} // ctor
/// <summary>Add a meta info value.</summary>
/// <param name="key">Meta key.</param>
/// <param name="getDataType">Data type of the value.</param>
/// <param name="value">Unconverted value of the meta key.</param>
protected void Add(string key, Func <Type> getDataType, object value)
{
if (String.IsNullOrEmpty(key))
{
throw new ArgumentNullException("key");
}
if (value == null)
{
metaInfo.Remove(key);
}
else
{
// change the type
if (WellknownMetaTypes.TryGetValue(key, out var dataType))
{
value = Procs.ChangeType(value, dataType);
}
else if (getDataType != null)
{
value = Procs.ChangeType(value, getDataType());
}
// add the key
if (value == null)
{
metaInfo.Remove(key);
}
else
{
metaInfo[key] = value;
}
}
} // proc Add
} // func TryGetProperty
internal Expression GetMetaConstantExpression(string key, bool generateException)
{
if (TryGetProperty(key, out var value))
{
return(Expression.Constant(value, typeof(object)));
}
else if (WellknownMetaTypes.TryGetValue(key, out var type))
{
return(Expression.Convert(Expression.Default(type), typeof(object)));
}
else if (generateException)
{
return(Expression.Throw(
Expression.New(Procs.ArgumentOutOfRangeConstructorInfo2,
new Expression[]
{
Expression.Constant(key),
Expression.Constant("Could not resolve key.")
}
), typeof(object)
));
}
else
{
return(Expression.Constant(null, typeof(object)));
}
} // func GetMetaConstantExpression