org.apache.empire.db.expr.column.DBConcatExpr Maven / Gradle / Ivy
/*
* 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.column;
import java.util.Set;
// Java
import org.apache.empire.data.DataType;
import org.apache.empire.db.DBColumn;
import org.apache.empire.db.DBColumnExpr;
import org.apache.empire.db.DBDatabase;
import org.apache.empire.db.DBExpr;
import org.apache.empire.db.DBRowSet;
import org.apache.empire.db.DBSQLBuilder;
import org.apache.empire.dbms.DBSqlPhrase;
import org.apache.empire.xml.XMLUtil;
import org.w3c.dom.Element;
/**
* This class is used for performing string concatenation in SQL
*
* There is no need to explicitly create instances of this class.
* Instead use {@link DBColumnExpr#append(Object) }
*/
public class DBConcatExpr extends DBColumnExpr
{
// *Deprecated* private static final long serialVersionUID = 1L;
protected final DBColumnExpr left;
protected final Object right;
/**
* Constructs a new DBConcatExpr object set the specified parameters to this object.
*
* @param left the left column for this concatenation
* @param right the right column for this concatenation
*/
public DBConcatExpr(DBColumnExpr left, Object right)
{
this.left = left;
this.right = right;
}
@SuppressWarnings("unchecked")
@Override
public final DBDatabase getDatabase()
{
return left.getDatabase();
}
/**
* Returns the data type: {@link DataType#VARCHAR}
*
* @return {@link DataType#VARCHAR}
*/
@Override
public DataType getDataType()
{
return DataType.VARCHAR;
}
/**
* Not an Enum. Returns null
*/
@Override
public Class> getEnumType()
{
return null;
}
@Override
public String getName()
{ // Get the expression name
String name = left.getName();
if (right instanceof DBColumnExpr)
{ // add other names
name += "_";
name += ((DBColumnExpr) right).getName();
}
return name;
}
/**
* Returns the underlying rowset
*/
@Override
public DBRowSet getRowSet()
{
return left.getRowSet();
}
/**
* Returns the underlying column
*/
@Override
public DBColumn getUpdateColumn()
{
return null;
}
/**
* Always returns false since a concat expression cannot be an aggregate.
*
* @return false
*/
@Override
public boolean isAggregate()
{
return false;
}
/**
* Returns true if other is equal to this expression
*/
@Override
public boolean equals(Object other)
{
if (other instanceof DBConcatExpr)
{ // Compare left and right
return left .equals(((DBConcatExpr)other).left)
&& right.equals(((DBConcatExpr)other).right);
}
return false;
}
/**
* @see org.apache.empire.db.DBExpr#addReferencedColumns(Set)
*/
@Override
public void addReferencedColumns(Set list)
{
left.addReferencedColumns(list);
// Check if right object is a DBExpr
if (right instanceof DBExpr)
((DBExpr)right).addReferencedColumns(list);
}
/**
* Creates the SQL-Command concatenate a specified column with
* a specified value sets the column with a specified value to
* the SQL-Command.
*
* @param sql the SQL statment
* @param context the current SQL-Command context
*/
@Override
public void addSQL(DBSQLBuilder sql, long context)
{ // Zusammenbauen
String template = getDatabase().getDbms().getSQLPhrase(DBSqlPhrase.SQL_CONCAT_EXPR);
context &= ~CTX_ALIAS; // No column aliases
// Find Separator
int sep = template.indexOf('?');
if (sep >= 0)
{ // Complex Pattern with placeholder ? for this expression and {0} for the value
sql.append(template.substring(0, sep));
left.addSQL(sql, context);
// template = template.substring(sep + 1)
int iph = template.indexOf("{0}", ++sep);
if (iph>0)
sql.append(template.substring(sep, iph));
else
sql.append(template.substring(sep));
// value
sql.appendValue(getDataType(), right, context, template);
// rest
if (iph>0)
sql.append(template.substring(iph+3));
}
else
{ // Simple Pattern without placeholders
left.addSQL(sql, context);
sql.append(template);
sql.appendValue(getDataType(), right, context, template);
}
}
@Override
public Element addXml(Element parent, long flags)
{
Element elem = XMLUtil.addElement(parent, "column");
elem.setAttribute("name", getName());
elem.setAttribute("function", "concat");
DBColumn source = getUpdateColumn();
if (source!=null)
{ Element elemSource = XMLUtil.addElement(elem, "source");
source.addXml(elemSource, flags);
// more
Object with = right;
while (with instanceof DBExpr)
{
if (with instanceof DBConcatExpr)
{
((DBConcatExpr)with).left.addXml(elemSource, flags);
with = ((DBConcatExpr)with).right;
continue;
}
if (with instanceof DBColumnExpr)
{
((DBColumnExpr)with).addXml(elemSource, flags);
}
with = null;
}
}
// Add Other Attributes
if (attributes!=null)
attributes.addXml(elem, flags);
// add All Options
if (options!=null)
options.addXml(elem, getDataType());
// Done
return elem;
}
}