src/main/java/com/fasterxml/jackson/databind/deser/std/EnumDeserializer.java

package com.fasterxml.jackson.databind.deser.std;

import java.io.IOException;

import com.fasterxml.jackson.core.*;
import com.fasterxml.jackson.databind.*;
import com.fasterxml.jackson.databind.annotation.JacksonStdImpl;
import com.fasterxml.jackson.databind.deser.SettableBeanProperty;
import com.fasterxml.jackson.databind.deser.ValueInstantiator;
import com.fasterxml.jackson.databind.introspect.AnnotatedMethod;
import com.fasterxml.jackson.databind.util.ClassUtil;
import com.fasterxml.jackson.databind.util.CompactStringObjectMap;
import com.fasterxml.jackson.databind.util.EnumResolver;

/**
 * Deserializer class that can deserialize instances of
 * specified Enum class from Strings and Integers.
 */
@JacksonStdImpl // was missing until 2.6
public class EnumDeserializer
    extends StdScalarDeserializer<Object>
{
    private static final long serialVersionUID = 1L;

    protected Object[] _enumsByIndex;
    
    /**
     * @since 2.8
     */
    private final Enum<?> _enumDefaultValue;

    /**
     * @since 2.7.3
     */
    protected final CompactStringObjectMap _lookupByName;

    /**
     * Alternatively, we may need a different lookup object if "use toString"
     * is defined.
     *
     * @since 2.7.3
     */
    protected CompactStringObjectMap _lookupByToString;
    
    public EnumDeserializer(EnumResolver byNameResolver)
    {
        super(byNameResolver.getEnumClass());
        _lookupByName = byNameResolver.constructLookup();
        _enumsByIndex = byNameResolver.getRawEnums();
        _enumDefaultValue = byNameResolver.getDefaultValue();
    }

    /**
     * @deprecated Since 2.8
     */
    @Deprecated
    public static JsonDeserializer<?> deserializerForCreator(DeserializationConfig config,
            Class<?> enumClass, AnnotatedMethod factory) {
        return deserializerForCreator(config, enumClass, factory, null, null);
    }

    /**
     * Factory method used when Enum instances are to be deserialized
     * using a creator (static factory method)
     * 
     * @return Deserializer based on given factory method
     *
     * @since 2.8
     */
    public static JsonDeserializer<?> deserializerForCreator(DeserializationConfig config,
            Class<?> enumClass, AnnotatedMethod factory,
            ValueInstantiator valueInstantiator, SettableBeanProperty[] creatorProps)
    {
        if (config.canOverrideAccessModifiers()) {
            ClassUtil.checkAndFixAccess(factory.getMember(),
                    config.isEnabled(MapperFeature.OVERRIDE_PUBLIC_ACCESS_MODIFIERS));
        }
        return new FactoryBasedEnumDeserializer(enumClass, factory,
                factory.getParameterType(0),
                valueInstantiator, creatorProps);
    }

    /**
     * Factory method used when Enum instances are to be deserialized
     * using a zero-/no-args factory method
     * 
     * @return Deserializer based on given no-args factory method
     *
     * @since 2.8
     */
    public static JsonDeserializer<?> deserializerForNoArgsCreator(DeserializationConfig config,
            Class<?> enumClass, AnnotatedMethod factory)
    {
        if (config.canOverrideAccessModifiers()) {
            ClassUtil.checkAndFixAccess(factory.getMember(),
                    config.isEnabled(MapperFeature.OVERRIDE_PUBLIC_ACCESS_MODIFIERS));
        }
        return new FactoryBasedEnumDeserializer(enumClass, factory);
    }

    /*
    /**********************************************************
    /* Default JsonDeserializer implementation
    /**********************************************************
     */

    /**
     * Because of costs associated with constructing Enum resolvers,
     * let's cache instances by default.
     */
    @Override
    public boolean isCachable() { return true; }

    @Override
    public Object deserialize(JsonParser p, DeserializationContext ctxt) throws IOException
    {
        JsonToken curr = p.getCurrentToken();
        
