org.codehaus.plexus.util.interpolation.EnvarBasedValueSource Maven / Gradle / Ivy

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A collection of various utility classes to ease working with strings, files, command lines, XML and more.

There is a newer version: 4.0.2

package org.codehaus.plexus.util.interpolation;
/*
 * Copyright 2007 The Codehaus Foundation.
 *
 * Licensed 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.
 */


import org.codehaus.plexus.util.cli.CommandLineUtils;

import java.io.IOException;
import java.util.Properties;

/**
 * @version $Id: EnvarBasedValueSource.java 5956 2007-02-28 08:26:16Z olamy $
 */
public class EnvarBasedValueSource
    implements ValueSource
{
    
    private Properties envars;
    private final boolean caseSensitive;

    /**
     * Create a new value source for interpolation based on shell environment variables. In this
     * case, envar keys ARE CASE SENSITIVE.
     * 
     * @throws IOException
     */
    public EnvarBasedValueSource() throws IOException
    {
        this( true );
    }

    /**
     * Create a new value source for interpolation based on shell environment variables.
     * 
     * @param caseSensitive Whether the environment variable key should be treated in a 
     *                      case-sensitive manner for lookups
     * @throws IOException
     */
    public EnvarBasedValueSource( boolean caseSensitive ) throws IOException
    {
        this.caseSensitive = caseSensitive;
        
        envars = CommandLineUtils.getSystemEnvVars( caseSensitive );
    }

    public Object getValue( String expression )
    {
        String expr = expression;
        
        if ( expr.startsWith( "env." ) )
        {
            expr = expr.substring( "env.".length() );
        }
        
        if ( !caseSensitive )
        {
            expr = expr.toUpperCase();
        }
        
        return envars.getProperty( expr );
    }
}