/*
* $Id: ChainAwareVariableResolver.java,v 1.5.4.1 2007/12/17 21:14:35 rlubke Exp $
*/
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package com.sun.faces.el;
import javax.el.ELResolver;
import javax.el.ValueExpression;
import javax.faces.context.FacesContext;
import javax.faces.el.EvaluationException;
import javax.faces.el.VariableResolver;
import com.sun.faces.util.RequestStateManager;
import com.sun.faces.el.FacesCompositeELResolver.ELResolverChainType;
/**
* <p> This special VariableResolver serves as the "original"
* VariableResolver that is passed to the one-arg ctor for the
* <b>first</b> custom VariableResolver that is encountered during
* application configuration. Subsequent VariableResolver instances get
* passed the previous VariableResolver instance, per section 10.4.5 of
* the spec. </p>
*
* <p>The "specialness" of this VariableResolver is found in its {@link
* #resolveVariable} method, which delegates to the head of the
* "correct" ELResolver chain based on the context in which this
* expression is being evaluated. If the expression being evaluated
* originated in a JSP page, the <code>Application</code>'s
* <code>ExpressionFactory</code> is used to create a
* <code>ValueExpression</code>, which is then evaluated to resolve the
* variable. This will cause the ELResolver chain described in section
* 5.6.1 of the spec to be used. If the expression being evaluated
* originated in a programmatic API call, the <code>Application</code>'s
* <code>ELResolver</code> is used to resolve the variable. This will
* cause the ELResolver chain described in section 5.6.2 of the spec to
* be used.</p>
*/
@SuppressWarnings("deprecation")
public class ChainAwareVariableResolver extends VariableResolver {
public ChainAwareVariableResolver() {
}
//
// Relationship Instance Variables
//
/**
* See the class javadocs.
*/
public Object resolveVariable(FacesContext context, String name)
throws EvaluationException {
Object result = null;
ELResolverChainType type = null;
Object valueObject = RequestStateManager.get(context,
RequestStateManager.EL_RESOLVER_CHAIN_TYPE_NAME);
if (null != valueObject &&
valueObject instanceof ELResolverChainType) {
type = (ELResolverChainType) valueObject;
}
if (ELResolverChainType.JSP == type) {
ValueExpression ve = context.getApplication().getExpressionFactory()
.createValueExpression(context.getELContext(),
"#{" + name + "}", Object.class);
result = ve.getValue(context.getELContext());
}
else if (ELResolverChainType.Faces == type) {
ELResolver elr = context.getApplication().getELResolver();
result = elr.getValue(context.getELContext(), null, name);
} else {
//noinspection ConstantConditions
assert(false);
}
return result;
}
}