internal static LambdaExpression NullableConversion(
ParameterConversionConfiguration config, Type type,
ExcelParameterRegistration paramReg, bool treatEmptyAsMissing,
bool treatNAErrorAsMissing)
{
// Decide whether to return a conversion function for this parameter
if (!type.IsGenericType || type.GetGenericTypeDefinition() != typeof(Nullable <>))
{
return(null);
}
var innerType = type.GetGenericArguments()[0]; // E.g. innerType is Complex
LambdaExpression innerTypeConversion = ParameterConversionRegistration.GetParameterConversion(config, innerType, paramReg) ??
TypeConversion.GetConversion(typeof(object), innerType);
ParameterExpression input = innerTypeConversion.Parameters[0];
// Here's the actual conversion function
var result =
Expression.Lambda(
Expression.Condition(
// if the value is missing (or possibly empty)
MissingTest(input, treatEmptyAsMissing, treatNAErrorAsMissing),
// cast null to int?
Expression.Constant(null, type),
// else convert to int, and cast that to int?
Expression.Convert(Expression.Invoke(innerTypeConversion, input), type)),
input);
return(result);
}
// Should return null if there are no conversions to apply
internal static List <LambdaExpression> GetParameterConversions(ParameterConversionConfiguration conversionConfig, Type initialParamType, ExcelParameterRegistration paramRegistration)
{
var appliedConversions = new List <LambdaExpression>();
// paramReg might be modified internally by the conversions, but won't become a different object
var paramType = initialParamType; // Might become a different type as we convert
foreach (var paramConversion in conversionConfig.ParameterConversions)
{
var lambda = paramConversion.Convert(paramType, paramRegistration);
if (lambda == null)
{
continue;
}
// We got one to apply...
// Some sanity checks
Debug.Assert(lambda.Parameters.Count == 1);
Debug.Assert(lambda.ReturnType == paramType || lambda.ReturnType.IsEquivalentTo(paramType));
appliedConversions.Add(lambda);
// Change the Parameter Type to be whatever the conversion function takes us to
// for the next round of processing
paramType = lambda.Parameters[0].Type;
}
if (appliedConversions.Count == 0)
{
return(null);
}
return(appliedConversions);
}
public ShimParameter(Type type, ExcelParameterRegistration reg, ParameterConversionConfiguration config)
: this(type, reg.CustomAttributes)
{
// Try to find a converter for EnumeratedType
ParameterRegistration = reg;
PreparePropertyConverters(config, reg, ParameterConversionRegistration.GetParameterConversion);
}
/// <summary>
/// Modifies RegistrationEntries which have [ExcelMapArrayFunction],
/// converting IEnumerable parameters to and from Excel Ranges (i.e. object[,]).
/// This allows idiomatic .NET functions (which use sequences and lists) to be used as UDFs.
///
/// Supports the use of Excel Array formulae where a UDF returns an enumerable.
///
/// 1-dimensional Excel arrays are mapped automatically to/from IEnumerable.
/// 2-dimensional Excel arrays can be mapped to a single function parameter with
/// [ExcelMapPropertiesToColumnHeaders].
/// </summary>
public static IEnumerable <ExcelFunctionRegistration> ProcessMapArrayFunctions(
this IEnumerable <ExcelFunctionRegistration> registrations,
ParameterConversionConfiguration config = null)
{
foreach (var reg in registrations)
{
if (!(reg.FunctionAttribute is ExcelMapArrayFunctionAttribute))
{
// Not considered at all
yield return(reg);
continue;
}
try
{
var inputShimParameters = reg.FunctionLambda.Parameters.ZipSameLengths(reg.ParameterRegistrations,
(p, r) => new ShimParameter(p.Type, r, config)).ToList();
var resultShimParameter = new ShimParameter(reg.FunctionLambda.ReturnType, reg.ReturnRegistration, config);
// create the shim function as a lambda, using reflection
LambdaExpression shim = MakeObjectArrayShim(
reg.FunctionLambda,
inputShimParameters,
resultShimParameter);
// create a description of the function, with a list of the output fields
string functionDescription = "Returns " + resultShimParameter.HelpString;
// create a description of each parameter, with a list of the input fields
var parameterDescriptions = inputShimParameters.Select(shimParameter => "Input " +
shimParameter.HelpString).ToArray();
// all ok so far - modify the registration
reg.FunctionLambda = shim;
if (String.IsNullOrEmpty(reg.FunctionAttribute.Description))
{
reg.FunctionAttribute.Description = functionDescription;
}
for (int param = 0; param != reg.ParameterRegistrations.Count; ++param)
{
if (String.IsNullOrEmpty(reg.ParameterRegistrations[param].ArgumentAttribute.Description))
{
reg.ParameterRegistrations[param].ArgumentAttribute.Description =
parameterDescriptions[param];
}
}
}
catch
{
// failed to shim, just pass on the original
}
yield return(reg);
}
}
void PreparePropertyConverters <Registration>(ParameterConversionConfiguration config,
Registration reg, Func <ParameterConversionConfiguration, Type, Registration, LambdaExpression> getConversion)
{
Type[] propTypes = (MappedProperties == null)
? new[] { EnumeratedType ?? Type }
: Array.ConvertAll(MappedProperties, p => p.PropertyType);
LambdaExpression[] lambdas = Array.ConvertAll(propTypes,
pt => (config == null) ? null : getConversion(config, EnumeratedType ?? Type, reg));
lambdas = Array.ConvertAll(lambdas, l => CastParamAndResult(l, typeof(object)));
PropertyConverters = Array.ConvertAll(lambdas,
l => (l == null) ? null : (Func <object, object>)l.Compile());
}
internal static LambdaExpression GetParameterConversion(ParameterConversionConfiguration conversionConfig,
Type initialParamType, ExcelParameterRegistration paramRegistration)
{
return(ComposeLambdas(GetParameterConversions(conversionConfig, initialParamType, paramRegistration)));
}
public static IEnumerable <ExcelFunctionRegistration> ProcessParameterConversions(this IEnumerable <ExcelFunctionRegistration> registrations, ParameterConversionConfiguration conversionConfig)
{
foreach (var reg in registrations)
{
// Keep a list of conversions for each parameter
// TODO: Prevent having a cycle, but allow arbitrary ordering...?
var paramsConversions = new List <List <LambdaExpression> >();
for (int i = 0; i < reg.FunctionLambda.Parameters.Count; i++)
{
var initialParamType = reg.FunctionLambda.Parameters[i].Type;
var paramReg = reg.ParameterRegistrations[i];
var paramConversions = GetParameterConversions(conversionConfig, initialParamType, paramReg);
paramsConversions.Add(paramConversions);
} // for each parameter !
// Process return conversions
var returnConversions = GetReturnConversions(conversionConfig, reg.FunctionLambda.ReturnType, reg.ReturnRegistration);
// Now we apply all the conversions
ApplyConversions(reg, paramsConversions, returnConversions);
yield return(reg);
}
}
internal static LambdaExpression GetReturnConversion(ParameterConversionConfiguration conversionConfig,
Type initialReturnType, ExcelReturnRegistration returnRegistration)
{
return(ComposeLambdas(GetReturnConversions(conversionConfig, initialReturnType, returnRegistration)));
}
public ShimParameter(Type type, ExcelReturnRegistration reg, ParameterConversionConfiguration config)
: this(type, reg.CustomAttributes)
{
ReturnRegistration = reg;
PreparePropertyConverters(config, reg, ParameterConversionRegistration.GetReturnConversion);
}