Implement Field#getGenericType()

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

classpath/java/lang/reflect/Field.java

@@ -66,6 +66,14 @@ public class Field<T> extends AccessibleObject {
        new String(vmField.spec, 0, vmField.spec.length - 1, false));
   }
 
+  public Type getGenericType() {
+    if (vmField.addendum == null || vmField.addendum.signature == null) {
+      return getType();
+    }
+    String signature = Classes.toString((byte[]) vmField.addendum.signature);
+    return SignatureParser.parse(vmField.class_.loader, signature);
+  }
+
   public Object get(Object instance) throws IllegalAccessException {
     Object target;
     if ((vmField.flags & Modifier.STATIC) != 0) {

classpath/java/lang/reflect/ParameterizedType.java

@@ -0,0 +1,17 @@
+/* Copyright (c) 2008-2013, Avian Contributors
+
+   Permission to use, copy, modify, and/or distribute this software
+   for any purpose with or without fee is hereby granted, provided
+   that the above copyright notice and this permission notice appear
+   in all copies.
+
+   There is NO WARRANTY for this software.  See license.txt for
+   details. */
+
+package java.lang.reflect;
+
+public interface ParameterizedType extends Type {
+  Type[] getActualTypeArguments();
+  Type getOwnerType();
+  Type getRawType();
+}

classpath/java/lang/reflect/SignatureParser.java

@@ -0,0 +1,135 @@
+/* Copyright (c) 2008-2013, Avian Contributors
+
+   Permission to use, copy, modify, and/or distribute this software
+   for any purpose with or without fee is hereby granted, provided
+   that the above copyright notice and this permission notice appear
+   in all copies.
+
+   There is NO WARRANTY for this software.  See license.txt for
+   details. */
+
+package java.lang.reflect;
+
+import java.util.ArrayList;
+import java.util.List;
+
+class SignatureParser {
+  private final ClassLoader loader;
+  private final char[] array;
+  private int offset;
+  private final Type type;
+
+  static Type parse(ClassLoader loader, String signature) {
+    return new SignatureParser(loader, signature).type;
+  }
+
+  private SignatureParser(ClassLoader loader, String signature) {
+    this.loader = loader;
+    array = signature.toCharArray();
+    type = parseType();
+    if (offset != array.length) {
+      throw new IllegalArgumentException("Extra characters after " + offset
+          + ": " + signature);
+    }
+  }
+
+  private Type parseType() {
+    char c = array[offset++];
+    if (c == 'B') {
+      return Byte.TYPE;
+    } else if (c == 'C') {
+      return Character.TYPE;
+    } else if (c == 'D') {
+      return Double.TYPE;
+    } else if (c == 'F') {
+      return Float.TYPE;
+    } else if (c == 'I') {
+      return Integer.TYPE;
+    } else if (c == 'J') {
+      return Long.TYPE;
+    } else if (c == 'S') {
+      return Short.TYPE;
+    } else if (c == 'Z') {
+      return Boolean.TYPE;
+    } else if (c != 'L') {
+      throw new IllegalArgumentException("Unexpected character: " + c);
+    }
+    StringBuilder builder = new StringBuilder();
+    Type ownerType = null;
+    for (;;) {
+      for (;;) {
+        c = array[offset++];
+        if (c == ';' || c == '<') {
+          break;
+        }
+        builder.append(c == '/' ? '.' : c);
+      }
+      String rawTypeName = builder.toString();
+      Class<?> rawType;
+      try {
+        rawType = loader.loadClass(rawTypeName);
+      } catch (ClassNotFoundException e) {
+        throw new RuntimeException("Could not find class " + rawTypeName);
+      }
+      if (c == ';') {
+        return rawType;
+      }
+      List<Type> args = new ArrayList<Type>();
+      while (array[offset] != '>') {
+        args.add(parseType());
+      }
+      ++offset;
+      c = array[offset++];
+      ParameterizedType type = makeType(args.toArray(new Type[args.size()]), ownerType, rawType);
+      if (c == ';') {
+        return type;
+      }
+      if (c != '.') {
+        throw new RuntimeException("TODO");
+      }
+      ownerType = type;
+      builder.append("$");
+    }
+  }
+
+  private static String typeName(Type type) {
+    if (type instanceof Class) {
+      Class<?> clazz = (Class<?>) type;
+      return clazz.getName();
+    }
+    return type.toString();
+  }
+
+  private static ParameterizedType makeType(final Type[] args, final Type owner, final Type raw) {
+    return new ParameterizedType() {
+      @Override
+        public Type getRawType() {
+          return raw;
+        }
+
+      @Override
+        public Type getOwnerType() {
+          return owner;
+        }
+
+      @Override
+        public Type[] getActualTypeArguments() {
+          return args;
+        }
+
+      @Override
+        public String toString() {
+          StringBuilder builder = new StringBuilder();
+          builder.append(typeName(raw));
+          builder.append('<');
+          String sep = "";
+          for (Type t : args) {
+            builder.append(sep).append(typeName(t));
+            sep = ", ";
+          }
+          builder.append('>');
+          return builder.toString();
+        }
+    };
+  }
+}

test/Reflection.java

@@ -1,5 +1,7 @@
-import java.lang.reflect.Method;
 import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+import java.lang.reflect.ParameterizedType;
+import java.lang.reflect.Type;
 
 public class Reflection {
   public static boolean booleanMethod() {
@@ -38,8 +40,8 @@ public class Reflection {
     if (! v) throw new RuntimeException();
   }
 
-  private static class Hello {
-    private class World { }
+  private static class Hello<T> {
+    private class World<S> { }
   }
 
   private static void innerClasses() throws Exception {
@@ -56,9 +58,44 @@ public class Reflection {
     expect(egads.getAnnotation(Deprecated.class) == null);
   }
 
+  public static Hello<Hello<Reflection>>.World<Hello<String>> pinky;
+
+  private static void genericType() throws Exception {
+    Field field = Reflection.class.getDeclaredField("egads");
+    expect(field.getGenericType() == Integer.TYPE);
+
+    field = Reflection.class.getField("pinky");
+    expect("Reflection$Hello$World".equals(field.getType().getName()));
+    expect(field.getGenericType() instanceof ParameterizedType);
+    ParameterizedType type = (ParameterizedType) field.getGenericType();
+
+    expect(type.getRawType() instanceof Class);
+    Class<?> clazz = (Class<?>) type.getRawType();
+    expect("Reflection$Hello$World".equals(clazz.getName()));
+
+    expect(type.getOwnerType() instanceof ParameterizedType);
+    ParameterizedType owner = (ParameterizedType) type.getOwnerType();
+    clazz = (Class<?>) owner.getRawType();
+    expect(clazz == Hello.class);
+
+    Type[] args = type.getActualTypeArguments();
+    expect(1 == args.length);
+    expect(args[0] instanceof ParameterizedType);
+
+    ParameterizedType arg = (ParameterizedType) args[0];
+    expect(arg.getRawType() instanceof Class);
+    clazz = (Class<?>) arg.getRawType();
+    expect("Reflection$Hello".equals(clazz.getName()));
+
+    args = arg.getActualTypeArguments();
+    expect(1 == args.length);
+    expect(args[0] == String.class);
+  }
+
   public static void main(String[] args) throws Exception {
     innerClasses();
     annotations();
+    genericType();
 
     Class system = Class.forName("java.lang.System");
     Field out = system.getDeclaredField("out");