/// <summary>
/// 查找合适的用户自定义类型转换方法。
/// </summary>
/// <returns>合适的用户自定义类型转换方法，如果不存在则为 <c>null</c>。</returns>
public MethodInfo FindConversion()
{
UserConversions convs = GetUserConversions(inputType);
if (convs != null)
{
Contract.Assume(convs.ConvertToIndex >= 0);
for (int i = convs.ConvertToIndex; i < convs.Methods.Length; i++)
{
UserConversionMethod method = convs.Methods[i];
ConversionType ctype = ConversionFactory.GetStandardConversion(outputType, method.OutputType);
if (ctype == ConversionType.None)
{
continue;
}
TypeRelation inputRelation = (method.InputType == inputType) ?
TypeRelation.Best : TypeRelation.Second;
TypeRelation outputRelation = TypeRelation.Best;
if (ctype >= ConversionType.ExplicitNumeric)
{
outputRelation = TypeRelation.Second;
}
else if (ctype > ConversionType.Identity)
{
outputRelation = TypeRelation.Thirt;
}
GetBestConversion(method, inputRelation, outputRelation);
}
}
convs = GetUserConversions(outputType);
if (convs != null)
{
for (int i = 0; i < convs.ConvertToIndex; i++)
{
UserConversionMethod method = convs.Methods[i];
ConversionType ctype = ConversionFactory.GetStandardConversion(method.InputType, inputType);
if (ctype == ConversionType.None)
{
continue;
}
TypeRelation outputRelation = (method.OutputType == outputType) ?
TypeRelation.Best : TypeRelation.Second;
TypeRelation inputRelation = TypeRelation.Best;
if (ctype >= ConversionType.ExplicitNumeric)
{
inputRelation = TypeRelation.Second;
}
else if (ctype > ConversionType.Identity)
{
inputRelation = TypeRelation.Thirt;
}
GetBestConversion(method, inputRelation, outputRelation);
}
}
if (bestMethod.IsUnique)
{
return(bestMethod.Value.Method);
}
if (bestMethod.IsAmbig)
{
throw CommonExceptions.AmbiguousUserDefinedConverter(inputType, outputType);
}
return(null);
}