Class DispatcherHandlerLinker

java.lang.Object
org.ek9lang.compiler.phase5.callgraph.DispatcherHandlerLinker
public final class DispatcherHandlerLinker extends Object
Links a dispatcher entry point to the handlers its dispatch table can route to, so a call that resolves to the entry point reaches the handler that actually runs.

Why this is needed. renderer.render(shape) with shape as Shape resolves to the entry point render(Shape); at runtime its dispatch table sends a Circle to render(Circle). No call site names the handler, so without these edges every handler reached that way looked unreachable: a valid @Test failed with E81007/E81011, and ek9_find_unused_code offered the running handlers for deletion. PolymorphicOverrideLinker does the same for ordinary virtual dispatch; a dispatcher is a different language feature, so it has its own linker.

Which handlers - THE shared set. The entry points and handlers are exactly DispatcherHandlers.entryPointsOf(IAggregateSymbol) and DispatcherHandlers.collectFor(IAggregateSymbol, MethodSymbol), the set phase 7 builds the dispatch table over, so the call graph cannot route over a different set.

RTA, as for overrides. A handler is linked only when every parameter it dispatches on can arrive: its type, or a concrete subtype of it, is allocated somewhere in the program. A handler for a type nothing constructs cannot run and stays reportable as dead. A parameter that is not an aggregate (a function type) is not filtered - linking is the conservative choice there.

  • Constructor Details

  • Method Details

    • link

      public void link()
      Add a polymorphic edge from each dispatcher entry point of every aggregate that owns a registered method to each of its handlers that can run.