1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2004 Free Software Foundation, Inc. --
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 2, 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 COPYING. If not, write --
19 -- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
20 -- MA 02111-1307, USA. --
22 -- As a special exception, if other files instantiate generics from this --
23 -- unit, or you link this unit with other files to produce an executable, --
24 -- this unit does not by itself cause the resulting executable to be --
25 -- covered by the GNU General Public License. This exception does not --
26 -- however invalidate any other reasons why the executable file might be --
27 -- covered by the GNU Public License. --
29 -- GNAT was originally developed by the GNAT team at New York University. --
30 -- Extensive contributions were provided by Ada Core Technologies Inc. --
32 ------------------------------------------------------------------------------
34 -- WARNING: There is a C version of this package. Any changes to this
35 -- source file must be properly reflected in the C header a-elists.h.
38 with Debug; use Debug;
39 with Output; use Output;
42 package body Elists is
44 -------------------------------------
45 -- Implementation of Element Lists --
46 -------------------------------------
48 -- Element lists are composed of three types of entities. The element
49 -- list header, which references the first and last elements of the
50 -- list, the elements themselves which are singly linked and also
51 -- reference the nodes on the list, and finally the nodes themselves.
52 -- The following diagram shows how an element list is represented:
54 -- +----------------------------------------------------+
55 -- | +------------------------------------------+ |
58 -- +-----|--+ +-------+ +-------+ +-------+ |
59 -- | Elmt | | 1st | | 2nd | | Last | |
60 -- | List |--->| Elmt |--->| Elmt ---...-->| Elmt ---+
61 -- | Header | | | | | | | | | |
62 -- +--------+ +---|---+ +---|---+ +---|---+
65 -- +-------+ +-------+ +-------+
67 -- | Node1 | | Node2 | | Node3 |
69 -- +-------+ +-------+ +-------+
71 -- The list header is an entry in the Elists table. The values used for
72 -- the type Elist_Id are subscripts into this table. The First_Elmt field
73 -- (Lfield1) points to the first element on the list, or to No_Elmt in the
74 -- case of an empty list. Similarly the Last_Elmt field (Lfield2) points to
75 -- the last element on the list or to No_Elmt in the case of an empty list.
77 -- The elements themselves are entries in the Elmts table. The Next field
78 -- of each entry points to the next element, or to the Elist header if this
79 -- is the last item in the list. The Node field points to the node which
80 -- is referenced by the corresponding list entry.
82 -------------------------
83 -- Element List Tables --
84 -------------------------
86 type Elist_Header is record
91 package Elists is new Table.Table (
92 Table_Component_Type => Elist_Header,
93 Table_Index_Type => Elist_Id,
94 Table_Low_Bound => First_Elist_Id,
95 Table_Initial => Alloc.Elists_Initial,
96 Table_Increment => Alloc.Elists_Increment,
97 Table_Name => "Elists");
99 type Elmt_Item is record
104 package Elmts is new Table.Table (
105 Table_Component_Type => Elmt_Item,
106 Table_Index_Type => Elmt_Id,
107 Table_Low_Bound => First_Elmt_Id,
108 Table_Initial => Alloc.Elmts_Initial,
109 Table_Increment => Alloc.Elmts_Increment,
110 Table_Name => "Elmts");
116 procedure Append_Elmt (Node : Node_Id; To : Elist_Id) is
117 L : constant Elmt_Id := Elists.Table (To).Last;
120 Elmts.Increment_Last;
121 Elmts.Table (Elmts.Last).Node := Node;
122 Elmts.Table (Elmts.Last).Next := Union_Id (To);
125 Elists.Table (To).First := Elmts.Last;
127 Elmts.Table (L).Next := Union_Id (Elmts.Last);
130 Elists.Table (To).Last := Elmts.Last;
133 Write_Str ("Append new element Elmt_Id = ");
134 Write_Int (Int (Elmts.Last));
135 Write_Str (" to list Elist_Id = ");
136 Write_Int (Int (To));
137 Write_Str (" referencing Node_Id = ");
138 Write_Int (Int (Node));
147 function Elists_Address return System.Address is
149 return Elists.Table (First_Elist_Id)'Address;
