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------------------------------------------------------------------------------ 31 32-- Resizable one dimensional array support 33 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. 38 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. 43 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. 47 48generic 49 type Table_Component_Type is private; 50 type Table_Index_Type is range <>; 51 52 Table_Low_Bound : Table_Index_Type; 53 Table_Initial : Positive; 54 Table_Increment : Natural; 55 56package GNAT.Table is 57 pragma Elaborate_Body; 58 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: 62 63 -- Table : array (Table_Index_Type range Table_Low_Bound .. <>) 64 -- of Table_Component_Type; 65 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. 70 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. 74 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. 77 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). 81 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). 86 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. 90 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. 94 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. 103 104 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. 114 115 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. 119 120 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. 126 127 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. 132 133 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. 139 140 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. 146 147 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. 152 153 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. 156 157 First : constant Table_Index_Type := Table_Low_Bound; 158 -- Export First as synonym for Low_Bound (parallel with use of Last) 159 160 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. 168 169 procedure Increment_Last; 170 pragma Inline (Increment_Last); 171 -- Adds 1 to Last (same as Set_Last (Last + 1) 172 173 procedure Decrement_Last; 174 pragma Inline (Decrement_Last); 175 -- Subtracts 1 from Last (same as Set_Last (Last - 1) 176 177 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. 184 185 procedure Append_All (New_Vals : Table_Type); 186 -- Appends all components of New_Vals 187 188 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. 196 197 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. 203 204 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. 212 213 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). 224 225end GNAT.Table; 226