/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * License: GNU Lesser General Public License (LGPL), version 2.1 or later.
 * See the lgpl.txt file in the root directory or <http://www.gnu.org/licenses/lgpl-2.1.html>.
 */
package org.hibernate.sql.ordering.antlr;

import antlr.collections.AST;

Models each sorting expression.
Author:
Steve Ebersole/**
 * Models each sorting expression.
 *
 * @author Steve Ebersole
 */
public class SortSpecification extends NodeSupport {
	
Locate the specified SortKey. 
Returns:
The sort key./**
	 * Locate the specified {@link SortKey}.
	 *
	 * @return The sort key.
	 */
	public SortKey getSortKey() {
		return ( SortKey ) getFirstChild();
	}

	
Locate the specified collation specification, if one.
Returns:
The collation specification, or null if none was specified./**
	 * Locate the specified <tt>collation specification</tt>, if one.
	 *
	 * @return The <tt>collation specification</tt>, or null if none was specified.
	 */
	public CollationSpecification getCollation() {
		AST possible = getSortKey().getNextSibling();
		return  possible != null && OrderByTemplateTokenTypes.COLLATE == possible.getType()
				? ( CollationSpecification ) possible
				: null;
	}

	
Locate the specified ordering specification, if one.
Returns:
The ordering specification, or null if none was specified./**
	 * Locate the specified <tt>ordering specification</tt>, if one.
	 *
	 * @return The <tt>ordering specification</tt>, or null if none was specified.
	 */
	public OrderingSpecification getOrdering() {
		// IMPL NOTE : the ordering-spec would be either the 2nd or 3rd child (of the overall sort-spec), if it existed,
		// 		depending on whether a collation-spec was specified.

		AST possible = getSortKey().getNextSibling();
		if ( possible == null ) {
			// There was no sort-spec parts specified other then the sort-key so there can be no ordering-spec...
			return null;
		}

		if ( OrderByTemplateTokenTypes.COLLATE == possible.getType() ) {
			// the 2nd child was a collation-spec, so we need to check the 3rd child instead.
			possible = possible.getNextSibling();
		}

		return possible != null && OrderByTemplateTokenTypes.ORDER_SPEC == possible.getType()
				?  ( OrderingSpecification ) possible
				:  null;
	}
}