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