PlatformHelper.java

/* PlatformHelper.java -- Isolate OS-specific IO helper methods and variables
   Copyright (C) 1998, 2002, 2006 Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath 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 2, or (at your option)
any later version.

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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.

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along with GNU Classpath; see the file COPYING.  If not, write to the
Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301 USA.

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
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As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
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independent module, the terms and conditions of the license of that
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this exception to your version of the library, but you are not
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package gnu.java.io;

/**
 * We had many changes in File.java, URLStreamHandler.java etc. to handle
 * path representations on different platforms (Windows/Unix-family).
 * Finally we'd like to collect all these ad hoc codes into this utility class.
 *       --Gansha
 */
public class PlatformHelper
{
  public static final boolean isWindows = System.getProperty("os.name").indexOf("Windows") >= 0;
  public static final String separator = System.getProperty("file.separator");
  public static final char separatorChar = separator.charAt(0);
  public static final String pathSeparator = System.getProperty("path.separator");
  public static final char pathSeparatorChar = pathSeparator.charAt(0);

  /**
   * On most platforms 260 is equal or greater than a max path value,
   * so we can set the initial buffer size of StringBuffer to half of this value
   * to improve performance.
   */
  public static final int INITIAL_MAX_PATH = 260/2;

  /**
   * This routine checks the input param "path" whether it begins with root path
   * prefix.
   * if not, return 0;
   * if yes, return the len of root path prefix;
   *   --for Unix-family platform, root path begins with "/" and len is 1
   *   --for Windows platform, root path begins with "drive:\\" and len is 3
   */
  public static final int beginWithRootPathPrefix(String path)
  {
    if (path.startsWith("/") || path.startsWith("\\"))
      return 1;

    if (!isWindows)
      return 0;

    if (path.length() > 2
        && Character.isLetter(path.charAt(0))
        && path.charAt(1) == ':'
        && (path.charAt(2) == '/' || path.charAt(2) == '\\'))
      return 3;

    return 0;
  }

  /**
   * This routine checks the input param "path" whether it's root directory.
   *  --for Unix-family platform, root directory is "/"
   *  --for Windows platform, root directory is "\\" or "drive:\\".
   */
  public static final boolean isRootDirectory(String path)
  {
    int len = path.length();
    return len > 0 && beginWithRootPathPrefix(path) == len;
  }

  /**
   * This routine checks whether input param "path" ends with separator
   */
  public static final boolean endWithSeparator(String path)
  {
    if (path.endsWith("\\") || path.endsWith("/"))
      return true;

    return false;
  }

  /**
   * This routine removes from input param "path" the tail separator if it exists,
   * and return the remain part.
   */
  public static final String removeTailSeparator(String path)
  {
    if (endWithSeparator(path) && !isRootDirectory(path))
      return path.substring(0, path.length() - 1);

    return path;
  }

  /**
   * This routine returns last index of separator in input param "path",
   * and return it.
   */
  public static final int lastIndexOfSeparator(String path)
  {
    return Math.max(path.lastIndexOf("/"), path.lastIndexOf("\\"));
  }

}