Deep_Initialize    : constant TNT := "DI";  -- Deep Initialize
84   TSS_Composite_Equality : constant TNT := "EQ";  -- Composite Equality
85   TSS_Finalize_Address   : constant TNT := "FD";  -- Finalize Address
86   TSS_From_Any           : constant TNT := "FA";  -- PolyORB/DSA From_Any
87   TSS_Init_Proc          : constant TNT := "IP";  -- Initialization Procedure
88   TSS_CPP_Init_Proc      : constant TNT := "IC";  -- Init C++ dispatch tables
89   TSS_RAS_Access         : constant TNT := "RA";  -- RAS type access
90   TSS_RAS_Dereference    : constant TNT := "RD";  -- RAS type dereference
91   TSS_Rep_To_Pos         : constant TNT := "RP";  -- Rep to Pos conversion
92   TSS_Slice_Assign       : constant TNT := "SA";  -- Slice assignment
93   TSS_Stream_Input       : constant TNT := "SI";  -- Stream Input attribute
94   TSS_Stream_Output      : constant TNT := "SO";  -- Stream Output attribute
95   TSS_Stream_Read        : constant TNT := "SR";  -- Stream Read attribute
96   TSS_Stream_Write       : constant TNT := "SW";  -- Stream Write attribute
97   TSS_To_Any             : constant TNT := "TA";  -- PolyORB/DSA To_Any
98   TSS_TypeCode           : constant TNT := "TC";  -- PolyORB/DSA TypeCode
99
100   --  The array below contains all valid TSS names
101
102   TSS_Names : constant array (Natural range <>) of TSS_Name_Type :=
103     (TSS_Deep_Adjust,
104      TSS_Deep_Finalize,
105      TSS_Deep_Initialize,
106      TSS_Composite_Equality,
107      TSS_Finalize_Address,
108      TSS_From_Any,
109      TSS_Init_Proc,
110      TSS_CPP_Init_Proc,
111      TSS_RAS_Access,
112      TSS_RAS_Dereference,
113      TSS_Rep_To_Pos,
114      TSS_Slice_Assign,
115      TSS_Stream_Input,
116      TSS_Stream_Output,
117      TSS_Stream_Read,
118      TSS_Stream_Write,
119      TSS_To_Any,
120      TSS_TypeCode);
121
122   TSS_Null : constant TNT := "  ";
123   --  Dummy entry used to indicated that this is not really a TSS
124
125   function Get_TSS_Name (E : Entity_Id) return TSS_Name_Type;
126   --  Given an entity, if it is a TSS, then return the corresponding TSS
127   --  name type, otherwise return TSS_Null.
128
129   function Make_TSS_Name
130     (Typ : Entity_Id;
131      Nam : TSS_Name_Type) return Name_Id;
132   --  Construct the name as described above for the given TSS routine
133   --  identified by Nam for the type identified by Typ.
134
135   function Make_TSS_Name_Local
136     (Typ : Entity_Id;
137      Nam : TSS_Name_Type) return Name_Id;
138   --  Similar to the above call, but a string of the form _nnn is inserted
139   --  before the TSS code suffix, where nnn is a unique serial number. This
140   --  is used when multiple instances of the same TSS routine may be
141   --  generated in the same scope (see also discussion above of current
142   --  limitations).
143
144   function Make_Init_Proc_Name (Typ : Entity_Id) return Name_Id;
145   --  Version for init procs, same as Make_TSS_Name (Typ, TSS_Init_Proc)
146
147   function Is_CPP_Init_Proc (E : Entity_Id) return Boolean;
148   --  Version for CPP init procs, same as Is_TSS (E, TSS_CPP_Init_Proc);
149
150   function Is_Init_Proc (E : Entity_Id) return Boolean;
151   --  Version for init procs, same as Is_TSS (E, TSS_Init_Proc);
152
153   function Is_TSS (E : Entity_Id; Nam : TSS_Name_Type) return Boolean;
154   --  Determines if given entity (E) is the name of a TSS identified by Nam
155
156   function Is_TSS (N : Name_Id; Nam : TSS_Name_Type) return Boolean;
157   --  Same test applied directly to a Name_Id value
158
159   -----------------------------------------
160   -- TSS Data structures and Subprograms --
161   -----------------------------------------
162
163   --  The TSS's for a given type are stored in an element list associated with
164   --  the type, and referenced from the TSS_Elist field of the N_Freeze_Entity
165   --  node associated with the type (all types that need TSS's always need to
166   --  be explicitly frozen, so the N_Freeze_Entity node always exists).
