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.dex.DexOptions;
20
21import java.util.ArrayList;
22
23/**
24 * Destination for {@link DalvInsn} instances being output. This class
25 * receives and collects instructions in two pieces — a primary
26 * list and a suffix (generally consisting of adjunct data referred to
27 * by the primary list, such as switch case tables) — which it
28 * merges and emits back out in the form of a {@link DalvInsnList}
29 * instance.
30 */
31public final class OutputCollector {
32    /**
33     * {@code non-null;} the associated finisher (which holds the instruction
34     * list in-progress)
35     */
36    private final OutputFinisher finisher;
37
38    /**
39     * {@code null-ok;} suffix for the output, or {@code null} if the suffix
40     * has been appended to the main output (by {@link #appendSuffixToOutput})
41     */
42    private ArrayList<DalvInsn> suffix;
43
44    /**
45     * Constructs an instance.
46     *
47     * @param dexOptions {@code non-null;} options for dex output
48     * @param initialCapacity {@code >= 0;} initial capacity of the output list
49     * @param suffixInitialCapacity {@code >= 0;} initial capacity of the output
50     * suffix
51     * @param regCount {@code >= 0;} register count for the method
52     */
53    public OutputCollector(DexOptions dexOptions, int initialCapacity, int suffixInitialCapacity,
54            int regCount) {
55        this.finisher = new OutputFinisher(dexOptions, initialCapacity, regCount);
56        this.suffix = new ArrayList<DalvInsn>(suffixInitialCapacity);
57    }
58
59    /**
60     * Adds an instruction to the output.
61     *
62     * @param insn {@code non-null;} the instruction to add
63     */
64    public void add(DalvInsn insn) {
65        finisher.add(insn);
66    }
67
68    /**
69     * Reverses a branch which is buried a given number of instructions
70     * backward in the output. It is illegal to call this unless the
71     * indicated instruction really is a reversible branch.
72     *
73     * @param which how many instructions back to find the branch;
74     * {@code 0} is the most recently added instruction,
75     * {@code 1} is the instruction before that, etc.
76     * @param newTarget {@code non-null;} the new target for the reversed branch
77     */
78    public void reverseBranch(int which, CodeAddress newTarget) {
79        finisher.reverseBranch(which, newTarget);
80    }
81
82    /**
83     * Adds an instruction to the output suffix.
84     *
85     * @param insn {@code non-null;} the instruction to add
86     */
87    public void addSuffix(DalvInsn insn) {
88        suffix.add(insn);
89    }
90
91    /**
92     * Gets the results of all the calls on this instance, in the form of
93     * an {@link OutputFinisher}.
94     *
95     * @return {@code non-null;} the output finisher
96     * @throws UnsupportedOperationException if this method has
97     * already been called
98     */
99    public OutputFinisher getFinisher() {
100        if (suffix == null) {
101            throw new UnsupportedOperationException("already processed");
102        }
103
104        appendSuffixToOutput();
105        return finisher;
106    }
107
108    /**
109     * Helper for {@link #getFinisher}, which appends the suffix to
110     * the primary output.
111     */
112    private void appendSuffixToOutput() {
113        int size = suffix.size();
114
115        for (int i = 0; i < size; i++) {
116            finisher.add(suffix.get(i));
117        }
118
119        suffix = null;
120    }
121}
122