1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
5 -- G N A T . D Y N A M I C _ T A B L E S --
9 -- Copyright (C) 2000-2009, AdaCore --
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 with GNAT.Heap_Sort_G;
35 with System; use System;
36 with System.Memory; use System.Memory;
38 with Ada.Unchecked_Conversion;
40 package body GNAT.Dynamic_Tables is
42 Min : constant Integer := Integer (Table_Low_Bound);
43 -- Subscript of the minimum entry in the currently allocated table
45 -----------------------
46 -- Local Subprograms --
47 -----------------------
49 procedure Reallocate (T : in out Instance);
50 -- Reallocate the existing table according to the current value stored
51 -- in Max. Works correctly to do an initial allocation if the table
54 pragma Warnings (Off);
55 -- These unchecked conversions are in fact safe, since they never
56 -- generate improperly aliased pointer values.
58 function To_Address is new Ada.Unchecked_Conversion (Table_Ptr, Address);
59 function To_Pointer is new Ada.Unchecked_Conversion (Address, Table_Ptr);
72 T.P.Last_Val := T.P.Last_Val + Num;
74 if T.P.Last_Val > T.P.Max then
83 procedure Append (T : in out Instance; New_Val : Table_Component_Type) is
85 Set_Item (T, Table_Index_Type (T.P.Last_Val + 1), New_Val);
92 procedure Append_All (T : in out Instance; New_Vals : Table_Type) is
94 for J in New_Vals'Range loop
95 Append (T, New_Vals (J));
103 procedure Decrement_Last (T : in out Instance) is
105 T.P.Last_Val := T.P.Last_Val - 1;
112 procedure For_Each (Table : Instance) is
113 Quit : Boolean := False;
115 for Index in Table_Low_Bound .. Table_Index_Type (Table.P.Last_Val) loop
116 Action (Index, Table.Table (Index), Quit);
125 procedure Free (T : in out Instance) is
127 Free (To_Address (T.Table));
136 procedure Increment_Last (T : in out Instance) is
138 T.P.Last_Val := T.P.Last_Val + 1;
140 if T.P.Last_Val > T.P.Max then
149 procedure Init (T : in out Instance) is
150 Old_Length : constant Integer := T.P.Length;
153 T.P.Last_Val := Min - 1;
154 T.P.Max := Min + Table_Initial - 1;
155 T.P.Length := T.P.Max - Min + 1;
157 -- If table is same size as before (happens when table is never
158 -- expanded which is a common case), then simply reuse it. Note
159 -- that this also means that an explicit Init call right after
160 -- the implicit one in the package body is harmless.
162 if Old_Length = T.P.Length then
165 -- Otherwise we can use Reallocate to get a table of the right size.
166 -- Note that Reallocate works fine to allocate a table of the right
167 -- initial size when it is first allocated.
178 function Last (T : Instance) return Table_Index_Type is
180 return Table_Index_Type (T.P.Last_Val);
187 procedure Reallocate (T : in out Instance) is
188 New_Length : Integer;
192 if T.P.Max < T.P.Last_Val then
193 while T.P.Max < T.P.Last_Val loop
194 New_Length := T.P.Length * (100 + Table_Increment) / 100;
196 if New_Length > T.P.Length then
197 T.P.Length := New_Length;
199 T.P.Length := T.P.Length + 1;
202 T.P.Max := Min + T.P.Length - 1;
207 size_t ((T.P.Max - Min + 1) *
208 (Table_Type'Component_Size / Storage_Unit));
210 if T.Table = null then
211 T.Table := To_Pointer (Alloc (New_Size));
213 elsif New_Size > 0 then
215 To_Pointer (Realloc (Ptr => To_Address (T.Table),
219 if T.P.Length /= 0 and then T.Table = null then
228 procedure Release (T : in out Instance) is
230 T.P.Length := T.P.Last_Val - Integer (Table_Low_Bound) + 1;
231 T.P.Max := T.P.Last_Val;
240 (T : in out Instance;
241 Index : Table_Index_Type;
242 Item : Table_Component_Type)
244 -- If Item is a value within the current allocation, and we are going to
245 -- reallocate, then we must preserve an intermediate copy here before
246 -- calling Increment_Last. Otherwise, if Table_Component_Type is passed
247 -- by reference, we are going to end up copying from storage that might
248 -- have been deallocated from Increment_Last calling Reallocate.
