<?xml version="1.0" encoding="UTF-8"?>
<!--

Documentation for LCL (Lazarus Component Library) and LazUtils (Lazarus 
Utilities) are published under the Creative Commons Attribution-ShareAlike 4.0 
International public license.

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file://../../cc-by-sa-4-0.txt

Copyright (c) 1997-2023, by the Lazarus Development Team.

-->
<fpdoc-descriptions>
<package name="lazutils">
<!--
====================================================================
ObjectLists
====================================================================
-->
<module name="ObjectLists">
<short>
Defines classes used to associate objects/pointers with objects/pointers.
</short>
<descr>
<p>
<file>objectlists.pas</file> defines classes used to associate 
objects/pointers with objects/pointers. Converted to use generics by Juha. 
Item and Object types can now be defined.
</p>
<p>
<file>objectlists.pas</file> is part of the <file>lazutils</file> package.
</p>
</descr>

<!-- used units -->
<element name="System"/>
<element name="Classes"/>
<element name="SysUtils"/>

<element name="T2Pointer">
<short>Record type with pointers to members in the association.</short>
<descr>
<p>
<var>T2Pointer</var> is a record type used to maintain an association between 
the pointers to the members in the record.
</p>
</descr>
<seealso></seealso>
</element>

<element name="T2Pointer.Item">
<short>Pointer to the item for the association.</short>
<descr></descr>
<seealso></seealso>
</element>

<element name="T2Pointer.Associated">
<short>Pointer to the associated item in the record.</short>
<descr></descr>
<seealso></seealso>
</element>

<element name="P2Pointer">
<short>Pointer to the T2Pointer record type.</short>
<descr>
<p>
Used to implement the list of item / object associations in 
<var>TObjectArray</var>.
</p>
</descr>
<seealso>
<link id="TObjectArray.Items"/>
<link id="TObjectArray.Objects"/>
</seealso>
</element>

<element name="TObjectArray">
<short>
Implements an array of items with their associated objects.
</short>
<descr>
<p>
<var>TObjectArray</var> is a generic type used to implement an array of items 
and their associated objects. TObjectArray allows the association to be 
defined using the TItem and TObj class types. Internally, it uses a list of 
records with pointers to the <var>Items</var> and <var>Objects</var> stored 
in the class. Properties and methods are provided to maintain and access the 
entries in the class instance, and the allocated storage for the array type.
</p>
</descr>
<seealso>
<link id="T2Pointer"/>
<link id="P2Pointer"/>
</seealso>
</element>

<element name="TObjectArray.FCapacity"/>
<element name="TObjectArray.FCount"/>
<element name="TObjectArray.FList"/>

<element name="TObjectArray.Get">
<short>Gets the value for the Items property.</short>
<descr/>
<seealso>
<link id="TObjectArray.Items"/>
<link id="TObjectArray.Put"/>
</seealso>
</element>
<element name="TObjectArray.Get.Result">
<short>TItem value for the property.</short>
</element>
<element name="TObjectArray.Get.Index">
<short>Ordinal position for the requested item.</short>
</element>

<element name="TObjectArray.Put">
<short>Sets the value for the Items property.</short>
<descr/>
<seealso>
<link id="TObjectArray.Items"/>
</seealso>
</element>
<element name="TObjectArray.Put.Index">
<short>Ordinal position for the updated item.</short>
</element>
<element name="TObjectArray.Put.AValue">
<short>New TItem value for the property.</short>
</element>

<element name="TObjectArray.GetObject">
<short>Gets the value for the Objects property.</short>
<descr/>
<seealso>
<link id="TObjectArray.Objects"/>
<link id="TObjectArray.PutObject"/>
</seealso>
</element>
<element name="TObjectArray.GetObject.Result">
<short>TObj value for the property.</short>
</element>
<element name="TObjectArray.GetObject.Index">
<short>Ordinal position for the requested object.</short>
</element>

<element name="TObjectArray.PutObject">
<short>Sets the value for the Objects property.</short>
<descr/>
<seealso>
<link id="TObjectArray.Objects"/>
<link id="TObjectArray.GetObject"/>
</seealso>
</element>
<element name="TObjectArray.PutObject.Index">
<short>Ordinal position for the updated object.</short>
</element>
<element name="TObjectArray.PutObject.AValue">
<short>New TObj value for the property.</short>
</element>

