public VowpalWabbitMultiExampleSerializerCompilerImpl(VowpalWabbitSettings settings, List <FeatureExpression> allFeatures, FeatureExpression multiFeature)
{
Contract.Requires(settings != null);
Contract.Requires(allFeatures != null);
Contract.Requires(multiFeature != null);
var nonMultiFeatures = allFeatures.Where(fe => fe != multiFeature).ToList();
this.sharedSerializerCompiler = nonMultiFeatures.Count == 0 ? null :
new VowpalWabbitSingleExampleSerializerCompiler <TExample>(
nonMultiFeatures,
settings == null ? null : settings.CustomFeaturizer,
!settings.EnableStringExampleGeneration);
this.adfSerializerComputer = new VowpalWabbitSingleExampleSerializerCompiler <TActionDependentFeature>(
AnnotationJsonInspector.ExtractFeatures(typeof(TActionDependentFeature)),
settings == null ? null : settings.CustomFeaturizer,
!settings.EnableStringExampleGeneration);
var exampleParameter = Expression.Parameter(typeof(TExample), "example");
// CODE condition1 && condition2 && condition3 ...
var condition = multiFeature.ValueValidExpressionFactories
.Skip(1)
.Aggregate(
multiFeature.ValueValidExpressionFactories.First()(exampleParameter),
(cond, factory) => Expression.AndAlso(cond, factory(exampleParameter)));
var multiExpression = multiFeature.ValueExpressionFactory(exampleParameter);
// CODE example => (IEnumerable<TActionDependentFeature>)(example._multi != null ? example._multi : null)
var expr = Expression.Lambda <Func <TExample, IEnumerable <TActionDependentFeature> > >(
Expression.Condition(
condition,
multiExpression,
Expression.Constant(null, multiExpression.Type),
typeof(IEnumerable <TActionDependentFeature>)),
exampleParameter);
this.adfAccessor = (Func <TExample, IEnumerable <TActionDependentFeature> >)expr.CompileToFunc();
}
/// <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);
}
}
if (settings.FeatureDiscovery == VowpalWabbitFeatureDiscovery.Json)
{
allFeatures = AnnotationJsonInspector.ExtractFeatures(typeof(TExample));
}
else
{
// TODO: 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);
}
}
// 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);
}