Class GuardedAssignmentPromotion

java.lang.Object

org.ek9lang.compiler.phase7.support.GuardedAssignmentPromotion

public final class GuardedAssignmentPromotion
extends Object

THE #^ promotion of a guarded assignment's right-hand side - use this, do not re-derive it.

Phase 3 deliberately permits coercion in a guard: ?= is a member of OperationIsAssignment, so TypesCompatibleOrError accepts any getCostOfMatch >= 0. Character -> String is coercible, so t ?= charSource() with t as String is a clean compile BY DESIGN. Phase 3 resolves the coercion; phase 7 must insert the _promote() call.

Where it is skipped, the RHS's declared type is stored into a slot typed by the target's declared type and the class fails JVM verification at load: "Type 'org/ek9/lang/Character' is not assignable to 'org/ek9/lang/String'". That is a clean compile followed by a hard failure, for a construct that is the language's designated replacement for early return.

Three copies of the guard lowering existed and only the if one promoted, so a guard under while, try, for and switch miscompiled while the identical guard under if ran correctly. This is the single place that decision is now made.

Constructor Summary

Constructors

Constructor	Description
GuardedAssignmentPromotion(PromotionCallGenerator promotionCallGenerator)

Method Summary

Modifier and Type	Method	Description
String	promoteIfRequired(List<IRInstr> target, ISymbol rhsSymbol, ISymbol targetSymbol, String rhsVariable, DebugInfo debugInfo)	Promote the guarded RHS to the target's declared type when the two differ but are coercible.

Methods inherited from class Object

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

Constructor Details

GuardedAssignmentPromotion

public GuardedAssignmentPromotion(PromotionCallGenerator promotionCallGenerator)

Method Details

promoteIfRequired

public String promoteIfRequired(List<IRInstr> target,
 ISymbol rhsSymbol,
 ISymbol targetSymbol,
 String rhsVariable,
 DebugInfo debugInfo)

Promote the guarded RHS to the target's declared type when the two differ but are coercible.

Parameters:

target - instruction list receiving any promotion call

rhsSymbol - the resolved symbol of the guard expression's right-hand side

targetSymbol - the resolved symbol of the guard's target identifier

rhsVariable - the IR variable currently holding the RHS value

debugInfo - debug info for any emitted promotion

Returns:

the variable to store - the promoted one where promotion applied, else the original