250 subtype Allocated_Table_T is
251 Table_Type (T.Table'First .. Table_Index_Type (T.P.Max + 1));
252 -- A constrained table subtype one element larger than the currently
255 Allocated_Table_Address : constant System.Address :=
257 -- Used for address clause below (we can't use non-static expression
258 -- Table.all'Address directly in the clause because some older versions
259 -- of the compiler do not allow it).
261 Allocated_Table : Allocated_Table_T;
262 pragma Import (Ada, Allocated_Table);
263 pragma Suppress (Range_Check, On => Allocated_Table);
264 for Allocated_Table'Address use Allocated_Table_Address;
265 -- Allocated_Table represents the currently allocated array, plus one
266 -- element (the supplementary element is used to have a convenient way
267 -- to the address just past the end of the current allocation). Range
268 -- checks are suppressed because this unit uses direct calls to
269 -- System.Memory for allocation, and this can yield misaligned storage
270 -- (and we cannot rely on the bootstrap compiler supporting specifically
271 -- disabling alignment checks, so we need to suppress all range checks).
272 -- It is safe to suppress this check here because we know that a
273 -- (possibly misaligned) object of that type does actually exist at that
275 -- ??? We should really improve the allocation circuitry here to
276 -- guarantee proper alignment.
278 Need_Realloc : constant Boolean := Integer (Index) > T.P.Max;
279 -- True if this operation requires storage reallocation (which may
280 -- involve moving table contents around).
283 -- If we're going to reallocate, check whether Item references an
284 -- element of the currently allocated table.
287 and then Allocated_Table'Address <= Item'Address
288 and then Item'Address <
289 Allocated_Table (Table_Index_Type (T.P.Max + 1))'Address
291 -- If so, save a copy on the stack because Increment_Last will
292 -- reallocate storage and might deallocate the current table.
295 Item_Copy : constant Table_Component_Type := Item;
298 T.Table (Index) := Item_Copy;
302 -- Here we know that either we won't reallocate (case of Index < Max)
303 -- or that Item is not in the currently allocated table.
305 if Integer (Index) > T.P.Last_Val then
309 T.Table (Index) := Item;
317 procedure Set_Last (T : in out Instance; New_Val : Table_Index_Type) is
319 if Integer (New_Val) < T.P.Last_Val then
320 T.P.Last_Val := Integer (New_Val);
323 T.P.Last_Val := Integer (New_Val);
325 if T.P.Last_Val > T.P.Max then
335 procedure Sort_Table (Table : in out Instance) is
337 Temp : Table_Component_Type;
338 -- A temporary position to simulate index 0
342 function Index_Of (Idx : Natural) return Table_Index_Type;
343 -- Return index of Idx'th element of table
345 function Lower_Than (Op1, Op2 : Natural) return Boolean;
346 -- Compare two components
348 procedure Move (From : Natural; To : Natural);
349 -- Move one component
351 package Heap_Sort is new GNAT.Heap_Sort_G (Move, Lower_Than);
357 function Index_Of (Idx : Natural) return Table_Index_Type is
358 J : constant Integer'Base :=
359 Table_Index_Type'Pos (First) + Idx - 1;
361 return Table_Index_Type'Val (J);
368 procedure Move (From : Natural; To : Natural) is
371 Table.Table (Index_Of (To)) := Temp;
374 Temp := Table.Table (Index_Of (From));
377 Table.Table (Index_Of (To)) :=
378 Table.Table (Index_Of (From));
386 function Lower_Than (Op1, Op2 : Natural) return Boolean is
389 return Lt (Temp, Table.Table (Index_Of (Op2)));
392 return Lt (Table.Table (Index_Of (Op1)), Temp);
396 Lt (Table.Table (Index_Of (Op1)),
397 Table.Table (Index_Of (Op2)));
401 -- Start of processing for Sort_Table
404 Heap_Sort.Sort (Natural (Last (Table) - First) + 1);
407 end GNAT.Dynamic_Tables;