/*
* 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;
// Java
import java.util.Set;
import org.apache.empire.commons.StringUtils;
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.DBDatabaseDriver;
import org.apache.empire.xml.XMLUtil;
import org.w3c.dom.Element;
/**
* This implements some basic functionality for SQL functions based on a column expression
*/
public abstract class DBAbstractFuncExpr extends DBColumnExpr
{
private final static long serialVersionUID = 1L;
protected final DBColumnExpr expr;
protected final DBColumn updateColumn; // optional
protected final boolean isAggregate;
protected final DataType dataType;
/**
* Constructs a new DBFuncExpr object set the specified parameters to this object.
* Do not use directly - use any of the DBColumnExpr.??? factory functions instead!
*
* @param expr the DBColumnExpr object
* @param updateColumn optional update column if any. This parameter may be null
* @param isAggregate indicates whether the function is an aggregate function (sum, min, max, avg, ...)
* @param dataType indicates the data type of the function result
*/
public DBAbstractFuncExpr(DBColumnExpr expr, DBColumn updateColumn, boolean isAggregate, DataType dataType)
{
this.expr = expr;
this.updateColumn = updateColumn;
this.isAggregate = isAggregate;
this.dataType = dataType;
}
/**
* returns the name of the function
* @return the function name
*/
protected abstract String getFunctionName();
/**
* returns the Database driver or null if the Expression is not attached to an open database<BR/>
* This function is intended for convenience only.
*/
protected final DBDatabaseDriver getDatabaseDriver()
{
DBDatabase db = getDatabase();
return (db!=null) ? db.getDriver() : null;
}
/**
* Returns the current DBDatabase object.
*
* @return the current DBDatabase object
*/
@Override
public DBDatabase getDatabase()
{
return expr.getDatabase();
}
/**
* Returns the data type of the DBColumnExpr object.
*
* @return the data type
*/
@Override
public DataType getDataType()
{
return this.dataType;
}
/**
* Returns the column name.
*
* @return the column name
*/
@Override
public String getName()
{
return expr.getName();
}
/**
* Returns the DBColunm object.
*
* @return the DBColunm object
*/
@Override
public DBColumn getUpdateColumn()
{
return updateColumn;
}
/**
* Returns whether the function is an aggegation function<br>
* that combines multiple rows to one result row.
*
* @return true if the function is an aggregate or false otherwise
*/
@Override
public boolean isAggregate()
{
return isAggregate || expr.isAggregate();
}
/**
* @see org.apache.empire.db.DBExpr#addReferencedColumns(Set)
*/
@Override
public void addReferencedColumns(Set<DBColumn> list)
{
expr.addReferencedColumns(list);
}
/**
* Creates the SQL-Command adds a function to the SQL-Command.
*
* The sql function string is built from a string template.
* The template string must contain a ? which is a placeholder for the column expression.
*
* @param sql the SQL-Command
* @param template the function template string.
* @param params an array of function parameters
* @param context the current SQL-Command context
*/
public final void addSQL(StringBuilder sql, String template, Object[] params, long context)
{
// Get Template
if (params != null)
{ // Replace Params
DataType dataType = expr.getDataType();
for (int i = 0; i < params.length; i++)
{ // String test =(params[i] != null) ? params[i].toString() : "";
String value = getObjectValue(dataType, params[i], CTX_DEFAULT, ",");
// template = template.replaceAll("\\{" + String.valueOf(i) + "\\}", value);
template = StringUtils.replaceAll(template, "{"+ String.valueOf(i) + "}", value);
}
}
// Get Prefix and Postfix
String prefix = template;
String postfix = "";
int sep = template.indexOf("?");
if (sep >= 0)
{
prefix = template.substring(0, sep);
postfix = template.substring(sep + 1);
}
// append
sql.append(prefix);
expr.addSQL(sql, (context & ~CTX_ALIAS));
sql.append(postfix);
}
@Override
public Element addXml(Element parent, long flags)
{
Element elem;
if (updateColumn!=null)
{ // Update Column
elem = updateColumn.addXml(parent, flags);
}
else
{ // Add a column expression for this function
elem = XMLUtil.addElement(parent, "column");
elem.setAttribute("name", getName());
// Add Other Attributes
if (attributes!=null)
attributes.addXml(elem, flags);
// add All Options
if (options!=null)
options.addXml(elem, flags);
}
// Done
elem.setAttribute("function", getFunctionName());
return elem;
}
}