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      1 /*
      2  * ProGuard -- shrinking, optimization, obfuscation, and preverification
      3  *             of Java bytecode.
      4  *
      5  * Copyright (c) 2002-2009 Eric Lafortune (eric (at) graphics.cornell.edu)
      6  *
      7  * This program is free software; you can redistribute it and/or modify it
      8  * under the terms of the GNU General Public License as published by the Free
      9  * Software Foundation; either version 2 of the License, or (at your option)
     10  * any later version.
     11  *
     12  * This program is distributed in the hope that it will be useful, but WITHOUT
     13  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
     14  * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
     15  * more details.
     16  *
     17  * You should have received a copy of the GNU General Public License along
     18  * with this program; if not, write to the Free Software Foundation, Inc.,
     19  * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
     20  */
     21 package proguard;
     22 
     23 import java.io.File;
     24 
     25 /**
     26  * This class checks whether the output is up to date.
     27  *
     28  * @author Eric Lafortune
     29  */
     30 public class UpToDateChecker
     31 {
     32     private final Configuration configuration;
     33 
     34 
     35     /**
     36      * Creates a new UpToDateChecker with the given configuration.
     37      */
     38     public UpToDateChecker(Configuration configuration)
     39     {
     40         this.configuration = configuration;
     41     }
     42 
     43 
     44     /**
     45      * Returns whether the output is up to date, based on the modification times
     46      * of the input jars, output jars, and library jars (or directories).
     47      */
     48     public boolean check()
     49     {
     50         long inputLastModified  = configuration.lastModified;
     51         long outputLastModified = Long.MAX_VALUE;
     52 
     53         ClassPath programJars = configuration.programJars;
     54         ClassPath libraryJars = configuration.libraryJars;
     55 
     56         // Check the dates of the program jars, if any.
     57         if (programJars != null)
     58         {
     59             for (int index = 0; index < programJars.size(); index++)
     60             {
     61                 // Break early, if possible.
     62                 if (inputLastModified >= outputLastModified)
     63                 {
     64                     break;
     65                 }
     66 
     67                 // Update the input and output modification times.
     68                 ClassPathEntry classPathEntry = programJars.get(index);
     69                 if (classPathEntry.isOutput())
     70                 {
     71                     long lastModified = lastModified(classPathEntry.getFile(), true);
     72                     if (outputLastModified > lastModified)
     73                     {
     74                         outputLastModified = lastModified;
     75                     }
     76                 }
     77                 else
     78                 {
     79                     long lastModified = lastModified(classPathEntry.getFile(), false);
     80                     if (inputLastModified < lastModified)
     81                     {
     82                         inputLastModified = lastModified;
     83                     }
     84                 }
     85             }
     86         }
     87 
     88         // Check the dates of the library jars, if any.
     89         if (libraryJars != null)
     90         {
     91             for (int index = 0; index < libraryJars.size(); index++)
     92             {
     93                 // Break early, if possible.
     94                 if (inputLastModified >= outputLastModified)
     95                 {
     96                     break;
     97                 }
     98 
     99                 // Update the input modification time.
    100                 ClassPathEntry classPathEntry = libraryJars.get(index);
    101                 long lastModified = lastModified(classPathEntry.getFile(), false);
    102                 if (inputLastModified < lastModified)
    103                 {
    104                     inputLastModified = lastModified;
    105                 }
    106             }
    107         }
    108 
    109         boolean outputUpToDate = inputLastModified < outputLastModified;
    110         if (outputUpToDate)
    111         {
    112             System.out.println("The output is up to date");
    113         }
    114 
    115         return outputUpToDate;
    116     }
    117 
    118 
    119     /**
    120      * Returns the minimum or maximum modification time of the given file or
    121      * of the files in the given directory (recursively).
    122      */
    123     private long lastModified(File file, boolean minimum)
    124     {
    125         // Is it a directory?
    126         if (file.isDirectory())
    127         {
    128             // Ignore the directory's modification time; just recurse on its files.
    129             File[] files = file.listFiles();
    130 
    131             // Still, an empty output directory is probably a sign that it is
    132             // not up to date.
    133             long lastModified = files.length != 0 && minimum ?
    134                 Long.MAX_VALUE : 0L;
    135 
    136             for (int index = 0; index < files.length; index++)
    137             {
    138                 long fileLastModified = lastModified(files[index], minimum);
    139                 if ((lastModified < fileLastModified) ^ minimum)
    140                 {
    141                     lastModified = fileLastModified;
    142                 }
    143             }
    144 
    145             return lastModified;
    146         }
    147         else
    148         {
    149             // Return the file's modification time.
    150             return file.lastModified();
    151         }
    152     }
    153 }
    154