gcc/ada/elists.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                               E L I S T S                                --
   6 --                                                                          --
   7 --                                 B o d y                                  --
   8 --                                                                          --
   9 --          Copyright (C) 1992-2010, 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.                                     --
  17 --                                                                          --
  18 -- As a special exception under Section 7 of GPL version 3, you are granted --
  19 -- additional permissions described in the GCC Runtime Library Exception,   --
  20 -- version 3.1, as published by the Free Software Foundation.               --
  21 --                                                                          --
  22 -- You should have received a copy of the GNU General Public License and    --
  23 -- a copy of the GCC Runtime Library Exception along with this program;     --
  24 -- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
  25 -- <http://www.gnu.org/licenses/>.                                          --
  26 --                                                                          --
  27 -- GNAT was originally developed  by the GNAT team at  New York University. --
  28 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  29 --                                                                          --
  30 ------------------------------------------------------------------------------
  31
  32 --  WARNING: There is a C version of this package. Any changes to this
  33 --  source file must be properly reflected in the C header a-elists.h.
  34
  35 with Alloc;
  36 with Debug;  use Debug;
  37 with Output; use Output;
  38 with Table;
  39
  40 package body Elists is
  41
  42    -------------------------------------
  43    -- Implementation of Element Lists --
  44    -------------------------------------
  45
  46    --  Element lists are composed of three types of entities. The element
  47    --  list header, which references the first and last elements of the
  48    --  list, the elements themselves which are singly linked and also
  49    --  reference the nodes on the list, and finally the nodes themselves.
  50    --  The following diagram shows how an element list is represented:
  51
  52    --       +----------------------------------------------------+
  53    --       |  +------------------------------------------+      |
  54    --       |  |                                          |      |
  55    --       V  |                                          V      |
  56    --    +-----|--+    +-------+    +-------+         +-------+  |
  57    --    |  Elmt  |    |  1st  |    |  2nd  |         |  Last |  |
  58    --    |  List  |--->|  Elmt |--->|  Elmt  ---...-->|  Elmt ---+
  59    --    | Header |    |   |   |    |   |   |         |   |   |
  60    --    +--------+    +---|---+    +---|---+         +---|---+
  61    --                      |            |                 |
  62    --                      V            V                 V
  63    --                  +-------+    +-------+         +-------+
  64    --                  |       |    |       |         |       |
  65    --                  | Node1 |    | Node2 |         | Node3 |
  66    --                  |       |    |       |         |       |
  67    --                  +-------+    +-------+         +-------+
  68
  69    --  The list header is an entry in the Elists table. The values used for
  70    --  the type Elist_Id are subscripts into this table. The First_Elmt field
  71    --  (Lfield1) points to the first element on the list, or to No_Elmt in the
  72    --  case of an empty list. Similarly the Last_Elmt field (Lfield2) points to
  73    --  the last element on the list or to No_Elmt in the case of an empty list.
  74
  75    --  The elements themselves are entries in the Elmts table. The Next field
  76    --  of each entry points to the next element, or to the Elist header if this
  77    --  is the last item in the list. The Node field points to the node which
  78    --  is referenced by the corresponding list entry.
