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

package geniusweb.issuevalue;

import java.io.IOException;

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

/**
 * A possible value for an Issue. Must be immutable and thread safe. Supported
 * values are {@link NumberValue} and {@link DiscreteValue}. All values are just
 * strings, a custom deserializer is used to determine which type it is.
 * 
 * Value must be de-serializable all by itself, because it can occur plain in a
 * Bid eg Bid["fte":0.8]
 */
@JsonDeserialize(using = ValueDeserializer.class)
public interface Value {
        /**
         * @return the contained value (String, BigDecimal)
         */
        public Object getValue();

}

/**
 * Deserializes a Value. Special deserializer is needed because by default
 * jackson deserializes numbers as double and thus cause rounding errors.
 */
@SuppressWarnings("serial")
class ValueDeserializer extends StdDeserializer<Value> {

        public ValueDeserializer() {
                this(null);
        }

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

        @Override
        public Value deserialize(JsonParser jp, DeserializationContext ctxt)
                        throws IOException, JsonProcessingException {
                String text = jp.getText();
                switch (jp.currentToken()) {
                case VALUE_NUMBER_FLOAT:
                case VALUE_NUMBER_INT:
                        return new NumberValue(text);
                case VALUE_STRING:
                        return new DiscreteValue(text);
                default:
                        throw new IOException(
                                        "Expected number of double quoted string but found " + text
                                                        + " of type " + jp.currentToken());
                }

        }

}