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      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 
     17 package com.android.dexgen.rop;
     18 
     19 import com.android.dexgen.util.Hex;
     20 import com.android.dexgen.util.IntList;
     21 import com.android.dexgen.util.LabeledItem;
     22 
     23 /**
     24  * Representation of a basic block in a bytecode array.
     25  */
     26 public final class ByteBlock implements LabeledItem {
     27     /** {@code >= 0;} label for this block */
     28     private final int label;
     29 
     30     /** {@code >= 0;} bytecode offset (inclusive) of the start of the block */
     31     private final int start;
     32 
     33     /** {@code > start;} bytecode offset (exclusive) of the end of the block */
     34     private final int end;
     35 
     36     /** {@code non-null;} list of successors that this block may branch to */
     37     private final IntList successors;
     38 
     39     /** {@code non-null;} list of exceptions caught and their handler targets */
     40     private final ByteCatchList catches;
     41 
     42     /**
     43      * Constructs an instance.
     44      *
     45      * @param label {@code >= 0;} target label for this block
     46      * @param start {@code >= 0;} bytecode offset (inclusive) of the start
     47      * of the block
     48      * @param end {@code > start;} bytecode offset (exclusive) of the end
     49      * of the block
     50      * @param successors {@code non-null;} list of successors that this block may
     51      * branch to
     52      * @param catches {@code non-null;} list of exceptions caught and their
     53      * handler targets
     54      */
     55     public ByteBlock(int label, int start, int end, IntList successors,
     56                      ByteCatchList catches) {
     57         if (label < 0) {
     58             throw new IllegalArgumentException("label < 0");
     59         }
     60 
     61         if (start < 0) {
     62             throw new IllegalArgumentException("start < 0");
     63         }
     64 
     65         if (end <= start) {
     66             throw new IllegalArgumentException("end <= start");
     67         }
     68 
     69         if (successors == null) {
     70             throw new NullPointerException("targets == null");
     71         }
     72 
     73         int sz = successors.size();
     74         for (int i = 0; i < sz; i++) {
     75             if (successors.get(i) < 0) {
     76                 throw new IllegalArgumentException("successors[" + i +
     77                                                    "] == " +
     78                                                    successors.get(i));
     79             }
     80         }
     81 
     82         if (catches == null) {
     83             throw new NullPointerException("catches == null");
     84         }
     85 
     86         this.label = label;
     87         this.start = start;
     88         this.end = end;
     89         this.successors = successors;
     90         this.catches = catches;
     91     }
     92 
     93     /** {@inheritDoc} */
     94     @Override
     95     public String toString() {
     96         return '{' + Hex.u2(label) + ": " + Hex.u2(start) + ".." +
     97             Hex.u2(end) + '}';
     98     }
     99 
    100     /**
    101      * Gets the label of this block.
    102      *
    103      * @return {@code >= 0;} the label
    104      */
    105     public int getLabel() {
    106         return label;
    107     }
    108 
    109     /**
    110      * Gets the bytecode offset (inclusive) of the start of this block.
    111      *
    112      * @return {@code >= 0;} the start offset
    113      */
    114     public int getStart() {
    115         return start;
    116     }
    117 
    118     /**
    119      * Gets the bytecode offset (exclusive) of the end of this block.
    120      *
    121      * @return {@code > getStart();} the end offset
    122      */
    123     public int getEnd() {
    124         return end;
    125     }
    126 
    127     /**
    128      * Gets the list of successors that this block may branch to
    129      * non-exceptionally.
    130      *
    131      * @return {@code non-null;} the successor list
    132      */
    133     public IntList getSuccessors() {
    134         return successors;
    135     }
    136 
    137     /**
    138      * Gets the list of exceptions caught and their handler targets.
    139      *
    140      * @return {@code non-null;} the catch list
    141      */
    142     public ByteCatchList getCatches() {
    143         return catches;
    144     }
    145 }
    146