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) 2000-2010, 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 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. --
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. --
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/>. --
27 -- GNAT was originally developed by the GNAT team at New York University. --
28 -- Extensive contributions were provided by Ada Core Technologies Inc. --
30 ------------------------------------------------------------------------------
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);
67 procedure Allocate (T : in out Instance; Num : Integer := 1) is
69 T.P.Last_Val := T.P.Last_Val + Num;
71 if T.P.Last_Val > T.P.Max then
80 procedure Append (T : in out Instance; New_Val : Table_Component_Type) is
82 Set_Item (T, Table_Index_Type (T.P.Last_Val + 1), New_Val);
89 procedure Append_All (T : in out Instance; New_Vals : Table_Type) is
91 for J in New_Vals'Range loop
92 Append (T, New_Vals (J));
100 procedure Decrement_Last (T : in out Instance) is
102 T.P.Last_Val := T.P.Last_Val - 1;
109 procedure For_Each (Table : Instance) is
110 Quit : Boolean := False;
112 for Index in Table_Low_Bound .. Table_Index_Type (Table.P.Last_Val) loop
113 Action (Index, Table.Table (Index), Quit);
122 procedure Free (T : in out Instance) is
124 Free (To_Address (T.Table));
133 procedure Increment_Last (T : in out Instance) is
135 T.P.Last_Val := T.P.Last_Val + 1;
137 if T.P.Last_Val > T.P.Max then
146 procedure Init (T : in out Instance) is
147 Old_Length : constant Integer := T.P.Length;
150 T.P.Last_Val := Min - 1;
151 T.P.Max := Min + Table_Initial - 1;
152 T.P.Length := T.P.Max - Min + 1;
154 -- If table is same size as before (happens when table is never
155 -- expanded which is a common case), then simply reuse it. Note
156 -- that this also means that an explicit Init call right after
157 -- the implicit one in the package body is harmless.
159 if Old_Length = T.P.Length then
162 -- Otherwise we can use Reallocate to get a table of the right size.
163 -- Note that Reallocate works fine to allocate a table of the right
164 -- initial size when it is first allocated.
175 function Last (T : Instance) return Table_Index_Type is
177 return Table_Index_Type (T.P.Last_Val);
184 procedure Reallocate (T : in out Instance) is
185 New_Length : Integer;
189 if T.P.Max < T.P.Last_Val then
190 while T.P.Max < T.P.Last_Val loop
191 New_Length := T.P.Length * (100 + Table_Increment) / 100;
193 if New_Length > T.P.Length then
194 T.P.Length := New_Length;
196 T.P.Length := T.P.Length + 1;
199 T.P.Max := Min + T.P.Length - 1;
204 size_t ((T.P.Max - Min + 1) *
205 (Table_Type'Component_Size / Storage_Unit));
207 if T.Table = null then
208 T.Table := To_Pointer (Alloc (New_Size));
210 elsif New_Size > 0 then
212 To_Pointer (Realloc (Ptr => To_Address (T.Table),
216 if T.P.Length /= 0 and then T.Table = null then
225 procedure Release (T : in out Instance) is
227 T.P.Length := T.P.Last_Val - Integer (Table_Low_Bound) + 1;
228 T.P.Max := T.P.Last_Val;
237 (T : in out Instance;
238 Index : Table_Index_Type;
239 Item : Table_Component_Type)
241 -- If Item is a value within the current allocation, and we are going to
242 -- reallocate, then we must preserve an intermediate copy here before
243 -- calling Increment_Last. Otherwise, if Table_Component_Type is passed
244 -- by reference, we are going to end up copying from storage that might
245 -- have been deallocated from Increment_Last calling Reallocate.
247 subtype Allocated_Table_T is
248 Table_Type (T.Table'First .. Table_Index_Type (T.P.Max + 1));
249 -- A constrained table subtype one element larger than the currently
252 Allocated_Table_Address : constant System.Address :=
254 -- Used for address clause below (we can't use non-static expression
255 -- Table.all'Address directly in the clause because some older versions
256 -- of the compiler do not allow it).
258 Allocated_Table : Allocated_Table_T;
259 pragma Import (Ada, Allocated_Table);
260 pragma Suppress (Range_Check, On => Allocated_Table);
261 for Allocated_Table'Address use Allocated_Table_Address;
262 -- Allocated_Table represents the currently allocated array, plus one
263 -- element (the supplementary element is used to have a convenient way
264 -- to the address just past the end of the current allocation). Range
265 -- checks are suppressed because this unit uses direct calls to
266 -- System.Memory for allocation, and this can yield misaligned storage
267 -- (and we cannot rely on the bootstrap compiler supporting specifically
268 -- disabling alignment checks, so we need to suppress all range checks).
269 -- It is safe to suppress this check here because we know that a
270 -- (possibly misaligned) object of that type does actually exist at that
272 -- ??? We should really improve the allocation circuitry here to
273 -- guarantee proper alignment.
275 Need_Realloc : constant Boolean := Integer (Index) > T.P.Max;
276 -- True if this operation requires storage reallocation (which may
277 -- involve moving table contents around).
280 -- If we're going to reallocate, check whether Item references an
281 -- element of the currently allocated table.
284 and then Allocated_Table'Address <= Item'Address
285 and then Item'Address <
286 Allocated_Table (Table_Index_Type (T.P.Max + 1))'Address
288 -- If so, save a copy on the stack because Increment_Last will
289 -- reallocate storage and might deallocate the current table.
292 Item_Copy : constant Table_Component_Type := Item;
295 T.Table (Index) := Item_Copy;
299 -- Here we know that either we won't reallocate (case of Index < Max)
300 -- or that Item is not in the currently allocated table.
302 if Integer (Index) > T.P.Last_Val then
306 T.Table (Index) := Item;
314 procedure Set_Last (T : in out Instance; New_Val : Table_Index_Type) is
316 if Integer (New_Val) < T.P.Last_Val then
317 T.P.Last_Val := Integer (New_Val);
320 T.P.Last_Val := Integer (New_Val);
322 if T.P.Last_Val > T.P.Max then
332 procedure Sort_Table (Table : in out Instance) is
334 Temp : Table_Component_Type;
335 -- A temporary position to simulate index 0
339 function Index_Of (Idx : Natural) return Table_Index_Type;
340 -- Return index of Idx'th element of table
342 function Lower_Than (Op1, Op2 : Natural) return Boolean;
343 -- Compare two components
345 procedure Move (From : Natural; To : Natural);
346 -- Move one component
348 package Heap_Sort is new GNAT.Heap_Sort_G (Move, Lower_Than);
354 function Index_Of (Idx : Natural) return Table_Index_Type is
355 J : constant Integer'Base :=
356 Table_Index_Type'Pos (First) + Idx - 1;
358 return Table_Index_Type'Val (J);
365 procedure Move (From : Natural; To : Natural) is
368 Table.Table (Index_Of (To)) := Temp;
371 Temp := Table.Table (Index_Of (From));
374 Table.Table (Index_Of (To)) :=
375 Table.Table (Index_Of (From));
383 function Lower_Than (Op1, Op2 : Natural) return Boolean is
386 return Lt (Temp, Table.Table (Index_Of (Op2)));
389 return Lt (Table.Table (Index_Of (Op1)), Temp);
393 Lt (Table.Table (Index_Of (Op1)),
394 Table.Table (Index_Of (Op2)));
398 -- Start of processing for Sort_Table
401 Heap_Sort.Sort (Natural (Last (Table) - First) + 1);
404 end GNAT.Dynamic_Tables;