001/*
002 * (C) Copyright 2010 Nuxeo SA (http://nuxeo.com/) and contributors.
003 *
004 * All rights reserved. This program and the accompanying materials
005 * are made available under the terms of the GNU Lesser General Public License
006 * (LGPL) version 2.1 which accompanies this distribution, and is available at
007 * http://www.gnu.org/licenses/lgpl.html
008 *
009 * This library is distributed in the hope that it will be useful,
010 * but WITHOUT ANY WARRANTY; without even the implied warranty of
011 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
012 * Lesser General Public License for more details.
013 *
014 * Contributors:
015 *     Anahide Tchertchian
016 */
017package org.nuxeo.ecm.platform.ui.web.binding.alias;
018
019import javax.el.ELContext;
020import javax.el.ValueExpression;
021import javax.faces.context.FacesContext;
022
023import org.apache.commons.logging.Log;
024import org.apache.commons.logging.LogFactory;
025
026/**
027 * Value expression that only stores a reference the {@link AliasVariableMapper} id so that the corresponding expression
028 * is found in the context, and is evaluated against contextual values.
029 *
030 * @author Anahide Tchertchian
031 * @since 5.4
032 */
033public class AliasValueExpression extends ValueExpression {
034
035    private static final Log log = LogFactory.getLog(AliasValueExpression.class);
036
037    private static final long serialVersionUID = 1L;
038
039    protected final String id;
040
041    protected final String var;
042
043    public AliasValueExpression(String id, String var) {
044        this.id = id;
045        this.var = var;
046    }
047
048    @Override
049    public boolean equals(Object obj) {
050        if (this == obj) {
051            return true;
052        }
053        if (!(obj instanceof AliasValueExpression)) {
054            return false;
055        }
056        AliasValueExpression other = (AliasValueExpression) obj;
057        return id.equals(other.id) && var.equals(other.var);
058    }
059
060    @Override
061    public int hashCode() {
062        return id.hashCode() + var.hashCode();
063    }
064
065    @Override
066    public String getExpressionString() {
067        return null;
068    }
069
070    @Override
071    public boolean isLiteralText() {
072        return false;
073    }
074
075    @Override
076    public Class<?> getExpectedType() {
077        return Object.class;
078    }
079
080    @Override
081    public Class<?> getType(ELContext context) {
082        ValueExpression ve = resolveExpression(context);
083        if (ve != null) {
084            return ve.getType(context);
085        }
086        return Object.class;
087    }
088
089    /**
090     * Looks up the {@link AliasVariableMapper} in the context, and if found, resolve the corresponding
091     * {@link ValueExpression}.
092     */
093    @Override
094    public Object getValue(ELContext context) {
095        ValueExpression ve = resolveExpression(context);
096        Object res = null;
097        if (ve != null) {
098            res = ve.getValue(context);
099        }
100        if (log.isDebugEnabled()) {
101            log.debug(String.format("Resolved expression var='%s' for mapper with id '%s': %s", var, id, res));
102        }
103        return res;
104    }
105
106    @Override
107    public boolean isReadOnly(ELContext context) {
108        ValueExpression ve = resolveExpression(context);
109        if (ve != null) {
110            return ve.isReadOnly(context);
111        }
112        return true;
113    }
114
115    @Override
116    public void setValue(ELContext context, Object value) {
117        ValueExpression ve = resolveExpression(context);
118        if (ve != null) {
119            ve.setValue(context, value);
120        }
121        if (log.isDebugEnabled()) {
122            log.debug(String.format("Resolved expression var='%s' for mapper with id '%s' and set value: %s", var, id,
123                    value));
124        }
125    }
126
127    protected ValueExpression resolveExpression(ELContext context) {
128        FacesContext facesContext = (FacesContext) context.getContext(FacesContext.class);
129        AliasVariableMapper vm = AliasVariableMapper.getVariableMapper(facesContext, id);
130
131        if (vm == null) {
132            if (log.isDebugEnabled()) {
133                log.debug(String.format("No alias variable mapper with id '%s' " + "found in request for var '%s'", id,
134                        var));
135            }
136            return null;
137        }
138
139        ValueExpression ve = vm.resolveVariable(var);
140        if (ve == null) {
141            log.error(String.format("Variable for var '%s' not found in alias variable mapper " + "with id '%s'", var,
142                    id));
143            return null;
144        }
145
146        return ve;
147    }
148}