1/*
2 * Copyright (C) 2007 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package com.android.dx.dex.code;
18
19import com.android.dx.rop.code.RegisterSpecList;
20import com.android.dx.rop.code.SourcePosition;
21import com.android.dx.util.AnnotatedOutput;
22
23/**
24 * Pseudo-instruction base class for zero-size (no code emitted)
25 * instructions, which are generally used for tracking metainformation
26 * about the code they are adjacent to.
27 */
28public abstract class ZeroSizeInsn extends DalvInsn {
29    /**
30     * Constructs an instance. The output address of this instance is initially
31     * unknown ({@code -1}).
32     *
33     * @param position {@code non-null;} source position
34     */
35    public ZeroSizeInsn(SourcePosition position) {
36        super(Dops.SPECIAL_FORMAT, position, RegisterSpecList.EMPTY);
37    }
38
39    /** {@inheritDoc} */
40    @Override
41    public final int codeSize() {
42        return 0;
43    }
44
45    /** {@inheritDoc} */
46    @Override
47    public final void writeTo(AnnotatedOutput out) {
48        // Nothing to do here, for this class.
49    }
50
51    /** {@inheritDoc} */
52    @Override
53    public final DalvInsn withOpcode(Dop opcode) {
54        throw new RuntimeException("unsupported");
55    }
56
57    /** {@inheritDoc} */
58    @Override
59    public DalvInsn withRegisterOffset(int delta) {
60        return withRegisters(getRegisters().withOffset(delta));
61    }
62}
63