<element name="TObjectArray.SetCapacity">
<short>Sets the value for the Capacity property.</short>
<descr>
<p>
<var>SetCapacity</var> calls <var>ReallocMem</var> to ensure that 
<var>List</var> contains enough memory for the number of <var>T2Pointer</var> 
instances specified in <var>AValue</var>. The <var>Count</var> property is 
also updated in the method (when needed) to reflect the new value for the 
property.
</p>
</descr>
<seealso>
<link id="TObjectArray.Capacity"/>
<link id="TObjectArray.Count"/>
</seealso>
</element>
<element name="TObjectArray.SetCapacity.AValue">
<short>New value for the property.</short>
</element>

<element name="TObjectArray.SetCount">
<short>Sets the value for the Count property.</short>
<descr>
<p>
<var>SetCount</var> calls <var>SetCapacity</var> when the new value for the 
property is larger than the existing value in <var>Capacity</var>.
</p>
</descr>
<seealso>
<link id="TObjectArray.Count"/>
<link id="TObjectArray.Capacity"/>
<link id="TObjectArray.SetCapacity"/>
</seealso>
</element>
<element name="TObjectArray.SetCount.AValue">
<short>New value for the property.</short>
</element>

<element name="TObjectArray.Grow">
<short>
Increases the storage Capacity for the class instance.
</short>
<descr>
<p>
<var>Grow</var> increases the storage <var>Capacity</var> (number of 
item/object associations) for the class instance. Grow ensures that Capacity 
has a minimum of size of five (<b>5</b>). Otherwise, the number of 
associations is always increased by doubling the value in the Capacity 
property, which in turn, reallocates the storage space needed for the 
<var>List</var>.
</p>
<p>
Grow is used in the implementation of the <var>AddObject</var> and 
<var>InsertObject</var> methods. To avoid rampant memory consumption in large 
lists, caused by doubling the value in Capacity, explicitly set the value in 
Capacity to a reasonable size prior to calling the <var>Add</var>, 
<var>AddObject</var>, <var>Insert</var>, or <var>InsertObject</var> methods.
</p>
</descr>
<seealso>
<link id="TObjectArray.Capacity"/>
<link id="TObjectArray.List"/>
<link id="TObjectArray.Add"/>
<link id="TObjectArray.AddObject"/>
<link id="TObjectArray.Insert"/>
<link id="TObjectArray.InsertObject"/>
</seealso>
</element>

<element name="TObjectArray.Shrink">
<short>
Decreases the Capacity and allocated storage for the class instance.
</short>
<descr>
<p>
<var>Shrink</var> is a procedure used to decrease the <var>Capacity</var> 
(and subsequently) the allocated storage for the class instance. Shrink 
always halves the value in the Capacity property. It is called from the 
<var>Delete</var> method when Capacity has at least four (4) times the number 
of associations in the <var>Count</var> property.
</p>
</descr>
<seealso>
<link id="TObjectArray.Delete"/>
<link id="TObjectArray.Capacity"/>
<link id="TObjectArray.SetCapacity"/>
<link id="TObjectArray.Count"/>
</seealso>
</element>

<element name="TObjectArray.Destroy">
<short>Destructor for the class instance.</short>
<descr>
<var>Destroy</var> is the overridden destructor for the class instance. It 
calls <var>ReallocMem</var> to reset the storage size in <var>List</var> to 
<b>0</b> (<b>zero</b>). It calls the inherited method prior to exit.
</descr>
<seealso>
<link id="TObjectArray.List"/>
<link id="#rtl.system.ReallocMem">ReallocMem</link>
</seealso>
</element>

<element name="TObjectArray.Add">
<short>Adds the specified item to the storage for the class instance.</short>
<descr>
<p>
<var>Add</var> is an <var>Integer</var> function used to add the item 
specified in <var>Item</var> to the storage for the class instance. Add calls 
the <var>AddObject</var> method to store the value in Item. The associated 
object is unassigned (<b>Nil)</b> in the method. Use <var>AddObject</var> to 
store an Item and its associated object.
</p>
<p>
The return value contains the ordinal position in <var>List</var> where the 
Item was stored.
</p>
</descr>
<seealso>
<link id="TObjectArray.AddObject"/>
<link id="TObjectArray.List"/>
<link id="TObjectArray.Count"/>
</seealso>
</element>
<element name="TObjectArray.Add.Result">
<short>Ordinal position in storage when the item was added.</short>
</element>
<element name="TObjectArray.Add.Item">
<short>Item added in the method.</short>
</element>

