common/plugins/org.eclipse.jpt.common.core/src/org/eclipse/jpt/common/core/internal/utility/jdt/AnnotationStringArrayExpressionConverter.java

/*******************************************************************************
 * Copyright (c) 2007, 2012 Oracle. All rights reserved.
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0, which accompanies this distribution
 * and is available at http://www.eclipse.org/legal/epl-v10.html.
 * 
 * Contributors:
 *     Oracle - initial API and implementation
 ******************************************************************************/
package org.eclipse.jpt.common.core.internal.utility.jdt;

import org.eclipse.jdt.core.dom.AST;
import org.eclipse.jdt.core.dom.ASTNode;
import org.eclipse.jdt.core.dom.ArrayInitializer;
import org.eclipse.jdt.core.dom.Expression;
import org.eclipse.jpt.common.core.utility.jdt.ExpressionConverter;
import org.eclipse.jpt.common.core.utility.jdt.IndexedExpressionConverter;
import org.eclipse.jpt.common.utility.internal.StringTools;

/**
 * Convert an array initializer or single expression to/from an array of
 * strings (e.g. {"text0", "text1"}).
 * E is the type of the expressions to be found either stand-alone or
 * as elements in the array initializer.
 */
public class AnnotationStringArrayExpressionConverter
	extends AbstractExpressionConverter<String[]>
	implements IndexedExpressionConverter<String>
{
	private final ExpressionConverter<String> elementConverter;
	private final StringArrayExpressionConverter arrayConverter;


	/**
	 * The default behavior is to remove the array initializer if it is empty.
	 */
	public AnnotationStringArrayExpressionConverter(ExpressionConverter<String> elementConverter) {
		this(elementConverter, true);
	}

	public AnnotationStringArrayExpressionConverter(ExpressionConverter<String> elementConverter, boolean removeArrayInitializerWhenEmpty) {
		super();
		this.elementConverter = elementConverter;
		this.arrayConverter = new StringArrayExpressionConverter(elementConverter, removeArrayInitializerWhenEmpty);
	}

	/**
	 * if we only have a single string in the array return the single expression,
	 * without braces, instead of an array initializer
	 */
	@Override
	protected Expression convertObject(String[] strings, AST ast) {
		return (strings.length == 1) ?
				this.elementConverter.convert(strings[0], ast) :
				this.arrayConverter.convertObject(strings, ast);
	}

	@Override
	protected String[] convertNull() {
		return this.arrayConverter.convertNull();
	}

	/**
	 * check for a single expression with no surrounding braces, implying a
	 * single-entry array
	 */
	@Override
	protected String[] convertExpression(Expression expression) {
		return (expression.getNodeType() == ASTNode.ARRAY_INITIALIZER) ?
				this.convertArrayInitializer((ArrayInitializer) expression) :
				this.convertNonArrayInitializer(expression);
	}

	protected String[] convertArrayInitializer(ArrayInitializer arrayInitializer) {
		return this.arrayConverter.convertArrayInitializer(arrayInitializer);
	}

	/**
	 * The specified expression is <em>not</em> an array initializer.
	 * If we have trouble converting the standalone expression, simply return an
	 * empty array (as opposed to an array with a <code>null</code> element).
	 */
	protected String[] convertNonArrayInitializer(Expression expression) {
		String element = this.elementConverter.convert(expression);
		return (element == null) ? StringTools.EMPTY_STRING_ARRAY : new String[] { element };
	}

	public Expression selectExpression(Expression expression, int index) {
		if (expression.getNodeType() == ASTNode.ARRAY_INITIALIZER) {
			return this.arrayConverter.selectExpression(expression, index);
		}
		if (index == 0) {
			return expression;
		}
		throw new ArrayIndexOutOfBoundsException();
	}


	// ********** factory methods **********

	/**
	 * Build an expression converter for an annotation element of type String[].
	 *     @Foo(bar={"text0", "text1"})
	 * or
	 *     @Foo(bar="text0")
	 */
	public static AnnotationStringArrayExpressionConverter forStrings() {
		return new AnnotationStringArrayExpressionConverter(StringExpressionConverter.instance());
	}

	/**
	 * Build an expression converter for an annotation element of type <enum>[].
	 *     @Foo(bar={BAZ, BAT})
	 * or
	 *     @Foo(bar=BAZ)
	 */
	public static AnnotationStringArrayExpressionConverter forNames() {
		return new AnnotationStringArrayExpressionConverter(NameStringExpressionConverter.instance());
	}


	/**
	 * Build an expression converter for an annotation element of type Class[].
	 *     @Foo(bar={Baz.class, Bat.class})
	 * or
	 *     @Foo(bar=Baz.class)
	 */
	public static AnnotationStringArrayExpressionConverter forTypes() {
		return new AnnotationStringArrayExpressionConverter(TypeStringExpressionConverter.instance());
	}
}