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/*
This file is part of GNUnet.
(C) 2011, 2012 Christian Grothoff (and other contributing authors)
GNUnet is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published
by the Free Software Foundation; either version 3, or (at your
option) any later version.
GNUnet is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License
along with GNUnet; see the file COPYING. If not, write to the
Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.
*/
package org.gnunet.construct;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.math.BigInteger;
import java.util.List;
public class ReflectUtil {
public static <T> T justInstantiate(Class<T> c) {
try {
return c.getConstructor().newInstance();
} catch (InstantiationException e) {
throw new AssertionError("Cannot instantiate " + c);
} catch (IllegalAccessException e) {
throw new AssertionError(
String.format("Cannot instantiate Message %s (illegal access)", c));
} catch (NoSuchMethodException e) {
throw new AssertionError(
String.format("No suitable default constructor for class %s", c));
} catch (InvocationTargetException e) {
throw new AssertionError(
String.format("Exception thrown while constructing object of class %s", c));
}
}
/**
* assign an enum value to each numeric type we want to serialize in
* order do switch statements on field types
*/
public enum NumFieldType {
BIGNUM, BYTE_PRIM, SHORT_PRIM, INT_PRIM, LONG_PRIM, CHAR_PRIM
}
/**
* Convenience wrapper for a field that stores a numeric value.
*/
public static class NumField {
final private Field targetField;
final private NumFieldType targetType;
public NumFieldType getNumFieldType() {
return targetType;
}
public NumField(Field f) {
this.targetField = f;
if (f.getType().equals(Long.TYPE)) {
targetType = NumFieldType.LONG_PRIM;
} else if (f.getType().equals(java.lang.Integer.TYPE)) {
targetType = NumFieldType.INT_PRIM;
} else if (f.getType().equals(Short.TYPE)) {
targetType = NumFieldType.SHORT_PRIM;
} else if (f.getType().equals(Byte.TYPE)) {
targetType = NumFieldType.BYTE_PRIM;
} else if (f.getType().equals(Character.TYPE)) {
targetType = NumFieldType.CHAR_PRIM;
} else if (f.getType().equals(BigInteger.class)) {
targetType = NumFieldType.BIGNUM;
} else {
throw new AssertionError(
"expected numeric type, got: " + f.getType());
}
}
public void set(Object obj, long val) {
try {
switch (targetType) {
case LONG_PRIM:
targetField.setLong(obj, val);
break;
case INT_PRIM:
targetField.setInt(obj, (int) val);
break;
case SHORT_PRIM:
targetField.setShort(obj, (short) val);
break;
case BYTE_PRIM:
targetField.setByte(obj, (byte) val);
break;
case CHAR_PRIM:
targetField.setChar(obj, (char) val);
break;
case BIGNUM:
targetField.set(obj, BigInteger.valueOf(val));
break;
}
} catch (IllegalArgumentException e) {
throw new AssertionError("cannot access field");
} catch (IllegalAccessException e) {
throw new AssertionError("cannot access field");
}
}
public void set(Object obj, BigInteger val) {
try {
targetField.set(obj, val);
} catch (IllegalAccessException e) {
throw new AssertionError("cannot access field");
}
}
public long get(Object obj) {
try {
switch (targetType) {
case LONG_PRIM:
return targetField.getLong(obj);
case INT_PRIM:
return targetField.getInt(obj);
case SHORT_PRIM:
return targetField.getShort(obj);
case BYTE_PRIM:
return targetField.getByte(obj);
case CHAR_PRIM:
return targetField.getChar(obj);
case BIGNUM:
throw new RuntimeException("get() called on NumField that is a BigInteger");
default:
throw new AssertionError("unreachable");
}
} catch (IllegalAccessException e) {
throw new AssertionError("cannot access field");
}
}
public BigInteger getBig(Object obj) {
if (isBig()) {
return (BigInteger) justGet(obj, targetField);
} else {
return BigInteger.valueOf(this.get(obj));
}
}
public boolean isBig() {
return targetType.equals(NumFieldType.BIGNUM);
}
}
public static Object followFieldPath(List<Field> fl, Object obj,
int depth) {
for (int i = 0; i < depth; ++i) {
try {
obj = fl.get(i).get(obj);
} catch (IllegalArgumentException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new AssertionError("cannot access field " + fl.get(i)
+ " of " + obj.getClass());
}
}
return obj;
}
public static Object followFieldPath(List<Field> fl, Object obj) {
return followFieldPath(fl, obj, fl.size());
}
public static Object followFieldPathToParent(List<Field> fl, Object obj) {
return followFieldPath(fl, obj, fl.size() - 1);
}
public static Object justGet(Object obj, Field f) {
try {
return f.get(obj);
} catch (IllegalAccessException e) {
throw new AssertionError(
String.format("Cannot access private field '%s' in class %s", f, obj.getClass()));
} catch (IllegalArgumentException e) {
throw new AssertionError("Cannot access field '" + f.getName() + "' in class " + obj.getClass());
}
}
public static void justSet(Object obj, Field f, Object val) {
try {
f.set(obj, val);
} catch (IllegalAccessException e) {
throw new AssertionError(
String.format("Cannot access private field %s in class %s", f, obj.getClass()));
}
}
}
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