/// <summary>
/// Creates a serializer for the given type and settings.
/// </summary>
/// <typeparam name="TExample">The user type to serialize.</typeparam>
/// <param name="settings"></param>
/// <returns></returns>
public static VowpalWabbitSerializerCompiled <TExample> CreateSerializer <TExample>(VowpalWabbitSettings settings = null)
{
List <FeatureExpression> allFeatures = null;
Type cacheKey = null;
if (settings != null && settings.AllFeatures != null)
{
allFeatures = settings.AllFeatures;
}
else
{
// only cache non-string generating serializer
if (!settings.EnableStringExampleGeneration)
{
cacheKey = typeof(TExample);
object serializer;
if (SerializerCache.TryGetValue(cacheKey, out serializer))
{
return((VowpalWabbitSerializerCompiled <TExample>)serializer);
}
}
// TOOD: enhance caching based on feature list & featurizer set
// if no feature mapping is provided, use [Feature] annotation on provided type.
Func <PropertyInfo, FeatureAttribute, bool> propertyPredicate = null;
switch (settings.FeatureDiscovery)
{
case VowpalWabbitFeatureDiscovery.Default:
propertyPredicate = (_, attr) => attr != null;
break;
case VowpalWabbitFeatureDiscovery.All:
propertyPredicate = (_, __) => true;
break;
}
allFeatures = AnnotationInspector.ExtractFeatures(typeof(TExample), propertyPredicate).ToList();
}
// need at least a single feature to do something sensible
if (allFeatures == null || allFeatures.Count == 0)
{
return(null);
}
var newSerializer = new VowpalWabbitSerializerCompiled <TExample>(
allFeatures,
settings == null ? null : settings.CustomFeaturizer,
!settings.EnableStringExampleGeneration);
if (cacheKey != null)
{
SerializerCache[cacheKey] = newSerializer;
}
return(newSerializer);
}
internal VowpalWabbitSerializer(VowpalWabbitSerializerCompiled <TExample> serializer, VowpalWabbit vw)
{
if (serializer == null)
{
throw new ArgumentNullException("serializer");
}
Contract.Ensures(vw != null);
Contract.EndContractBlock();
this.vw = vw;
this.serializer = serializer;
this.serializerFunc = serializer.Func(vw);
var cacheableAttribute = (CacheableAttribute)typeof(TExample).GetCustomAttributes(typeof(CacheableAttribute), true).FirstOrDefault();
if (cacheableAttribute == null)
{
return;
}
if (this.vw.Settings.EnableExampleCaching)
{
if (cacheableAttribute.EqualityComparer == null)
{
this.exampleCache = new Dictionary <TExample, CacheEntry>();
}
else
{
if (!typeof(IEqualityComparer <TExample>).IsAssignableFrom(cacheableAttribute.EqualityComparer))
{
throw new ArgumentException(
string.Format(
CultureInfo.InvariantCulture,
"EqualityComparer ({1}) specified in [Cachable] of {0} must implement IEqualityComparer<{0}>",
typeof(TExample),
cacheableAttribute.EqualityComparer));
}
var comparer = (IEqualityComparer <TExample>)Activator.CreateInstance(cacheableAttribute.EqualityComparer);
this.exampleCache = new Dictionary <TExample, CacheEntry>(comparer);
}
#if DEBUG
this.reverseLookup = new Dictionary <VowpalWabbitExample, CacheEntry>(new ReferenceEqualityComparer <VowpalWabbitExample>());
#endif
}
}