/// <summary>
/// Converts a value from the source vocabulary item units to
/// the base units of the vocabulary.
/// </summary>
///
/// <remarks>
/// This method does not check the sign of the value. The caller
/// is responsible for ensuring the input data value make sense for
/// the input vocabulary item.
/// </remarks>
///
/// <param name="vocabularyItem">The vocabulary item of the data
/// value to convert to base units.</param>
///
/// <param name="value">The data value to convert to base units.
/// </param>
///
/// <returns>The converted data value in the base units for the
/// vocabulary.
/// </returns>
///
/// <exception cref="ArgumentNullException">
/// The <paramref name="vocabularyItem"/> parameter is <b>null</b>.
/// </exception>
///
/// <exception cref="NotSupportedException">
/// The <paramref name="vocabularyItem"/> parameter does not
/// support conversions to base units.
/// </exception>
///
/// <exception cref="ConversionFailureException">
/// An unknown or unsupported conversion is encountered or
/// an error occurs during the conversion to base units.
/// </exception>
///
public static double ConvertToBaseUnits(
VocabularyItem vocabularyItem,
double value)
{
Validator.ThrowIfArgumentNull(vocabularyItem, "vocabularyItem", "VocabularyItemNull");
if (vocabularyItem.InfoXml == null)
{
throw Validator.NotSupportedException("VocabularyItemConversionNotSupported");
}
XPathNavigator nav = vocabularyItem.InfoXml.CreateNavigator();
try
{
nav = nav.SelectSingleNode("unit-conversions/base-unit-conversion");
}
catch(Exception)
{
//this can occur if conversion xml is corrupted. We don't
//want to expose xml parse issues here to the outside world
//as recommended by the .NET documentation for
//XPathNavigator
throw new ConversionFailureException(
ResourceRetriever.GetResourceString(
"VocabularyItemConversionGeneralException"));
}
if (nav == null)
{
throw Validator.NotSupportedException("VocabularyItemConversionNotSupported");
}
return DoConversion(nav, value);
}
internal override void AddVocabularyItem(string key, VocabularyItem item)
{
base.AddVocabularyItem(key, item);
_orderedItemsList.Add(item);
}