DispatchTabellen

DispatchTabellen (dispatch tables) are data structures used to map input codes to handlers, enabling fast and deterministic dispatch of actions in software systems. They provide a means to decouple input interpretation from the execution of corresponding logic, improving modularity and performance in many event-driven contexts.

They are typically implemented as arrays for dense, compact code sets or as hash maps for sparse codes. Variants include direct dispatch tables, which use the input code as an index to a handler, and indirect tables that resolve to a function pointer after a secondary lookup. In some contexts, perfect hash tables are used to guarantee collision-free lookups at compile time. The choice of structure depends on code density, update frequency, and memory constraints.

Common applications include command parsers, protocol or message dispatchers, event routers in GUI frameworks, interpreters and virtual machines, and other systems that must quickly route inputs to specific actions. DispatchTabellen are especially useful when the set of valid codes is known ahead of time and performance is critical.

Advantages of using dispatch tables include constant-time lookups, straightforward extension by adding new entries, and good cache locality. Challenges involve managing memory overhead, keeping mappings synchronized with available handlers, handling unknown codes gracefully, and ensuring thread-safety in concurrent environments.

Relation to related concepts includes similarities to vtables, jump tables, and patterns such as the command pattern or visitor pattern. In German-language software literature, DispatchTabellen describe these lookup structures and their role in routing input to the appropriate handler.