156 function Elmts_Address return System.Address is
158 return Elmts.Table (First_Elmt_Id)'Address;
165 function First_Elmt (List : Elist_Id) return Elmt_Id is
167 pragma Assert (List > Elist_Low_Bound);
168 return Elists.Table (List).First;
175 procedure Initialize is
181 -----------------------
182 -- Insert_Elmt_After --
183 -----------------------
185 procedure Insert_Elmt_After (Node : Node_Id; Elmt : Elmt_Id) is
186 N : constant Union_Id := Elmts.Table (Elmt).Next;
190 pragma Assert (Elmt /= No_Elmt);
192 Elmts.Increment_Last;
193 Elmts.Table (Elmts.Last).Node := Node;
194 Elmts.Table (Elmts.Last).Next := N;
196 Elmts.Table (Elmt).Next := Union_Id (Elmts.Last);
198 if N in Elist_Range then
199 Elists.Table (Elist_Id (N)).Last := Elmts.Last;
201 end Insert_Elmt_After;
203 ------------------------
204 -- Is_Empty_Elmt_List --
205 ------------------------
207 function Is_Empty_Elmt_List (List : Elist_Id) return Boolean is
209 return Elists.Table (List).First = No_Elmt;
210 end Is_Empty_Elmt_List;
216 function Last_Elist_Id return Elist_Id is
225 function Last_Elmt (List : Elist_Id) return Elmt_Id is
227 return Elists.Table (List).Last;
234 function Last_Elmt_Id return Elmt_Id is
245 Elists.Locked := True;
246 Elmts.Locked := True;
255 function New_Elmt_List return Elist_Id is
257 Elists.Increment_Last;
258 Elists.Table (Elists.Last).First := No_Elmt;
259 Elists.Table (Elists.Last).Last := No_Elmt;
262 Write_Str ("Allocate new element list, returned ID = ");
263 Write_Int (Int (Elists.Last));
274 function Next_Elmt (Elmt : Elmt_Id) return Elmt_Id is
275 N : constant Union_Id := Elmts.Table (Elmt).Next;
278 if N in Elist_Range then
285 procedure Next_Elmt (Elmt : in out Elmt_Id) is
287 Elmt := Next_Elmt (Elmt);
294 function No (List : Elist_Id) return Boolean is
296 return List = No_Elist;
299 function No (Elmt : Elmt_Id) return Boolean is
301 return Elmt = No_Elmt;
308 function Node (Elmt : Elmt_Id) return Node_Id is
310 if Elmt = No_Elmt then
313 return Elmts.Table (Elmt).Node;
321 function Num_Elists return Nat is
323 return Int (Elmts.Last) - Int (Elmts.First) + 1;
330 procedure Prepend_Elmt (Node : Node_Id; To : Elist_Id) is
331 F : constant Elmt_Id := Elists.Table (To).First;
334 Elmts.Increment_Last;
335 Elmts.Table (Elmts.Last).Node := Node;
338 Elists.Table (To).Last := Elmts.Last;
339 Elmts.Table (Elmts.Last).Next := Union_Id (To);
341 Elmts.Table (Elmts.Last).Next := Union_Id (F);
344 Elists.Table (To).First := Elmts.Last;
352 function Present (List : Elist_Id) return Boolean is
354 return List /= No_Elist;
357 function Present (Elmt : Elmt_Id) return Boolean is
359 return Elmt /= No_Elmt;
366 procedure Remove_Elmt (List : Elist_Id; Elmt : Elmt_Id) is
371 Nxt := Elists.Table (List).First;
373 -- Case of removing only element in the list
375 if Elmts.Table (Nxt).Next in Elist_Range then
377 pragma Assert (Nxt = Elmt);
379 Elists.Table (List).First := No_Elmt;
380 Elists.Table (List).Last := No_Elmt;
382 -- Case of removing the first element in the list
384 elsif Nxt = Elmt then
385 Elists.Table (List).First := Elmt_Id (Elmts.Table (Nxt).Next);
387 -- Case of removing second or later element in the list
392 Nxt := Elmt_Id (Elmts.Table (Prv).Next);
394 or else Elmts.Table (Nxt).Next in Elist_Range;
397 pragma Assert (Nxt = Elmt);
399 Elmts.Table (Prv).Next := Elmts.Table (Nxt).Next;
401 if Elmts.Table (Prv).Next in Elist_Range then
402 Elists.Table (List).Last := Prv;
407 ----------------------
408 -- Remove_Last_Elmt --
409 ----------------------
411 procedure Remove_Last_Elmt (List : Elist_Id) is
416 Nxt := Elists.Table (List).First;
418 -- Case of removing only element in the list
420 if Elmts.Table (Nxt).Next in Elist_Range then
421 Elists.Table (List).First := No_Elmt;
422 Elists.Table (List).Last := No_Elmt;
424 -- Case of at least two elements in list
429 Nxt := Elmt_Id (Elmts.Table (Prv).Next);
430 exit when Elmts.Table (Nxt).Next in Elist_Range;
433 Elmts.Table (Prv).Next := Elmts.Table (Nxt).Next;
434 Elists.Table (List).Last := Prv;
436 end Remove_Last_Elmt;
442 procedure Replace_Elmt (Elmt : Elmt_Id; New_Node : Node_Id) is
444 Elmts.Table (Elmt).Node := New_Node;
451 procedure Tree_Read is
461 procedure Tree_Write is