1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
10 -- Copyright (C) 1992-2001 Free Software Foundation, Inc. --
12 -- GNAT is free software; you can redistribute it and/or modify it under --
13 -- terms of the GNU General Public License as published by the Free Soft- --
14 -- ware Foundation; either version 2, or (at your option) any later ver- --
15 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
16 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
17 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
18 -- for more details. You should have received a copy of the GNU General --
19 -- Public License distributed with GNAT; see file COPYING. If not, write --
20 -- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
21 -- MA 02111-1307, USA. --
23 -- As a special exception, if other files instantiate generics from this --
24 -- unit, or you link this unit with other files to produce an executable, --
25 -- this unit does not by itself cause the resulting executable to be --
26 -- covered by the GNU General Public License. This exception does not --
27 -- however invalidate any other reasons why the executable file might be --
28 -- covered by the GNU Public License. --
30 -- GNAT was originally developed by the GNAT team at New York University. --
31 -- It is now maintained by Ada Core Technologies Inc (http://www.gnat.com). --
33 ------------------------------------------------------------------------------
35 -- WARNING: There is a C version of this package. Any changes to this
36 -- source file must be properly reflected in the C header a-elists.h.
39 with Debug; use Debug;
40 with Output; use Output;
43 package body Elists is
45 -------------------------------------
46 -- Implementation of Element Lists --
47 -------------------------------------
49 -- Element lists are composed of three types of entities. The element
50 -- list header, which references the first and last elements of the
51 -- list, the elements themselves which are singly linked and also
52 -- reference the nodes on the list, and finally the nodes themselves.
53 -- The following diagram shows how an element list is represented:
55 -- +----------------------------------------------------+
56 -- | +------------------------------------------+ |
59 -- +-----|--+ +-------+ +-------+ +-------+ |
60 -- | Elmt | | 1st | | 2nd | | Last | |
61 -- | List |--->| Elmt |--->| Elmt ---...-->| Elmt ---+
62 -- | Header | | | | | | | | | |
63 -- +--------+ +---|---+ +---|---+ +---|---+
66 -- +-------+ +-------+ +-------+
68 -- | Node1 | | Node2 | | Node3 |
70 -- +-------+ +-------+ +-------+
72 -- The list header is an entry in the Elists table. The values used for
73 -- the type Elist_Id are subscripts into this table. The First_Elmt field
74 -- (Lfield1) points to the first element on the list, or to No_Elmt in the
75 -- case of an empty list. Similarly the Last_Elmt field (Lfield2) points to
76 -- the last element on the list or to No_Elmt in the case of an empty list.
78 -- The elements themselves are entries in the Elmts table. The Next field
79 -- of each entry points to the next element, or to the Elist header if this
80 -- is the last item in the list. The Node field points to the node which
81 -- is referenced by the corresponding list entry.
83 --------------------------
84 -- Element List Tables --
85 --------------------------
87 type Elist_Header is record
92 package Elists is new Table.Table (
93 Table_Component_Type => Elist_Header,
94 Table_Index_Type => Elist_Id,
95 Table_Low_Bound => First_Elist_Id,
96 Table_Initial => Alloc.Elists_Initial,
97 Table_Increment => Alloc.Elists_Increment,
98 Table_Name => "Elists");
100 type Elmt_Item is record
105 package Elmts is new Table.Table (
106 Table_Component_Type => Elmt_Item,
107 Table_Index_Type => Elmt_Id,
108 Table_Low_Bound => First_Elmt_Id,
109 Table_Initial => Alloc.Elmts_Initial,
110 Table_Increment => Alloc.Elmts_Increment,
111 Table_Name => "Elmts");
117 procedure Append_Elmt (Node : Node_Id; To : Elist_Id) is
118 L : constant Elmt_Id := Elists.Table (To).Last;
121 Elmts.Increment_Last;
122 Elmts.Table (Elmts.Last).Node := Node;
123 Elmts.Table (Elmts.Last).Next := Union_Id (To);
126 Elists.Table (To).First := Elmts.Last;
128 Elmts.Table (L).Next := Union_Id (Elmts.Last);
131 Elists.Table (To).Last := Elmts.Last;
134 Write_Str ("Append new element Elmt_Id = ");
135 Write_Int (Int (Elmts.Last));
