zkoss/zk

/* FunctionMapperInfo.java

    Purpose:
        
    Description:
        
    History:
        Mon May  5 14:41:03     2008, Created by tomyeh

Copyright (C) 2008 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.zk.ui.metainfo;

import java.util.Map;

import org.zkoss.lang.Classes;
import org.zkoss.xel.FunctionMapper;
import org.zkoss.zk.ui.Page;
import org.zkoss.zk.ui.UiException;
import org.zkoss.zk.xel.Evaluator;
import org.zkoss.zk.xel.ExValue;

/**
 * A definition of the function mapper ({@link FunctionMapper}).
 *
 * <p>Note: we resolve the class by using Classes.forNameByThread.
 * In other words, it doesn't support the class defined in zscript.
 * Why not? Since there is no way to run zscript before the function-mapper
 * directive (and better performance).
 * </p>
 * <p>Note: it is not serializable.</p>
 * @author tomyeh
 * @since 3.5.0
 */
public class FunctionMapperInfo extends ArgumentInfo { //directive
    /** A class, an ExValue or an FunctionMapper. */
    private Object _mapper;

    /** Constructs with a class.
     * @param args the map of arguments. Ignored if null.<br/>
     * Notice that, once assigned, the map belongs to this object, and the caller
     * shall not access it again
     * @since 3.6.1
     */
    public FunctionMapperInfo(Class<? extends FunctionMapper> cls, Map<String, String> args) {
        super(args);
        checkClass(cls);
        _mapper = cls;
    }

    /** Constructs with a class.
     */
    public FunctionMapperInfo(Class<? extends FunctionMapper> cls) {
        this(cls, null);
    }

    private static void checkClass(Class<?> cls) {
        if (!FunctionMapper.class.isAssignableFrom(cls))
            throw new UiException(FunctionMapper.class + " must be implemented: " + cls);
    }

    /** Constructs with a class name.
     *
     * @param clsnm the class name; it could be an EL expression.
     */
    public FunctionMapperInfo(String clsnm, Map<String, String> args) throws ClassNotFoundException {
        super(args);

        if (clsnm == null || clsnm.length() == 0)
            throw new IllegalArgumentException("empty");

        if (clsnm.indexOf("${") < 0) {
            if (clsnm.indexOf('.') >= 0) { //resolve it now
                try {
                    final Class<?> cls = Classes.forNameByThread(clsnm);
                    checkClass(cls);
                    _mapper = cls;
                } catch (ClassNotFoundException ex) {
                    throw new ClassNotFoundException("Class not found: " + clsnm, ex);
                }
            } else { //it might depend on <?import?>
                _mapper = clsnm;
            }
        } else {
            _mapper = new ExValue(clsnm, String.class);
        }
    }

    /** Constructs with a class name.
     *
     * @param clsnm the class name; it could be an EL expression.
     */
    public FunctionMapperInfo(String clsnm) throws ClassNotFoundException {
        this(clsnm, null);
    }

    /** Constructs with an initiator that will be reuse each time
     * {@link #newFunctionMapper} is called.
     */
    public FunctionMapperInfo(FunctionMapper mapper) {
        super(null);

        if (mapper == null)
            throw new IllegalArgumentException("null");
        _mapper = mapper;
    }

    /** Creates and returns the function mapper for the specified pagedefinition and page.
     */
    public FunctionMapper newFunctionMapper(PageDefinition pgdef, Page page) throws Exception {
        return newFunctionMapper(pgdef.getEvaluator(), page);
    }

    /** Creates and returns the function mapper for the specified evaluator and page.
     * @since 3.6.2
     */
    public FunctionMapper newFunctionMapper(Evaluator eval, Page page) throws Exception {
        if (_mapper instanceof FunctionMapper)
            return (FunctionMapper) _mapper;

        String clsnm = null;
        if (_mapper instanceof ExValue) {
            clsnm = (String) ((ExValue) _mapper).getValue(eval, page);
            if (clsnm == null || clsnm.length() == 0) {
                return null; //ignore it!!
            }
        } else if (_mapper instanceof String) {
            clsnm = (String) _mapper;
        }

        final Class<?> cls;
        if (clsnm != null) {
            try {
                cls = page != null ? page.resolveClass(clsnm) : Classes.forNameByThread(clsnm);
                checkClass(cls);
            } catch (ClassNotFoundException ex) {
                throw new ClassNotFoundException("Class not found: " + clsnm + " (" + _mapper + ")", ex);
            }
            if (clsnm.equals(_mapper))
                _mapper = cls; //cache it for better performance
        } else {
            cls = (Class<?>) _mapper;
        }

        return (FunctionMapper) newInstance(cls, eval, page);
    }

    //Object//
    public String toString() {
        return "[function-mapper " + _mapper + "]";
    }
}