static LambdaExpression WrapMethodParams(LambdaExpression functionLambda)
{
/* We are converting:
* [ExcelFunction(...)]
* public static string myFunc(string input, int otherInput, params object[] args)
* {
* ...
* }
*
* into:
* [ExcelFunction(...)]
* public static string myFunc(string input, int otherInput, object arg3, object arg4, object arg5, object arg6, {...until...}, object arg125)
* {
* // First we figure where in the list to stop building the param array
* int lastArgToAdd = 0;
* if (!(arg3 is ExcelMissing)) lastArgToAdd = 3;
* if (!(arg4 is ExcelMissing)) lastArgToAdd = 4;
* ...
* if (!(arg125 is ExcelMissing)) lastArgToAdd = 125;
*
* // Then add until we get there
* List<object> args = new List<object>();
* if (lastArgToAdd >= 3) args.Add(arg3);
* if (lastArgToAdd >= 4) args.Add(arg4);
* ...
* if (lastArgToAdd >= 125) args.Add(arg125);
*
* Array<object> argsArray = args.ToArray();
* return myFunc(input, otherInput, argsArray);
* }
*
*
*/
int maxArguments;
if (ExcelDnaUtil.ExcelVersion >= 12.0)
{
maxArguments = 125; // Constrained by 255 char registration string, take off 3 type chars, use up to 2 chars per param (before we start doing object...) (& also return)
// CONSIDER: Might improve this if we generate the delegate based on the max length...
}
else
{
maxArguments = 29; // Or maybe 30?
}
var normalParams = functionLambda.Parameters.Take(functionLambda.Parameters.Count() - 1).ToList();
var normalParamCount = normalParams.Count;
var paramsParamCount = maxArguments - normalParamCount;
var allParamExprs = new List <ParameterExpression>(normalParams);
var blockExprs = new List <Expression>();
var blockVars = new List <ParameterExpression>();
// Run through the arguments looking for the position of the last non-ExcelMissing argument
var lastArgVarExpr = Expression.Variable(typeof(int));
blockVars.Add(lastArgVarExpr);
blockExprs.Add(Expression.Assign(lastArgVarExpr, Expression.Constant(0)));
for (int i = normalParamCount + 1; i <= maxArguments; i++)
{
allParamExprs.Add(Expression.Parameter(typeof(object), "arg" + i));
var lenTestParam = Expression.IfThen(Expression.Not(Expression.TypeIs(allParamExprs[i - 1], typeof(ExcelMissing))),
Expression.Assign(lastArgVarExpr, Expression.Constant(i)));
blockExprs.Add(lenTestParam);
}
// We know that last parameter is an array type
// Create a new list to hold the values
var argsArrayType = functionLambda.Parameters.Last().Type;
var argsType = argsArrayType.GetElementType();
var argsListType = typeof(List <>).MakeGenericType(argsType);
var argsListVarExpr = Expression.Variable(argsListType);
blockVars.Add(argsListVarExpr);
var argListAssignExpr = Expression.Assign(argsListVarExpr, Expression.New(argsListType));
blockExprs.Add(argListAssignExpr);
// And put the (converted) arguments into the list
for (int i = normalParamCount + 1; i <= maxArguments; i++)
{
var testParam = Expression.IfThen(Expression.GreaterThanOrEqual(lastArgVarExpr, Expression.Constant(i)),
Expression.Call(argsListVarExpr, "Add", null,
TypeConversion.GetConversion(allParamExprs[i - 1], argsType)));
blockExprs.Add(testParam);
}
var argArrayVarExpr = Expression.Variable(argsArrayType);
blockVars.Add(argArrayVarExpr);
var argArrayAssignExpr = Expression.Assign(argArrayVarExpr, Expression.Call(argsListVarExpr, "ToArray", null));
blockExprs.Add(argArrayAssignExpr);
var innerParams = new List <Expression>(normalParams)
{
argArrayVarExpr
};
var callInner = Expression.Invoke(functionLambda, innerParams);
blockExprs.Add(callInner);
var blockExpr = Expression.Block(blockVars, blockExprs);
// Build the delegate type to return
var allParamTypes = normalParams.Select(pi => pi.Type).ToList();
var toAdd = maxArguments - allParamTypes.Count;
for (int i = 0; i < toAdd; i++)
{
allParamTypes.Add(typeof(object));
}
allParamTypes.Add(functionLambda.ReturnType);
Type delegateType;
if (maxArguments == 125)
{
delegateType = typeof(CustomFunc125 <, , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , ,>)
.MakeGenericType(allParamTypes.ToArray());
}
else // if (maxArguments == 29)
{
delegateType = typeof(CustomFunc29 <, , , , , , , , , , , , , , , , , , , , , , , , , , , , ,>)
.MakeGenericType(allParamTypes.ToArray());
}
return(Expression.Lambda(delegateType, blockExpr, allParamExprs));
}