<element name="TObjectArray.AddObject">
<short>
Adds the specified item and its associated object to the storage in the class 
instance.
</short>
<descr>
<p>
<var>AddObject</var> is an <var>Integer</var> function which adds the 
specified item and its associated object to the storage in the class 
instance. AddObject calls the <var>Grow</var> method to increase storage in 
the class instance when <var>Count</var> reaches the value in 
<var>Capacity</var>.
</p>
<p>
AddObject uses the <var>List</var> property to store the values in 
<var>Item</var> and <var>Associated</var> to the corresponding properties at 
the position in <var>Count</var>. The value in Count is incremented prior to 
exiting from the method.
</p>
<p>
Use <var>Add</var> to store an Item with an unassigned associated object.
</p>
<p>
Use methods like <var>Delete</var>, <var>Remove</var>, and <var>Clear</var> 
to remove one or all associations stored in List.
</p>
<p>
Use the indexed <var>Items</var> and <var>Objects</var> properties to access 
values stored in an association at a specific position.
</p>
</descr>
<seealso>
<link id="TObjectArray.List"/>
<link id="TObjectArray.Count"/>
<link id="TObjectArray.Capacity"/>
<link id="TObjectArray.Add"/>
<link id="TObjectArray.InsertObject"/>
<link id="TObjectArray.Delete"/>
<link id="TObjectArray.Remove"/>
<link id="TObjectArray.Clear"/>
<link id="TObjectArray.Items"/>
<link id="TObjectArray.Objects"/>
</seealso>
</element>
<element name="TObjectArray.AddObject.Result">
<short>
Ordinal position where the association for the item and the object was stored.
</short>
</element>
<element name="TObjectArray.AddObject.Item">
<short>Item stored in the association.</short>
</element>
<element name="TObjectArray.AddObject.Associated">
<short>Object stored in the association.</short>
</element>

<element name="TObjectArray.Clear">
<short>
Removes all item/object associations stored in the List.
</short>
<descr>
<p>
<var>Clear</var> is a procedure used to remove all item/object associations 
stored in the <var>List</var>. Clear sets the values in <var>Count</var> and 
<var>Capacity</var> to zero (<b>0</b>), and calls <var>ReallocMem</var> to 
set the allocated memory size in List to zero (<b>0</b>).
</p>
<p>
Use <var>Delete</var> or <var>Remove</var> to delete a single association by 
its position or item content.
</p>
</descr>
<seealso>
<link id="TObjectArray.Count"/>
<link id="TObjectArray.Capacity"/>
<link id="TObjectArray.List"/>
<link id="TObjectArray.Delete"/>
<link id="TObjectArray.Remove"/>
</seealso>
</element>

<element name="TObjectArray.Delete">
<short>
Deletes an item/object association stored at the specified position in the 
List.
</short>
<descr>
<p>
<var>Delete</var> is a procedure used to deletes an item/object association 
stored at the specified position in the <var>List</var>. When List has a 
length greater than the value in <var>Index</var><b>+1</b>, the Move routine 
in the <file>System.pp</file> unit is called to relocate any associations 
that occur after the position requested.
</p>
<p>
Delete decrements the value in <var>Count</var>. The <var>Shrink</var> method 
is called when <var>Capacity</var> is larger than four (<b>4</b>) times the 
new value in Count.
</p>
<p>
Use <var>Remove</var> to delete an association with a specific TItem class 
instance.
</p>
</descr>
<seealso>
<link id="TObjectArray.List"/>
<link id="TObjectArray.Capacity"/>
<link id="TObjectArray.Count"/>
<link id="TObjectArray.Shrink"/>
<link id="TObjectArray.Remove"/>
</seealso>
</element>
<element name="TObjectArray.Delete.Index">
<short>
Ordinal position in List for the association deleted in the method.
</short>
</element>

