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/*
 * Copyright 2013 greg.
 *
 * Licensed 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 nz.co.gregs.dbvolution.results;

import nz.co.gregs.dbvolution.expressions.DBExpression;

/**
 * Interface required to be implemented by all DBExpressions that produce
 * Boolean results
 *
 * 
 * DBvolution attempts to maintain type safety using the *Result interfaces.
 * Most operations requiring a boolean will not accept anything other than an
 * actual Boolean or a BooleanResult.
 *
 * 

 * Add {@code implements BooleanResult} to your class and override the copy
 * method so that it returns your class type.
 *
 * 
Support DBvolution at
 * Patreon
 *
 * @author Gregory Graham
 * @see DBExpression
 */
public interface BooleanResult extends EqualResult {

	@Override
	public BooleanResult copy();

	/**
	 * Indicates whether the result is a boolean statement or boolean value.
	 *
	 * 
	 * A boolean statement is a a comparison like 1=1 which results in a boolean
	 * value and is used in the where clause. Conversely a boolean value is the
	 * database representation TRUE or FALSE.
	 *
	 * 
	 * The distinction is subtle but required to deal with databases which do not
	 * have a full-feature boolean datatype.
	 *
	 * Support DBvolution at
	 * Patreon
	 *
	 * @return TRUE if the BooleanResult is a boolean statement, FALSE otherwise.
	 */
	boolean isBooleanStatement();

}