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1
21 package com.db4o;
22
23 import com.db4o.foundation.Tree;
24
25
28 public final class TreeReader
29 {
30 private final Readable  i_template;
31 private final YapReader i_bytes;
32 private int i_current = 0;
33 private int i_levels = 0;
34 private int i_size;
35 private boolean i_orderOnRead;
36
37 public TreeReader(YapReader a_bytes, Readable a_template) {
38 this(a_bytes, a_template, false);
39 }
40
41 public TreeReader(YapReader a_bytes, Readable a_template, boolean a_orderOnRead) {
42 i_template = a_template;
43 i_bytes = a_bytes;
44 i_orderOnRead = a_orderOnRead;
45 }
46
47 public Tree read() {
48 return read(i_bytes.readInt());
49 }
50
51 public Tree read(int a_size){
52 i_size = a_size;
53 if(i_size > 0){
54 if(i_orderOnRead){
55 Tree tree = null;
56 for (int i = 0; i < i_size; i++) {
57 tree = Tree.add(tree, (Tree)i_template.read(i_bytes));
58 }
59 return tree;
60 }
61 while ((1 << i_levels) < (i_size + 1)){
62 i_levels ++;
63 }
64 return linkUp(null, i_levels);
65 }
66 return null;
67 }
68
69 private final Tree linkUp(Tree a_preceding, int a_level){
70 Tree node = (Tree)i_template.read(i_bytes);
71 i_current++;
72 node._preceding = a_preceding;
73 node._subsequent = linkDown(a_level + 1);
74 node.calculateSize();
75 if(i_current < i_size){
76 return linkUp(node, a_level - 1);
77 }
78 return node;
79
80 }
81
82 private final Tree linkDown(int a_level){
83 if(i_current < i_size){
84 i_current++;
85 if(a_level < i_levels) {
86 Tree preceding = linkDown(a_level + 1);
87 Tree node = (Tree)i_template.read(i_bytes);
88 node._preceding = preceding;
89 node._subsequent = linkDown(a_level + 1);
90 node.calculateSize();
91 return node;
92 }
93 return (Tree)i_template.read(i_bytes);
94 }
95 return null;
96 }
97 }
98 |
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