zkoss/zk

/* InterpretResolver.java

    Purpose:
        
    Description:
        
    History:
        Sat Sep 17 17:03:58     2005, Created by tomyeh

Copyright (C) 2004 Potix Corporation. All Rights Reserved.

{{IS_RIGHT
    This program is distributed under LGPL Version 2.1 in the hope that
    it will be useful, but WITHOUT ANY WARRANTY.
}}IS_RIGHT
*/
package org.zkoss.web.servlet.dsp.impl;

import java.util.Collections;
import java.util.HashMap;
import java.util.Map;

import org.zkoss.web.servlet.dsp.Interpretation;
import org.zkoss.web.servlet.dsp.action.ActionContext;
import org.zkoss.xel.VariableResolver;
import org.zkoss.xel.XelException;
import org.zkoss.xel.util.Evaluators;

/**
 * The resolver used to interpret an {@link Interpretation}.
 *
 * @author tomyeh
 */
class InterpretResolver implements VariableResolver {
    private final VariableResolver _parent;
    private final Map<String, Object> _attrs = new HashMap<String, Object>();

    InterpretResolver(VariableResolver parent) {
        assert !(parent instanceof InterpretResolver);
        _parent = parent;
    }

    /** Returns the attributes of the given scope.
     */
    @SuppressWarnings("unchecked")
    Map<String, Object> getAttributes(int scope) throws XelException {
        if (scope == ActionContext.PAGE_SCOPE)
            return _attrs;

        Map attrs = null;
        if (_parent != null) {
            switch (scope) {
            case ActionContext.REQUEST_SCOPE:
                attrs = (Map) Evaluators.resolveVariable(_parent, "requestScope");
                break;
            case ActionContext.SESSION_SCOPE:
                attrs = (Map) Evaluators.resolveVariable(_parent, "sessionScope");
                break;
            case ActionContext.APPLICATION_SCOPE:
                attrs = (Map) Evaluators.resolveVariable(_parent, "applicationScope");
                break;
            }
        }
        return attrs != null ? attrs : Collections.EMPTY_MAP;
    }

    //-- VariableResolver --//
    public Object resolveVariable(String name) throws XelException {
        if ("pageScope".equals(name))
            return _attrs;
        final Object o = _attrs.get(name);
        return o != null ? o : Evaluators.resolveVariable(_parent, name);
    }
}