'' examples/manual/proguide/dynamicmemory.bas
''
'' Example extracted from the FreeBASIC Manual
'' from topic 'Dynamic memory management with FreeBASIC'
''
'' See Also: https://www.freebasic.net/wiki/wikka.php?wakka=ProPgDynamicMemory
'' --------
''
'' Resource ownership:
''
'' p1 owns manually constructed objects and is released with their matching
'' destructors followed by Deallocate.  p2 is a New[] allocation owned by
'' Delete[].  The objects placed in array must be destructed before its storage
'' is erased.  p4 owns its dynamic array storage until Erase.

Type UDT
	Dim As String S = "FreeBASIC"              '' induce an implicit constructor and destructor
End Type

' 3 then 4 objects: Callocate, Reallocate, Deallocate, (+ .constructor + .destructor)
Dim As UDT Ptr p1 = CAllocate(3, SizeOf(UDT))  '' allocate cleared memory for 3 elements (string descriptors cleared,
												   ''     but maybe useless because of the constructor's call right behind)
If p1 = 0 Then
	Print "Could not allocate the first object array"
Else
	For I As Integer = 0 To 2
		p1[I].Constructor()                    '' call the constructor on each element
	Next I
	For I As Integer = 0 To 2
		'' This fixed three-element tutorial loop appends one short index per object.
		'' FB-LINTER: DISABLE-NEXT-LINE FBL503
		p1[I].S &= Str(I)                      '' add the element number to the string of each element
	Next I
	For I As Integer = 0 To 2
		Print "'" & p1[I].S & "'",             '' print each element string
	Next I
	Print
	Dim As UDT Ptr p1_resized = Reallocate(p1, 4 * SizeOf(UDT))
	If p1_resized = 0 Then
		Print "Could not resize the first object array"
		For I As Integer = 0 To 2
			p1[I].Destructor()
		Next I
		Deallocate(p1)
		p1 = 0
	Else
		p1 = p1_resized                         '' retain ownership only after Reallocate succeeds
		Clear p1[3], 0, 3 * SizeOf(Integer)     '' clear the descriptor of the additional element,
												   ''     but maybe useless because of the constructor's call right behind
		p1[3].Constructor()                      '' call the constructor on the additional element
		p1[3].S &= Str(3)                        '' add the element number to the string of the additional element
		For I As Integer = 0 To 3
			Print "'" & p1[I].S & "'",           '' print each element string
		Next I
		Print
		For I As Integer = 0 To 3
			p1[I].Destructor()                    '' call the destructor on each element
		Next I
		Deallocate(p1)                           '' deallocate the memory
		p1 = 0
	End If
End If
Print

' 3 objects: New, Delete
Dim As UDT Ptr p2 = New UDT[3]                 '' allocate memory and construct 3 elements
If p2 = 0 Then
	Print "Could not allocate the second object array"
Else
	For I As Integer = 0 To 2
		'' This fixed three-element tutorial loop appends one short index per object.
		'' FB-LINTER: DISABLE-NEXT-LINE FBL503
		p2[I].S &= Str(I)                      '' add the element number to the string of each element
	Next I
	For I As Integer = 0 To 2
		Print "'" & p2[I].S & "'",             '' print each element string
	Next I
	Print
	Delete [] p2                               '' destroy the 3 element and deallocate the memory
	p2 = 0
End If
Print

' 3 objects: Placement New, (+ .destructor)
ReDim As Byte array(0 To 3 * SizeOf(UDT) - 1)  '' allocate buffer for 3 elements
Dim As Any Ptr p = @array(0)
'' array is exactly three UDT-sized slots, and the destructor loop below runs before Erase.
'' FB-LINTER: DISABLE-NEXT-LINE FBL525 FBL-PTR-023
Dim As UDT Ptr p3 = New(p) UDT[3]              '' only construct the 3 elements in the buffer (placement New)
For I As Integer = 0 To 2
	'' This fixed three-element tutorial loop appends one short index per object.
	'' FB-LINTER: DISABLE-NEXT-LINE FBL503
	p3[I].S &= Str(I)                          '' add the element number to the string of each element
Next I
For I As Integer = 0 To 2
	Print "'" & p3[I].S & "'",                 '' print each element string
Next I
Print
For I As Integer = 0 To 2
	p3[I].Destructor()                         '' call the destructor on each element
Next I
Erase array                                    '' deallocate the buffer
Print

' 3 then 4 objects: Redim, Erase
ReDim As UDT p4(0 To 2)                        '' define a dynamic array of 3 elements
For I As Integer = 0 To 2
	'' This fixed three-element tutorial loop appends one short index per object.
	'' FB-LINTER: DISABLE-NEXT-LINE FBL503
	p4(I).S &= Str(I)                          '' add the element number to the string of each element
Next I
For I As Integer = 0 To 2
	Print "'" & p4(I).S & "'",                 '' print each element string
Next I
Print
ReDim Preserve p4(0 To 3)                      '' resize the dynamic array for one additional element
p4(3).S &= Str(3)                              '' add the element number to the string of the additional element
For I As Integer = 0 To 3
	Print "'" & p4(I).S & "'",                 '' print each element string
Next I
Print
Erase p4                                       '' erase the dynamic array
Print


Sleep