/// <summary>
/// Appends the fields and values defined by the given object of the given Class.
/// </summary>
/// <param name="builder">the builder to Append to</param>
/// <param name="clazz">the class to Append details of</param>
/// <param name="lhs">the left hand object</param>
/// <param name="rhs">the right hand object</param>
/// <param name="useTransients">whether to test transient fields</param>
private static void ReflectionAppend(
Object lhs,
Object rhs,
Type clazz,
EqualsBuilder builder,
bool useTransients)
{
/*
* In Java version of this ReflectionAppend, we have to call
* AccessibleObject.setAccessible() right after class.GetFields() to
* make non-public fields accessible. In C#, it is easier to do. We simply
* add BindingFlags.NonPublic, which makes non-public fields accessible
* (subject to security manager restrictions, of course).
*/
FieldInfo[] fields = clazz.GetFields(BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic |
BindingFlags.DeclaredOnly);
for (int i = 0; i < fields.Length && builder.isEqual; i++)
{
FieldInfo f = fields[i];
if ((f.Name.IndexOf('$') == -1) &&
(useTransients || !isTransient(f)) &&
!f.IsStatic)
{
try
{
builder.Append(f.GetValue(lhs), f.GetValue(rhs));
}
/*
* According to FieldInfo's documentation, getValue() can throw the
* following exceptions: TargetException, NotSupportedException,
* FieldAccessException and ArgumentException.
*
* TargetException is thrown if the field is non-static and obj is
* a null reference. In our case, the field is non-static (because of
* BindingFlags.Instance) but obj should never be null because of
* null checks in the calling method (i.e. reflectionEquals()).
* I guess we can just throw an unexpected exception.
*
* NotSupportedException is thrown if the field is marked Literal, but
* the field does not have one of the accepted literal types. Literal
* means that the field's value is a compile-time (static or early
* bound) constant. I think this exception can be just eaten because
* constants should always be equal in lhs and rhs and default value
* of isEqual is true.
*
* FieldAccessException is thrown if the caller does not have
* permission to access this field. If this code is fully trusted
* (not sure how to verify this), access restrictions are ignored.
* This means that private fields are accessible. If this code is not
* fully trusted, it can still access private fields if this code
* has been granted ReflectedPermission with the
* ReflectionPermisionFlag.RestrictedMemberAccess flag and if the
* grant set of the non-public members is restricted to the caller's
* grant set, or subset thereof. Whew, that's a mouthful to say!
* I guess it's best just to let FieldAccessException bubble up
* to callers so that user can grant permissions, if desired.
*
* Finally, ArgumentException is thrown if the method is neither
* declared nor inherited by the class of obj. This could happen
* if lhs is a subclass of rhs (or vice-versa) and the field is
* declared in the subclass. In Java, Field.get() would throw
* IllegalArgumentException in this case. In Java version of
* reflectionAppend(), IllegalArgumentException
* bubbles up to reflectionEquals(), where it is dealt with.
* It seems logical that use the same technique in the C#
* version. That is, we allow ArgumentException to bubble up
* to ReflectionEquals() and deal with it there.
*/
catch (TargetException te)
{
throw new Exception("Unexpected TargetException", te);
}
catch (NotSupportedException)
{
// eat it!
}
/* Don't catch FieldAccessException and ArgumentException so that
* they can bubble up to caller. Alternatively, we could catch and
* rethrow.
*/
//catch (FieldAccessException fae) { throw; }
//catch (ArgumentException fae) { throw; }
}
}
}
/// <summary>
/// This method uses reflection to determine if the two Object
/// are equal.
///
/// It uses AccessibleObject.setAccessible to gain access to private
/// fields. This means that it will throw a security exception if run under
/// a security manager, if the permissions are not set up correctly. It is also
/// not as efficient as testing explicitly.
///
/// If the testTransients parameter is set to true, transient
/// members will be tested, otherwise they are ignored, as they are likely
/// derived fields, and not part of the value of the Object.
///
/// Static fields will not be included. Superclass fields will be appended
/// up to and including the specified superclass. A null superclass is treated
/// as java.lang.Object.
/// </summary>
/// <param name="lhs">this object</param>
/// <param name="rhs">the other object</param>
/// <param name="testTransients">whether to include transient fields</param>
/// <param name="reflectUpToClass">the superclass to reflect up to (inclusive), may be null</param>
/// <returns>true if the two Objects have tested equals.</returns>
public static bool ReflectionEquals(Object lhs, Object rhs, bool testTransients, Type reflectUpToClass)
{
if (lhs == rhs)
{
return(true);
}
if (lhs == null || rhs == null)
{
return(false);
}
// Find the leaf class since there may be transients in the leaf
// class or in classes between the leaf and root.
// If we are not testing transients or a subclass has no ivars,
// then a subclass can test equals to a superclass.
Type lhsClass = lhs.GetType();
Type rhsClass = rhs.GetType();
Type testClass;
if (lhsClass.IsInstanceOfType(rhs))
{
testClass = lhsClass;
if (!rhsClass.IsInstanceOfType(lhs))
{
// rhsClass is a subclass of lhsClass
testClass = rhsClass;
}
}
else if (rhsClass.IsInstanceOfType(lhs))
{
testClass = rhsClass;
if (!lhsClass.IsInstanceOfType(rhs))
{
// lhsClass is a subclass of rhsClass
testClass = lhsClass;
}
}
else
{
// The two classes are not related.
return(false);
}
EqualsBuilder equalsBuilder = new EqualsBuilder();
try
{
ReflectionAppend(lhs, rhs, testClass, equalsBuilder, testTransients);
while (testClass.BaseType != null && testClass != reflectUpToClass)
{
testClass = testClass.BaseType;
ReflectionAppend(lhs, rhs, testClass, equalsBuilder, testTransients);
}
}
catch (ArgumentException)
{
// In this case, we tried to test a subclass vs. a superclass and
// the subclass has ivars or the ivars are transient and
// we are testing transients.
// If a subclass has ivars that we are trying to test them, we get an
// exception and we know that the objects are not equal.
return(false);
}
return(equalsBuilder.IsEquals());
}