/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.commons.configuration2.interpol;

import org.apache.commons.text.lookup.StringLookupFactory;

 A specialized implementation of the Lookup interface that allows access to system properties. 
 This implementation relies on StrLookup.systemPropertiesLookup() from the Commons Lang project to resolve system properties. It can be used for referencing system properties in configuration files in an easy way, for instance: 
current.user = ${sys:user.name}

 SystemPropertiesLookup is one of the standard lookups that is registered per default for each configuration. 
Since:
2.0
Deprecated:
Use DefaultLookups.SYSTEM_PROPERTIES./**
 * <p>
 * A specialized implementation of the {@code Lookup} interface that allows
 * access to system properties.
 * </p>
 * <p>
 * This implementation relies on {@code StrLookup.systemPropertiesLookup()} from
 * the Commons Lang project to resolve system properties. It can be used for
 * referencing system properties in configuration files in an easy way, for
 * instance:
 * </p>
 *
 * <pre>
 * current.user = ${sys:user.name}
 * </pre>
 *
 * <p>
 * {@code SystemPropertiesLookup} is one of the standard lookups that is
 * registered per default for each configuration.
 * </p>
 *
 * @since 2.0
 * @deprecated Use {@link DefaultLookups#SYSTEM_PROPERTIES}.
 */
@Deprecated
public class SystemPropertiesLookup implements Lookup
{
    @Override
    public Object lookup(final String variable)
    {
        return StringLookupFactory.INSTANCE.systemPropertyStringLookup().lookup(variable);
    }
}