| 1 | /* ============================================================= |
| 2 | * SmallSQL : a free Java DBMS library for the Java(tm) platform |
| 3 | * ============================================================= |
| 4 | * |
| 5 | * (C) Copyright 2004-2006, by Volker Berlin. |
| 6 | * |
| 7 | * Project Info: http://www.smallsql.de/ |
| 8 | * |
| 9 | * This library is free software; you can redistribute it and/or modify it |
| 10 | * under the terms of the GNU Lesser General Public License as published by |
| 11 | * the Free Software Foundation; either version 2.1 of the License, or |
| 12 | * (at your option) any later version. |
| 13 | * |
| 14 | * This library is distributed in the hope that it will be useful, but |
| 15 | * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY |
| 16 | * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public |
| 17 | * License for more details. |
| 18 | * |
| 19 | * You should have received a copy of the GNU Lesser General Public |
| 20 | * License along with this library; if not, write to the Free Software |
| 21 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, |
| 22 | * USA. |
| 23 | * |
| 24 | * [Java is a trademark or registered trademark of Sun Microsystems, Inc. |
| 25 | * in the United States and other countries.] |
| 26 | * |
| 27 | * --------------- |
| 28 | * Scrollable.java |
| 29 | * --------------- |
| 30 | * Author: Volker Berlin |
| 31 | * |
| 32 | * Created on 05.07.2004 |
| 33 | */ |
| 34 | package smallsql.database; |
| 35 | |
| 36 | /** |
| 37 | * Scrollable is a RowSource wrapper to add the feature of scrollable to any RowSource. |
| 38 | * @author Volker Berlin |
| 39 | */ |
| 40 | class Scrollable extends RowSource { |
| 41 | |
| 42 | /** The internal not scrollable RowSource */ |
| 43 | private final RowSource rowSource; |
| 44 | |
| 45 | /** The current row number */ |
| 46 | private int rowIdx; |
| 47 | |
| 48 | /** A map of row number to the RowPositions of the internal RowSource */ |
| 49 | private final LongList rowList = new LongList(); |
| 50 | |
| 51 | /** Detect if on any previous scrolling the last row was recheched. */ |
| 52 | //private boolean lastIsFound; |
| 53 | |
| 54 | |
| 55 | Scrollable(RowSource rowSource){ |
| 56 | this.rowSource = rowSource; |
| 57 | } |
| 58 | |
| 59 | |
| 60 | final boolean isScrollable(){ |
| 61 | return true; |
| 62 | } |
| 63 | |
| 64 | |
| 65 | void beforeFirst() throws Exception { |
| 66 | rowIdx = -1; |
| 67 | rowSource.beforeFirst(); |
| 68 | } |
| 69 | |
| 70 | |
| 71 | boolean isBeforeFirst(){ |
| 72 | return rowIdx == -1; |
| 73 | } |
| 74 | |
| 75 | |
| 76 | boolean isFirst(){ |
| 77 | return rowIdx == 0; |
| 78 | } |
| 79 | |
| 80 | |
| 81 | boolean first() throws Exception { |
| 82 | rowIdx = -1; |
| 83 | return next(); |
| 84 | } |
| 85 | |
| 86 | |
| 87 | boolean previous() throws Exception{ |
| 88 | if(rowIdx > -1){ |
| 89 | rowIdx--; |
| 90 | if(rowIdx > -1 && rowIdx < rowList.size()){ |
| 91 | rowSource.setRowPosition( rowList.get(rowIdx) ); |
| 92 | return true; |
| 93 | } |
| 94 | } |
| 95 | rowSource.beforeFirst(); |
| 96 | return false; |
| 97 | } |
| 98 | |
| 99 | |
| 100 | boolean next() throws Exception { |
| 101 | if(++rowIdx < rowList.size()){ |
| 102 | rowSource.setRowPosition( rowList.get(rowIdx) ); |
