1/*
2 * Copyright (C) 2009 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.RegisterSpec;
20import com.android.dx.rop.code.RegisterSpecList;
21import com.android.dx.rop.code.SourcePosition;
22
23/**
24 * Pseudo-instruction which is used to explicitly end the mapping of a
25 * register to a named local variable. That is, an instance of this
26 * class in an instruction stream indicates that starting with the
27 * subsequent instruction, the indicated variable is no longer valid.
28 */
29public final class LocalEnd extends ZeroSizeInsn {
30    /**
31     * {@code non-null;} register spec representing the local variable ended
32     * by this instance. <b>Note:</b> Technically, only the register
33     * number needs to be recorded here as the rest of the information
34     * is implicit in the ambient local variable state, but other code
35     * will check the other info for consistency.
36     */
37    private final RegisterSpec local;
38
39    /**
40     * Constructs an instance. The output address of this instance is initially
41     * unknown ({@code -1}).
42     *
43     * @param position {@code non-null;} source position
44     * @param local {@code non-null;} register spec representing the local
45     * variable introduced by this instance
46     */
47    public LocalEnd(SourcePosition position, RegisterSpec local) {
48        super(position);
49
50        if (local == null) {
51            throw new NullPointerException("local == null");
52        }
53
54        this.local = local;
55    }
56
57    /** {@inheritDoc} */
58    @Override
59    public DalvInsn withRegisterOffset(int delta) {
60        return new LocalEnd(getPosition(), local.withOffset(delta));
61    }
62
63    /** {@inheritDoc} */
64    @Override
65    public DalvInsn withRegisters(RegisterSpecList registers) {
66        return new LocalEnd(getPosition(), local);
67    }
68
69    /**
70     * Gets the register spec representing the local variable ended
71     * by this instance.
72     *
73     * @return {@code non-null;} the register spec
74     */
75    public RegisterSpec getLocal() {
76        return local;
77    }
78
79    /** {@inheritDoc} */
80    @Override
81    protected String argString() {
82        return local.toString();
83    }
84
85    /** {@inheritDoc} */
86    @Override
87    protected String listingString0(boolean noteIndices) {
88        return "local-end " + LocalStart.localString(local);
89    }
90}
91