Class ConstructionRecursionOrError

java.lang.Object

org.ek9lang.compiler.phase5.construction.ConstructionRecursionOrError

public final class ConstructionRecursionOrError
extends Object

FE77: construction that can never complete (E08263). A type whose construction ALWAYS constructs the same type again - through a property initialiser, a constructor body, a this(...) cycle, a function or a closed method, or a generic's T() - compiles to a guaranteed StackOverflowError, so it is a compile error.

The graph. Nodes are callables - constructors, _i_init, functions, methods - and each edge is a call that ALWAYS runs and is statically dispatched (ConstructionEdges). A cycle in that graph means that once any member runs none can finish. A cycle is reported when it contains a constructor or an _i_init, whether or not anything constructs the type yet: the type can never be built.

🔑 A generic's members are a node PER PARAMETERISATION. A node is the call-graph identity together with the parameterisation it runs as. The call graph deliberately folds every parameterisation onto its template (D15); using that folded key here would merge Base of X with Base of Y and invent cycles. So a template's always-run calls are recorded once and applied to each parameterisation as it is reached: T() becomes a construction of the substituted type, and Inner of T the existing Inner of Leaf.

Sound, and partial on purpose. Calls that only MAY run (any conditional, loop, catch, short-circuit, :=?, stream stage) and calls that dispatch at run time (trait, open-type and abstract methods, dispatchers, function delegates) are not followed, and a substitution FULL_RESOLUTION never made is not invented. Each of those can only hide a cycle, never report one that cannot happen.

Constructor Summary

Constructors

Constructor	Description
ConstructionRecursionOrError(ConstructionEdges constructionEdges, Parameterisations parameterisations, Function<IToken, ErrorListener> errorListenerForToken)	Create the check over the always-run calls collected in this compile.

Method Summary

Modifier and Type	Method	Description
void	check()	Find every construction cycle and report each one once, in source order.

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

ConstructionRecursionOrError

public ConstructionRecursionOrError(ConstructionEdges constructionEdges,
 Parameterisations parameterisations,
 Function<IToken, ErrorListener> errorListenerForToken)

Create the check over the always-run calls collected in this compile.

Parameters:

constructionEdges - the always-run calls from the call-graph walk

parameterisations - every concrete parameterisation in the program

errorListenerForToken - the error listener of the source a token is in

Method Details

check

public void check()

Find every construction cycle and report each one once, in source order. The search order does not matter: a node belongs to the same cycle whichever root reaches it first, and each error's place is chosen from the cycle itself.