Microsoft.Scripting.Ast.TryStatementBuilder.ToExpression C# (CSharp) Method

        public Expression ToExpression() {

            //
            // We can't emit a real filter or fault because they don't
            // work in DynamicMethods. Instead we do a simple transformation:
            //   fault -> catch (Exception) { ...; rethrow }
            //   filter -> catch (ExceptionType) { if (!filter) rethrow; ... }
            //
            // Note that the filter transformation is not quite equivalent to
            // real CLR semantics, but it's what IronPython and IronRuby
            // expect. If we get CLR support we'll switch over to real filter
            // and fault blocks.
            //

            var handlers = new List<CatchBlock>(_catchBlocks);
            for (int i = 0, n = handlers.Count; i < n ; i++) {
                CatchBlock handler = handlers[i];
                if (handler.Filter != null) {
                    handlers[i] = Expression.MakeCatchBlock(
                        handler.Test,
                        handler.Variable,
                        Expression.Condition(
                            handler.Filter,
                            handler.Body,
                            Expression.Rethrow(handler.Body.Type)
                        ),
                        null
                    );
                }
            }

            if (_fault != null) {
                ContractUtils.Requires(handlers.Count == 0, "fault cannot be used with catch or finally clauses");
                handlers.Add(Expression.Catch(typeof(Exception), Expression.Block(_fault, Expression.Rethrow(_try.Type))));
            }

            var result = Expression.MakeTry(null, _try, _finally, null, handlers);
            if (_enableJumpsFromFinally) {
                return Utils.FinallyFlowControl(result);
            }
            return result;
        }
    }