Class GuardedAssignmentAsmGenerator

java.lang.Object

org.ek9lang.compiler.backend.jvm.AbstractAsmGenerator

org.ek9lang.compiler.backend.jvm.AbstractControlFlowAsmGenerator

org.ek9lang.compiler.backend.jvm.GuardedAssignmentAsmGenerator

final class GuardedAssignmentAsmGenerator
extends AbstractControlFlowAsmGenerator

Specialized generator for EK9 guarded assignment (:=?). Handles CONTROL_FLOW_CHAIN with chain_type: "GUARDED_ASSIGNMENT".

EK9 Guarded Assignment Pattern: variable :=? value

• Assigns value to variable only if variable is null or not set
• Prevents overwriting already-initialized variables
• Useful for default value initialization

Current Status: NOT YET IMPLEMENTED (throws CompilerException).

Implementation Plan (after IR generator is finalized):

• Evaluate condition (variable? returns false if null/unset)
• If condition false: execute assignment
• If condition true: skip assignment
• Follow pattern similar to QuestionOperatorAsmGenerator

Blocked By: IR generation for GUARDED_ASSIGNMENT must be finalized and tested first. The IR generator (ControlFlowChainGenerator.generateGuardedAssignment) exists but bytecode generation is deferred pending complete testing of question operator foundation.

Nested Class Summary

Nested classes/interfaces inherited from class AbstractAsmGenerator

AbstractAsmGenerator.LocalVariableInfo, AbstractAsmGenerator.MethodContext, AbstractAsmGenerator.ScopeInfo, AbstractAsmGenerator.TempVariableSource

Field Summary

Fields inherited from class AbstractControlFlowAsmGenerator

context

Fields inherited from class AbstractAsmGenerator

classWriter, constructTargetTuple, outputVisitor

Constructor Summary

Constructors

Constructor	Description
GuardedAssignmentAsmGenerator(ConstructTargetTuple constructTargetTuple, OutputVisitor outputVisitor, org.objectweb.asm.ClassWriter classWriter, BytecodeGenerationContext context)

Method Summary

Modifier and Type	Method	Description
void	generate(ControlFlowChainInstr instr)	Generate bytecode for guarded assignment.

Methods inherited from class AbstractControlFlowAsmGenerator

branchIfFalse, branchIfTrue, copyResultVariable, createControlFlowLabel, jumpTo, placeLabel, processBodyEvaluation, processConditionCase, processConditionCaseWithoutLabelPlacement, processConditionEvaluation, processInstructions

Methods inherited from class AbstractAsmGenerator

convertToJvmDescriptor, convertToJvmName, extractFieldName, generateBooleanLiteral, generateCharacterLiteral, generateDebugInfo, generateFloatLiteral, generateIntegerLiteral, generateLoadVariable, generateLocalVariableTable, generateMethodDescriptor, generateObjectLiteral, generateStackOperation, generateStoreVariable, generateStringLiteral, getCurrentMethodVisitor, getFieldDescriptor, getMethodContext, getOrCreateLabel, getOwnerClassName, getVariableIndex, isFieldAccess, isVariableAllocated, setCurrentMethodVisitor, setSharedMethodContext, trackTempVariableFromLiteral, trackTempVariableFromLoad

Methods inherited from class Object

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

Constructor Details

GuardedAssignmentAsmGenerator

GuardedAssignmentAsmGenerator(ConstructTargetTuple constructTargetTuple,
 OutputVisitor outputVisitor,
 org.objectweb.asm.ClassWriter classWriter,
 BytecodeGenerationContext context)

Method Details

generate

public void generate(ControlFlowChainInstr instr)

Generate bytecode for guarded assignment.

EK9 Pattern: variable :=? value

Semantic Flow:

1. Check if target variable is unset (null or _isSet() returns false)
2. If UNSET: evaluate RHS expression and assign to target
3. If SET: skip assignment (fall through to end)

Stack Frame Invariant: Pre-condition: stack is empty Post-condition: stack is empty (assignment stored in variable)

Parameters:

instr - CONTROL_FLOW_CHAIN instruction with GUARDED_ASSIGNMENT type