<element name="TObjectArray.Exchange">
<short>
Swaps the item/object associations at the specified positions in List.
</short>
<descr>
<p>
<var>Exchange</var> is a procedure used to swap the item/object associations 
in the <var>List</var> at the ordinal positions specified in 
<var>Index1</var> and <var>Index2</var>.
</p>
<p>
Use Move to change the location for an item/object association, and reorder 
the List as needed.
</p>
</descr>
<seealso>
<link id="TObjectArray.List"/>
<link id="TObjectArray.Move"/>
<link id="T2Pointer"/>
</seealso>
</element>
<element name="TObjectArray.Exchange.Index1">
<short>
Ordinal position for the first item/object association.
</short>
</element>
<element name="TObjectArray.Exchange.Index2">
<short>
Ordinal position for the second item/object association.
</short>
</element>

<element name="TObjectArray.First">
<short>
Gets the first TItem class instance in the List, or Nil when empty.
</short>
<descr>
<p>
<var>First</var> is a <var>TItem</var> function used to get the class 
instance stored in the first association. First uses the <var>List</var> to 
access the <var>T2Pointer</var> stored in element zero (<b>0</b>) for the 
array.
</p>
<p>
The return value is the <var>Item</var> in the association cast to the TItem 
class type used for the generic class specialization. When <var>Count</var> 
contains zero (<b>0</b>), the return value is <b>Nil</b>. </p>
</descr>
<seealso>
<link id="TObjectArray.List"/>
<link id="TObjectArray.Count"/>
<link id="T2Pointer"/>
</seealso>
</element>
<element name="TObjectArray.First.Result">
<short>TItem class instance at the first position in the List.</short>
</element>

<element name="TObjectArray.IndexOf">
<short>
Gets the ordinal position in List where the specified TItem instance is 
stored.
</short>
<descr>
<p>
<var>IndexOf</var> is an <var>Integer</var> function used to get the ordinal 
position in <var>List</var> where the TItem instance specified in 
<var>Item</var> is stored. IndexOf iterates over the storage in List in 
reverse order.
</p>
<p>
The return value contains the ordinal position where the 
<var>T2Pointer.Item</var> member and the Item argument contain the same class 
instance. The return value is <b>-1</b> when Item is not located in the 
associations stored in List.
</p>
</descr>
<seealso>
<link id="TObjectArray.List"/>
<link id="T2Pointer"/>
</seealso>
</element>
<element name="TObjectArray.IndexOf.Result">
<short>Ordinal position for the requested TItem instance.</short>
</element>
<element name="TObjectArray.IndexOf.Item">
<short>TItem instance to locate in the List of associations.</short>
</element>

<element name="TObjectArray.Insert">
<short>
Inserts a new association at the specified position in List.
</short>
<descr>
<p>
<var>Insert</var> is a procedure used to insert a new association at the 
specified position in <var>List</var>. <var>Item</var> contains the TItem 
class instance for the association. The object for the association is always 
set to <b>Nil</b> in the method.
</p>
<p>
Use InsertObject to insert a new association using both an item and an object.
</p>
<p>
Use Add or AddObject to append a new item/object association.
</p>
</descr>
<seealso>
<link id="TObjectArray.InsertObject"/>
<link id="TObjectArray.AddObject"/>
<link id="TObjectArray.Add"/>
<link id="TObjectArray.List"/>
<link id="T2Pointer"/>
</seealso>
</element>
<element name="TObjectArray.Insert.Index">
<short>Ordinal position where the association is inserted.</short>
</element>
<element name="TObjectArray.Insert.Item">
<short>TItem instance used in the inserted association.</short>
</element>

<element name="TObjectArray.InsertObject">
<short>
Inserts an item/object association at the specified position in the List.
</short>
<descr></descr>
<seealso></seealso>
</element>
<element name="TObjectArray.InsertObject.Index">
<short>Ordinal position in List where the association is inserted.</short>
</element>
<element name="TObjectArray.InsertObject.Item">
<short>TItem instance for the new association.</short>
</element>
<element name="TObjectArray.InsertObject.Associated">
<short>TObj instance for the association.</short>
</element>

