org.spearce.jgit.pgm/src/org/spearce/jgit/pgm/CommandRef.java

   1 /*
   2  * Copyright (C) 2008, Shawn O. Pearce <spearce@spearce.org>
   3  *
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or
   7  * without modification, are permitted provided that the following
   8  * conditions are met:
   9  *
  10  * - Redistributions of source code must retain the above copyright
  11  *   notice, this list of conditions and the following disclaimer.
  12  *
  13  * - Redistributions in binary form must reproduce the above
  14  *   copyright notice, this list of conditions and the following
  15  *   disclaimer in the documentation and/or other materials provided
  16  *   with the distribution.
  17  *
  18  * - Neither the name of the Git Development Community nor the
  19  *   names of its contributors may be used to endorse or promote
  20  *   products derived from this software without specific prior
  21  *   written permission.
  22  *
  23  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
  24  * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
  25  * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  26  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
  28  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  29  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  30  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  31  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  32  * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  33  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  34  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
  35  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  36  */
  37
  38 package org.spearce.jgit.pgm;
  39
  40 import java.lang.reflect.Constructor;
  41 import java.lang.reflect.InvocationTargetException;
  42
  43 /**
  44  * Description of a command (a {@link TextBuiltin} subclass.
  45  * <p>
  46  * These descriptions are lightweight compared to creating a command instance
  47  * and are therefore suitable for catalogs of "known" commands without linking
  48  * the command's implementation and creating a dummy instance of the command.
  49  */
  50 public class CommandRef {
  51         private final Class<? extends TextBuiltin> impl;
  52
  53         private final String name;
  54
  55         private String usage;
  56
  57         boolean common;
  58
  59         CommandRef(final Class<? extends TextBuiltin> clazz) {
  60                 this(clazz, guessName(clazz));
  61         }
  62
  63         CommandRef(final Class<? extends TextBuiltin> clazz, final Command cmd) {
  64                 this(clazz, cmd.name().length() > 0 ? cmd.name() : guessName(clazz));
  65                 usage = cmd.usage();
  66                 common = cmd.common();
  67         }
  68
  69         private CommandRef(final Class<? extends TextBuiltin> clazz, final String cn) {
  70                 impl = clazz;
  71                 name = cn;
  72                 usage = "";
  73         }
  74
  75         private static String guessName(final Class<? extends TextBuiltin> clazz) {
  76                 final StringBuilder s = new StringBuilder();
  77                 if (clazz.getName().startsWith("org.spearce.jgit.pgm.debug."))
  78                         s.append("debug-");
  79
  80                 boolean lastWasDash = true;
  81                 for (final char c : clazz.getSimpleName().toCharArray()) {
  82                         if (Character.isUpperCase(c)) {
  83                                 if (!lastWasDash)
  84                                         s.append('-');
  85                                 lastWasDash = !lastWasDash;
  86                                 s.append(Character.toLowerCase(c));
  87                         } else {
  88                                 s.append(c);
  89                         }
  90                 }
  91                 return s.toString();
  92         }
  93
  94         /**
  95          * @return name the command is invoked as from the command line.
  96          */
  97         public String getName() {
  98                 return name;
  99         }
 100
 101         /**
 102          * @return one line description of the command's feature set.
 103          */
 104         public String getUsage() {
 105                 return usage;
 106         }
 107
 108         /**
 109          * @return true if this command is considered to be commonly used.
 110          */
 111         public boolean isCommon() {
 112                 return common;
 113         }
 114
 115         /**
 116          * @return name of the Java class which implements this command.
 117          */
 118         public String getImplementationClassName() {
 119                 return impl.getName();
 120         }
 121
 122         /**
 123          * @return a new instance of the command implementation.
 124          */
 125         public TextBuiltin create() {
 126                 final Constructor<? extends TextBuiltin> c;
 127                 try {
 128                         c = impl.getDeclaredConstructor();
 129                 } catch (SecurityException e) {
 130                         throw new RuntimeException("Cannot create command " + getName(), e);
 131                 } catch (NoSuchMethodException e) {
 132                         throw new RuntimeException("Cannot create command " + getName(), e);
 133                 }
 134                 c.setAccessible(true);
 135
 136                 final TextBuiltin r;
 137                 try {
 138                         r = c.newInstance();
 139                 } catch (InstantiationException e) {
 140                         throw new RuntimeException("Cannot create command " + getName(), e);
 141                 } catch (IllegalAccessException e) {
 142                         throw new RuntimeException("Cannot create command " + getName(), e);
 143                 } catch (IllegalArgumentException e) {
 144                         throw new RuntimeException("Cannot create command " + getName(), e);
 145                 } catch (InvocationTargetException e) {
 146                         throw new RuntimeException("Cannot create command " + getName(), e);
 147                 }
 148                 r.setCommandName(getName());
 149                 return r;
 150         }
 151 }