001    package cpw.mods.fml.common.asm.transformers;
002    
003    import java.util.Iterator;
004    import java.util.List;
005    
006    import org.objectweb.asm.ClassReader;
007    import org.objectweb.asm.ClassWriter;
008    import org.objectweb.asm.Type;
009    import org.objectweb.asm.tree.AnnotationNode;
010    import org.objectweb.asm.tree.ClassNode;
011    import org.objectweb.asm.tree.FieldNode;
012    import org.objectweb.asm.tree.MethodNode;
013    
014    import cpw.mods.fml.relauncher.FMLRelauncher;
015    import cpw.mods.fml.relauncher.IClassTransformer;
016    import cpw.mods.fml.relauncher.SideOnly;
017    
018    public class SideTransformer implements IClassTransformer
019    {
020        private static String SIDE = FMLRelauncher.side();
021        private static final boolean DEBUG = false;
022        @SuppressWarnings("unchecked")
023        @Override
024        public byte[] transform(String name, byte[] bytes)
025        {
026            if (bytes == null) { return null; }
027    
028            ClassNode classNode = new ClassNode();
029            ClassReader classReader = new ClassReader(bytes);
030            classReader.accept(classNode, 0);
031    
032            if (remove((List<AnnotationNode>)classNode.visibleAnnotations, SIDE))
033            {
034                if (DEBUG)
035                {
036                    System.out.println(String.format("Attempted to load class %s for invalid side %s", classNode.name, SIDE));
037                }
038                throw new RuntimeException(String.format("Attempted to load class %s for invalid side %s", classNode.name, SIDE));
039            }
040    
041            Iterator<FieldNode> fields = classNode.fields.iterator();
042            while(fields.hasNext())
043            {
044                FieldNode field = fields.next();
045                if (remove((List<AnnotationNode>)field.visibleAnnotations, SIDE))
046                {
047                    if (DEBUG)
048                    {
049                        System.out.println(String.format("Removing Field: %s.%s", classNode.name, field.name));
050                    }
051                    fields.remove();
052                }
053            }
054            Iterator<MethodNode> methods = classNode.methods.iterator();
055            while(methods.hasNext())
056            {
057                MethodNode method = methods.next();
058                if (remove((List<AnnotationNode>)method.visibleAnnotations, SIDE))
059                {
060                    if (DEBUG)
061                    {
062                        System.out.println(String.format("Removing Method: %s.%s%s", classNode.name, method.name, method.desc));
063                    }
064                    methods.remove();
065                }
066            }
067    
068            ClassWriter writer = new ClassWriter(ClassWriter.COMPUTE_MAXS);
069            classNode.accept(writer);
070            return writer.toByteArray();
071        }
072        
073        private boolean remove(List<AnnotationNode> anns, String side)
074        {
075            if (anns == null)
076            {
077                return false;
078            }
079            for (AnnotationNode ann : anns)
080            {
081                if (ann.desc.equals(Type.getDescriptor(SideOnly.class)))
082                {
083                    if (ann.values != null)
084                    {
085                        for (int x = 0; x < ann.values.size() - 1; x += 2)
086                        {
087                            Object key = ann.values.get(x);
088                            Object value = ann.values.get(x+1);
089                            if (key instanceof String && key.equals("value"))
090                            {
091                                if (value instanceof String[] )
092                                {
093                                    if (!((String[])value)[1].equals(side))
094                                    {
095                                        return true;
096                                    }
097                                }
098                            }
099                        }
100                    }
101                }
102            }
103            return false;
104        }
105    }