/*
* 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.openjpa.jdbc.kernel.exps;
import org.apache.openjpa.jdbc.meta.ClassMapping;
import org.apache.openjpa.jdbc.meta.FieldMapping;
import org.apache.openjpa.jdbc.schema.Column;
import org.apache.openjpa.jdbc.schema.Table;
import org.apache.openjpa.jdbc.sql.SQLBuffer;
import org.apache.openjpa.meta.XMLMetaData;
/**
* The simplified public view of any non-operator in a query filter,
* including constants, variables, and object fields.
*
* @author Abe White
*/
public interface FilterValue {
/**
* Return the expected type of this value.
*/
public Class getType();
/**
* Return the number of SQL elements in this value. Usually 1.
*/
public int length();
/**
* Append the first SQL element for this value to the given buffer.
*/
public void appendTo(SQLBuffer buf);
/**
* Append the <code>index</code>th SQL element for this value to the
* given buffer.
*/
public void appendTo(SQLBuffer buf, int index);
/**
* Return the alias to use for the given column (this includes the table
* alias prefix, if any).
*/
public String getColumnAlias(Column col);
/**
* Return the alias to use for the given column (this includes the table
* alias prefix, if any).
*/
public String getColumnAlias(String col, Table table);
/**
* Transform the given value into its datastore equivalent.
*/
public Object toDataStoreValue(Object val);
/**
* Return true if this value represents a literal or parameter.
*/
public boolean isConstant();
/**
* If this is a constant, return its value, else return null.
*/
public Object getValue();
/**
* If this is a constant, returns its value as it would be represented
* in the database in this context, else return null.
*/
public Object getSQLValue();
/**
* Return true if this value represents a persistent field traversal,
* such as 'this', 'address.street', or 'projectVariable.title'.
*/
public boolean isPath();
/**
* If this is a path to a persistent object, return its class mapping,
* else return null.
*/
public ClassMapping getClassMapping();
/**
* If this is a path to a persistent field, return its mapping, else
* return null.
*/
public FieldMapping getFieldMapping();
/**
* If this is an XPath, return it,
* else return null;
*/
public PCPath getXPath();
/**
* If this is an XPath, return XML mapping metadata,
* else return null;
*/
public XMLMetaData getXmlMapping();
/**
* return true if CAST is required for this filter value
* else return false.
*/
public boolean requiresCast();
}