  79
  80    -------------------------
  81    -- Element List Tables --
  82    -------------------------
  83
  84    type Elist_Header is record
  85       First : Elmt_Id;
  86       Last  : Elmt_Id;
  87    end record;
  88
  89    package Elists is new Table.Table (
  90      Table_Component_Type => Elist_Header,
  91      Table_Index_Type     => Elist_Id'Base,
  92      Table_Low_Bound      => First_Elist_Id,
  93      Table_Initial        => Alloc.Elists_Initial,
  94      Table_Increment      => Alloc.Elists_Increment,
  95      Table_Name           => "Elists");
  96
  97    type Elmt_Item is record
  98       Node : Node_Or_Entity_Id;
  99       Next : Union_Id;
 100    end record;
 101
 102    package Elmts is new Table.Table (
 103      Table_Component_Type => Elmt_Item,
 104      Table_Index_Type     => Elmt_Id'Base,
 105      Table_Low_Bound      => First_Elmt_Id,
 106      Table_Initial        => Alloc.Elmts_Initial,
 107      Table_Increment      => Alloc.Elmts_Increment,
 108      Table_Name           => "Elmts");
 109
 110    -----------------
 111    -- Append_Elmt --
 112    -----------------
 113
 114    procedure Append_Elmt (N : Node_Or_Entity_Id; To : Elist_Id) is
 115       L : constant Elmt_Id := Elists.Table (To).Last;
 116
 117    begin
 118       Elmts.Increment_Last;
 119       Elmts.Table (Elmts.Last).Node := N;
 120       Elmts.Table (Elmts.Last).Next := Union_Id (To);
 121
 122       if L = No_Elmt then
 123          Elists.Table (To).First := Elmts.Last;
 124       else
 125          Elmts.Table (L).Next := Union_Id (Elmts.Last);
 126       end if;
 127
 128       Elists.Table (To).Last  := Elmts.Last;
 129
 130       if Debug_Flag_N then
 131          Write_Str ("Append new element Elmt_Id = ");
 132          Write_Int (Int (Elmts.Last));
 133          Write_Str (" to list Elist_Id = ");
 134          Write_Int (Int (To));
 135          Write_Str (" referencing Node_Or_Entity_Id = ");
 136          Write_Int (Int (N));
 137          Write_Eol;
 138       end if;
 139    end Append_Elmt;
 140
 141    ------------------------
 142    -- Append_Unique_Elmt --
 143    ------------------------
 144
 145    procedure Append_Unique_Elmt (N : Node_Or_Entity_Id; To : Elist_Id) is
 146       Elmt : Elmt_Id;
 147    begin
 148       Elmt := First_Elmt (To);
 149       loop
 150          if No (Elmt) then
 151             Append_Elmt (N, To);
 152             return;
 153          elsif Node (Elmt) = N then
 154             return;
 155          else
 156             Next_Elmt (Elmt);
 157          end if;
 158       end loop;
 159    end Append_Unique_Elmt;
 160
 161    --------------------
 162    -- Elists_Address --
 163    --------------------
 164
 165    function Elists_Address return System.Address is
 166    begin
 167       return Elists.Table (First_Elist_Id)'Address;
 168    end Elists_Address;
 169
 170    -------------------
 171    -- Elmts_Address --
 172    -------------------
 173
 174    function Elmts_Address return System.Address is
 175    begin
 176       return Elmts.Table (First_Elmt_Id)'Address;
 177    end Elmts_Address;
 178
 179    ----------------
 180    -- First_Elmt --
 181    ----------------
 182
 183    function First_Elmt (List : Elist_Id) return Elmt_Id is
 184    begin
 185       pragma Assert (List > Elist_Low_Bound);
 186       return Elists.Table (List).First;
 187    end First_Elmt;
 188
 189    ----------------
 190    -- Initialize --
 191    ----------------
 192
 193    procedure Initialize is
 194    begin
 195       Elists.Init;
 196       Elmts.Init;
 197    end Initialize;
 198
 199    -----------------------
 200    -- Insert_Elmt_After --
 201    -----------------------
 202
 203    procedure Insert_Elmt_After (N : Node_Or_Entity_Id; Elmt : Elmt_Id) is
 204       Nxt : constant Union_Id := Elmts.Table (Elmt).Next;