167
168   function TSS (Typ : Entity_Id; Nam : TSS_Name_Type) return Entity_Id;
169   --  Finds the TSS with the given name associated with the given type
170   --  If no such TSS exists, then Empty is returned;
171
172   function TSS (Typ : Entity_Id; Nam : Name_Id) return Entity_Id;
173   --  Finds the TSS with the given name associated with the given type. If
174   --  no such TSS exists, then Empty is returned.
175
176   function Same_TSS (E1, E2 : Entity_Id) return Boolean;
177   --  Returns True if E1 and E2 are the same kind of TSS, even if the names
178   --  are different (i.e. if the names of E1 and E2 end with two upper case
179   --  letters that are the same).
180
181   procedure Set_TSS (Typ : Entity_Id; TSS : Entity_Id);
182   --  This procedure is used to install a newly created TSS. The second
183   --  argument is the entity for such a new TSS. This entity is placed in the
184   --  TSS list for the type given as the first argument, replacing an old
185   --  entry of the same name if one was present. The tree for the body of this
186   --  TSS, which is not analyzed yet, is placed in the actions field of the
187   --  freeze node for the type. All such bodies are inserted into the main
188   --  tree and analyzed at the point at which the freeze node itself is
189   --  expanded.
190
191   procedure Copy_TSS (TSS : Entity_Id; Typ : Entity_Id);
192   --  Given an existing TSS for another type (which is already installed,
193   --  analyzed and expanded), install it as the corresponding TSS for Typ.
194   --  Note that this just copies a reference, not the tree. This can also be
195   --  used to initially install a TSS in the case where the subprogram for the
196   --  TSS has already been created and its declaration processed.
197
198   function CPP_Init_Proc (Typ : Entity_Id) return Entity_Id;
199   --  Obtains the CPP_Init TSS entity the given type. The CPP_Init TSS is a
200   --  procedure used to initialize the C++ part of the primary and secondary
201   --  dispatch tables of a tagged type derived from CPP types.
202
203   function Init_Proc
204     (Typ : Entity_Id;
205      Ref : Entity_Id := Empty) return Entity_Id;
206   --  Obtains the _init TSS entry for the given type. This function call is
207   --  equivalent to TSS (Typ, Name_uInit). The _init TSS is the procedure
208   --  used to initialize otherwise uninitialized instances of a type. If
209   --  there is no _init TSS, then the type requires no initialization. Note
210   --  that subtypes and implicit types never have an _init TSS since subtype
211   --  objects are always initialized using the initialization procedure for
212   --  the corresponding base type (see Base_Init_Proc function). A special
213   --  case arises for concurrent types. Such types do not themselves have an
214   --  init proc TSS, but initialization is required. The init proc used is
215   --  the one for the corresponding record type (see Base_Init_Proc). If
216   --  Ref is present it is call to a subprogram whose profile matches the
217   --  profile of the required constructor (this argument is used to handle
218   --  non-default CPP constructors).
219
220   function Base_Init_Proc
221     (Typ : Entity_Id;
222      Ref : Entity_Id := Empty) return Entity_Id;
223   --  Obtains the _Init TSS entry from the base type of the entity, and also
224   --  deals with going indirect through the Corresponding_Record_Type field
225   --  for concurrent objects (which are initialized with the initialization
226   --  routine for the corresponding record type). Returns Empty if there is no
227   --  _Init TSS entry for the base type. If Ref is present it is a call to a
228   --  subprogram whose profile matches the profile of the required constructor
229   --  (this argument is used to handle non-default CPP constructors).
230
231   procedure Set_Init_Proc (Typ : Entity_Id; Init : Entity_Id);
232   pragma Inline (Set_Init_Proc);
233   --  The second argument is the _init TSS to be established for the type
234   --  given as the first argument. Equivalent to Set_TSS (Typ, Init).
235
236   function Has_Non_Null_Base_Init_Proc (Typ : Entity_Id) return Boolean;
237   --  Returns true if the given type has a defined Base_Init_Proc and
238   --  this init proc is not a null init proc (null init procs occur as
239   --  a result of the processing for Initialize_Scalars). This function
240   --  is used to test for the presence of an init proc in cases where
241   --  a null init proc is considered equivalent to no init proc.
242
243   function Find_Inherited_TSS
244     (Typ : Entity_Id;
245      Nam : TSS_Name_Type) return Entity_Id;
246   --  Returns the TSS of name Nam of Typ, or of its closest ancestor defining
247   --  such a TSS. Empty is returned is neither Typ nor any of its ancestors
248   --  have such a TSS.
249
250end Exp_Tss;
251