<element name="TObjectArray.Last">
<short>
Gets the last TItem instance in the List, or Nil when empty.
</short>
<descr>
<p>
<var>Last</var> is a <var>TItem</var> function used to get the last item 
instance in the allocated storage in List. Last uses the value in 
<var>Count</var> to determine the position for the last item/object 
association. When Count is zero (<b>0</b>), the List is empty and the return 
value is set to <b>Nil</b>.
</p>
</descr>
<seealso>
<link id="TObjectArray.List"/>
<link id="TObjectArray.Count"/>
<link id="T2Pointer"/>
</seealso>
</element>
<element name="TObjectArray.Last.Result">
<short>TItem instance stored at the last position in List.</short>
</element>

<element name="TObjectArray.Move">
<short>
Relocates the association stored at the position in CurIndex to the position 
in NewIndex.
</short>
<descr>
<p>
<var>Move</var> is a procedure used to relocate the association stored at the 
position in <var>CurIndex</var> to the position in <var>NewIndex</var>. No 
actions are performed in the method when CurIndex and Index contain the same 
value.
</p>
<p>
Move gets the <var>T2Pointer</var> stored at the position in CurIndex from 
the <var>List</var>. Move call the Move routine in the <file>System.pp</file> 
unit to relocate any associations stored between the positions in CurIndex 
and NewIndex. The relocated associations are moved towards the end of List 
when CurIndex is greater than NewIndex.
</p>
<p>
The T2Pointer is reassigned to the position in NewIndex.
</p>
</descr>
<seealso>
<link id="TObjectArray.List"/>
<link id="T2Pointer"/>
</seealso>
</element>
<element name="TObjectArray.Move.CurIndex">
<short>Ordinal position where the association is currently stored </short>
</element>
<element name="TObjectArray.Move.NewIndex">
<short>Ordinal position where the association is moved.</short>
</element>

<element name="TObjectArray.Assign">
<short>
Assigns TItem class instances specified in SrcList to the List storage in the 
class.
</short>
<descr>
<p>
<var>Assign</var> is a procedure used to stored <var>TItem</var> class 
instances in <var>SrcList</var> to the <var>List</var> storage for the class. 
Assign calls the <var>Clear</var> method to remove all existing item/object 
associations stored in List.
</p>
<p>
Assign sets the the value in <var>Count</var> to the the length in SrcList. 
The method iterates over the values in the TList instance, and stores the 
TItem instances in the corresponding positions in List. The associated object 
for all entries in List is unassigned (<b>Nil</b>).
</p>
</descr>
<seealso>
<link id="TObjectArray.Clear"/>
<link id="TObjectArray.Count"/>
<link id="TObjectArray.List"/>
<link id="T2Pointer"/>
</seealso>
</element>
<element name="TObjectArray.Assign.SrcList">
<short>
TList with the TItem class instances stored in the method.
</short>
</element>

<element name="TObjectArray.Remove">
<short>
Removes the association with the specified TItem class instance.
</short>
<descr>
<p>
<var>Remove</var> is an <var>Integer</var> function used to delete the 
item/object association with the specified <var>TItem</var> class instance. 
The return value contains the result returned from <var>IndexOf</var>. The 
return value is <b>-1</b> when Item is not found in <var>List</var>. When 
Item exists in List, the <var>Delete</var> method is called to remove the 
association at the position in the return value.
</p>
</descr>
<seealso>
<link id="TObjectArray.List"/>
<link id="TObjectArray.IndexOf"/>
<link id="TObjectArray.Delete"/>
</seealso>
</element>
<element name="TObjectArray.Remove.Result">
<short>Ordinal position for the association removed in the method.</short>
</element>
<element name="TObjectArray.Remove.Item">
<short>TItem class instance to locate in the List.</short>
</element>

<element name="TObjectArray.Pack">
<short>
Removes all associations where the Item class instance is unassigned 
(contains Nil).
</short>
<descr>
<p>
<var>Pack</var> is a procedure used to remove all associations where the Item 
class instance is unassigned (contains <b>Nil</b>). Pack iterates over the 
allocated storage in <var>List</var> to determine if the 
<var>T2Pointer.Item</var> member is unassigned. When an an unassigned item is 
found, subsequent associations are moved to fill the storage position(s) for 
any unused items. Pack updates the value in the <var>Count</var> property to 
reflect the new number of associations in List.
</p>
</descr>
<seealso>
<list id="TObjectArray.List"/>
<list id="TObjectArray.Count"/>
<list id="T2Pointer"/>
</seealso>
</element>

