protected internal void AddMapping <TProperty>(ExcelPropertyMap mapping, Expression <Func <T, TProperty> > expression)
{
var expressionBody = expression.Body;
var expressions = new Stack <MemberExpression>();
while (true)
{
if (!(expressionBody is MemberExpression memberExpressionBody))
{
// Each mapping is of the form (parameter => member).
if (expressionBody is ParameterExpression _)
{
break;
}
throw new ArgumentException($"Expression can only contain member accesses, but found {expressionBody}.", nameof(expression));
}
expressions.Push(memberExpressionBody);
expressionBody = memberExpressionBody.Expression;
}
if (expressions.Count == 1)
{
// Simple case: parameter => prop
Mappings.Add(mapping);
}
else
{
// Go through the chain of members and make sure that they are valid.
// E.g. parameter => parameter.prop.subprop.field.
CreateObjectMap(mapping, expressions);
}
}
private void CreateObjectMapGeneric <TProperty>(ExcelPropertyMap propertyMap, MemberExpression memberExpression, Stack <MemberExpression> memberExpressions)
{
ExcelPropertyMap map = Properties.FirstOrDefault(m => m.Member.Equals(memberExpression.Member));
ExcelClassMap <TProperty> objectPropertyMap;
if (map == null)
{
objectPropertyMap = new ExcelClassMap <TProperty>();
Properties.Add(new ExcelPropertyMap(memberExpression.Member, objectPropertyMap));
}
else if (!(map.Map is ExcelClassMap <TProperty> existingMap))
{
throw new InvalidOperationException($"Expression is already mapped differently as {map.GetType().ToString()}.");
}
else
{
objectPropertyMap = existingMap;
}
objectPropertyMap.CreateObjectMap(propertyMap, memberExpressions);
}
/// <summary>
/// Traverses through a list of member expressions, starting with the member closest to the type
/// of this class map, and creates a map for each sub member access.
/// This enables support for expressions such as p => p.prop.subprop.field.final.
/// </summary>
/// <param name="propertymap">The map for the final member access in the stack.</param>
/// <param name="memberExpressions">A stack of each MemberExpression in the list of member access expressions.</param>
protected internal void CreateObjectMap(ExcelPropertyMap propertymap, Stack <MemberExpression> memberExpressions)
{
MemberExpression memberExpression = memberExpressions.Pop();
if (memberExpressions.Count == 0)
{
// This is the final member.
Properties.Add(propertymap);
return;
}
Type memberType = memberExpression.Member.MemberType();
MethodInfo method = MapObjectMethod.MakeGenericMethod(memberType);
try
{
method.Invoke(this, new object[] { propertymap, memberExpression, memberExpressions });
}
catch (TargetInvocationException exception)
{
throw exception.InnerException;
}
}