experimental/trunk_core_with_pluggable_logger/core/src/main/java/org/apache/myfaces/extensions/validator/util/ELUtils.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.apache.myfaces.extensions.validator.util;

import org.apache.myfaces.extensions.validator.internal.ToDo;
import org.apache.myfaces.extensions.validator.internal.Priority;
import org.apache.myfaces.extensions.validator.internal.UsageInformation;
import org.apache.myfaces.extensions.validator.internal.UsageCategory;

import javax.el.ValueExpression;
import javax.faces.component.UIComponent;
import javax.faces.context.FacesContext;

/**
 * in order to centralize the jsf version dependency within the core
 *
 * @author Gerhard Petracek
 */
@ToDo(Priority.MEDIUM)
@UsageInformation(UsageCategory.INTERNAL)
public class ELUtils
{
    public static Class getTypeOfValueBindingForExpression(FacesContext facesContext, String valueBindingExpression)
    {
        //due to a restriction with the ri
        Object bean = ELUtils.getValueOfExpression(facesContext, valueBindingExpression);
        return (bean != null) ? bean.getClass() : null;
    }

    public static Object getBean(String beanName)
    {
        FacesContext facesContext = FacesContext.getCurrentInstance();
        return facesContext.getApplication().getELResolver().getValue(facesContext.getELContext(), null, beanName);
    }

    @ToDo(value = Priority.MEDIUM, description = "refactor - problem - static values - jsf 1.2 e.g.: ${value}")
    public static Object getBaseObject(String valueBindingExpression, UIComponent uiComponent)
    {
        if (valueBindingExpression.lastIndexOf(".") == -1)
        {
            return uiComponent.getValueExpression("value").getValue(FacesContext.getCurrentInstance().getELContext());
        }
        return getBaseObject(valueBindingExpression);
    }

    public static Object getBaseObject(String valueBindingExpression)
    {
        String newExpression = valueBindingExpression.substring(0, valueBindingExpression.lastIndexOf(".")) + "}";

        return getValueOfExpression(FacesContext.getCurrentInstance(), newExpression);
    }

    public static Object getValueOfExpression(FacesContext facesContext, String valueBindingExpression)
    {
        return (valueBindingExpression != null) ? facesContext.getApplication().evaluateExpressionGet(
            facesContext, valueBindingExpression, Object.class) : null;
    }

    public static boolean isExpressionValid(FacesContext facesContext, String valueBindingExpression)
    {
        try
        {
            facesContext.getApplication().evaluateExpressionGet(facesContext, valueBindingExpression, Object.class);
        }
        catch (Throwable t)
        {
            return false;
        }
        return true;
    }

    public static String getReliableValueBindingExpression(
        UIComponent uiComponent)
    {
        String valueBindingExpression = getValueBindingExpression(uiComponent);

        String baseExpression = valueBindingExpression;

        //for input components without value-binding
        //(e.g. for special component libs -> issue with ExtValRendererWrapper#encodeBegin)
        if(baseExpression == null)
        {
            //TODO logging
            return null;
        }

        if (baseExpression.contains("."))
        {
            baseExpression = baseExpression.substring(0, valueBindingExpression.lastIndexOf(".")) + "}";
        }

        if (getTypeOfValueBindingForExpression(FacesContext.getCurrentInstance(), baseExpression) == null)
        {
            valueBindingExpression = FaceletsTaglibExpressionUtils.
                tryToCreateValueBindingForFaceletsBinding(uiComponent);
        }
        return valueBindingExpression;
    }

    public static String getValueBindingExpression(UIComponent uiComponent)
    {
        ValueExpression valueExpression = uiComponent.getValueExpression("value");

        return (valueExpression != null) ? valueExpression.getExpressionString() : null;
    }

    public static Class getTypeOfValueBindingForComponent(FacesContext facesContext, UIComponent uiComponent)
    {
        ValueExpression valueExpression = uiComponent.getValueExpression("value");

        return (valueExpression != null) ? valueExpression.getType(facesContext.getELContext()) : null;
    }
}