/*
* Copyright 2011 <a href="mailto:lincolnbaxter@gmail.com">Lincoln Baxter, III</a>
*
* 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 org.ocpsoft.rewrite.cdi;
import javax.el.ELContext;
import javax.el.ELException;
import javax.el.ExpressionFactory;
import javax.el.ValueExpression;
import javax.enterprise.inject.Instance;
import javax.inject.Inject;
import org.ocpsoft.rewrite.cdi.expressions.Expressions;
import org.ocpsoft.rewrite.el.spi.ExpressionLanguageProvider;
/**
* @author <a href="mailto:lincolnbaxter@gmail.com">Lincoln Baxter, III</a>
*/
public class CdiExpressionLanguageProvider implements ExpressionLanguageProvider
{
/**
* We cannot simply inject an instance of Expressions here, because {@link CdiExpressionLanguageProvider} is created
* only once for the entire application and {@link Expressions} is not thread-safe because it holds only a single
* {@link ELContext} instance.
*/
@Inject
private Instance<Expressions> expressionsInstance;
@Override
public int priority()
{
return 10;
}
@Override
public Object retrieveValue(final String expression)
{
Expressions expressions = expressionsInstance.get();
return getValue(expressions.getELContext(), expressions.getExpressionFactory(),
groomExpression(expression));
}
@Override
public void submitValue(final String expression, final Object value)
{
Expressions expressions = expressionsInstance.get();
String el = groomExpression(expression);
if (getExpectedType(expressions.getELContext(), expressions.getExpressionFactory(), el).isArray())
{
Object[] toInject = null;
if ((value != null) && !value.getClass().isArray())
{
toInject = new Object[] { value };
}
else
toInject = (Object[]) value;
setValue(expressions.getELContext(), expressions.getExpressionFactory(), el, toInject);
}
else
{
Object toInject = value;
if ((value != null) && value.getClass().isArray())
{
Object[] array = (Object[]) value;
if (array.length > 0)
{
toInject = array[0];
}
else
{
toInject = "";
}
}
setValue(expressions.getELContext(), expressions.getExpressionFactory(), el, toInject);
}
}
public String groomExpression(String expression)
{
String result = expression.trim();
if (!result.startsWith("#{"))
return expressionsInstance.get().toExpression(result);
return result;
}
@Override
public Object evaluateMethodExpression(final String expression)
{
String el = groomExpression(expression);
return expressionsInstance.get().evaluateMethodExpression(el);
}
@Override
public Object evaluateMethodExpression(final String expression, final Object... values)
{
String el = groomExpression(expression);
return expressionsInstance.get().evaluateMethodExpression(el, values);
}
/**
* Helpers
*/
private Class<?> getExpectedType(final ELContext context, final ExpressionFactory factory, final String expression)
throws ELException
{
ValueExpression ve = factory.createValueExpression(context, expression, Object.class);
return ve.getType(context);
}
private Object getValue(final ELContext context, final ExpressionFactory factory, final String expression)
throws ELException
{
ValueExpression ve = factory.createValueExpression(context, expression, Object.class);
return ve.getValue(context);
}
private void setValue(final ELContext context, final ExpressionFactory factory, final String expression,
final Object value) throws ELException
{
ValueExpression ve = factory.createValueExpression(context, expression, Object.class);
ve.setValue(context, factory.coerceToType(value, ve.getType(context)));
}
}