propertystring.java

FuncPlotter is a combined Java application and applet for displaying two-dimensional plots of explic

/*====================================================================*\

PropertyString.java

Property string class.

------------------------------------------------------------------------

This file is part of FuncPlotter, a combined Java application and applet
for plotting explicit functions in one variable.
Copyright 2005-2007 Andy Morgan-Richards.

FuncPlotter is free software: you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation, either version 3 of the License, or (at your
option) any later version.

This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

You should have received a copy of the GNU General Public License along
with this program.  If not, see <http://www.gnu.org/licenses/>.

\*====================================================================*/


// PACKAGE


package util;

//----------------------------------------------------------------------


// IMPORTS


import java.io.File;

//----------------------------------------------------------------------


// PROPERTY STRING CLASS


public class PropertyString
{

////////////////////////////////////////////////////////////////////////
//  Constants
////////////////////////////////////////////////////////////////////////

    public static final     String  KEY_PREFIX  = "${";
    public static final     String  KEY_SUFFIX  = "}";

    public static final     String  USER_HOME_PREFIX    = "~";

    private static final    int KEY_PREFIX_LENGTH   = KEY_PREFIX.length( );
    private static final    int KEY_SUFFIX_LENGTH   = KEY_SUFFIX.length( );

    private static final    String  ENV_PREFIX_KEY  = "app.envPrefix";

    private static final    String  DEFAULT_ENV_PREFIX  = "env.";

////////////////////////////////////////////////////////////////////////
//  Constructors
////////////////////////////////////////////////////////////////////////

    private PropertyString( )
    {
    }

    //------------------------------------------------------------------

////////////////////////////////////////////////////////////////////////
//  Class methods
////////////////////////////////////////////////////////////////////////

    public static String parse( String str )
    {
        if ( str == null )
            return null;

        if ( envPrefix == null )
        {
            envPrefix = DEFAULT_ENV_PREFIX;
            try
            {
                String value = System.getProperty( ENV_PREFIX_KEY );
                if ( value != null )
                    envPrefix = value + ".";
            }
            catch ( SecurityException e )
            {
                // ignore
            }
        }

        StringBuilder buffer = new StringBuilder( str );
        int index = 0;
        while ( index < buffer.length( ) )
        {
            index = buffer.indexOf( KEY_PREFIX, index );
            if ( index < 0 )
                break;
            index += KEY_PREFIX_LENGTH;
            int startIndex = index;
            index = buffer.indexOf( KEY_SUFFIX, index );
            if ( index < 0 )
                index = startIndex;
            else
            {
                String propertyValue = new String( );
                if ( index > startIndex )
                {
                    boolean env = false;
                    String key = buffer.substring( startIndex, index );
                    if ( key.startsWith( envPrefix ) )
                    {
                        key = key.substring( envPrefix.length( ) );
                        env = true;
                    }
                    try
                    {
                        String value = env ? System.getenv( key ) : System.getProperty( key );
                        if ( value != null )
                            propertyValue = value;
                    }
                    catch ( SecurityException e )
                    {
                        // ignore
                    }
                }
                buffer.replace( startIndex - KEY_PREFIX_LENGTH, index + KEY_SUFFIX_LENGTH, propertyValue );
                index = startIndex - KEY_PREFIX_LENGTH + propertyValue.length( );
            }
        }

        return buffer.toString( );
    }

    //------------------------------------------------------------------

    public static String parsePathname( String str )
    {
        if ( str.startsWith( USER_HOME_PREFIX ) )
        {
            int prefixLength = USER_HOME_PREFIX.length( );
            if ( (str.length( ) == prefixLength) || (str.charAt( prefixLength ) == File.separatorChar) ||
                 (str.charAt( prefixLength ) == '/') )
            try
            {
                String pathname = System.getProperty( "user.home" );
                if ( pathname != null )
                    str = pathname + str.substring( prefixLength );
            }
            catch ( SecurityException e )
            {
                // ignore
            }
        }
        return parse( str );
    }

    //------------------------------------------------------------------

////////////////////////////////////////////////////////////////////////
//  Class variables
////////////////////////////////////////////////////////////////////////

    private static  String  envPrefix;

}

//----------------------------------------------------------------------