<element name="TObjectArray.Capacity">
<short>
Specifies the number of associations that can be stored in the List.
</short>
<descr>
<p>
<var>Capacity</var> is an <var>Integer</var> property which specifies the 
number of item/object associations that can be stored in the <var>List</var>. 
Changing the value in Capacity causes the memory in List to be reallocated to 
accommodate the new capacity value. The value in <var>Count</var> may also be 
affected when the value in Capacity is reduced.
</p>
</descr>
<seealso>
<link id="TObjectArray.List"/>
<link id="TObjectArray.Count"/>
<link id="T2Pointer"/>
</seealso>
</element>

<element name="TObjectArray.Count">
<short>
Number of item/object associations currently stored in the List.
</short>
<descr>
<p>
<var>Count</var> is an <var>Integer</var> property which indicates the number 
of item/object associations currently stored in the <var>List</var>. Changing 
the value in Count causes <var>Capacity</var> to be updated when Count 
exceeds the value in Capacity.
</p>
<p>
The value in Count is maintained in method which add or remove item/object 
associations in List, such as: <var>Add</var>, <var>AddObject</var>, 
<var>Insert</var>, <var>InsertObject</var>, <var>Delete</var>, 
<var>Remove</var>, <var>Clear</var> and <var>Pack</var>.
</p>
</descr>
<seealso>
<link id="TObjectArray.List"/>
<link id="TObjectArray.Capacity"/>
<link id="TObjectArray.Add"/>
<link id="TObjectArray.AddObject"/>
<link id="TObjectArray.Insert"/>
<link id="TObjectArray.InsertObject"/>
<link id="TObjectArray.Delete"/>
<link id="TObjectArray.Remove"/>
<link id="TObjectArray.Clear"/>
<link id="TObjectArray.Pack"/>
</seealso>
</element>

<element name="TObjectArray.Items">
<short>
Provides indexed access to the TItem class instances stored in the List.
</short>
<descr>
<p>
<var>Items</var> is an indexed property which provides access to the     
<var>TItem</var> class instances stored in the List.
</p>
</descr>
<seealso>
<link id="TObjectArray.Get"/>
<link id="TObjectArray.Put"/>
<link id="TObjectArray.List"/>
</seealso>
</element>
<element name="TObjectArray.Items.Index">
<short>Ordinal position for the requested value.</short>
</element>

<element name="TObjectArray.Objects">
<short>
Provides indexed access to the TObj class instances stored in the List.
</short>
<descr>
<p>
<var>Objects</var> is an indexed property used to provide access to the   
<var>TObj</var> class instances stored in the <var>List</var>.
</p>
</descr>
<seealso>
<link id="TObjectArray.List"/>
<link id="TObjectArray.GetObject"/>
<link id="TObjectArray.PutObject"/>
</seealso>
</element>
<element name="TObjectArray.Objects.Index">
<short>Ordinal position for the requested value.</short>
</element>

<element name="TObjectArray.List">
<short>
Provides access to the list which implements the storage for the item/object 
associations in the class instance.
</short>
<descr>
<p>
<var>List</var> is a read-only <var>P2Pointer</var> property which provides 
access to the list which implements the storage for the class instance. It is 
organized as pointers to a sequence of T2Pointer records. To access the 
record, and its Item and Object properties, use a subscript in the range 
0..Count-1. For example:
</p>
<code>
// type TMyObjStrsArr = specialize TObjectArray&lt;TMyObject, TStrings&gt;;
// var aObjArr: TMyObjStrsArr;
// var lFound: Boolean;

lFound := False;
for iPos := 0 to aObjArr.Count-1 do
begin
   lFound :=  (aObjArr.List[iPos].Item.Name = 'Foo');
   if lFound then break;
end;
Exit(lFound);
</code>
<p>
Content in the record can be accessed using the indexed Items and Objects 
properties as well.
</p>
</descr>
<seealso>
<link id="TObjectArray.Items"/>
<link id="TObjectArray.Objects"/>
<link id="T2Pointer"/>
<link id="P2Pointer"/>
</seealso>
</element>

</module>
<!-- ObjectLists -->

</package>
</fpdoc-descriptions>
