| 1 | ------------------------------------------------------------------------------ |
|---|---|
| 2 | --: Copyright © 2003 … 2023 Martin Krischik «krischik@users.sourceforge.net» |
| 3 | ------------------------------------------------------------------------------ |
| 4 | --: This library is free software; you can redistribute it and/or modify it |
| 5 | --: under the terms of the GNU Library General Public License as published by |
| 6 | --: the Free Software Foundation; either version 2 of the License, or (at your |
| 7 | --: option) any later version. |
| 8 | --: |
| 9 | --: This library is distributed in the hope that it will be useful, but |
| 10 | --: WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY |
| 11 | --: or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public |
| 12 | --: License for more details. |
| 13 | --: |
| 14 | --: You should have received a copy of the GNU Library General Public License |
| 15 | --: along with this library; if not, write to the Free Software Foundation, |
| 16 | --: Inc., 675 Mass Ave,Cambridge, MA 02139, USA. |
| 17 | ---------------------------------------------------------------------------- |
| 18 | pragma License (Modified_Gpl); |
| 19 | pragma Ada_2022; |
| 20 | |
| 21 | with AdaCL.Limited_Base; |
| 22 | with Ada.Strings.Text_Buffers; |
| 23 | |
| 24 | --- |
| 25 | -- @summary |
| 26 | -- Ada Class Library |
| 27 | -- Base Class for Reference Counted Instances. |
| 28 | -- |
| 29 | -- @description |
| 30 | -- Element and Holder: A reference counted smart pointer for tagged types where the reference is kept inside the |
| 31 | -- tagged type. This is slightly faster, uses less memory and is more reliable. However it can only be uses for |
| 32 | -- limited tagged types and you need to implement the interface. |
| 33 | package AdaCL.Pointer.Element is |
| 34 | |
| 35 | ---------- Interface ------------------------------------------------------ |
| 36 | |
| 37 | --- |
| 38 | -- Interface Class for Reference Counted Instances |
| 39 | -- |
| 40 | -- Use the interface in when using the base class is not possible. |
| 41 | -- |
| 42 | -- Type for which we want to supply a reference counter. Since, in Ada one can not overload the ":=" operator the |
| 43 | -- type need to be limited so the counter is not damaged by assignment. |
| 44 | -- |
| 45 | -- Mind you, in C++ I almost always make the operator = private in in Reference counted classes as well. |
| 46 | -- |
| 47 | type Object_Interface is limited interface and AdaCL.Limited_Base.Object_Interface; |
| 48 | |
| 49 | --- |
| 50 | -- Add a reference |
| 51 | -- |
| 52 | --: @param This Object itself. |
| 53 | procedure Add_Reference (This : in out Object_Interface) is abstract; |
| 54 | |
| 55 | --- |
| 56 | -- Remove a reference. However since an object and a pointer is passed the instance is not deleted. |
| 57 | -- |
| 58 | -- The caller is responsible to call Use_Count and check if delete is needed. |
| 59 | -- |
| 60 | -- Concurrency: Guarded |
| 61 | -- |
| 62 | --: @param This Object itself. |
| 63 | procedure Remove_Reference (This : in out Object_Interface) is abstract; |
| 64 | |
| 65 | --- |
| 66 | -- Current reference counter. |
| 67 | -- |
| 68 | --: @param This Object itself. |
| 69 | function Use_Count (This : in Object_Interface) return Natural is abstract; |
| 70 | |
| 71 | --- |
| 72 | -- Get name of Class. |
| 73 | -- |
| 74 | --: @param This Object itself. |
| 75 | overriding function Get_Name (This : in Object_Interface) return String is abstract; |
| 76 | |
| 77 | ---------- Class ---------------------------------------------------------- |
| 78 | |
| 79 | --- |
| 80 | -- Base Class for Reference Counted Instances. |
| 81 | -- |
| 82 | type Object is new AdaCL.Limited_Base.Object and Object_Interface with private; |
| 83 | |
| 84 | type Object_Class is access Object'Class; |
| 85 | |
| 86 | --- |
| 87 | -- Add a reference |
| 88 | -- |
| 89 | --: @param This Object itself. |
| 90 | overriding procedure Add_Reference (This : in out Object) with |
| 91 | Inline; |
| 92 | |
| 93 | --- |
| 94 | -- Remove a reference. However since an object and a pointer is passed the instance is not deleted. |
| 95 | -- |
| 96 | -- The caller is responsible to call Use_Count and check if delete is needed. |
| 97 | -- |
| 98 | --: @param This Object itself. |
| 99 | overriding procedure Remove_Reference (This : in out Object); |
| 100 | |
| 101 | --- |
| 102 | -- Current reference counter. |
| 103 | -- |
| 104 | --: @param This Object itself. |
| 105 | overriding function Use_Count (This : in Object) return Natural with |
| 106 | Inline; |
| 107 | |
| 108 | private |
| 109 | |
| 110 | --- |
| 111 | -- Base class for Reference Counted Instances. |
| 112 | -- |
| 113 | --: @field RefCount Reference Counter. |
| 114 | type Object is new AdaCL.Limited_Base.Object and Object_Interface with record |
| 115 | RefCount : Natural := 0; |
| 116 | end record with |
| 117 | Put_Image => Object_Image; |
| 118 | |
| 119 | procedure Object_Image (Output : in out Ada.Strings.Text_Buffers.Root_Buffer_Type'Class; This : Object); |
| 120 | |
| 121 | --- |
| 122 | -- Remove a reference and if the use count reaches 0 the instance is deleted. |
| 123 | -- |
| 124 | --: @param This Object itself. |
| 125 | --: @return current use count |
| 126 | overriding function Use_Count (This : in Object) return Natural is (This.RefCount); |
| 127 | |
| 128 | end AdaCL.Pointer.Element; |
| 129 | |
| 130 | ---------------------------------------------------------------- {{{ ---------- |
| 131 | --: vim: set textwidth=0 nowrap tabstop=8 shiftwidth=3 softtabstop=3 expandtab : |
| 132 | --: vim: set filetype=ada fileencoding=utf-8 fileformat=unix foldmethod=expr : |
| 133 | --: vim: set spell spelllang=en_gb : |