/* -*- mode: Java; c-basic-offset: 2; indent-tabs-mode: nil; coding: utf-8-unix -*-
*
* Copyright (c) 2013-2014 Edugility LLC.
*
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated documentation
* files (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use, copy,
* modify, merge, publish, distribute, sublicense and/or sell copies
* of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THIS SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS IN THE SOFTWARE.
*
* The original copy of this license is available at
* http://www.opensource.org/license/mit-license.html.
*/
package com.edugility.nomen.mvel;
import java.io.Serializable; // for javadoc only
import com.edugility.nomen.AbstractNamed;
import com.edugility.nomen.Name;
import com.edugility.nomen.Named;
import com.edugility.nomen.NameType;
import com.edugility.nomen.NameValue;
import org.mvel2.integration.VariableResolver;
import org.mvel2.integration.impl.BaseVariableResolverFactory;
import org.mvel2.integration.impl.SimpleValueResolver;
/**
* An <a href="http://mvel.codehaus.org/">MVEL</a> {@link
* VariableResolver} for resolving MVEL variables from a {@link
* Named}.
*
* @author <a href="http://about.me/lairdnelson"
* target="_parent">Laird Nelson</a>
*
* @see NameResolverFactory
*
* @see VariableResolver
*
* @see <a href="http://mvel.codehaus.org">MVEL</a>
*/
public final class NameResolver implements VariableResolver, Named {
/*
* Static fields.
*/
/**
* The version of this class for {@linkplain Serializable
* serialization purposes}.
*
* @see Serializable
*/
private static final long serialVersionUID = 1L;
/*
* Instance fields.
*/
/**
* The {@link Named} that owns {@link Name}s that might be resolved
* by this {@link NameResolver}.
*
* <p>This field will never be {@code null}.</p>
*
* @see Named
*/
private final Named named;
/**
* The {@link NameType} used by this {@link NameResolver} to {@linkplain
* #getName(NameType) look up <code>Name</code>s}.
*
* <p>This field will never be {@code null}.</p>
*
* @see #getName(NameType)
*
* @see NameType
*/
private final NameType nameType;
/*
* Constructors.
*/
/**
* Creates a new {@link NameResolver}.
*
* @param named the {@link Named} that will be used by the {@link
* #getValue()} method; must not be {@code null}
*
* @param nameType the {@link NameType} with which this {@link
* NameResolver} will be affiliated; must not be {@code null}
*
* @exception IllegalArgumentException if either {@code named} or
* {@code nameType} is {@code null}
*/
public NameResolver(final Named named, final NameType nameType) {
super();
if (named == null) {
throw new IllegalArgumentException("named", new NullPointerException("named"));
}
if (nameType == null) {
throw new IllegalArgumentException("nameType", new NullPointerException("nameType"));
}
this.named = named;
this.nameType = nameType;
}
/*
* Instance methods.
*/
/**
* Returns {@code 0}, following the recommendations of the <a
* href="http://mvel.codehaus.org/">MVEL</a> project.
*
* <p>The {@link VariableResolver} documentation does not describe
* what this method is used for.</p>
*
* @return {@code 0}
*
* @see VariableResolver#getFlags()
*/
@Override
public final int getFlags() {
return 0; // per VariableResolver "documentation"
}
/**
* Returns the {@link String} that is the {@linkplain
* NameType#getValue() value} of the {@link NameType} supplied at
* {@linkplain #NameResolver(Named, NameType) construction time}.
*
* <p>This method never returns {@code null}.</p>
*
* @return a non-{@code null} {@link String} naming the {@link Name}
* whose value will be returned by the {@link #getValue()} method
*
* @see #getValue()
*
* @see VariableResolver#getName()
*/
@Override
public final String getName() {
assert this.nameType != null;
return this.nameType.getValue();
}
/**
* Returns a {@link Name} for the supplied {@link NameType}, or
* {@code null} if no such {@link Name} could be found.
*
* @param nameType the {@link NameType} to use as a key; may be
* {@code null}
*
* @return a {@link Name}, or {@code null}
*
* @see Named#getName(NameType)
*/
@Override
public final Name getName(final NameType nameType) {
assert this.named != null;
return this.named.getName(nameType);
}
/**
* Returns the value of {@link Name}{@code .class} when invoked.
*
* <p>This method never returns {@code null}.</p>
*
* @return {@code Name.class}
*/
@Override
public final Class<Name> getType() {
return Name.class;
}
/**
* Returns the value of a {@link Name} reference in a <a
* href="http://mvel.codehaus.org/">MVEL</a> program whose name is
* given by the return value of this {@link NameResolver}'s {@link
* #getName()} method.
*
* <p>If a suitable value cannot be determined, then the {@linkplain
* String#isEmpty() empty string} ("") is returned.</p>
*
* <p>This method never returns {@code null}.</p>
*
* @return a non-{@code null} {@link String}
*
* @see #getName()
*
* @see VariableResolver#getValue()
*/
@Override
public final Object getValue() {
Object returnValue = null;
final Name n = this.getName(this.nameType);
if (n != null) {
returnValue = n.getValue();
}
if (returnValue == null) {
returnValue = "";
}
return returnValue;
}
/**
* Does nothing.
*
* @param type ignored
*
* @see #getType()
*/
@Override
@SuppressWarnings("rawtypes")
public final void setStaticType(final Class type) {
}
/**
* Does nothing when invoked.
*
* @param value ignored
*/
@Override
public final void setValue(final Object value) {
}
}