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/*
 *      Copyright (C) 2012-2015 DataStax 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.datastax.driver.extras.codecs;

import com.datastax.driver.core.ProtocolVersion;
import com.datastax.driver.core.TypeCodec;
import com.datastax.driver.core.exceptions.InvalidTypeException;
import com.google.common.reflect.TypeToken;

import java.nio.ByteBuffer;

/**
 * An abstract {@link TypeCodec} that stores JAVA objects as serialized strings.
 * This can serve as a base for codecs dealing with XML or JSON formats.
 * 

* This codec can be seen as a convenience base class to help * implementing Java-to-XML or Java-to-JSON mappings, but it comes * with a performance penalty: each Java object is serialized * in two steps: first to a String, and then to a {@link ByteBuffer}, * which means that each serialization actually incurs in two potentially * expensive operations being carried. *

* If you are using an XML or JSON library that supports writing Java objects * directly to {@link ByteBuffer}s, consider writing your own codec instead of * using this one. * * @param The Java type this codec serializes from and deserializes to. */ public abstract class ParsingCodec extends TypeCodec { private final TypeCodec innerCodec; public ParsingCodec(Class javaType) { this(TypeToken.of(javaType)); } public ParsingCodec(TypeToken javaType) { this(TypeCodec.varchar(), javaType); } public ParsingCodec(TypeCodec innerCodec, Class javaType) { this(innerCodec, TypeToken.of(javaType)); } public ParsingCodec(TypeCodec innerCodec, TypeToken javaType) { super(innerCodec.getCqlType(), javaType); this.innerCodec = innerCodec; } @Override public ByteBuffer serialize(T value, ProtocolVersion protocolVersion) throws InvalidTypeException { return value == null ? null : innerCodec.serialize(toString(value), protocolVersion); } @Override public T deserialize(ByteBuffer bytes, ProtocolVersion protocolVersion) throws InvalidTypeException { String value = innerCodec.deserialize(bytes, protocolVersion); return value == null ? null : fromString(value); } @Override public String format(T value) throws InvalidTypeException { return value == null ? null : innerCodec.format(toString(value)); } @Override public T parse(String value) throws InvalidTypeException { return value == null || value.isEmpty() || value.equalsIgnoreCase("NULL") ? null : fromString(innerCodec.parse(value)); } /** * Return the String representation of the given object; * no special CQL quoting should be applied here. * Null values should be accepted; in most cases, implementors * should return null for null inputs. * * @param value the value to convert into a string * @return the String representation of the given object */ protected abstract String toString(T value); /** * Parse the given string into an object; * no special CQL unquoting should be applied here. * Null values should be accepted; in most cases, implementors * should return null for null inputs. * * @param value the string to parse * @return the parsed object. */ protected abstract T fromString(String value); }





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