        // Usually should just get string value:
        if (curr == JsonToken.VALUE_STRING || curr == JsonToken.FIELD_NAME) {
            CompactStringObjectMap lookup = ctxt.isEnabled(DeserializationFeature.READ_ENUMS_USING_TO_STRING)
                    ? _getToStringLookup(ctxt) : _lookupByName;
            final String name = p.getText();
            Object result = lookup.find(name);
            if (result == null) {
                return _deserializeAltString(p, ctxt, lookup, name);
            }
            return result;
        }
        // But let's consider int acceptable as well (if within ordinal range)
        if (curr == JsonToken.VALUE_NUMBER_INT) {
            // ... unless told not to do that
            int index = p.getIntValue();
            if (ctxt.isEnabled(DeserializationFeature.FAIL_ON_NUMBERS_FOR_ENUMS)) {
                return ctxt.handleWeirdNumberValue(_enumClass(), index,
                        "not allowed to deserialize Enum value out of number: disable DeserializationConfig.DeserializationFeature.FAIL_ON_NUMBERS_FOR_ENUMS to allow"
                        );
            }
            if (index >= 0 && index < _enumsByIndex.length) {
                return _enumsByIndex[index];
            }
            if ((_enumDefaultValue != null)
                    && ctxt.isEnabled(DeserializationFeature.READ_UNKNOWN_ENUM_VALUES_USING_DEFAULT_VALUE)) {
                return _enumDefaultValue;
            }
            if (!ctxt.isEnabled(DeserializationFeature.READ_UNKNOWN_ENUM_VALUES_AS_NULL)) {
                return ctxt.handleWeirdNumberValue(_enumClass(), index,
                        "index value outside legal index range [0..%s]",
                        _enumsByIndex.length-1);
            }
            return null;
        }
        return _deserializeOther(p, ctxt);
    }

    /*
    /**********************************************************
    /* Internal helper methods
    /**********************************************************
     */
    
    private final Object _deserializeAltString(JsonParser p, DeserializationContext ctxt,
            CompactStringObjectMap lookup, String name) throws IOException
    {
        name = name.trim();
        if (name.length() == 0) {
            if (ctxt.isEnabled(DeserializationFeature.ACCEPT_EMPTY_STRING_AS_NULL_OBJECT)) {
                return getEmptyValue(ctxt);
            }
        } else if (!ctxt.isEnabled(DeserializationFeature.FAIL_ON_NUMBERS_FOR_ENUMS)) {
            // [databind#149]: Allow use of 'String' indexes as well -- unless prohibited (as per above)
            char c = name.charAt(0);
            if (c >= '0' && c <= '9') {
                try {
                    int index = Integer.parseInt(name);
                    if (index >= 0 && index < _enumsByIndex.length) {
                        return _enumsByIndex[index];
                    }
                } catch (NumberFormatException e) {
                    // fine, ignore, was not an integer
                }
            }
        }
        if ((_enumDefaultValue != null)
                && ctxt.isEnabled(DeserializationFeature.READ_UNKNOWN_ENUM_VALUES_USING_DEFAULT_VALUE)) {
            return _enumDefaultValue;
        }
        if (!ctxt.isEnabled(DeserializationFeature.READ_UNKNOWN_ENUM_VALUES_AS_NULL)) {
            return ctxt.handleWeirdStringValue(_enumClass(), name,
                    "value not one of declared Enum instance names: %s", lookup.keys());
        }
        return null;
    }

    protected Object _deserializeOther(JsonParser p, DeserializationContext ctxt) throws IOException
    {
        // [databind#381]
        if (p.hasToken(JsonToken.START_ARRAY)) {
            return _deserializeFromArray(p, ctxt);
        }
        return ctxt.handleUnexpectedToken(_enumClass(), p);
    }

    protected Class<?> _enumClass() {
        return handledType();
    }

    protected CompactStringObjectMap _getToStringLookup(DeserializationContext ctxt)
    {
        CompactStringObjectMap lookup = _lookupByToString;
        // note: exact locking not needed; all we care for here is to try to
        // reduce contention for the initial resolution
        if (lookup == null) {
            synchronized (this) {
                lookup = EnumResolver.constructUnsafeUsingToString(_enumClass(),
                        ctxt.getAnnotationIntrospector())
                    .constructLookup();
            }
            _lookupByToString = lookup;
        }
        return lookup;
    }
}