| 103 | return true; |
| 104 | } |
| 105 | final boolean result = rowSource.next(); |
| 106 | if(result){ |
| 107 | rowList.add( rowSource.getRowPosition()); |
| 108 | return true; |
| 109 | } |
| 110 | return false; |
| 111 | } |
| 112 | |
| 113 | |
| 114 | boolean last() throws Exception{ |
| 115 | afterLast(); |
| 116 | return previous(); |
| 117 | } |
| 118 | |
| 119 | |
| 120 | boolean isLast() throws Exception{ |
| 121 | if(rowIdx+1 != rowList.size()) return false; |
| 122 | if(next()){ |
| 123 | previous(); |
| 124 | return false; |
| 125 | } |
| 126 | return true; |
| 127 | } |
| 128 | |
| 129 | boolean isAfterLast() throws Exception{ |
| 130 | if(rowIdx >= rowList.size()) return true; |
| 131 | if(isBeforeFirst() && rowList.size() == 0){ |
| 132 | next(); |
| 133 | previous(); |
| 134 | if(rowList.size() == 0) return true; |
| 135 | } |
| 136 | return false; |
| 137 | } |
| 138 | |
| 139 | |
| 140 | void afterLast() throws Exception { |
| 141 | if(rowIdx+1 < rowList.size()){ |
| 142 | rowIdx = rowList.size()-1; |
| 143 | rowSource.setRowPosition( rowList.get(rowIdx) ); |
| 144 | } |
| 145 | while(next()); |
| 146 | } |
| 147 | |
| 148 | |
| 149 | boolean absolute(int row) throws Exception{ |
| 150 | if(row == 0) |
| 151 | throw Utils.createSQLException("The call absolute(0) is invalid."); |
| 152 | if(row < 0){ |
| 153 | afterLast(); |
| 154 | rowIdx = rowList.size() + row; |
| 155 | if(rowIdx < 0){ |
| 156 | beforeFirst(); |
| 157 | return false; |
| 158 | }else{ |
| 159 | rowSource.setRowPosition( rowList.get(rowIdx) ); |
| 160 | return true; |
| 161 | } |
| 162 | } |
| 163 | if(row <= rowList.size()){ |
| 164 | rowIdx = row-1; |
| 165 | rowSource.setRowPosition( rowList.get(rowIdx) ); |
| 166 | return true; |
| 167 | } |
| 168 | |
| 169 | rowIdx = rowList.size()-1; |
| 170 | if(rowIdx >= 0) |
| 171 | rowSource.setRowPosition( rowList.get(rowIdx) ); |
| 172 | boolean result; |
| 173 | while((result = next()) && row-1 > rowIdx); |
| 174 | return result; |
| 175 | } |
| 176 | |
| 177 | |
| 178 | boolean relative(int rows) throws Exception{ |
| 179 | int newRow = rows + rowIdx + 1; |
| 180 | if(newRow <= 0){ |
| 181 | beforeFirst(); |
| 182 | return false; |
| 183 | }else{ |
| 184 | return absolute(newRow); |
| 185 | } |
| 186 | } |
| 187 | |
| 188 | |
| 189 | int getRow() throws Exception { |
| 190 | if(rowIdx >= rowList.size()) return 0; |
| 191 | return rowIdx + 1; |
| 192 | } |
| 193 | |
| 194 | |
| 195 | long getRowPosition() { |
| 196 | return rowIdx; |
| 197 | } |
| 198 | |
| 199 | |
| 200 | void setRowPosition(long rowPosition) throws Exception { |
| 201 | rowIdx = (int)rowPosition; |
| 202 | } |
| 203 | |
| 204 | |
| 205 | final boolean rowInserted(){ |
| 206 | return rowSource.rowInserted(); |
| 207 | } |
| 208 | |
| 209 | |
| 210 | final boolean rowDeleted(){ |
| 211 | return rowSource.rowDeleted(); |
| 212 | } |
| 213 | |
| 214 | |
| 215 | void nullRow() { |
| 216 | rowSource.nullRow(); |
| 217 | rowIdx = -1; |
| 218 | } |
| 219 | |
| 220 | |
| 221 | void noRow() { |
| 222 | rowSource.noRow(); |
| 223 | rowIdx = -1; |
| 224 | } |
| 225 | |
| 226 | |
| 227 | void execute() throws Exception{ |
| 228 | rowSource.execute(); |
| 229 | rowList.clear(); |
| 230 | rowIdx = -1; |
| 231 | } |
| 232 | } |