PR target/58115
[official-gcc.git] / gcc / ada / g-table.ads
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1 ------------------------------------------------------------------------------
2 -- --
3 -- GNAT RUN-TIME COMPONENTS --
4 -- --
5 -- G N A T . T A B L E --
6 -- --
7 -- S p e c --
8 -- --
9 -- Copyright (C) 1998-2013, AdaCore --
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 ------------------------------------------------------------------------------
32 -- Resizable one dimensional array support
34 -- This package provides an implementation of dynamically resizable one
35 -- dimensional arrays. The idea is to mimic the normal Ada semantics for
36 -- arrays as closely as possible with the one additional capability of
37 -- dynamically modifying the value of the Last attribute.
39 -- This package provides a facility similar to that of GNAT.Dynamic_Tables,
40 -- except that this package declares a single instance of the table type,
41 -- while an instantiation of GNAT.Dynamic_Tables creates a type that can be
42 -- used to define dynamic instances of the table.
44 -- Note that this interface should remain synchronized with those in
45 -- GNAT.Dynamic_Tables and the GNAT compiler source unit Table to keep
46 -- as much coherency as possible between these three related units.
48 generic
49 type Table_Component_Type is private;
50 type Table_Index_Type is range <>;
52 Table_Low_Bound : Table_Index_Type;
53 Table_Initial : Positive;
54 Table_Increment : Natural;
56 package GNAT.Table is
57 pragma Elaborate_Body;
59 -- Table_Component_Type and Table_Index_Type specify the type of the
60 -- array, Table_Low_Bound is the lower bound. Index_type must be an
61 -- integer type. The effect is roughly to declare:
63 -- Table : array (Table_Index_Type range Table_Low_Bound .. <>)
64 -- of Table_Component_Type;
66 -- Note: since the upper bound can be one less than the lower
67 -- bound for an empty array, the table index type must be able
68 -- to cover this range, e.g. if the lower bound is 1, then the
69 -- Table_Index_Type should be Natural rather than Positive.
71 -- Table_Component_Type may be any Ada type, except that controlled
72 -- types are not supported. Note however that default initialization
73 -- will NOT occur for array components.
75 -- The Table_Initial values controls the allocation of the table when
76 -- it is first allocated, either by default, or by an explicit Init call.
78 -- The Table_Increment value controls the amount of increase, if the
79 -- table has to be increased in size. The value given is a percentage
80 -- value (e.g. 100 = increase table size by 100%, i.e. double it).
82 -- The Last and Set_Last subprograms provide control over the current
83 -- logical allocation. They are quite efficient, so they can be used
84 -- freely (expensive reallocation occurs only at major granularity
85 -- chunks controlled by the allocation parameters).
87 -- Note: we do not make the table components aliased, since this would
88 -- restrict the use of table for discriminated types. If it is necessary
89 -- to take the access of a table element, use Unrestricted_Access.
91 -- WARNING: On HPPA, the virtual addressing approach used in this unit
92 -- is incompatible with the indexing instructions on the HPPA. So when
93 -- using this unit, compile your application with -mdisable-indexing.
95 -- WARNING: If the table is reallocated, then the address of all its
96 -- components will change. So do not capture the address of an element
97 -- and then use the address later after the table may be reallocated.
98 -- One tricky case of this is passing an element of the table to a
99 -- subprogram by reference where the table gets reallocated during
100 -- the execution of the subprogram. The best rule to follow is never
101 -- to pass a table element as a parameter except for the case of IN
102 -- mode parameters with scalar values.
104 type Table_Type is
105 array (Table_Index_Type range <>) of Table_Component_Type;
106 subtype Big_Table_Type is
107 Table_Type (Table_Low_Bound .. Table_Index_Type'Last);
108 -- We work with pointers to a bogus array type that is constrained
109 -- with the maximum possible range bound. This means that the pointer
110 -- is a thin pointer, which is more efficient. Since subscript checks
111 -- in any case must be on the logical, rather than physical bounds,
112 -- safety is not compromised by this approach. These types should never
113 -- be used by the client.
115 type Table_Ptr is access all Big_Table_Type;
116 for Table_Ptr'Storage_Size use 0;
117 -- The table is actually represented as a pointer to allow reallocation.
118 -- This type should never be used by the client.
120 Table : aliased Table_Ptr := null;
121 -- The table itself. The lower bound is the value of Low_Bound.