136 Write_Str (" to list Elist_Id = ");
137 Write_Int (Int (To));
138 Write_Str (" referencing Node_Id = ");
139 Write_Int (Int (Node));
148 function Elists_Address return System.Address is
150 return Elists.Table (First_Elist_Id)'Address;
157 function Elmts_Address return System.Address is
159 return Elmts.Table (First_Elmt_Id)'Address;
166 function First_Elmt (List : Elist_Id) return Elmt_Id is
168 pragma Assert (List > Elist_Low_Bound);
169 return Elists.Table (List).First;
176 procedure Initialize is
182 -----------------------
183 -- Insert_Elmt_After --
184 -----------------------
186 procedure Insert_Elmt_After (Node : Node_Id; Elmt : Elmt_Id) is
187 N : constant Union_Id := Elmts.Table (Elmt).Next;
191 pragma Assert (Elmt /= No_Elmt);
193 Elmts.Increment_Last;
194 Elmts.Table (Elmts.Last).Node := Node;
195 Elmts.Table (Elmts.Last).Next := N;
197 Elmts.Table (Elmt).Next := Union_Id (Elmts.Last);
199 if N in Elist_Range then
200 Elists.Table (Elist_Id (N)).Last := Elmts.Last;
202 end Insert_Elmt_After;
204 ------------------------
205 -- Is_Empty_Elmt_List --
206 ------------------------
208 function Is_Empty_Elmt_List (List : Elist_Id) return Boolean is
210 return Elists.Table (List).First = No_Elmt;
211 end Is_Empty_Elmt_List;
217 function Last_Elist_Id return Elist_Id is
226 function Last_Elmt (List : Elist_Id) return Elmt_Id is
228 return Elists.Table (List).Last;
235 function Last_Elmt_Id return Elmt_Id is
246 Elists.Locked := True;
247 Elmts.Locked := True;
256 function New_Elmt_List return Elist_Id is
258 Elists.Increment_Last;
259 Elists.Table (Elists.Last).First := No_Elmt;
260 Elists.Table (Elists.Last).Last := No_Elmt;
263 Write_Str ("Allocate new element list, returned ID = ");
264 Write_Int (Int (Elists.Last));
275 function Next_Elmt (Elmt : Elmt_Id) return Elmt_Id is
276 N : constant Union_Id := Elmts.Table (Elmt).Next;
279 if N in Elist_Range then
286 procedure Next_Elmt (Elmt : in out Elmt_Id) is
288 Elmt := Next_Elmt (Elmt);
295 function No (List : Elist_Id) return Boolean is
297 return List = No_Elist;
300 function No (Elmt : Elmt_Id) return Boolean is
302 return Elmt = No_Elmt;
309 function Node (Elmt : Elmt_Id) return Node_Id is
311 if Elmt = No_Elmt then
314 return Elmts.Table (Elmt).Node;
322 function Num_Elists return Nat is
324 return Int (Elmts.Last) - Int (Elmts.First) + 1;
331 procedure Prepend_Elmt (Node : Node_Id; To : Elist_Id) is
332 F : constant Elmt_Id := Elists.Table (To).First;
335 Elmts.Increment_Last;
336 Elmts.Table (Elmts.Last).Node := Node;
339 Elists.Table (To).Last := Elmts.Last;
340 Elmts.Table (Elmts.Last).Next := Union_Id (To);
342 Elmts.Table (Elmts.Last).Next := Union_Id (F);
345 Elists.Table (To).First := Elmts.Last;
353 function Present (List : Elist_Id) return Boolean is
355 return List /= No_Elist;
358 function Present (Elmt : Elmt_Id) return Boolean is
360 return Elmt /= No_Elmt;
367 procedure Remove_Elmt (List : Elist_Id; Elmt : Elmt_Id) is
372 Nxt := Elists.Table (List).First;
374 -- Case of removing only element in the list
376 if Elmts.Table (Nxt).Next in Elist_Range then
378 pragma Assert (Nxt = Elmt);
380 Elists.Table (List).First := No_Elmt;
381 Elists.Table (List).Last := No_Elmt;
383 -- Case of removing the first element in the list
385 elsif Nxt = Elmt then
386 Elists.Table (List).First := Elmt_Id (Elmts.Table (Nxt).Next);
388 -- Case of removing second or later element in the list
393 Nxt := Elmt_Id (Elmts.Table (Prv).Next);
395 or else Elmts.Table (Nxt).Next in Elist_Range;
398 pragma Assert (Nxt = Elmt);
400 Elmts.Table (Prv).Next := Elmts.Table (Nxt).Next;
402 if Elmts.Table (Prv).Next in Elist_Range then
403 Elists.Table (List).Last := Prv;
408 ----------------------
409 -- Remove_Last_Elmt --
410 ----------------------
412 procedure Remove_Last_Elmt (List : Elist_Id) is
417 Nxt := Elists.Table (List).First;
419 -- Case of removing only element in the list
421 if Elmts.Table (Nxt).Next in Elist_Range then
422 Elists.Table (List).First := No_Elmt;
423 Elists.Table (List).Last := No_Elmt;
425 -- Case of at least two elements in list
430 Nxt := Elmt_Id (Elmts.Table (Prv).Next);
431 exit when Elmts.Table (Nxt).Next in Elist_Range;
434 Elmts.Table (Prv).Next := Elmts.Table (Nxt).Next;
435 Elists.Table (List).Last := Prv;
437 end Remove_Last_Elmt;
443 procedure Replace_Elmt (Elmt : Elmt_Id; New_Node : Node_Id) is
445 Elmts.Table (Elmt).Node := New_Node;
452 procedure Tree_Read is
462 procedure Tree_Write is