Class ControlFlowChainGenerator

java.lang.Object
org.ek9lang.compiler.phase7.generator.AbstractGenerator
org.ek9lang.compiler.phase7.generator.ControlFlowChainGenerator
All Implemented Interfaces:
Function<ControlFlowChainDetails, List<IRInstr>>
public final class ControlFlowChainGenerator extends AbstractGenerator implements Function<ControlFlowChainDetails, List<IRInstr>>
Unified IR generator for EK9 control flow operators using CONTROL_FLOW_CHAIN.

Supported Operators:

  • Question operator (?) - null/set checking
  • Guarded assignment (:=?) - conditional assignment
  • Null coalescing operator (??) - returns LHS if allocated, else RHS
  • Elvis coalescing operator (:?) - returns LHS if allocated AND set, else RHS
  • Comparison coalescing operators (<?, >?, <=?, >=?) - safe comparison with null/unset handling

Key architectural benefits:
- Single source of truth for operator control flow logic
- Consistent memory management patterns across all operators
- Unified optimization metadata for backend code generation
- Reduced code duplication and maintenance burden

NOTE: If/else, switch, while, do-while, for, and try/catch statements have their own dedicated IR generators and are NOT generated by this class.

  • Constructor Details

  • Method Details

    • apply

      public List<IRInstr> apply(ControlFlowChainDetails details)
      Specified by:
      apply in interface Function<ControlFlowChainDetails, List<IRInstr>>

    • generateQuestionOperator

      public List<IRInstr> generateQuestionOperator(ExprProcessingDetails exprDetails)
      Generate SWITCH_CHAIN_BLOCK for Question operator (?). Converts "operand?" to a two-case chain: null check + _isSet() default. Question operator is self-contained - no RETAIN/SCOPE_REGISTER needed on input.

    • generateQuestionOperatorForVariable

      public List<IRInstr> generateQuestionOperatorForVariable(ISymbol variableSymbol, String resultVariable, DebugInfo debugInfo)
      Generate SWITCH_CHAIN_BLOCK for Question operator applied to a variable. Used by guarded assignment composition.

    • generateGuardedAssignment

      public List<IRInstr> generateGuardedAssignment(ISymbol lhsSymbol, List<IRInstr> assignmentEvaluation, String assignmentResult, DebugInfo debugInfo)
      Generate SWITCH_CHAIN_BLOCK for guarded assignment (:=?). Composes question operator logic: assign only if LHS is null OR !LHS._isSet().

    • generateNullCoalescing

      public List<IRInstr> generateNullCoalescing(ExprProcessingDetails lhsDetails, ExprProcessingDetails rhsDetails)
      Generate CONTROL_FLOW_CHAIN for Null Coalescing operator (??). Returns LHS if memory allocated (even if unset), else evaluates and returns RHS.

      IR Structure: 1 case + default
      Case 1: NULL_CHECK - if LHS is null → evaluate and return RHS
      Default: LHS not null → return LHS (even if unset)

    • generateElvisCoalescing

      public List<IRInstr> generateElvisCoalescing(ExprProcessingDetails lhsDetails, ExprProcessingDetails rhsDetails)
      Generate CONTROL_FLOW_CHAIN for Elvis Coalescing operator (:?). Returns LHS if memory allocated AND set, else evaluates and returns RHS.

      IR Structure: 2 cases + default
      Case 1: NULL_CHECK - if LHS is null → evaluate and return RHS
      Case 2: IS_SET check - if LHS is not set → evaluate and return RHS
      Default: LHS is set → return LHS

      Safety: NULL_CHECK always precedes _isSet() call to prevent accessing unallocated memory.

    • generateComparisonCoalescing

      public List<IRInstr> generateComparisonCoalescing(ExprProcessingDetails lhsDetails, ExprProcessingDetails rhsDetails, String comparisonOperator, String chainType)
      Generate CONTROL_FLOW_CHAIN for Comparison Coalescing operators (<?, >?, <=?, >=?). Returns LHS if both operands valid and comparison true, else gracefully handles null/unset.

      IR Structure: 6 cases + default
      Case 1: NULL_CHECK on LHS → if null, return RHS
      Case 2: IS_SET check on LHS → if not set, return RHS
      Case 3: NULL_CHECK on RHS → if null, return LHS
      Case 4: IS_SET check on RHS → if not set, return LHS
      Case 5: COMPARISON (LHS comp RHS) → if true, return LHS
      Default: return RHS

      Parameters:
      comparisonOperator - The comparison operator method name (e.g., "_lt", "_gt", "_lteq", "_gteq")
      chainType - The chain type for IR (e.g., "LESS_THAN_COALESCING_OPERATOR")