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/*******************************************************************************
* Copyright (c) 2006, 2008 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.Expression;
import org.eclipse.jpt.common.core.utility.jdt.ExpressionConverter;
import org.eclipse.jpt.common.utility.internal.StringTools;
/**
* Gather together the common implementation behavior.
* T is the type of the object to be converted to and from an expression.
*
* We're still figuring out Java Generics here.... The methods in this abstract
* class work fine with any subclass of Expression E; but a ClassCastException
* will occur as soon as we call any method implemented by a subclass
* (e.g. StringExpressionConverter) that expects a particular subclass of
* Expression (e.g. StringLiteral).
*/
public abstract class AbstractExpressionConverter<T>
implements ExpressionConverter<T>
{
protected AbstractExpressionConverter() {
super();
}
// ********** object -> expression **********
public Expression convert(T object, AST ast) {
return (object == null) ? this.convertNull(ast) : this.convertObject(object, ast);
}
/**
* Return the expression for a null object. By default, a null object will
* be converted into a null expression.
*/
protected Expression convertNull(@SuppressWarnings("unused") AST ast) {
return null;
}
/**
* The specified object is not null.
* @see #convert(Object, AST)
*/
protected abstract Expression convertObject(T object, AST ast);
// ********** expression -> object **********
public T convert(Expression expression) {
return (expression == null) ? this.convertNull() : this.convertExpression(expression);
}
/**
* Return the object for a null expression. By default, a null expression will
* be converted into a null object.
*/
protected T convertNull() {
return null;
}
/**
* The specified expression is not null.
* @see #convert(Expression)
*/
protected abstract T convertExpression(Expression expression);
@Override
public String toString() {
return StringTools.buildToStringFor(this);
}
}
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