01: /* Copyright (C) 2004 - 2007 db4objects Inc. http://www.db4o.com
02:
03: This file is part of the db4o open source object database.
04:
05: db4o is free software; you can redistribute it and/or modify it under
06: the terms of version 2 of the GNU General Public License as published
07: by the Free Software Foundation and as clarified by db4objects' GPL
08: interpretation policy, available at
09: http://www.db4o.com/about/company/legalpolicies/gplinterpretation/
10: Alternatively you can write to db4objects, Inc., 1900 S Norfolk Street,
11: Suite 350, San Mateo, CA 94403, USA.
12:
13: db4o is distributed in the hope that it will be useful, but WITHOUT ANY
14: WARRANTY; without even the implied warranty of MERCHANTABILITY or
15: FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16: for more details.
17:
18: You should have received a copy of the GNU General Public License along
19: with this program; if not, write to the Free Software Foundation, Inc.,
20: 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
21: package com.db4o.internal.handlers;
22:
23: import com.db4o.internal.*;
24: import com.db4o.internal.marshall.*;
25: import com.db4o.marshall.*;
26:
27: /**
28: * Common base class for StringHandler and ArrayHandler:
29: * The common pattern for both is that a slot is one indirection in the database file to this.
30: *
31: * @exclude
32: */
33: public abstract class VariableLengthTypeHandler implements TypeHandler4 {
34:
35: private final ObjectContainerBase _container;
36:
37: public VariableLengthTypeHandler(ObjectContainerBase container) {
38: _container = container;
39: }
40:
41: public final int linkLength() {
42:
43: // TODO: Now that array and string are embedded into their parent
44: // object from marshaller family 1 on, the length part is no
45: // longer needed. To stay compatible with marshaller family 0
46: // it was considered a bad idea to change this value.
47:
48: return Const4.INT_LENGTH + Const4.ID_LENGTH;
49: }
50:
51: // redundant, only added to make Sun JDK 1.2's java happy :(
52: public abstract Comparable4 prepareComparison(Object obj);
53:
54: public abstract int compareTo(Object obj);
55:
56: public abstract void defrag(MarshallerFamily mf,
57: BufferPair readers, boolean redirect);
58:
59: public ObjectContainerBase container() {
60: return _container;
61: }
62:
63: protected Buffer readIndirectedBuffer(ReadContext readContext) {
64: InternalReadContext context = (InternalReadContext) readContext;
65: int address = context.readInt();
66: int length = context.readInt();
67: if (address == 0) {
68: return null;
69: }
70: return context.container().bufferByAddress(address, length);
71: }
72:
73: }
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