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a Java JDBC driver for reading comma-separated-value files
/*
* CsvJdbc - a JDBC driver for CSV files
* Copyright (C) 2014 Simon Chenery
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
package org.relique.jdbc.csv;
import java.lang.reflect.Array;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.sql.SQLException;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Set;
class SQLUserFunction extends Expression
{
String name;
List expressions;
public SQLUserFunction(String name, List expressions)
{
this.name = name.toUpperCase();
this.expressions = expressions;
}
public Object eval(Map env) throws SQLException
{
Object retval = null;
CsvStatement statement = (CsvStatement)env.get(CsvStatement.STATEMENT_COLUMN_NAME);
CsvConnection connection = (CsvConnection)statement.getConnection();
Method method = connection.getSqlFunctions().get(name);
if (method == null)
throw new SQLException(CsvResources.getString("noFunction") + ": " + name);
Class[] parameterTypes = method.getParameterTypes();
StringConverter converter = (StringConverter)env.get(StringConverter.COLUMN_NAME);
boolean isVarArgs = method.isVarArgs();
Object lastArg = null;
if (isVarArgs && expressions.size() >= parameterTypes.length)
{
/*
* Strip '[]' from end of parameter class name.
*/
String parameterDataType = parameterTypes[parameterTypes.length - 1].getSimpleName();
parameterDataType = parameterDataType.substring(0, parameterDataType.length() - 2);
Class parameterClass = getParameterClass(converter, parameterDataType);
lastArg = Array.newInstance(parameterClass, expressions.size() - parameterTypes.length + 1);
}
else if (parameterTypes.length != expressions.size())
{
throw new SQLException(CsvResources.getString("functionArgCount") + ": " + name);
}
Object []args = new Object[parameterTypes.length];
String parameterDataType = null;
try
{
int i = 0;
int varArgsIndex = 0;
for (Expression expr : expressions)
{
Object obj = expr.eval(env);
if (obj != null)
{
/*
* Convert each expression to correct data type for Java method.
*/
parameterDataType = parameterTypes[i].getSimpleName();
if (isVarArgs && i >= parameterTypes.length - 1)
{
/*
* Fill array for variable argument method.
*/
parameterDataType = parameterDataType.substring(0, parameterDataType.length() - 2);
Class parameterClass = getParameterClass(converter, parameterDataType);
if (parameterClass == Object.class)
{
/*
* Everything is an Object class so nothing to do.
*/
}
else if (parameterClass == CharSequence.class)
{
obj = obj.toString();
}
else if (!parameterClass.equals(obj.getClass()))
{
obj = converter.convert(parameterDataType, obj.toString());
}
Array.set(lastArg, varArgsIndex++, obj);
}
else
{
Class parameterClass = getParameterClass(converter, parameterDataType);
if (parameterClass == Object.class)
{
/*
* Everything is an Object class so nothing to do.
*/
}
else if (parameterClass == CharSequence.class)
{
obj = obj.toString();
}
else if (!parameterClass.equals(obj.getClass()))
{
obj = converter.convert(parameterDataType, obj.toString());
}
args[i++] = obj;
}
}
}
if (isVarArgs)
args[args.length - 1] = lastArg;
retval = method.invoke(null, args);
}
catch (IllegalArgumentException e)
{
throw new SQLException(getInvokeString(args), e);
}
catch (IllegalAccessException e)
{
throw new SQLException(name + ": " + e.getMessage(), e);
}
catch (InvocationTargetException e)
{
throw new SQLException(getInvokeString(args), e);
}
return retval;
}
private Class getParameterClass(StringConverter converter, String parameterDataType)
throws SQLException
{
Class parameterClass = null;
if (parameterDataType.equals(Object.class.getSimpleName()))
parameterClass = Object.class;
else if (parameterDataType.equals(CharSequence.class.getSimpleName()))
parameterClass = CharSequence.class;
else
parameterClass = converter.forSQLName(parameterDataType);
if (parameterClass == null)
throw new SQLException(CsvResources.getString("functionArgClass") + ": " + parameterDataType);
return parameterClass;
}
public String getInvokeString(Object []args)
{
StringBuilder sb = new StringBuilder();
sb.append(name);
sb.append("(");
String separator = "";
for (Object o : args)
{
sb.append(separator);
if (o != null)
sb.append(o.toString());
else
sb.append("null");
separator = ",";
}
sb.append(")");
return sb.toString();
}
public String toString()
{
StringBuilder sb = new StringBuilder();
sb.append(name);
sb.append("(");
String separator = "";
for (Expression expression : expressions)
{
sb.append(separator);
sb.append(expression.toString());
separator = ", ";
}
sb.append(")");
return sb.toString();
}
public List usedColumns(Set availableColumns)
{
List result = new LinkedList();
for (Expression expression : expressions)
{
result.addAll(expression.usedColumns(availableColumns));
}
return result;
}
public List aggregateFunctions()
{
List result = new LinkedList();
for (Expression expression : expressions)
{
result.addAll(expression.aggregateFunctions());
}
return result;
}
}