1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2006, 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, 51 Franklin Street, Fifth Floor, --
20 -- Boston, MA 02110-1301, 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;
189 pragma Assert (Elmt /= No_Elmt);
191 Elmts.Increment_Last;
192 Elmts.Table (Elmts.Last).Node := Node;
193 Elmts.Table (Elmts.Last).Next := N;
195 Elmts.Table (Elmt).Next := Union_Id (Elmts.Last);
197 if N in Elist_Range then
198 Elists.Table (Elist_Id (N)).Last := Elmts.Last;
200 end Insert_Elmt_After;
202 ------------------------
203 -- Is_Empty_Elmt_List --
204 ------------------------
206 function Is_Empty_Elmt_List (List : Elist_Id) return Boolean is
208 return Elists.Table (List).First = No_Elmt;
209 end Is_Empty_Elmt_List;
215 function Last_Elist_Id return Elist_Id is
224 function Last_Elmt (List : Elist_Id) return Elmt_Id is
226 return Elists.Table (List).Last;
233 function Last_Elmt_Id return Elmt_Id is
244 Elists.Locked := True;
245 Elmts.Locked := True;
254 function New_Elmt_List return Elist_Id is
256 Elists.Increment_Last;
257 Elists.Table (Elists.Last).First := No_Elmt;
258 Elists.Table (Elists.Last).Last := No_Elmt;
261 Write_Str ("Allocate new element list, returned ID = ");
262 Write_Int (Int (Elists.Last));
273 function Next_Elmt (Elmt : Elmt_Id) return Elmt_Id is
274 N : constant Union_Id := Elmts.Table (Elmt).Next;
277 if N in Elist_Range then
284 procedure Next_Elmt (Elmt : in out Elmt_Id) is
286 Elmt := Next_Elmt (Elmt);
293 function No (List : Elist_Id) return Boolean is
295 return List = No_Elist;
298 function No (Elmt : Elmt_Id) return Boolean is
300 return Elmt = No_Elmt;
307 function Node (Elmt : Elmt_Id) return Node_Or_Entity_Id is
309 if Elmt = No_Elmt then
312 return Elmts.Table (Elmt).Node;
320 function Num_Elists return Nat is
322 return Int (Elmts.Last) - Int (Elmts.First) + 1;
329 procedure Prepend_Elmt (Node : Node_Id; To : Elist_Id) is
330 F : constant Elmt_Id := Elists.Table (To).First;
333 Elmts.Increment_Last;
334 Elmts.Table (Elmts.Last).Node := Node;
337 Elists.Table (To).Last := Elmts.Last;
338 Elmts.Table (Elmts.Last).Next := Union_Id (To);
340 Elmts.Table (Elmts.Last).Next := Union_Id (F);
343 Elists.Table (To).First := Elmts.Last;
351 function Present (List : Elist_Id) return Boolean is
353 return List /= No_Elist;
356 function Present (Elmt : Elmt_Id) return Boolean is
358 return Elmt /= No_Elmt;
365 procedure Remove_Elmt (List : Elist_Id; Elmt : Elmt_Id) is
370 Nxt := Elists.Table (List).First;
372 -- Case of removing only element in the list
374 if Elmts.Table (Nxt).Next in Elist_Range then
376 pragma Assert (Nxt = Elmt);
378 Elists.Table (List).First := No_Elmt;
379 Elists.Table (List).Last := No_Elmt;
381 -- Case of removing the first element in the list
383 elsif Nxt = Elmt then
384 Elists.Table (List).First := Elmt_Id (Elmts.Table (Nxt).Next);
386 -- Case of removing second or later element in the list
391 Nxt := Elmt_Id (Elmts.Table (Prv).Next);
393 or else Elmts.Table (Nxt).Next in Elist_Range;
396 pragma Assert (Nxt = Elmt);
398 Elmts.Table (Prv).Next := Elmts.Table (Nxt).Next;
400 if Elmts.Table (Prv).Next in Elist_Range then
401 Elists.Table (List).Last := Prv;
406 ----------------------
407 -- Remove_Last_Elmt --
408 ----------------------
410 procedure Remove_Last_Elmt (List : Elist_Id) is
415 Nxt := Elists.Table (List).First;
417 -- Case of removing only element in the list
419 if Elmts.Table (Nxt).Next in Elist_Range then
420 Elists.Table (List).First := No_Elmt;
421 Elists.Table (List).Last := No_Elmt;
423 -- Case of at least two elements in list
428 Nxt := Elmt_Id (Elmts.Table (Prv).Next);
429 exit when Elmts.Table (Nxt).Next in Elist_Range;
432 Elmts.Table (Prv).Next := Elmts.Table (Nxt).Next;
433 Elists.Table (List).Last := Prv;
435 end Remove_Last_Elmt;
441 procedure Replace_Elmt (Elmt : Elmt_Id; New_Node : Node_Id) is
443 Elmts.Table (Elmt).Node := New_Node;
450 procedure Tree_Read is
460 procedure Tree_Write is