@startuml

actor User
participant View
participant Presenter
database UnitDatabase
participant ExpressionParser
participant Unit

User -> View : Set input & output expressions
View -> Presenter : Call convertExpressions()
View <-- Presenter : Get user input
Presenter -> UnitDatabase : Send raw user input
UnitDatabase -> ExpressionParser : Send inputted expressions
UnitDatabase <-- ExpressionParser : Return parsed expressions
Presenter <-- UnitDatabase : Return unit/value objects
Presenter -> Unit : Convert provided units
Presenter <-- Unit : Return converted value
View <-- Presenter : Return converted units
User <-- View : Show conversion output

@enduml