|
1
5 package org.h2.result;
6
7 import java.sql.SQLException  ;
8
9 import org.h2.engine.Constants;
10 import org.h2.engine.Database;
11 import org.h2.expression.Expression;
12 import org.h2.util.ObjectArray;
13 import org.h2.util.StringUtils;
14 import org.h2.value.Value;
15 import org.h2.value.ValueNull;
16
17
20
21 public class SortOrder {
22 public static final int ASCENDING = 0, DESCENDING = 1;
23 public static final int NULLS_FIRST = 2, NULLS_LAST = 4;
24
25 private Database database;
26 private int len;
27 private int[] indexes;
28 private int[] sortTypes;
29
30 public SortOrder(Database database, int[] index, int[] sortType) {
31 this.database = database;
32 this.indexes = index;
33 this.sortTypes = sortType;
34 len = index.length;
35 }
36
37 public String getSQL(Expression[] list, int visible) {
38 StringBuffer buff = new StringBuffer ();
39 for (int i = 0; i < len; i++) {
40 if (i > 0) {
41 buff.append(", ");
42 }
43 int idx = indexes[i];
44 if (idx < visible) {
45 buff.append(idx + 1);
46 } else {
47 buff.append("=");
48 buff.append(StringUtils.unEnclose(list[idx].getSQL()));
49 }
50 int type = sortTypes[i];
51 if ((type & DESCENDING) != 0) {
52 buff.append(" DESC");
53 }
54 if ((type & NULLS_FIRST) != 0) {
55 buff.append(" NULLS FIRST");
56 } else if ((type & NULLS_LAST) != 0) {
57 buff.append(" NULLS LAST");
58 }
59 }
60 return buff.toString();
61 }
62
63 public int compare(Value[] a, Value[] b) throws SQLException {
64 for (int i = 0; i < len; i++) {
65 int idx = indexes[i];
66 int type = sortTypes[i];
67 Value o1 = a[idx];
68 Value o2 = b[idx];
69 boolean b1 = o1 == ValueNull.INSTANCE, b2 = o2 == ValueNull.INSTANCE;
70 if (b1 || b2) {
71 if (b1 == b2) {
72 continue;
73 }
74 if ((type & NULLS_FIRST) != 0) {
75 return b1 ? -1 : 1;
76 } else if ((type & NULLS_LAST) != 0) {
77 return b1 ? 1 : -1;
78 } else {
79 int comp;
81 if (Constants.NULL_SORT_DEFAULT == Constants.NULL_SORT_LOW) {
82 comp = b1 ? -1 : 1;
83 return (type & DESCENDING) == 0 ? comp : -comp;
84 } else if (Constants.NULL_SORT_DEFAULT == Constants.NULL_SORT_HIGH) {
85 comp = b1 ? 1 : -1;
86 return (type & DESCENDING) == 0 ? comp : -comp;
87 } else if (Constants.NULL_SORT_DEFAULT == Constants.NULL_SORT_START) {
88 return b1 ? 1 : -1;
89 } else {
90 return b1 ? -1 : 1;
91 }
92 }
93 }
94 int comp = database.compare(o1, o2);
95 if (comp != 0) {
96 return (type & DESCENDING) == 0 ? comp : -comp;
97 }
98 }
99 return 0;
100 }
101
102 public void sort(ObjectArray rows) throws SQLException {
103 sort(rows, 0, rows.size() - 1);
104 }
105
106 private void swap(ObjectArray rows, int a, int b) {
107 Object t = rows.get(a);
108 rows.set(a, rows.get(b));
109 rows.set(b, t);
110 }
111
112 private void sort(ObjectArray rows, int l, int r) throws SQLException {
113 int i, j;
114 while (r - l > 10) {
115 i = (r + l) >> 1;
116 if (compare((Value[]) rows.get(l), (Value[]) rows.get(r)) > 0) {
117 swap(rows, l, r);
118 }
119 if (compare((Value[]) rows.get(i), (Value[]) rows.get(l)) < 0) {
120 swap(rows, l, i);
121 } else if (compare((Value[]) rows.get(i), (Value[]) rows.get(r)) > 0) {
122 swap(rows, i, r);
123 }
124 j = r - 1;
125 swap(rows, i, j);
126 Value[] p = (Value[]) rows.get(j);
127 i = l;
128 while (true) {
129 do {
130 ++i;
131 } while (compare((Value[]) rows.get(i), p) < 0);
132 do {
133 --j;
134 } while (compare((Value[]) rows.get(j), p) > 0);
135 if (i >= j) {
136 break;
137 }
138 swap(rows, i, j);
139 }
140 swap(rows, i, r - 1);
141 sort(rows, l, i - 1);
142 l = i + 1;
143 }
144 for (i = l + 1; i <= r; i++) {
145 Value[] t = (Value[]) rows.get(i);
146 for (j = i - 1; j >= l && (compare((Value[]) rows.get(j), t) > 0); j--) {
147 rows.set(j + 1, rows.get(j));
148 }
149 rows.set(j + 1, t);
150 }
151 }
152
153 public int[] getIndexes() {
154 return indexes;
155 }
156
157 public int[] getSortTypes() {
158 return sortTypes;
159 }
160
161 }
162 |
Popular Tags |
Java API By Example, From Geeks To Geeks.