BindEvaluatorXUtil.java

/* BindEvaluatorXUtil

	Purpose:
		
	Description:
		
	History:
		Oct 19, 2011 5:17:48 PM, Created by dennis

Copyright (C) 2011 Potix Corporation. All Rights Reserved.
*/
package org.zkoss.bind.impl;

import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Map.Entry;

import org.zkoss.bind.BindContext;
import org.zkoss.bind.sys.BindEvaluatorX;
import org.zkoss.bind.xel.zel.ImplicitObjectELResolver;
import org.zkoss.lang.Classes;
import org.zkoss.lang.Library;
import org.zkoss.lang.Strings;
import org.zkoss.xel.ExpressionX;
import org.zkoss.xel.FunctionMapper;
import org.zkoss.zk.ui.Component;
import org.zkoss.zk.ui.UiException;

/**
 * an internal utility to help doing evaluation.
 * @author dennis
 * @since 6.0.0
 */
public class BindEvaluatorXUtil {

	//eval args, it it is an ExpressionX, than evaluate the value to instance
	public static Map<String, Object> evalArgs(BindEvaluatorX eval, Component comp, Map<String, Object> args) {
		return evalArgs(eval, comp, args, null);
	}

	public static Map<String, Object> evalArgs(BindEvaluatorX eval, Component comp, Map<String, Object> args,
			Map<String, Object> implicit) {
		if (args == null) {
			return null;
		}
		//ZK-1032 Able to wire Event to command method
		//for implicit objects, see ImplicitObjectELResolver
		BindContext ctx = null;
		if (implicit != null) {
			ctx = new BindContextImpl(null, null, false, null, null, null);
			ctx.setAttribute(ImplicitObjectELResolver.IMPLICIT_OBJECTS, implicit);
		}

		final Map<String, Object> result = new LinkedHashMap<String, Object>(args.size());
		for (final Iterator<Entry<String, Object>> it = args.entrySet().iterator(); it.hasNext();) {
			final Entry<String, Object> entry = it.next();
			final String key = entry.getKey();
			final Object value = entry.getValue();
			//evaluate the arg if it is an ExpressionX
			final Object evalValue = value == null ? null
					: (value instanceof ExpressionX) ? eval.getValue(ctx, comp, (ExpressionX) value) : value;
			result.put(key, evalValue);
		}
		return result;
	}

	// parse args , if it is a string, than parse it to an ExpressionX
	public static Map<String, Object> parseArgs(BindEvaluatorX eval, Map<String, String[]> args) {
		final Map<String, Object> result = AllocUtil.inst.newLinkedHashMap(args.size()); //ZK-2289
		for (final Iterator<Entry<String, String[]>> it = args.entrySet().iterator(); it.hasNext();) {
			final Entry<String, String[]> entry = it.next();
			final String key = entry.getKey();
			final String[] value = entry.getValue();

			addArg(eval, result, key, value);
		}
		return result;
	}

	private static void addArg(BindEvaluatorX eval, Map<String, Object> result, String key, String[] valueScript) {
		Object val = null;
		if (valueScript.length == 1) {
			val = eval.parseExpressionX(null, valueScript[0], Object.class);
		} else {
			//TODO support multiple value of a arg
			val = valueScript;
		}
		result.put(key, val);
	}

	@SuppressWarnings("unchecked")
	public static BindEvaluatorX createEvaluator(FunctionMapper fnampper) {
		String clznm = Library.getProperty("org.zkoss.bind.BindEvaluatorX.class");
		if (clznm != null) {
			Class<BindEvaluatorX> clz;
			try {
				clz = (Class<BindEvaluatorX>) Classes.forNameByThread(clznm);
				return clz.getConstructor(FunctionMapper.class).newInstance(fnampper);
			} catch (Exception e) {
				UiException.Aide.wrap(e, "Can't initialize BindEvaluatorX");
			}
		}
		return new BindEvaluatorXImpl(fnampper, org.zkoss.bind.xel.BindXelFactory.class);
	}

	public static <T> T eval(BindEvaluatorX evalx, Component comp, String expression, Class<T> expectedType) {
		return eval(evalx, comp, expression, expectedType, null);
	}

	@SuppressWarnings("unchecked")
	public static <T> T eval(BindEvaluatorX evalx, Component comp, String expression, Class<T> expectedType,
			Map<String, Object> implicit) {
		if (Strings.isBlank(expression))
			return null;
		final int len = expression.length();
		if (len > 2) {
			// string only
			if (expression.charAt(0) == '\'' && expression.charAt(len - 1) == '\'') {
				String result = expression.substring(1, len - 1);
				if (!result.contains("'"))
					return (T) result;
			}
		}
		BindContext ctx = null;
		ctx = new BindContextImpl(null, null, false, null, comp, null);
		if (implicit != null) {
			ctx.setAttribute(ImplicitObjectELResolver.IMPLICIT_OBJECTS, implicit);
		}

		ExpressionX expr = evalx.parseExpressionX(ctx, expression, expectedType);
		Object obj = evalx.getValue(ctx, comp, expr);
		return (T) obj;
	}

	//remove ${ and }
	public static String getExpressionString(ExpressionX expr) {
		if (expr == null) {
			return null;
		}
		final String evalstr = expr.getExpressionString();
		return evalstr.substring(2, evalstr.length() - 1);
	}
}