ActionNode.java

/* ActionNode.java

	Purpose:
		
	Description:
		
	History:
		Sat Sep 17 15:03:33     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.io.IOException;
import java.lang.reflect.Method;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import org.zkoss.lang.Classes;
import org.zkoss.web.servlet.dsp.DspException;
import org.zkoss.web.servlet.dsp.action.Action;
import org.zkoss.xel.Expression;
import org.zkoss.xel.XelException;

/**
 * Represents an action node.
 *
 * @author tomyeh
 */
class ActionNode extends Node {
	private static final Logger log = LoggerFactory.getLogger(ActionNode.class);

	private final Class<?> _cls;
	private List<Attr> _attrs;
	private final int _nLines;

	/**
	 * @param nLines which line this action is located.
	 */
	ActionNode(Class<?> cls, int nLines) {
		_cls = cls;
		_nLines = nLines;
	}

	void interpret(InterpretContext ic) throws DspException, IOException {
		final Action parent = ic.action;
		try {
			ic.action = newAction();
			//1. apply attributes
			if (_attrs != null)
				for (Attr attr : _attrs)
					attr.apply(ic, ic.action);

			//2. render
			ic.action.render(new ActionContextImpl(ic, parent, this, _nLines), _children != null);
		} finally {
			ic.action = parent;
		}
	}

	/** Creates an instance of Action. */
	private Action newAction() throws DspException {
		try {
			return (Action) _cls.newInstance();
		} catch (Exception ex) {
			log.error("", ex); //Web server might 'eat'
			throw DspException.Aide.wrap(ex, "Failed to create " + _cls);
		}
	}

	/** Returns the line number */
	int getLineNumber() {
		return _nLines;
	}

	/** Renders the nested fragment. */
	void renderFragment(InterpretContext ic) throws DspException, IOException {
		if (_children == null)
			return;
		for (Iterator it = _children.iterator(); it.hasNext();) {
			((Node) it.next()).interpret(ic);
		}
	}

	/** Adds an attribute. */
	void addAttribute(String nm, String val, ParseContext ctx)
			throws NoSuchMethodException, ClassCastException, XelException {
		if (nm == null || val == null)
			throw new IllegalArgumentException("null");
		if (_attrs == null)
			_attrs = new LinkedList<Attr>();

		final Method mtd = (Method) Classes.getAccessibleObject(_cls, nm, new Class[] { null },
				Classes.B_SET | Classes.B_PUBLIC_ONLY | Classes.B_METHOD_ONLY);
		final Class type = mtd.getParameterTypes()[0];
		if (val.indexOf("${") >= 0) {
			_attrs.add(new Attr(mtd, ctx.getExpressionFactory().parseExpression(ctx, val, type)));
		} else {
			_attrs.add(new Attr(mtd, Classes.coerce(type, val)));
		}
	}

	private static class Attr {
		private final Method _method;
		private final Object _value;

		/**
		 * @param val the value. Either Expression or String.
		 */
		private Attr(Method mtd, Object val) {
			_method = mtd;
			_value = val;
		}

		/** Applies this attribute to the specified action. */
		private void apply(InterpretContext ic, Action action) throws DspException {
			final Object[] args = new Object[1];
			try {
				if (_value instanceof Expression) {
					args[0] = ((Expression) _value).evaluate(ic.xelc);
					//if (log.finerable()) log.finer("attr "+_method.getName()+"="+_value+" to "+args[0]);
				} else {
					args[0] = _value;
				}
				_method.invoke(action, args);
			} catch (Exception ex) {
				log.error("", ex); //Web server might 'eat'
				throw DspException.Aide.wrap(ex, "Failed to invoke " + _method + " with " + args[0]
						+ (args[0] != null ? " @" + args[0].getClass().getName() : ""));
			}
		}
	}

	public String toString() {
		return "Action[" + _cls.getName() + ']';
	}
}