Class PreFlowCanSkipBody

java.lang.Object

org.ek9lang.compiler.support.PreFlowCanSkipBody

All Implemented Interfaces:

Predicate<EK9Parser.PreFlowStatementContext>

public final class PreFlowCanSkipBody
extends Object
implements Predicate<EK9Parser.PreFlowStatementContext>

THE single definition of "can this control-flow pre-flow skip the construct body?".

A pre-flow (the head of an if/while/do/for/switch/try) is a body-skipping guard iff its operator performs an isSet check that can skip the body:

• <- (EK9Parser.LEFT_ARROW) - declaration guard
• :=? (EK9Parser.ASSIGN_UNSET) - assign-if-unset guard

A plain :=/= assignment (EK9Parser.ASSIGN/EK9Parser.ASSIGN2) is NOT a guard - the body always runs unless the control says otherwise (if x := f() then x? is the explicit re-point-and-gate that replaced the removed ?= guard, Steve 2026-10-07, D3). A null pre-flow is not a guard.

This is the SOLE authority, consumed by BOTH phase 5 and phase 7, so the two phases can never drift on what a guard is (that drift was the root cause of a null-safety bug where an expression-form return declared as T? could be left as a raw Java null on the skip path):

• Phase 5 uses it to decide when an expression-form return MUST be initialised (RETURN_NOT_ALWAYS_INITIALISED / E08050) - a skippable body means the return's initial value is the result on the skip path, so an uninitialised <- rtn as T? is an error.
• Phase 7 uses it (GuardedConditionEvaluator, LoopGuardHelper, the switch) to decide whether to emit a guard entry-check that gates the body.

Do NOT re-derive a variant of this classification - hold one of these and ask it. Built on it: GuardTargetNode (the variable a guard set-checks), GuardSkipsWholeSwitchOrTry (D40) and PreFlowOperatorToken (the operator token itself).

Constructor Summary

Constructors

Constructor	Description
PreFlowCanSkipBody()

Method Summary

Modifier and Type	Method	Description
boolean	test(EK9Parser.PreFlowStatementContext preFlow)	True iff this pre-flow is a body-skipping guard (<-, :=?).

Methods inherited from class Object

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

Methods inherited from interface Predicate

and, negate, or

Constructor Details

PreFlowCanSkipBody

public PreFlowCanSkipBody()

Method Details

test

public boolean test(EK9Parser.PreFlowStatementContext preFlow)

True iff this pre-flow is a body-skipping guard (<-, :=?).

Specified by:

test in interface Predicate<EK9Parser.PreFlowStatementContext>

Parameters:

preFlow - the pre-flow statement context (may be null)

Returns:

true if the pre-flow can skip the construct body