 205
 206    begin
 207       pragma Assert (Elmt /= No_Elmt);
 208
 209       Elmts.Increment_Last;
 210       Elmts.Table (Elmts.Last).Node := N;
 211       Elmts.Table (Elmts.Last).Next := Nxt;
 212
 213       Elmts.Table (Elmt).Next := Union_Id (Elmts.Last);
 214
 215       if Nxt in Elist_Range then
 216          Elists.Table (Elist_Id (Nxt)).Last := Elmts.Last;
 217       end if;
 218    end Insert_Elmt_After;
 219
 220    ------------------------
 221    -- Is_Empty_Elmt_List --
 222    ------------------------
 223
 224    function Is_Empty_Elmt_List (List : Elist_Id) return Boolean is
 225    begin
 226       return Elists.Table (List).First = No_Elmt;
 227    end Is_Empty_Elmt_List;
 228
 229    -------------------
 230    -- Last_Elist_Id --
 231    -------------------
 232
 233    function Last_Elist_Id return Elist_Id is
 234    begin
 235       return Elists.Last;
 236    end Last_Elist_Id;
 237
 238    ---------------
 239    -- Last_Elmt --
 240    ---------------
 241
 242    function Last_Elmt (List : Elist_Id) return Elmt_Id is
 243    begin
 244       return Elists.Table (List).Last;
 245    end Last_Elmt;
 246
 247    ------------------
 248    -- Last_Elmt_Id --
 249    ------------------
 250
 251    function Last_Elmt_Id return Elmt_Id is
 252    begin
 253       return Elmts.Last;
 254    end Last_Elmt_Id;
 255
 256    ----------
 257    -- Lock --
 258    ----------
 259
 260    procedure Lock is
 261    begin
 262       Elists.Locked := True;
 263       Elmts.Locked := True;
 264       Elists.Release;
 265       Elmts.Release;
 266    end Lock;
 267
 268    -------------------
 269    -- New_Elmt_List --
 270    -------------------
 271
 272    function New_Elmt_List return Elist_Id is
 273    begin
 274       Elists.Increment_Last;
 275       Elists.Table (Elists.Last).First := No_Elmt;
 276       Elists.Table (Elists.Last).Last  := No_Elmt;
 277
 278       if Debug_Flag_N then
 279          Write_Str ("Allocate new element list, returned ID = ");
 280          Write_Int (Int (Elists.Last));
 281          Write_Eol;
 282       end if;
 283
 284       return Elists.Last;
 285    end New_Elmt_List;
 286
 287    ---------------
 288    -- Next_Elmt --
 289    ---------------
 290
 291    function Next_Elmt (Elmt : Elmt_Id) return Elmt_Id is
 292       N : constant Union_Id := Elmts.Table (Elmt).Next;
 293
 294    begin
 295       if N in Elist_Range then
 296          return No_Elmt;
 297       else
 298          return Elmt_Id (N);
 299       end if;
 300    end Next_Elmt;
 301
 302    procedure Next_Elmt (Elmt : in out Elmt_Id) is
 303    begin
 304       Elmt := Next_Elmt (Elmt);
 305    end Next_Elmt;
 306
 307    --------
 308    -- No --
 309    --------
 310
 311    function No (List : Elist_Id) return Boolean is
 312    begin
 313       return List = No_Elist;
 314    end No;
 315
 316    function No (Elmt : Elmt_Id) return Boolean is
 317    begin
 318       return Elmt = No_Elmt;
 319    end No;
 320
 321    ----------
 322    -- Node --
 323    ----------
 324
 325    function Node (Elmt : Elmt_Id) return Node_Or_Entity_Id is
 326    begin
 327       if Elmt = No_Elmt then
 328          return Empty;
 329       else
 330          return Elmts.Table (Elmt).Node;
 331       end if;
 332    end Node;
 333
 334    ----------------
 335    -- Num_Elists --
 336    ----------------
 337
 338    function Num_Elists return Nat is
 339    begin
 340       return Int (Elmts.Last) - Int (Elmts.First) + 1;
 341    end Num_Elists;
 342
 343    ------------------
 344    -- Prepend_Elmt --
 345    ------------------
 346
 347    procedure Prepend_Elmt (N : Node_Or_Entity_Id; To : Elist_Id) is
 348       F : constant Elmt_Id := Elists.Table (To).First;
 349
 350    begin
 351       Elmts.Increment_Last;
 352       Elmts.Table (Elmts.Last).Node := N;
 353
