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 -- Resizable one dimensional array support
36 -- This package provides an implementation of dynamically resizable one
37 -- dimensional arrays. The idea is to mimic the normal Ada semantics for
38 -- arrays as closely as possible with the one additional capability of
39 -- dynamically modifying the value of the Last attribute.
41 -- This package provides a facility similar to that of GNAT.Table, except
42 -- that this package declares a type that can be used to define dynamic
43 -- instances of the table, while an instantiation of GNAT.Table creates a
44 -- single instance of the table type.
46 -- Note that this interface should remain synchronized with those in
47 -- GNAT.Table and the GNAT compiler source unit Table to keep as much
48 -- coherency as possible between these three related units.
53 type Table_Component_Type
is private;
54 type Table_Index_Type
is range <>;
56 Table_Low_Bound
: Table_Index_Type
;
57 Table_Initial
: Positive;
58 Table_Increment
: Natural;
60 package GNAT
.Dynamic_Tables
is
62 -- Table_Component_Type and Table_Index_Type specify the type of the
63 -- array, Table_Low_Bound is the lower bound. Index_type must be an
64 -- integer type. The effect is roughly to declare:
66 -- Table : array (Table_Low_Bound .. <>) of Table_Component_Type;
68 -- Note: since the upper bound can be one less than the lower
69 -- bound for an empty array, the table index type must be able
70 -- to cover this range, e.g. if the lower bound is 1, then the
71 -- Table_Index_Type should be Natural rather than Positive.
73 -- Table_Component_Type may be any Ada type, except that controlled
74 -- types are not supported. Note however that default initialization
75 -- will NOT occur for array components.
77 -- The Table_Initial values controls the allocation of the table when
78 -- it is first allocated, either by default, or by an explicit Init
81 -- The Table_Increment value controls the amount of increase, if the
82 -- table has to be increased in size. The value given is a percentage
83 -- value (e.g. 100 = increase table size by 100%, i.e. double it).
85 -- The Last and Set_Last subprograms provide control over the current
86 -- logical allocation. They are quite efficient, so they can be used
87 -- freely (expensive reallocation occurs only at major granularity
88 -- chunks controlled by the allocation parameters).
90 -- Note: we do not make the table components aliased, since this would
91 -- restrict the use of table for discriminated types. If it is necessary
92 -- to take the access of a table element, use Unrestricted_Access.
95 array (Table_Index_Type
range <>) of Table_Component_Type
;
96 subtype Big_Table_Type
is
97 Table_Type
(Table_Low_Bound
.. Table_Index_Type
'Last);
98 -- We work with pointers to a bogus array type that is constrained with
99 -- the maximum possible range bound. This means that the pointer is a thin
100 -- pointer, which is more efficient. Since subscript checks in any case
101 -- must be on the logical, rather than physical bounds, safety is not
102 -- compromised by this approach. These types should not be used by the
105 type Table_Ptr
is access all Big_Table_Type
;
106 for Table_Ptr
'Storage_Size use 0;
107 -- The table is actually represented as a pointer to allow reallocation.
108 -- This type should not be used by the client.
110 type Table_Private
is private;
111 -- Table private data that is not exported in Instance
113 type Instance
is record
114 Table
: aliased Table_Ptr
:= null;
115 -- The table itself. The lower bound is the value of Low_Bound.
116 -- Logically the upper bound is the current value of Last (although
117 -- the actual size of the allocated table may be larger than this).
118 -- The program may only access and modify Table entries in the
119 -- range First .. Last.
124 procedure Init
(T
: in out Instance
);
125 -- This procedure allocates a new table of size Initial (freeing any
126 -- previously allocated larger table). Init must be called before using
127 -- the table. Init is convenient in reestablishing a table for new use.
129 function Last
(T
: Instance
) return Table_Index_Type
;
130 pragma Inline
(Last
);
131 -- Returns the current value of the last used entry in the table,
132 -- which can then be used as a subscript for Table. Note that the
133 -- only way to modify Last is to call the Set_Last procedure. Last
134 -- must always be used to determine the logically last entry.
136 procedure Release
(T
: in out Instance
);
137 -- Storage is allocated in chunks according to the values given in the
138 -- Initial and Increment parameters. A call to Release releases all
139 -- storage that is allocated, but is not logically part of the current
140 -- array value. Current array values are not affected by this call.
142 procedure Free
(T
: in out Instance
);
143 -- Free all allocated memory for the table. A call to init is required
144 -- before any use of this table after calling Free.
146 First
: constant Table_Index_Type
:= Table_Low_Bound
;
147 -- Export First as synonym for Low_Bound (parallel with use of Last)
149 procedure Set_Last
(T
: in out Instance
; New_Val
: Table_Index_Type
);
150 pragma Inline
(Set_Last
);
151 -- This procedure sets Last to the indicated value. If necessary the
152 -- table is reallocated to accommodate the new value (i.e. on return
153 -- the allocated table has an upper bound of at least Last). If
154 -- Set_Last reduces the size of the table, then logically entries are
155 -- removed from the table. If Set_Last increases the size of the
156 -- table, then new entries are logically added to the table.
158 procedure Increment_Last
(T
: in out Instance
);
159 pragma Inline
(Increment_Last
);
160 -- Adds 1 to Last (same as Set_Last (Last + 1)
162 procedure Decrement_Last
(T
: in out Instance
);
163 pragma Inline
(Decrement_Last
);
164 -- Subtracts 1 from Last (same as Set_Last (Last - 1)
166 procedure Append
(T
: in out Instance
; New_Val
: Table_Component_Type
);
167 pragma Inline
(Append
);
169 -- Increment_Last (T);
170 -- T.Table (T.Last) := New_Val;
171 -- i.e. the table size is increased by one, and the given new item
172 -- stored in the newly created table element.
174 procedure Append_All
(T
: in out Instance
; New_Vals
: Table_Type
);
175 -- Appends all components of New_Vals
178 (T
: in out Instance
;
179 Index
: Table_Index_Type
;
180 Item
: Table_Component_Type
);
181 pragma Inline
(Set_Item
);
182 -- Put Item in the table at position Index. The table is expanded if
183 -- current table length is less than Index and in that case Last is set to
184 -- Index. Item will replace any value already present in the table at this
187 procedure Allocate
(T
: in out Instance
; Num
: Integer := 1);
188 pragma Inline
(Allocate
);
192 with procedure Action
193 (Index
: Table_Index_Type
;
194 Item
: Table_Component_Type
;
195 Quit
: in out Boolean) is <>;
196 procedure For_Each
(Table
: Instance
);
197 -- Calls procedure Action for each component of the table Table, or until
198 -- one of these calls set Quit to True.
201 with function Lt
(Comp1
, Comp2
: Table_Component_Type
) return Boolean;
202 procedure Sort_Table
(Table
: in out Instance
);
203 -- This procedure sorts the components of table Table into ascending
204 -- order making calls to Lt to do required comparisons, and using
205 -- assignments to move components around. The Lt function returns True
206 -- if Comp1 is less than Comp2 (in the sense of the desired sort), and
207 -- False if Comp1 is greater than Comp2. For equal objects it does not
208 -- matter if True or False is returned (it is slightly more efficient
209 -- to return False). The sort is not stable (the order of equal items
210 -- in the table is not preserved).
213 type Table_Private
is record
215 -- Subscript of the maximum entry in the currently allocated table
217 Length
: Integer := 0;
218 -- Number of entries in currently allocated table. The value of zero
219 -- ensures that we initially allocate the table.
222 -- Current value of Last
225 end GNAT
.Dynamic_Tables
;