/// <summary>
/// Generate an expression to handle the 'is the object null' case
/// </summary>
/// <param name="type">Type of the object</param>
/// <param name="inputStream">Stream to read from</param>
/// <param name="objTracker">Reference tracker</param>
/// <param name="newInstance">New deserialized object</param>
/// <param name="notTrackedExpressions">Expressions to execute if the object is not tracked</param>
/// <param name="trackType">Type of the tracked object</param>
/// <param name="variables">Global variables for the expression tree</param>
/// <returns>An expression tree to handle the 'is the object null' case</returns>
internal static Expression GenerateNullTrackedOrUntrackedExpression(Type type,
ParameterExpression inputStream,
ParameterExpression objTracker,
ParameterExpression newInstance,
List <Expression> notTrackedExpressions,
ParameterExpression trackType,
List <ParameterExpression> variables)
{
var alreadyTrackedExpr = Expression.Assign(newInstance, Expression.Convert(Expression.Call(objTracker, DeserializerObjectTrackerMih.GetTrackedObject(), PrimitiveHelpers.ReadInt32(inputStream, objTracker)), type));
var notAlreadyTrackedExpr = Expression.Block(notTrackedExpressions);
var isNotNullExpr = Expression.Block(Expression.Assign(trackType, Expression.Convert(PrimitiveHelpers.ReadByte(inputStream, objTracker), typeof(byte))),
Expression.IfThenElse(Expression.Equal(trackType, Expression.Constant(SerializerObjectTracker.Value0)),
alreadyTrackedExpr,
notAlreadyTrackedExpr));
var expr = Expression.IfThenElse(Expression.Equal(Expression.Convert(PrimitiveHelpers.ReadByte(inputStream, objTracker), typeof(byte)), Expression.Constant(SerializerObjectTracker.Value0)),
Expression.Assign(newInstance, Expression.Convert(Expression.Constant(null), type)),
isNotNullExpr);
return(Expression.Block(variables, expr, newInstance));
}
