/* Namespaces.java{{IS_NOTE	Purpose:			Description:			History:		Fri Jun 16 00:01:09     2006, Created by tomyeh}}IS_NOTECopyright (C) 2006 Potix Corporation. All Rights Reserved.{{IS_RIGHT}}IS_RIGHT*/package org.zkoss.zk.ui.util;import java.util.Map;import org.zkoss.zk.ui.Desktop;import org.zkoss.zk.ui.Page;import org.zkoss.zk.ui.Component;import org.zkoss.zk.ui.Execution;import org.zkoss.zk.ui.Executions;/** * {@link Namespace} relevant utilities. * * @author tomyeh */public class Namespaces {	/** Prepares builtin variable before calling {@link Page#interpret}.	 *	 * <p>Typical use:	 * <pre><code>	 * final Namespace ns = Namespaces.beforeInterpret(exec, comp);	 * try {	 *   page.interpret(zscript, ns);	 * } finally {	 *   Namespaces.afterInterpret(ns);	 * }	 * </code></pre>	 *	 * <p>Note: beforeInterpret() actually use {@link Namespace#backupVariable}	 * to maintain what was modified, and then {@link #afterInterpret}	 * restore them by use of {@link Namespace#restoreVariables}.	 * Thus, you can back up more variables after calling this method	 * with {@link Namespace#backupVariable} (by specifying newBlock as false).	 *	 * @param exec the current execution.	 * If null, {@link Desktop#getExecution} is used.	 * @param comp the component, never null.	 * @return the namespace that owns the specified component	 */	public static final	Namespace beforeInterpret(Execution exec, Component comp) {		final Namespace ns = comp.getNamespace();		ns.backupVariable("self", true);		ns.backupVariable("componentScope", false);		ns.setVariable("self", comp, true);		ns.setVariable("componentScope",			comp.getAttributes(Component.COMPONENT_SCOPE), true);		final Object arg = getArg(exec, comp);		if (arg != null) {			ns.backupVariable("arg", false);			ns.setVariable("arg", arg, true);		}		return ns;	}	/** Prepares builtin variable before calling	 * {@link org.zkoss.zk.ui.Page#interpret}.	 *	 * @see #beforeInterpret(Execution,Component)	 * @param exec the current execution.	 * If null, {@link Desktop#getExecution} is used.	 * @param page the page, never null.	 * @return the namespace that owns the specified page	 */	public static final Namespace beforeInterpret(Execution exec, Page page) {		final Namespace ns = page.getNamespace();		ns.backupVariable(null, true);		final Object arg = getArg(exec, page);		if (arg != null) {			ns.backupVariable("arg", false);			ns.setVariable("arg", arg, true);		}		return ns;	}	/** Used with {@link #beforeInterpret(Execution,Component)} to clean up builtin	 * variables.	 */	public static final void afterInterpret(Namespace ns) {		ns.restoreVariables();	}	private static Map getArg(Execution exec, Component comp) {		if (exec == null) {			exec = Executions.getCurrent();			if (exec == null && comp != null) {				final Desktop dt = comp.getDesktop();				if (dt != null) exec = dt.getExecution();			}			if (exec == null) return null;		}		return exec.getArg();	}	private static Map getArg(Execution exec, Page page) {		if (exec == null) {			exec = Executions.getCurrent();			if (exec == null && page != null) {				final Desktop dt = page.getDesktop();				if (dt != null) exec = dt.getExecution();			}			if (exec == null) return null;		}		return exec.getArg();	}}