1 files changed, 91 insertions, 0 deletions
diff --git a/src/fjbg/ch/epfl/lamp/fjbg/JAttributeFactory.java b/src/fjbg/ch/epfl/lamp/fjbg/JAttributeFactory.java
new file mode 100644
index 0000000000..a0f575e7d0
--- /dev/null
+++ b/src/fjbg/ch/epfl/lamp/fjbg/JAttributeFactory.java
@@ -0,0 +1,91 @@
+// $Id$
+
+package ch.epfl.lamp.fjbg;
+
+import java.io.*;
+import java.util.*;
+import java.lang.reflect.Constructor;
+import java.lang.reflect.InvocationTargetException;
+
+/**
+ * Extensible factory to build subclasses of JAttribute based on an
+ * attribute name.
+ *
+ * @author Michel Schinz
+ * @version 1.0
+ */
+
+public class JAttributeFactory {
+    protected FJBGContext context;
+    protected HashMap/*<String, Constructor>*/ constructors = new HashMap();
+
+    protected final static Class[] CONSTRUCTOR_ARGS = new Class[] {
+        FJBGContext.class,
+        JClass.class,
+        Object.class,
+        String.class,
+        int.class,
+        DataInputStream.class
+    };
+
+    protected final static Constructor defaultDefaultConstructor;
+    static {
+        try {
+            defaultDefaultConstructor =
+                 JOtherAttribute.class.getConstructor(CONSTRUCTOR_ARGS);
+        } catch (NoSuchMethodException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    protected final Constructor defaultConstructor;
+
+    public JAttributeFactory(FJBGContext context,
+                             Constructor defaultConstructor) {
+        this.context = context;
+        this.defaultConstructor = defaultConstructor;
+        registerClass("Code", JCodeAttribute.class);
+        registerClass("LineNumberTable", JLineNumberTableAttribute.class);
+        registerClass("SourceFile", JSourceFileAttribute.class);
+    }
+
+    public JAttributeFactory(FJBGContext context) {
+        this(context, defaultDefaultConstructor);
+    }
+
+    public void registerClass(String attributeName,
+                              Class clazz) {
+        if (! JAttribute.class.isAssignableFrom(clazz))
+            throw new IllegalArgumentException("Not a subclass of JAttribute: "
+                                               + clazz);
+
+        try {
+            Constructor constr = clazz.getConstructor(CONSTRUCTOR_ARGS);
+            constructors.put(attributeName, constr);
+        } catch (NoSuchMethodException e) {
+            throw new IllegalArgumentException("No appropriate constructor for "
+                                               + clazz);
+        }
+    }
+
+    public JAttribute newInstance(JClass clazz,
+                                  Object owner,
+                                  DataInputStream stream)
+        throws IOException {
+        String name = clazz.getConstantPool().lookupUtf8(stream.readShort());
+        Integer size = new Integer(stream.readInt());
+        Constructor constr = (Constructor)constructors.get(name);
+        if (constr == null) constr = defaultConstructor;
+
+        Object[] args = new Object[] { context, clazz, owner, name, size, stream };
+        try {
+            return (JAttribute)constr.newInstance(args);
+        } catch (InstantiationException e) {
+            throw new RuntimeException(e);
+        } catch (IllegalAccessException e) {
+            throw new RuntimeException(e);
+        } catch (InvocationTargetException e) {
+            throw new RuntimeException(e);
+        }
+    }
+}