IronRuby.Compiler.Ast.AstGenerator.MakeMethodBlockParameterRead C# (CSharp) Method

        internal MSA.Expression/*!*/ MakeMethodBlockParameterRead() {
            VariableScope lambdaScope = GetCurrentLambdaScope();
            if (lambdaScope == CurrentMethod && CurrentMethod.BlockVariable != null) {
                return CurrentMethod.BlockVariable;
            } else {
                // TODO: we can optimize and inline for 1..n levels of nesting:
                return Methods.GetMethodBlockParameter.OpCall(CurrentScopeVariable);
            }
        }

        // see Ruby Language.doc/Runtime/Control Flow Implementation/Yield
        internal override MSA.Expression/*!*/ TransformRead(AstGenerator/*!*/ gen) {
            MSA.Expression bfcVariable = gen.CurrentScope.DefineHiddenVariable("#yielded-bfc", typeof(BlockParam));
            MSA.Expression resultVariable = gen.CurrentScope.DefineHiddenVariable("#result", typeof(object));
            MSA.Expression evalUnwinder = gen.CurrentScope.DefineHiddenVariable("#unwinder", typeof(EvalUnwinder));

            MSA.Expression postYield;

            if (gen.CompilerOptions.IsEval) {
                // eval:
                postYield = Methods.EvalYield.OpCall(gen.CurrentRfcVariable, bfcVariable, resultVariable);
            } else if (gen.CurrentBlock != null) {
                // block:
                postYield = Methods.BlockYield.OpCall(gen.CurrentRfcVariable, gen.CurrentBlock.BfcVariable, bfcVariable, resultVariable);
            } else {
                // method:
                postYield = Methods.MethodYield.OpCall(gen.CurrentRfcVariable, bfcVariable, resultVariable);
            }

            return AstFactory.Block(
                gen.DebugMarker("#RB: yield begin"),

                Ast.Assign(bfcVariable, Methods.CreateBfcForYield.OpCall(gen.MakeMethodBlockParameterRead())),

                Ast.Assign(resultVariable, (Arguments ?? Arguments.Empty).TransformToYield(gen, bfcVariable,
                    Ast.Property(AstUtils.Convert(gen.MakeMethodBlockParameterRead(), typeof(Proc)), Proc.SelfProperty)
                )),

                AstUtils.IfThen(postYield, gen.Return(resultVariable)),

                gen.DebugMarker("#RB: yield end"),

                resultVariable
            );
        }