internal static Delegate BinaryOperationHelper <Delegate, Left, Right, Return>(BinaryOperationHelperDelegate operation)
{
// shared expressions
ParameterExpression _left = Expression.Parameter(typeof(Left));
ParameterExpression _right = Expression.Parameter(typeof(Right));
LabelTarget _label = Expression.Label(typeof(Return));
// code builder
ListLinked <Expression> expressions = new ListLinked <Expression>();
// null checks
if (!typeof(Left).IsValueType) // is nullable?
{
expressions.Add(
Expression.IfThen(
Expression.Equal(_left, Expression.Constant(null, typeof(Left))),
Expression.Throw(Expression.New(typeof(System.ArgumentNullException).GetConstructor(new System.Type[] { typeof(string) }), Expression.Constant("left")))));
}
if (!typeof(Right).IsValueType) // is nullable?
{
expressions.Add(
Expression.IfThen(
Expression.Equal(_right, Expression.Constant(null, typeof(Right))),
Expression.Throw(Expression.New(typeof(System.ArgumentNullException).GetConstructor(new System.Type[] { typeof(string) }), Expression.Constant("right")))));
}
// code
expressions.Add(operation(_left, _right, _label));
expressions.Add(Expression.Label(_label, Expression.Constant(default(Return), typeof(Return))));
// build expression
Expression expression = Expression.Block(expressions.ToArray());
// compile
return(Expression.Lambda <Delegate>(expression, _left, _right).Compile());
}
internal static Delegate UnaryOperationHelper <Delegate, Operand, Return>(UnaryOperationHelperDelegate operation)
{
// shared expressions
ParameterExpression _operand = Expression.Parameter(typeof(Operand));
LabelTarget _label = Expression.Label(typeof(Return));
// code builder
ListLinked <Expression> expressions = new ListLinked <Expression>();
// null checks
if (!typeof(Operand).IsValueType) // is nullable?
{
expressions.Add(
Expression.IfThen(
Expression.Equal(_operand, Expression.Constant(null, typeof(Operand))),
Expression.Throw(Expression.New(typeof(System.ArgumentNullException).GetConstructor(new System.Type[] { typeof(string) }), Expression.Constant("operand")))));
}
// code
expressions.Add(operation(_operand, _label));
expressions.Add(Expression.Label(_label, Expression.Constant(default(Return))));
// build
return(Expression.Lambda <Delegate>(
Expression.Block(expressions.ToArray()),
_operand).Compile());
}