001/*
002 * (C) Copyright 2007 Nuxeo SA (http://nuxeo.com/) and others.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *     http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 *
016 * Contributors:
017 *     Nuxeo - initial API and implementation
018 *
019 * $Id: MetaValueHolderRule.java 28460 2008-01-03 15:34:05Z sfermigier $
020 */
021
022package org.nuxeo.ecm.platform.ui.web.tag.jsf;
023
024import javax.el.ValueExpression;
025import javax.faces.component.UIComponent;
026import javax.faces.component.ValueHolder;
027import javax.faces.view.facelets.FaceletContext;
028import javax.faces.view.facelets.MetaRule;
029import javax.faces.view.facelets.Metadata;
030import javax.faces.view.facelets.MetadataTarget;
031import javax.faces.view.facelets.TagAttribute;
032
033import org.nuxeo.ecm.platform.ui.web.binding.MetaValueExpression;
034
035/**
036 * Meta value rule, used to evaluate an expression as a regular value expression, or invoking it again as another value
037 * expression or method expression.
038 * <p>
039 * The method can have parameters and the expression must use parentheses even if no parameters are needed.
040 *
041 * @author <a href="mailto:at@nuxeo.com">Anahide Tchertchian</a>
042 */
043public class MetaValueHolderRule extends MetaRule {
044
045    static final class LiteralValueMetadata extends Metadata {
046
047        private final String value;
048
049        LiteralValueMetadata(String value) {
050            this.value = value;
051        }
052
053        @Override
054        public void applyMetadata(FaceletContext ctx, Object instance) {
055            ((ValueHolder) instance).setValue(value);
056        }
057    }
058
059    static final class MetaValueExpressionMetadata extends Metadata {
060
061        private final TagAttribute attr;
062
063        MetaValueExpressionMetadata(TagAttribute attr) {
064            this.attr = attr;
065        }
066
067        @Override
068        public void applyMetadata(FaceletContext ctx, Object instance) {
069            ValueExpression originalExpression = attr.getValueExpression(ctx, Object.class);
070            ((UIComponent) instance).setValueExpression("value",
071                    new MetaValueExpression(originalExpression, ctx.getFunctionMapper(), ctx.getVariableMapper()));
072        }
073    }
074
075    public static final MetaValueHolderRule Instance = new MetaValueHolderRule();
076
077    @Override
078    public Metadata applyRule(String name, TagAttribute attribute, MetadataTarget meta) {
079        if (meta.isTargetInstanceOf(ValueHolder.class)) {
080            if ("value".equals(name)) {
081                if (attribute.isLiteral()) {
082                    return new LiteralValueMetadata(attribute.getValue());
083                } else {
084                    return new MetaValueExpressionMetadata(attribute);
085                }
086            }
087
088        }
089        return null;
090    }
091
092}