| 1 | /* |
| 2 | |
| 3 | Derby - Class org.apache.derby.impl.sql.GenericColumnDescriptor |
| 4 | |
| 5 | Copyright 1998, 2004 The Apache Software Foundation or its licensors, as applicable. |
| 6 | |
| 7 | Licensed under the Apache License, Version 2.0 (the "License"); |
| 8 | you may not use this file except in compliance with the License. |
| 9 | You may obtain a copy of the License at |
| 10 | |
| 11 | http://www.apache.org/licenses/LICENSE-2.0 |
| 12 | |
| 13 | Unless required by applicable law or agreed to in writing, software |
| 14 | distributed under the License is distributed on an "AS IS" BASIS, |
| 15 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 16 | See the License for the specific language governing permissions and |
| 17 | limitations under the License. |
| 18 | |
| 19 | */ |
| 20 | |
| 21 | package org.apache.derby.impl.sql; |
| 22 | |
| 23 | import org.apache.derby.iapi.sql.ResultColumnDescriptor; |
| 24 | import org.apache.derby.iapi.types.DataTypeDescriptor; |
| 25 | |
| 26 | import org.apache.derby.iapi.services.sanity.SanityManager; |
| 27 | |
| 28 | import org.apache.derby.iapi.services.io.StoredFormatIds; |
| 29 | import org.apache.derby.iapi.services.io.FormatIdUtil; |
| 30 | import org.apache.derby.iapi.services.io.Formatable; |
| 31 | |
| 32 | import org.apache.derby.iapi.services.io.FormatableHashtable; |
| 33 | import org.apache.derby.iapi.services.io.FormatableIntHolder; |
| 34 | |
| 35 | import java.io.ObjectOutput; |
| 36 | import java.io.ObjectInput; |
| 37 | import java.io.IOException; |
| 38 | /** |
| 39 | * This is a stripped down implementation of a column |
| 40 | * descriptor that is intended for generic use. It |
| 41 | * can be seralized and attached to plans. |
| 42 | * |
| 43 | * @author jamie |
| 44 | */ |
| 45 | public final class GenericColumnDescriptor |
| 46 | implements ResultColumnDescriptor, Formatable |
| 47 | { |
| 48 | |
| 49 | /******************************************************** |
| 50 | ** |
| 51 | ** This class implements Formatable. That means that it |
| 52 | ** can write itself to and from a formatted stream. If |
| 53 | ** you add more fields to this class, make sure that you |
| 54 | ** also write/read them with the writeExternal()/readExternal() |
| 55 | ** methods. |
| 56 | ** |
| 57 | ** If, inbetween releases, you add more fields to this class, |
| 58 | ** then you should bump the version number emitted by the getTypeFormatId() |
| 59 | ** method. |
| 60 | ** |
| 61 | ********************************************************/ |
| 62 | |
| 63 | private String name; |
| 64 | private String schemaName; |
| 65 | private String tableName; |
| 66 | private int columnPos; |
| 67 | private DataTypeDescriptor type; |
| 68 | private boolean isAutoincrement; |
| 69 | private boolean updatableByCursor; |
| 70 | |
| 71 | /** |
| 72 | * Niladic constructor for Formatable |
| 73 | */ |
| 74 | public GenericColumnDescriptor() |
| 75 | { |
| 76 | } |
| 77 | |
| 78 | public GenericColumnDescriptor(String name, DataTypeDescriptor type) { |
| 79 | this.name = name; |
| 80 | this.type = type; |
| 81 | } |
| 82 | |
| 83 | /** |
| 84 | * This constructor is used to build a generic (and |
| 85 | * formatable) ColumnDescriptor. The idea is that |
| 86 | * it can be passed a ColumnDescriptor from a query |
| 87 | * tree and convert it to something that can be used |
| 88 | * anywhere. |
| 89 | * |
| 90 | * @param rcd the ResultColumnDescriptor |
| 91 | */ |
| 92 | public GenericColumnDescriptor(ResultColumnDescriptor rcd) |
| 93 | { |
| 94 | name = rcd.getName(); |
| 95 | tableName = rcd.getSourceTableName(); |
| 96 | schemaName = rcd.getSourceSchemaName(); |
| 97 | columnPos = rcd.getColumnPosition(); |
| 98 | type = rcd.getType(); |
| 99 | isAutoincrement = rcd.isAutoincrement(); |
| 100 | updatableByCursor = rcd.updatableByCursor(); |
| 101 | } |
| 102 | |
| 103 | /** |
| 104 | * Returns a DataTypeDescriptor for the column. This DataTypeDescriptor |
| 105 | * will not represent an actual value, it will only represent the type |
| 106 | * that all values in the column will have. |
| 107 | * |
| 108 | * @return A DataTypeDescriptor describing the type of the column. |
| 109 | */ |
| 110 | public DataTypeDescriptor getType() |
| 111 | { |
| 112 | return type; |
| 113 | } |
