Class SwitchAsmGenerator

java.lang.Object

org.ek9lang.compiler.backend.jvm.AbstractAsmGenerator

org.ek9lang.compiler.backend.jvm.AbstractControlFlowAsmGenerator

org.ek9lang.compiler.backend.jvm.SwitchAsmGenerator

final class SwitchAsmGenerator
extends AbstractControlFlowAsmGenerator

Specialized generator for EK9 switch statements. Handles CONTROL_FLOW_CHAIN with chain_type: "SWITCH".

EK9 Switch Semantics: - Sequential condition evaluation (if/else-if pattern) - Supports rich operators: equality, contains, matches, comparison - Works with Integer, String, Float, Character types - Multiple case literals per case - Optional default clause

Bytecode Pattern (Sequential Evaluation):

; Evaluation variable setup (switch expression)
[evaluation variable instructions]

; Case 1
[condition evaluation]
iload primitive_condition
ifeq case_2                    ; Branch if false
[case 1 body]
goto end                       ; Exit switch

case_2:
[condition evaluation]
iload primitive_condition
ifeq default_label             ; Branch if false
[case 2 body]
goto end

default_label:
[default body]                 ; Fall through to end

end:
; All paths converge here

Stack Frame Invariant: All paths arrive at 'end' label with empty stack. Statement form has no result variable (unlike expression form which would).

Design Note: EK9 switch uses sequential evaluation rather than JVM tableswitch/lookupswitch because it supports rich operator semantics (contains, matches) and multiple types (String, Float) that don't map to JVM switch instructions. This provides maximum flexibility while maintaining correct semantics.

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
SwitchAsmGenerator(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 switch statement.

Methods inherited from class AbstractControlFlowAsmGenerator

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

Methods inherited from class AbstractAsmGenerator

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

Methods inherited from class Object

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

Constructor Details

SwitchAsmGenerator

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

Method Details

generate

public void generate(ControlFlowChainInstr instr)

Generate bytecode for switch statement.

Control Flow:

1. Process evaluation variable setup (switch expression)
2. For each case: evaluate condition, branch if false, execute body, jump to end
3. Process default case (if present)
4. Place end label where all paths converge

Stack Frame Invariant: Pre-condition: stack is empty Post-condition: stack is empty

Parameters:

instr - CONTROL_FLOW_CHAIN instruction with SWITCH type