ch2-3-x-slice-to-y-slice.plantuml

' Copyright 2017 <chaishushan{AT}gmail.com>. All rights reserved.
' Use of this source code is governed by a Apache
' license that can be found in the LICENSE file.


'var p []X
'var q []Y // q = p

'pHdr := (*reflect.SliceHeader)(unsafe.Pointer(&p))
'qHdr := (*reflect.SliceHeader)(unsafe.Pointer(&q))

'pHdr.Data = qHdr.Data
'pHdr.Len = qHdr.Len * unsafe.Sizeof(q[0]) / unsafe.Sizeof(p[0])
'pHdr.Cap = qHdr.Cap * unsafe.Sizeof(q[0]) / unsafe.Sizeof(p[0])


@startuml

title []X <=> []Y

participant "var x []X\nvar y []Y" as slice
participant "var px *SliceHeader\nvar py *SliceHeader" as slice_header

== []X and []Y to *reflect.SliceHeader  ==

slice -> slice_header: px := (*reflect.SliceHeader)(unsafe.Pointer(&x))\npy := (*reflect.SliceHeader)(unsafe.Pointer(&y))

== copy *px to *py ==

slice_header -> slice_header: ~*py = *px

== y changed by *py ==

slice -> slice: y = x

@enduml