122 -- Logically the upper bound is the current value of Last (although
123 -- the actual size of the allocated table may be larger than this).
124 -- The program may only access and modify Table entries in the range
125 -- First .. Last.
127 Locked : Boolean := False;
128 -- Table expansion is permitted only if this switch is set to False. A
129 -- client may set Locked to True, in which case any attempt to expand
130 -- the table will cause an assertion failure. Note that while a table
131 -- is locked, its address in memory remains fixed and unchanging.
133 procedure Init;
134 -- This procedure allocates a new table of size Initial (freeing any
135 -- previously allocated larger table). It is not necessary to call
136 -- Init when a table is first instantiated (since the instantiation does
137 -- the same initialization steps). However, it is harmless to do so, and
138 -- Init is convenient in reestablishing a table for new use.
140 function Last return Table_Index_Type;
141 pragma Inline (Last);
142 -- Returns the current value of the last used entry in the table, which
143 -- can then be used as a subscript for Table. Note that the only way to
144 -- modify Last is to call the Set_Last procedure. Last must always be
145 -- used to determine the logically last entry.
147 procedure Release;
148 -- Storage is allocated in chunks according to the values given in the
149 -- Initial and Increment parameters. A call to Release releases all
150 -- storage that is allocated, but is not logically part of the current
151 -- array value. Current array values are not affected by this call.
153 procedure Free;
154 -- Free all allocated memory for the table. A call to Init is required
155 -- before any use of this table after calling Free.
157 First : constant Table_Index_Type := Table_Low_Bound;
158 -- Export First as synonym for Low_Bound (parallel with use of Last)
160 procedure Set_Last (New_Val : Table_Index_Type);
161 pragma Inline (Set_Last);
162 -- This procedure sets Last to the indicated value. If necessary the
163 -- table is reallocated to accommodate the new value (i.e. on return
164 -- the allocated table has an upper bound of at least Last). If Set_Last
165 -- reduces the size of the table, then logically entries are removed
166 -- from the table. If Set_Last increases the size of the table, then
167 -- new entries are logically added to the table.
169 procedure Increment_Last;
170 pragma Inline (Increment_Last);
171 -- Adds 1 to Last (same as Set_Last (Last + 1)
173 procedure Decrement_Last;
174 pragma Inline (Decrement_Last);
175 -- Subtracts 1 from Last (same as Set_Last (Last - 1)
177 procedure Append (New_Val : Table_Component_Type);
178 pragma Inline (Append);
179 -- Equivalent to:
180 -- x.Increment_Last;
181 -- x.Table (x.Last) := New_Val;
182 -- i.e. the table size is increased by one, and the given new item
183 -- stored in the newly created table element.
185 procedure Append_All (New_Vals : Table_Type);
186 -- Appends all components of New_Vals
188 procedure Set_Item
189 (Index : Table_Index_Type;
190 Item : Table_Component_Type);
191 pragma Inline (Set_Item);
192 -- Put Item in the table at position Index. The table is expanded if the
193 -- current table length is less than Index and in that case Last is set to
194 -- Index. Item will replace any value already present in the table at this
195 -- position.
197 function Allocate (Num : Integer := 1) return Table_Index_Type;
198 pragma Inline (Allocate);
199 -- Adds Num to Last, and returns the old value of Last + 1. Note that
200 -- this function has the possible side effect of reallocating the table.
201 -- This means that a reference X.Table (X.Allocate) is incorrect, since
202 -- the call to X.Allocate may modify the results of calling X.Table.
204 generic
205 with procedure Action
206 (Index : Table_Index_Type;
207 Item : Table_Component_Type;
208 Quit : in out Boolean) is <>;
209 procedure For_Each;
210 -- Calls procedure Action for each component of the table, or until
211 -- one of these calls set Quit to True.
213 generic
214 with function Lt (Comp1, Comp2 : Table_Component_Type) return Boolean;
215 procedure Sort_Table;
216 -- This procedure sorts the components of the table into ascending
217 -- order making calls to Lt to do required comparisons, and using
218 -- assignments to move components around. The Lt function returns True
219 -- if Comp1 is less than Comp2 (in the sense of the desired sort), and
220 -- False if Comp1 is greater than Comp2. For equal objects it does not
221 -- matter if True or False is returned (it is slightly more efficient
222 -- to return False). The sort is not stable (the order of equal items
223 -- in the table is not preserved).
225 end GNAT.Table;