internal static object GetConstantByExpression(Expression expression)
{
ConstantExpressionVisitor constantExpressionVisitor = null;
if (expression is ConstantExpression)
{
constantExpressionVisitor = new ConstantExpressionVisitor();
}
else if (expression is MemberExpression)
{
constantExpressionVisitor = new MemberConstantExpressionVisitor();
}
else if (expression is MethodCallExpression)
{
constantExpressionVisitor = new MethodConstantExpressionVisitor();
}
else if (expression is ConditionalExpression)
{
constantExpressionVisitor = new ConditionalConstantExpressionVisitor();
}
else if (expression.GetType().Name == "MethodBinaryExpression")
{
constantExpressionVisitor = new MethodBinaryConstantExpressionVisitor();
}
else
{
throw new Exception($"Unknow expression {expression.GetType()}");
}
constantExpressionVisitor.Visit(expression);
return(constantExpressionVisitor.Value);
}
protected override Expression VisitMember(MemberExpression node)
{
var visitor = new MemberConstantExpressionVisitor();
visitor.Visit(node.Expression);
Type type = visitor.Value.GetType();
switch (node.Member.MemberType)
{
case MemberTypes.Field:
FieldInfo fieldInfo = type.GetField(node.Member.Name);
Value = fieldInfo.GetValue(visitor.Value);
break;
case MemberTypes.Property:
PropertyInfo propertyInfo = type.GetProperty(node.Member.Name);
Value = propertyInfo.GetValue(visitor.Value);
break;
default:
throw new NotSupportedException($"Unknow Member type {node.Member.MemberType}");
}
return(node);
}
