https://ant.apache.org/: master POM (The Apache Software Foundation) 
/*
 *  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
 *
 *      https://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.tools.ant.property;

import java.text.ParsePosition;

import org.apache.tools.ant.PropertyHelper;


Responsible for locating a property reference inside a String.

Since:Ant 1.8.0
/**
 * Responsible for locating a property reference inside a String.
 * @since Ant 1.8.0
 */
public interface PropertyExpander extends PropertyHelper.Delegate {

    
Determine whether there is a property reference at the current
ParsePosition and return its name (or null if there is none).

Implementations should advance the ParsePosition to the last
character that makes up the property reference.  E.g. the
default implementation would return "foo" for
${foo} and advance the ParsePosition to the
} character.


Params:
  • s – the String to parse.
  • pos – the ParsePosition in use, the location is expected
to be modified if a property reference has been found (and may
even be modified if no reference has been found).
  • parseNextProperty – provides access to the Project and may
be used to look up property values.
Returns:property name if any, else null.
/**
     * Determine whether there is a property reference at the current
     * ParsePosition and return its name (or null if there is none).
     *
     * <p>Implementations should advance the ParsePosition to the last
     * character that makes up the property reference.  E.g. the
     * default implementation would return <code>"foo"</code> for
     * <code>${foo}</code> and advance the ParsePosition to the
     * <code>}</code> character.</p>
     *
     * @param s the String to parse.
     * @param pos the ParsePosition in use, the location is expected
     * to be modified if a property reference has been found (and may
     * even be modified if no reference has been found).
     * @param parseNextProperty provides access to the Project and may
     * be used to look up property values.
     * @return property name if any, else <code>null</code>.
     */
    String parsePropertyName(String s, ParsePosition pos,
                             ParseNextProperty parseNextProperty);
}