 354       if F = No_Elmt then
 355          Elists.Table (To).Last := Elmts.Last;
 356          Elmts.Table (Elmts.Last).Next := Union_Id (To);
 357       else
 358          Elmts.Table (Elmts.Last).Next := Union_Id (F);
 359       end if;
 360
 361       Elists.Table (To).First  := Elmts.Last;
 362    end Prepend_Elmt;
 363
 364    -------------
 365    -- Present --
 366    -------------
 367
 368    function Present (List : Elist_Id) return Boolean is
 369    begin
 370       return List /= No_Elist;
 371    end Present;
 372
 373    function Present (Elmt : Elmt_Id) return Boolean is
 374    begin
 375       return Elmt /= No_Elmt;
 376    end Present;
 377
 378    -----------------
 379    -- Remove_Elmt --
 380    -----------------
 381
 382    procedure Remove_Elmt (List : Elist_Id; Elmt : Elmt_Id) is
 383       Nxt : Elmt_Id;
 384       Prv : Elmt_Id;
 385
 386    begin
 387       Nxt := Elists.Table (List).First;
 388
 389       --  Case of removing only element in the list
 390
 391       if Elmts.Table (Nxt).Next in Elist_Range then
 392          pragma Assert (Nxt = Elmt);
 393
 394          Elists.Table (List).First := No_Elmt;
 395          Elists.Table (List).Last  := No_Elmt;
 396
 397       --  Case of removing the first element in the list
 398
 399       elsif Nxt = Elmt then
 400          Elists.Table (List).First := Elmt_Id (Elmts.Table (Nxt).Next);
 401
 402       --  Case of removing second or later element in the list
 403
 404       else
 405          loop
 406             Prv := Nxt;
 407             Nxt := Elmt_Id (Elmts.Table (Prv).Next);
 408             exit when Nxt = Elmt
 409               or else Elmts.Table (Nxt).Next in Elist_Range;
 410          end loop;
 411
 412          pragma Assert (Nxt = Elmt);
 413
 414          Elmts.Table (Prv).Next := Elmts.Table (Nxt).Next;
 415
 416          if Elmts.Table (Prv).Next in Elist_Range then
 417             Elists.Table (List).Last := Prv;
 418          end if;
 419       end if;
 420    end Remove_Elmt;
 421
 422    ----------------------
 423    -- Remove_Last_Elmt --
 424    ----------------------
 425
 426    procedure Remove_Last_Elmt (List : Elist_Id) is
 427       Nxt : Elmt_Id;
 428       Prv : Elmt_Id;
 429
 430    begin
 431       Nxt := Elists.Table (List).First;
 432
 433       --  Case of removing only element in the list
 434
 435       if Elmts.Table (Nxt).Next in Elist_Range then
 436          Elists.Table (List).First := No_Elmt;
 437          Elists.Table (List).Last  := No_Elmt;
 438
 439       --  Case of at least two elements in list
 440
 441       else
 442          loop
 443             Prv := Nxt;
 444             Nxt := Elmt_Id (Elmts.Table (Prv).Next);
 445             exit when Elmts.Table (Nxt).Next in Elist_Range;
 446          end loop;
 447
 448          Elmts.Table (Prv).Next   := Elmts.Table (Nxt).Next;
 449          Elists.Table (List).Last := Prv;
 450       end if;
 451    end Remove_Last_Elmt;
 452
 453    ------------------
 454    -- Replace_Elmt --
 455    ------------------
 456
 457    procedure Replace_Elmt (Elmt : Elmt_Id; New_Node : Node_Or_Entity_Id) is
 458    begin
 459       Elmts.Table (Elmt).Node := New_Node;
 460    end Replace_Elmt;
 461
 462    ---------------
 463    -- Tree_Read --
 464    ---------------
 465
 466    procedure Tree_Read is
 467    begin
 468       Elists.Tree_Read;
 469       Elmts.Tree_Read;
 470    end Tree_Read;
 471
 472    ----------------
 473    -- Tree_Write --
 474    ----------------
 475
 476    procedure Tree_Write is
 477    begin
 478       Elists.Tree_Write;
 479       Elmts.Tree_Write;
 480    end Tree_Write;
 481
 482    ------------
 483    -- Unlock --
 484    ------------
 485
 486    procedure Unlock is
 487    begin
 488       Elists.Locked := False;
 489       Elmts.Locked := False;
 490    end Unlock;
 491
 492 end Elists;