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/*******************************************************************
 * © 2024 SAP SE or an SAP affiliate company. All rights reserved. *
 *******************************************************************/
package com.sap.cds.ql;

import com.sap.cds.ql.cqn.CqnCaseExpression;
import com.sap.cds.ql.cqn.CqnPredicate;
import com.sap.cds.ql.cqn.CqnValue;

public interface Then {

	/**
	 * Connects a next {@link CqnCaseExpression.Case case}) to a chain of when-then
	 * expressions.
	 * 
	 * @param pred the {@link CqnCaseExpression.Case#condition() condition} of the
	 *             next case.
	 * @return a builder to specify the case's return value
	 */
	When when(CqnPredicate pred);

	/**
	 * Converts a chain of when-then expressions (a list of
	 * {@link CqnCaseExpression.Case cases}) to a {@link CqnCaseExpression case
	 * expression}, which returns a given default value if no condition of any case
	 * matches.
	 * 
	 * @param defaultValue the default value
	 * 
	 * @return the case expression
	 * 
	 * @see #when(CqnPredicate)
	 * @see CQL#when(CqnPredicate)
	 * @see StructuredType#when(CqnPredicate)
	 * @see When#then(CqnValue)
	 */
	 & CqnCaseExpression> T orElse(CqnValue defaultValue);

	/**
	 * Converts a chain of when-then expressions (a list of
	 * {@link CqnCaseExpression.Case cases}) to a {@link CqnCaseExpression case
	 * expression}, which returns a given default value if no condition of
	 * any case matches.
	 * 
	 * @param defaultValue the default value
	 * 
	 * @return the case expression
	 * 
	 * @see #when(CqnPredicate)
	 * @see CQL#when(CqnPredicate)
	 * @see StructuredType#when(CqnPredicate)
	 * @see When#then(CqnValue)
	 */
	 & CqnCaseExpression> T orElse(Object defaultValue);
}