source: issuevalue/src/main/java/geniusweb/issuevalue/ValueSet.java

package geniusweb.issuevalue;

import java.io.IOException;

import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.core.ObjectCodec;
import com.fasterxml.jackson.databind.DeserializationContext;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
import com.fasterxml.jackson.databind.deser.std.StdDeserializer;

import tudelft.utilities.immutablelist.ImmutableList;

/**
 * A set of possible {@link Value}s (usually, of an Issue (which is represented
 * by a String)).
 * 
 * Value is the type of objects in this value set. We do not implement ValueSet
 * right away because types are lost at runtime. Implementing separate classes
 * for implementing the ValueSet ensures we can get back the type at runtime.
 * immutable. Thread safe.
 */
@JsonDeserialize(using = ValueSetDeserializer.class)
public interface ValueSet extends ImmutableList<Value> {

        /**
         * 
         * @param value the value to check
         * @return true iff this set contains given value
         */
        Boolean contains(Value value);

}

/**
 * Deserializes a ValueSet by checking the name of the (one and only) property
 * in there.}. This property is coming from the concrete implementations that we
 * have: {@link NumberValueSet} and {@link DiscreteValueSet}. This way we can
 * avoid putting (redundant) type info in each and every valueset.
 * 
 */
@SuppressWarnings("serial")
class ValueSetDeserializer extends StdDeserializer<ValueSet> {

        public ValueSetDeserializer() {
                this(null);
        }

        public ValueSetDeserializer(Class<?> vc) {
                super(vc);
        }

        @Override
        public ValueSet deserialize(JsonParser jp, DeserializationContext ctxt)
                        throws IOException, JsonProcessingException {
                ObjectCodec codec = jp.getCodec();
                JsonNode node = codec.readTree(jp);
                if (node.get("range") != null) {
                        return codec.treeToValue(node, NumberValueSet.class);
                } else if (node.get("values") != null) {
                        return codec.treeToValue(node, DiscreteValueSet.class);
                }
                throw new IllegalArgumentException(
                                "Expected 'range' or 'values' property for ValueSet contents");
        }

}