| 114 | |
| 115 | /** |
| 116 | * Returns the name of the Column. |
| 117 | * |
| 118 | * @return A String containing the name of the column. |
| 119 | */ |
| 120 | public String getName() |
| 121 | { |
| 122 | return name; |
| 123 | } |
| 124 | |
| 125 | /** |
| 126 | * Get the name of the schema for the Column's base table, if any. |
| 127 | * Following example queries will all return APP (assuming user is in schema APP) |
| 128 | * select t.a from t |
| 129 | * select b.a from t as b |
| 130 | * select app.t.a from t |
| 131 | * |
| 132 | * @return A String containing the name of the schema of the Column's table. |
| 133 | * If the column is not in a schema (i.e. is a derived column), it returns NULL. |
| 134 | */ |
| 135 | public String getSourceSchemaName() |
| 136 | { |
| 137 | return schemaName; |
| 138 | } |
| 139 | |
| 140 | /** |
| 141 | * Get the name of the underlying(base) table this column comes from, if any. |
| 142 | * Following example queries will all return T |
| 143 | * select a from t |
| 144 | * select b.a from t as b |
| 145 | * select t.a from t |
| 146 | * |
| 147 | * @return A String containing the name of the Column's base table. |
| 148 | * If the column is not in a table (i.e. is a derived column), it returns NULL. |
| 149 | */ |
| 150 | public String getSourceTableName() |
| 151 | { |
| 152 | return tableName; |
| 153 | } |
| 154 | |
| 155 | /** |
| 156 | * Get the position of the Column. |
| 157 | * NOTE - position is 1-based. |
| 158 | * |
| 159 | * @return An int containing the position of the Column |
| 160 | * within the table. |
| 161 | */ |
| 162 | public int getColumnPosition() |
| 163 | { |
| 164 | return columnPos; |
| 165 | } |
| 166 | |
| 167 | public boolean isAutoincrement() |
| 168 | { |
| 169 | return isAutoincrement; |
| 170 | } |
| 171 | |
| 172 | public boolean updatableByCursor() |
| 173 | { |
| 174 | return updatableByCursor; |
| 175 | } |
| 176 | |
| 177 | ////////////////////////////////////////////// |
| 178 | // |
| 179 | // FORMATABLE |
| 180 | // |
| 181 | ////////////////////////////////////////////// |
| 182 | /** |
| 183 | * Write this object out |
| 184 | * |
| 185 | * @param out write bytes here |
| 186 | * |
| 187 | * @exception IOException thrown on error |
| 188 | */ |
| 189 | public void writeExternal(ObjectOutput out) throws IOException |
| 190 | { |
| 191 | FormatableHashtable fh = new FormatableHashtable(); |
| 192 | fh.put("name", name); |
| 193 | fh.put("tableName", tableName); |
| 194 | fh.put("schemaName", schemaName); |
| 195 | fh.putInt("columnPos", columnPos); |
| 196 | fh.put("type", type); |
| 197 | fh.putBoolean("isAutoincrement", isAutoincrement); |
| 198 | fh.putBoolean("updatableByCursor", updatableByCursor); |
| 199 | out.writeObject(fh); |
| 200 | return; |
| 201 | } |
| 202 | |
| 203 | public void djdrcd() {} |
| 204 | /** |
| 205 | * Read this object from a stream of stored objects. |
| 206 | * |
| 207 | * @param in read this. |
| 208 | * |
| 209 | * @exception IOException thrown on error |
| 210 | * @exception ClassNotFoundException thrown on error |
| 211 | */ |
| 212 | public void readExternal(ObjectInput in) |
| 213 | throws IOException, ClassNotFoundException |
| 214 | { |
| 215 | FormatableHashtable fh = (FormatableHashtable)in.readObject(); |
| 216 | name = (String)fh.get("name"); |
| 217 | tableName = (String)fh.get("tableName"); |
| 218 | schemaName = (String)fh.get("schemaName"); |
| 219 | columnPos = fh.getInt("columnPos"); |
| 220 | type = (DataTypeDescriptor)fh.get("type"); |
| 221 | isAutoincrement = fh.getBoolean("isAutoincrement"); |
| 222 | updatableByCursor = fh.getBoolean("updatableByCursor"); |
| 223 | } |
| 224 | |
| 225 | /** |
| 226 | * Get the formatID which corresponds to this class. |
| 227 | * |
| 228 | * @return the formatID of this class |
| 229 | */ |
| 230 | public int getTypeFormatId() { return StoredFormatIds.GENERIC_COLUMN_DESCRIPTOR_V02_ID; } |
| 231 | |
| 232 | public String toString() |
| 233 | { |
| 234 | if (SanityManager.DEBUG) |
| 235 | { |
| 236 | return "GenericColumnDescriptor\n\tname: "+name+ |
| 237 | "\n\tTable: "+schemaName+"."+tableName+ |
| 238 | "\n\tcolumnPos: "+columnPos+ |
| 239 | "\n\tType: "+type; |
| 240 | } |
| 241 | else |
| 242 | { |
| 243 | return ""; |
| 244 | } |
| 245 | } |
| 246 | } |