| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, |
| * software distributed under the License is distributed on an |
| * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| * KIND, either express or implied. See the License for the |
| * specific language governing permissions and limitations |
| * under the License. |
| */ |
| package org.apache.empire.db.expr.join; |
| |
| import java.util.Set; |
| |
| import org.apache.empire.db.DBColumn; |
| import org.apache.empire.db.DBColumnExpr; |
| import org.apache.empire.db.DBDatabase; |
| import org.apache.empire.db.DBJoinType; |
| import org.apache.empire.db.DBQuery; |
| import org.apache.empire.db.DBRowSet; |
| |
| /** |
| * This class is used for building a join expression of an SQL statement. |
| * <P> |
| * There is no need to explicitly create instances of this class.<BR> |
| * Instead use @link {@link org.apache.empire.db.DBCommand#join(DBColumnExpr, DBColumn, DBJoinType)} |
| * <P> |
| * |
| */ |
| public class DBCrossJoinExpr extends DBJoinExpr |
| { |
| // *Deprecated* private static final long serialVersionUID = 1L; |
| |
| protected DBRowSet left; |
| protected DBRowSet right; |
| |
| /** |
| * Constructs a new DBJoinExpr object initialize this object with |
| * the left and right column and the data type of the join |
| * expression. |
| * |
| * @param left left value |
| * @param right right value |
| * @param type data type (JOIN_INNER, JOIN_LEFT or JOIN_RIGHT) |
| */ |
| public DBCrossJoinExpr(DBRowSet left, DBRowSet right) |
| { |
| super(DBJoinType.FULL); |
| this.left = left; |
| this.right = right; |
| } |
| |
| /** |
| * Returns the current DBDatabase object. |
| * |
| * @return the current DBDatabase object |
| */ |
| @SuppressWarnings("unchecked") |
| @Override |
| public final DBDatabase getDatabase() |
| { |
| return left.getDatabase(); |
| } |
| |
| /** |
| * returns the RowSet on the left of the join |
| */ |
| @Override |
| public DBRowSet getLeftTable() |
| { |
| return left; |
| } |
| |
| /** |
| * returns the RowSet on the right of the join |
| */ |
| @Override |
| public DBRowSet getRightTable() |
| { |
| return right; |
| } |
| |
| /** |
| * returns true if this join is using the given table or view or false otherwise |
| */ |
| @Override |
| public boolean isJoinOn(DBRowSet rowset) |
| { |
| if (rowset==null) |
| return false; |
| return rowset.equals(left) || rowset.equals(right); |
| } |
| |
| /** |
| * returns true if this join is using the given column or false otherwise |
| */ |
| @Override |
| public boolean isJoinOn(DBColumn column) |
| { |
| return false; |
| } |
| |
| /** |
| * Returns the left table name if the data type= JOIN_LEFT and returns |
| * the right table if the data type= JOIN_RIGHT. If the |
| * data type = JOIN_INNER the return value is null. |
| * |
| * @return the current DBDatabase object |
| */ |
| @Override |
| public DBRowSet getOuterTable() |
| { |
| return null; // no outer table! |
| } |
| |
| /** |
| * This function swaps the left and the right statements of the join expression. |
| */ |
| @Override |
| public void reverse() |
| { // Swap Type of Join |
| DBRowSet swap = left; |
| left = right; |
| right = swap; |
| } |
| |
| /** |
| * @see org.apache.empire.db.DBExpr#addReferencedColumns(Set) |
| */ |
| @Override |
| public void addReferencedColumns(Set<DBColumn> list) |
| { |
| // No referenced columns |
| } |
| |
| /** Not allowed, this operation have to be done in the DBCommand object. */ |
| @Override |
| public void addSQL(StringBuilder buf, long context) |
| { |
| if ((context & CTX_NAME) != 0) |
| left.addSQL(buf, CTX_DEFAULT | CTX_ALIAS); |
| if ((context & CTX_VALUE) != 0) |
| { // Join Type |
| buf.append(" CROSS JOIN "); |
| right.addSQL(buf, CTX_DEFAULT | CTX_ALIAS); |
| } |
| } |
| |
| /** |
| * Returns the subquery Params |
| * Valid only directly after addSQL() has been called! |
| * @param which: both (==0) | left (<=0) | right (>=0) |
| * @return the subquery params; |
| */ |
| @Override |
| public Object[] getSubqueryParams(int which) |
| { |
| Object[] leftParams = (which<=0 && (left instanceof DBQuery)) ? ((DBQuery)left ).getCommandExpr().getParamValues() : null; |
| Object[] rightParams = (which>=0 && (right instanceof DBQuery)) ? ((DBQuery)right).getCommandExpr().getParamValues() : null; |
| if (leftParams!=null && rightParams!=null) |
| { // combine |
| Object[] both = new Object[leftParams.length+rightParams.length]; |
| int index = 0; |
| for (int i=0; i<leftParams.length; i++) |
| both[index++] = leftParams[i]; |
| for (int i=0; i<rightParams.length; i++) |
| both[index++] = rightParams[i]; |
| return both; |
| } |
| return (leftParams!=null ? leftParams : rightParams); |
| } |
| |
| /** |
| * Compares two DBJoinExpr objects. |
| * |
| * @param obj other DBJoinExpr object |
| * @return true if the other DBJoinExpr object is equal to this object |
| */ |
| @Override |
| public boolean equals(Object obj) |
| { |
| if (!(obj instanceof DBCrossJoinExpr)) |
| return super.equals(obj); |
| // object |
| DBCrossJoinExpr other = (DBCrossJoinExpr) obj; |
| if (left.equals(other.left) && right.equals(other.right)) |
| return true; |
| // reversed |
| if (left.equals(other.right) && right.equals(other.left)) |
| return true; |
| // not equal |
| return false; |
| } |
| |
| } |