/*
* Copyright 2010 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not
* use this file except in compliance with the License. You may obtain a copy of
* the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
* the License.
*/
package com.google.gwt.autobean.shared;
import com.google.gwt.autobean.shared.impl.LazySplittable;
import com.google.gwt.autobean.shared.impl.StringQuoter;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.Collections;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;
/**
* Provides unified encoding and decoding of value objects.
*/
public class ValueCodex {
enum Type {
BIG_DECIMAL(BigDecimal.class) {
@Override
public boolean canUpcast(Object value) {
return value instanceof BigDecimal;
}
@Override
public BigDecimal decode(Class<?> clazz, String value) {
return new BigDecimal(value);
}
@Override
public String toJsonExpression(Object value) {
return StringQuoter.quote(((BigDecimal) value).toString());
}
},
BIG_INTEGER(BigInteger.class) {
@Override
public boolean canUpcast(Object value) {
return value instanceof BigInteger;
}
@Override
public BigInteger decode(Class<?> clazz, String value) {
return new BigInteger(value);
}
@Override
public String toJsonExpression(Object value) {
return StringQuoter.quote(((BigInteger) value).toString());
}
},
BOOLEAN(Boolean.class, boolean.class, false) {
@Override
public Boolean decode(Class<?> clazz, String value) {
return Boolean.valueOf(value);
}
},
BYTE(Byte.class, byte.class, (byte) 0) {
@Override
public Byte decode(Class<?> clazz, String value) {
return Byte.valueOf(value);
}
},
CHARACTER(Character.class, char.class, (char) 0) {
@Override
public Character decode(Class<?> clazz, String value) {
return value.charAt(0);
}
},
DATE(Date.class) {
@Override
public boolean canUpcast(Object value) {
return value instanceof Date;
}
@Override
public Date decode(Class<?> clazz, String value) {
return new Date(Long.valueOf(value));
}
@Override
public String toJsonExpression(Object value) {
return String.valueOf(((Date) value).getTime());
}
},
DOUBLE(Double.class, double.class, 0d) {
@Override
public Double decode(Class<?> clazz, String value) {
return Double.valueOf(value);
}
},
ENUM(Enum.class) {
@Override
public Enum<?> decode(Class<?> clazz, String value) {
return (Enum<?>) clazz.getEnumConstants()[Integer.valueOf(value)];
}
@Override
public String toJsonExpression(Object value) {
return String.valueOf(((Enum<?>) value).ordinal());
}
},
FLOAT(Float.class, float.class, 0f) {
@Override
public Float decode(Class<?> clazz, String value) {
return Float.valueOf(value);
}
},
INTEGER(Integer.class, int.class, 0) {
@Override
public Integer decode(Class<?> clazz, String value) {
return Integer.valueOf(value);
}
},
LONG(Long.class, long.class, 0L) {
@Override
public Long decode(Class<?> clazz, String value) {
return Long.valueOf(value);
}
@Override
public String toJsonExpression(Object value) {
// Longs cannot be expressed as a JS double
return StringQuoter.quote(String.valueOf((Long) value));
}
},
SHORT(Short.class, short.class, (short) 0) {
@Override
public Short decode(Class<?> clazz, String value) {
return Short.valueOf(value);
}
},
STRING(String.class) {
@Override
public String decode(Class<?> clazz, String value) {
return value;
}
@Override
public String toJsonExpression(Object value) {
return StringQuoter.quote((String) value);
}
},
VOID(Void.class, void.class, null) {
@Override
public Void decode(Class<?> clazz, String value) {
return null;
}
};
private final Object defaultValue;
private final Class<?> type;
private final Class<?> primitiveType;
Type(Class<?> objectType) {
this(objectType, null, null);
}
Type(Class<?> objectType, Class<?> primitiveType, Object defaultValue) {
this.type = objectType;
this.primitiveType = primitiveType;
this.defaultValue = defaultValue;
}
/**
* Determines whether or not the Type can handle the given value via
* upcasting semantics.
*/
public boolean canUpcast(Object value) {
// Most value types are final, so this method is meaningless
return false;
}
public abstract Object decode(Class<?> clazz, String value);
public Object getDefaultValue() {
return defaultValue;
}
public Class<?> getPrimitiveType() {
return primitiveType;
}
public Class<?> getType() {
return type;
}
public String toJsonExpression(Object value) {
return String.valueOf(value);
}
}
private static final Set<Class<?>> ALL_VALUE_TYPES;
private static final Map<Class<?>, Type> TYPES_BY_CLASS;
static {
Map<Class<?>, Type> temp = new HashMap<Class<?>, Type>();
for (Type t : Type.values()) {
temp.put(t.getType(), t);
if (t.getPrimitiveType() != null) {
temp.put(t.getPrimitiveType(), t);
}
}
ALL_VALUE_TYPES = Collections.unmodifiableSet(temp.keySet());
TYPES_BY_CLASS = Collections.unmodifiableMap(temp);
}
/**
* Returns true if ValueCodex can operate on values of the given type.
*
* @param clazz a Class object
* @return {@code true} if the given object type can be decoded
*/
public static boolean canDecode(Class<?> clazz) {
if (findType(clazz) != null) {
return true;
}
// Use other platform-specific tests
return ValueCodexHelper.canDecode(clazz);
}
public static <T> T decode(Class<T> clazz, Splittable split) {
if (split == null || split == LazySplittable.NULL) {
return null;
}
return decode(clazz, split.asString());
}
@SuppressWarnings("unchecked")
public static <T> T decode(Class<T> clazz, String string) {
if (string == null) {
return null;
}
return (T) getTypeOrDie(clazz).decode(clazz, string);
}
/**
* Encode a value object when the wire format type is known. This method
* should be preferred over {@link #encode(Object)} when possible.
*/
public static Splittable encode(Class<?> clazz, Object obj) {
if (obj == null) {
return LazySplittable.NULL;
}
return new LazySplittable(getTypeOrDie(clazz).toJsonExpression(obj));
}
public static Splittable encode(Object obj) {
if (obj == null) {
return LazySplittable.NULL;
}
Type t = findType(obj.getClass());
// Try upcasting
if (t == null) {
for (Type maybe : Type.values()) {
if (maybe.canUpcast(obj)) {
t = maybe;
break;
}
}
}
if (t == null) {
throw new UnsupportedOperationException(obj.getClass().getName());
}
return new LazySplittable(t.toJsonExpression(obj));
}
/**
* Return all Value types that can be processed by the ValueCodex.
*/
public static Set<Class<?>> getAllValueTypes() {
return ALL_VALUE_TYPES;
}
/**
* Returns the uninitialized field value for the given primitive type.
*/
public static Object getUninitializedFieldValue(Class<?> clazz) {
Type type = getTypeOrDie(clazz);
if (clazz.equals(type.getPrimitiveType())) {
return type.getDefaultValue();
}
return null;
}
/**
* May return <code>null</code>.
*/
private static <T> Type findType(Class<T> clazz) {
if (clazz.isEnum()) {
return Type.ENUM;
}
return TYPES_BY_CLASS.get(clazz);
}
private static <T> Type getTypeOrDie(Class<T> clazz) {
Type toReturn = findType(clazz);
if (toReturn == null) {
throw new UnsupportedOperationException(clazz.getName());
}
return toReturn;
}
}