package org.springframework.core.convert.support;
import java.lang.reflect.Array;
import java.util.Collection;
import java.util.LinkedHashSet;
import java.util.Optional;
import java.util.Set;
import org.springframework.core.convert.ConversionService;
import org.springframework.core.convert.TypeDescriptor;
import org.springframework.core.convert.converter.ConditionalGenericConverter;
import org.springframework.lang.Nullable;
final class ObjectToOptionalConverter implements ConditionalGenericConverter {
private final ConversionService conversionService;
public ObjectToOptionalConverter(ConversionService conversionService) {
this.conversionService = conversionService;
}
@Override
public Set<ConvertiblePair> getConvertibleTypes() {
Set<ConvertiblePair> convertibleTypes = new LinkedHashSet<>(4);
convertibleTypes.add(new ConvertiblePair(Collection.class, Optional.class));
convertibleTypes.add(new ConvertiblePair(Object[].class, Optional.class));
convertibleTypes.add(new ConvertiblePair(Object.class, Optional.class));
return convertibleTypes;
}
@Override
public boolean matches(TypeDescriptor sourceType, TypeDescriptor targetType) {
if (targetType.getResolvableType().hasGenerics()) {
return this.conversionService.canConvert(sourceType, new GenericTypeDescriptor(targetType));
}
else {
return true;
}
}
@Override
public Object convert(@Nullable Object source, TypeDescriptor sourceType, TypeDescriptor targetType) {
if (source == null) {
return Optional.empty();
}
else if (source instanceof Optional) {
return source;
}
else if (targetType.getResolvableType().hasGenerics()) {
Object target = this.conversionService.convert(source, sourceType, new GenericTypeDescriptor(targetType));
if (target == null || (target.getClass().isArray() && Array.getLength(target) == 0) ||
(target instanceof Collection && ((Collection<?>) target).isEmpty())) {
return Optional.empty();
}
return Optional.of(target);
}
else {
return Optional.of(source);
}
}
@SuppressWarnings("serial")
private static class GenericTypeDescriptor extends TypeDescriptor {
public GenericTypeDescriptor(TypeDescriptor typeDescriptor) {
super(typeDescriptor.getResolvableType().getGeneric(), null, typeDescriptor.getAnnotations());
}
}
}