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Alexandre Dutra
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JAVA-565: Codec support for Java arrays.
This commit introduces codecs that map CQL types to Java arrays directly. Object arrays and arrays of primitive types are both supported.
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‎changelog/README.md‎

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- [new feature] JAVA-846: Provide custom codecs library as an extra module.
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- [new feature] JAVA-742: Codec Support for JSON.
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- [new feature] JAVA-606: Codec support for Java 8.
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- [new feature] JAVA-565: Codec support for Java arrays.
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Merged from 2.1 branch:
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‎driver-core/src/test/java/com/datastax/driver/core/TypeCodecArraysIntegrationTest.java‎

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‎driver-extras/src/main/java/com/datastax/driver/extras/codecs/arrays/AbstractArrayCodec.java‎

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/*
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* Copyright (C) 2012-2015 DataStax Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.datastax.driver.extras.codecs.arrays;
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import java.lang.reflect.Array;
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import static com.google.common.base.Preconditions.checkArgument;
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import com.datastax.driver.core.DataType;
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import com.datastax.driver.core.ParseUtils;
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import com.datastax.driver.core.TypeCodec;
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import com.datastax.driver.core.exceptions.InvalidTypeException;
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import static com.datastax.driver.core.ParseUtils.skipSpaces;
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/**
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* Base class for all codecs dealing with Java arrays.
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* This class aims to reduce the amount of code required to create such codecs.
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*
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* @param <T> The Java array type this codec handles
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*/
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public abstract class AbstractArrayCodec<T> extends TypeCodec<T> {
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/**
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* @param cqlType The CQL type. Must be a list type.
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* @param javaClass The Java type. Must be an array class.
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*/
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public AbstractArrayCodec(DataType.CollectionType cqlType, Class<T> javaClass) {
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super(cqlType, javaClass);
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checkArgument(cqlType.getName() == DataType.Name.LIST, "Expecting CQL list type, got %s", cqlType);
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checkArgument(javaClass.isArray(), "Expecting Java array class, got %s", javaClass);
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}
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@Override
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public String format(T array) throws InvalidTypeException {
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if (array == null)
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return "NULL";
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int length = Array.getLength(array);
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StringBuilder sb = new StringBuilder();
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sb.append('[');
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for (int i = 0; i < length; i++) {
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if (i != 0)
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sb.append(",");
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formatElement(sb, array, i);
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}
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sb.append(']');
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return sb.toString();
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}
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@Override
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public T parse(String value) throws InvalidTypeException {
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if (value == null || value.isEmpty() || value.equalsIgnoreCase("NULL"))
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return null;
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int idx = skipSpaces(value, 0);
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if (value.charAt(idx++) != '[')
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throw new InvalidTypeException(String.format("cannot parse list value from \"%s\", at character %d expecting '[' but got '%c'", value, idx, value.charAt(idx)));
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idx = skipSpaces(value, idx);
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if (value.charAt(idx) == ']')
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return newInstance(0);
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// first pass: determine array length
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int length = getArrayLength(value, idx);
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// second pass: parse elements
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T array = newInstance(length);
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int i = 0;
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for( ; idx < value.length(); i++) {
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int n = skipLiteral(value, idx);
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parseElement(value.substring(idx, n), array, i);
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idx = skipSpaces(value, n);
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if (value.charAt(idx) == ']')
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return array;
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idx = skipComma(value, idx);
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idx = skipSpaces(value, idx);
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}
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throw new InvalidTypeException(String.format("Malformed list value \"%s\", missing closing ']'", value));
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}
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/**
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* Create a new array instance with the given size.
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*
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* @param size The size of the array to instantiate.
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* @return a new array instance with the given size.
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*/
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protected abstract T newInstance(int size);
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/**
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* Format the {@code index}th element of {@code array} to {@code output}.
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*
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* @param output The StringBuilder to write to.
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* @param array The array to read from.
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* @param index The element index.
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*/
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protected abstract void formatElement(StringBuilder output, T array, int index);
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/**
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* Parse the {@code index}th element of {@code array} from {@code input}.
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*
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* @param input The String to read from.
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* @param array The array to write to.
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* @param index The element index.
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*/
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protected abstract void parseElement(String input, T array, int index);
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private int getArrayLength(String value, int idx) {
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int length = 1;
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for( ; idx < value.length(); length++) {
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idx = skipLiteral(value, idx);
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idx = skipSpaces(value, idx);
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if (value.charAt(idx) == ']')
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break;
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idx = skipComma(value, idx);
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idx = skipSpaces(value, idx);
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}
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return length;
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}
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private int skipComma(String value, int idx) {
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if (value.charAt(idx) != ',')
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throw new InvalidTypeException(String.format("Cannot parse list value from \"%s\", at character %d expecting ',' but got '%c'", value, idx, value.charAt(idx)));
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return idx + 1;
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}
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private int skipLiteral(String value, int idx) {
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try {
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return ParseUtils.skipCQLValue(value, idx);
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} catch (IllegalArgumentException e) {
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throw new InvalidTypeException(String.format("Cannot parse list value from \"%s\", invalid CQL value at character %d", value, idx), e);
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}
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}
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}

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