1------------------------------------------------------------------------------ 2-- -- 3-- GNAT COMPILER COMPONENTS -- 4-- -- 5-- G N A T . D Y N A M I C _ T A B L E S -- 6-- -- 7-- S p e c -- 8-- -- 9-- Copyright (C) 2000-2013, 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.Table, except 40-- that this package declares a type that can be used to define dynamic 41-- instances of the table, while an instantiation of GNAT.Table creates a 42-- single instance of the table type. 43 44-- Note that this interface should remain synchronized with those in 45-- GNAT.Table and the GNAT compiler source unit Table to keep as much 46-- coherency as possible between these three related units. 47 48pragma Compiler_Unit_Warning; 49 50generic 51 type Table_Component_Type is private; 52 type Table_Index_Type is range <>; 53 54 Table_Low_Bound : Table_Index_Type; 55 Table_Initial : Positive; 56 Table_Increment : Natural; 57 58package GNAT.Dynamic_Tables is 59 60 -- Table_Component_Type and Table_Index_Type specify the type of the 61 -- array, Table_Low_Bound is the lower bound. Index_type must be an 62 -- integer type. The effect is roughly to declare: 63 64 -- Table : array (Table_Low_Bound .. <>) 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 77 -- call. 78 79 -- The Table_Increment value controls the amount of increase, if the 80 -- table has to be increased in size. The value given is a percentage 81 -- value (e.g. 100 = increase table size by 100%, i.e. double it). 82 83 -- The Last and Set_Last subprograms provide control over the current 84 -- logical allocation. They are quite efficient, so they can be used 85 -- freely (expensive reallocation occurs only at major granularity 86 -- chunks controlled by the allocation parameters). 87 88 -- Note: we do not make the table components aliased, since this would 89 -- restrict the use of table for discriminated types. If it is necessary 90 -- to take the access of a table element, use Unrestricted_Access. 91 92 type Table_Type is 93 array (Table_Index_Type range <>) of Table_Component_Type; 94 subtype Big_Table_Type is 95 Table_Type (Table_Low_Bound .. Table_Index_Type'Last); 96 -- We work with pointers to a bogus array type that is constrained with 97 -- the maximum possible range bound. This means that the pointer is a thin 98 -- pointer, which is more efficient. Since subscript checks in any case 99 -- must be on the logical, rather than physical bounds, safety is not 100 -- compromised by this approach. These types should not be used by the 101 -- client. 102 103 type Table_Ptr is access all Big_Table_Type; 104 for Table_Ptr'Storage_Size use 0; 105 -- The table is actually represented as a pointer to allow reallocation. 106 -- This type should not be used by the client. 107 108 type Table_Private is private; 109 -- Table private data that is not exported in Instance 110 111 type Instance is record 112 Table : aliased Table_Ptr := null; 113 -- The table itself. The lower bound is the value of Low_Bound. 114 -- Logically the upper bound is the current value of Last (although 115 -- the actual size of the allocated table may be larger than this). 116 -- The program may only access and modify Table entries in the 117 -- range First .. Last. 118 119 P : Table_Private; 120 end record; 121 122 procedure Init (T : in out Instance); 123 -- This procedure allocates a new table of size Initial (freeing any 124 -- previously allocated larger table). Init must be called before using 125 -- the table. Init is convenient in reestablishing a table for new use. 126 127 function Last (T : Instance) return Table_Index_Type; 128 pragma Inline (Last); 129 -- Returns the current value of the last used entry in the table, 130 -- which can then be used as a subscript for Table. Note that the 131 -- only way to modify Last is to call the Set_Last procedure. Last 132 -- must always be used to determine the logically last entry. 133 134 procedure Release (T : in out Instance); 135 -- Storage is allocated in chunks according to the values given in the 136 -- Initial and Increment parameters. A call to Release releases all 137 -- storage that is allocated, but is not logically part of the current 138 -- array value. Current array values are not affected by this call. 139 140 procedure Free (T : in out Instance); 141 -- Free all allocated memory for the table. A call to init is required 142 -- before any use of this table after calling Free. 143 144 First : constant Table_Index_Type := Table_Low_Bound; 145 -- Export First as synonym for Low_Bound (parallel with use of Last) 146 147 procedure Set_Last (T : in out Instance; New_Val : Table_Index_Type); 148 pragma Inline (Set_Last); 149 -- This procedure sets Last to the indicated value. If necessary the 150 -- table is reallocated to accommodate the new value (i.e. on return 151 -- the allocated table has an upper bound of at least Last). If 152 -- Set_Last reduces the size of the table, then logically entries are 153 -- removed from the table. If Set_Last increases the size of the 154 -- table, then new entries are logically added to the table. 155 156 procedure Increment_Last (T : in out Instance); 157 pragma Inline (Increment_Last); 158 -- Adds 1 to Last (same as Set_Last (Last + 1) 159 160 procedure Decrement_Last (T : in out Instance); 161 pragma Inline (Decrement_Last); 162 -- Subtracts 1 from Last (same as Set_Last (Last - 1) 163 164 procedure Append (T : in out Instance; New_Val : Table_Component_Type); 165 pragma Inline (Append); 166 -- Equivalent to: 167 -- Increment_Last (T); 168 -- T.Table (T.Last) := New_Val; 169 -- i.e. the table size is increased by one, and the given new item 170 -- stored in the newly created table element. 171 172 procedure Append_All (T : in out Instance; New_Vals : Table_Type); 173 -- Appends all components of New_Vals 174 175 procedure Set_Item 176 (T : in out Instance; 177 Index : Table_Index_Type; 178 Item : Table_Component_Type); 179 pragma Inline (Set_Item); 180 -- Put Item in the table at position Index. The table is expanded if 181 -- current table length is less than Index and in that case Last is set to 182 -- Index. Item will replace any value already present in the table at this 183 -- position. 184 185 procedure Allocate (T : in out Instance; Num : Integer := 1); 186 pragma Inline (Allocate); 187 -- Adds Num to Last 188 189 generic 190 with procedure Action 191 (Index : Table_Index_Type; 192 Item : Table_Component_Type; 193 Quit : in out Boolean) is <>; 194 procedure For_Each (Table : Instance); 195 -- Calls procedure Action for each component of the table Table, or until 196 -- one of these calls set Quit to True. 197 198 generic 199 with function Lt (Comp1, Comp2 : Table_Component_Type) return Boolean; 200 procedure Sort_Table (Table : in out Instance); 201 -- This procedure sorts the components of table Table into ascending 202 -- order making calls to Lt to do required comparisons, and using 203 -- assignments to move components around. The Lt function returns True 204 -- if Comp1 is less than Comp2 (in the sense of the desired sort), and 205 -- False if Comp1 is greater than Comp2. For equal objects it does not 206 -- matter if True or False is returned (it is slightly more efficient 207 -- to return False). The sort is not stable (the order of equal items 208 -- in the table is not preserved). 209 210private 211 type Table_Private is record 212 Max : Integer; 213 -- Subscript of the maximum entry in the currently allocated table 214 215 Length : Integer := 0; 216 -- Number of entries in currently allocated table. The value of zero 217 -- ensures that we initially allocate the table. 218 219 Last_Val : Integer; 220 -- Current value of Last 221 end record; 222 223end GNAT.Dynamic_Tables; 224