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Hibernate example source code file (AbstractAnsiTrimEmulationFunction.java)

This example Hibernate source code file (AbstractAnsiTrimEmulationFunction.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Hibernate tags/keywords

arraylist, early, exit, list, mapping, override, override, queryexception, queryexception, sqlfunction, sqlfunction, string, string, type, util

The Hibernate AbstractAnsiTrimEmulationFunction.java source code

/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * Copyright (c) 2010, Red Hat Inc. or third-party contributors as
 * indicated by the @author tags or express copyright attribution
 * statements applied by the authors.  All third-party contributions are
 * distributed under license by Red Hat Inc.
 *
 * This copyrighted material is made available to anyone wishing to use, modify,
 * copy, or redistribute it subject to the terms and conditions of the GNU
 * Lesser General Public License, as published by the Free Software Foundation.
 *
 * This program 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 distribution; if not, write to:
 * Free Software Foundation, Inc.
 * 51 Franklin Street, Fifth Floor
 * Boston, MA  02110-1301  USA
 */
package org.hibernate.dialect.function;

import java.util.ArrayList;
import java.util.List;

import org.hibernate.QueryException;
import org.hibernate.engine.spi.Mapping;
import org.hibernate.engine.spi.SessionFactoryImplementor;
import org.hibernate.type.StandardBasicTypes;
import org.hibernate.type.Type;

/**
 * A {@link org.hibernate.dialect.function.SQLFunction} providing support for implementing TRIM functionality
 * (as defined by both the ANSI SQL and JPA specs) in cases where the dialect may not support the full <tt>trim
 * function itself.
 * <p/>
 * Follows the <a href="http://en.wikipedia.org/wiki/Template_method_pattern">template pattern in order to implement
 * the {@link #render} method.
 *
 * @author Steve Ebersole
 */
public abstract class AbstractAnsiTrimEmulationFunction implements SQLFunction {
	@Override
	public final boolean hasArguments() {
		return true;
	}

	@Override
	public final boolean hasParenthesesIfNoArguments() {
		return false;
	}

	@Override
	public final Type getReturnType(Type argumentType, Mapping mapping) throws QueryException {
		return StandardBasicTypes.STRING;
	}

	@Override
	public final String render(Type argumentType, List args, SessionFactoryImplementor factory) throws QueryException {
		// According to both the ANSI-SQL and JPA specs, trim takes a variable number of parameters between 1 and 4.
		// at least one paramer (trimSource) is required.  From the SQL spec:
		//
		// <trim function> ::=
		//      TRIM <left paren>  
		//
		// <trim operands> ::=
		//      [ [ <trim specification> ] [  ] FROM ] 
		//
		// <trim specification> ::=
		//      LEADING
		//      | TRAILING
		//      | BOTH
		//
		// If <trim specification> is omitted, BOTH is assumed.
		// If <trim character> is omitted, space is assumed
		if ( args.size() == 1 ) {
			// we have the form: trim(trimSource)
			//      so we trim leading and trailing spaces
			return resolveBothSpaceTrimFunction().render( argumentType, args, factory );			// EARLY EXIT!!!!
		}
		else if ( "from".equalsIgnoreCase( ( String ) args.get( 0 ) ) ) {
			// we have the form: trim(from trimSource).
			//      This is functionally equivalent to trim(trimSource)
			return resolveBothSpaceTrimFromFunction().render( argumentType, args, factory );  		// EARLY EXIT!!!!
		}
		else {
			// otherwise, a trim-specification and/or a trim-character
			// have been specified;  we need to decide which options
			// are present and "do the right thing"
			boolean leading = true;         // should leading trim-characters be trimmed?
			boolean trailing = true;        // should trailing trim-characters be trimmed?
			String trimCharacter;    		// the trim-character (what is to be trimmed off?)
			String trimSource;       		// the trim-source (from where should it be trimmed?)

			// potentialTrimCharacterArgIndex = 1 assumes that a
			// trim-specification has been specified.  we handle the
			// exception to that explicitly
			int potentialTrimCharacterArgIndex = 1;
			String firstArg = ( String ) args.get( 0 );
			if ( "leading".equalsIgnoreCase( firstArg ) ) {
				trailing = false;
			}
			else if ( "trailing".equalsIgnoreCase( firstArg ) ) {
				leading = false;
			}
			else if ( "both".equalsIgnoreCase( firstArg ) ) {
			}
			else {
				potentialTrimCharacterArgIndex = 0;
			}

			String potentialTrimCharacter = ( String ) args.get( potentialTrimCharacterArgIndex );
			if ( "from".equalsIgnoreCase( potentialTrimCharacter ) ) { 
				trimCharacter = "' '";
				trimSource = ( String ) args.get( potentialTrimCharacterArgIndex + 1 );
			}
			else if ( potentialTrimCharacterArgIndex + 1 >= args.size() ) {
				trimCharacter = "' '";
				trimSource = potentialTrimCharacter;
			}
			else {
				trimCharacter = potentialTrimCharacter;
				if ( "from".equalsIgnoreCase( ( String ) args.get( potentialTrimCharacterArgIndex + 1 ) ) ) {
					trimSource = ( String ) args.get( potentialTrimCharacterArgIndex + 2 );
				}
				else {
					trimSource = ( String ) args.get( potentialTrimCharacterArgIndex + 1 );
				}
			}

			List<String> argsToUse = new ArrayList();
			argsToUse.add( trimSource );
			argsToUse.add( trimCharacter );

			if ( trimCharacter.equals( "' '" ) ) {
				if ( leading && trailing ) {
					return resolveBothSpaceTrimFunction().render( argumentType, argsToUse, factory );
				}
				else if ( leading ) {
					return resolveLeadingSpaceTrimFunction().render( argumentType, argsToUse, factory );
				}
				else {
					return resolveTrailingSpaceTrimFunction().render( argumentType, argsToUse, factory );
				}
			}
			else {
				if ( leading && trailing ) {
					return resolveBothTrimFunction().render( argumentType, argsToUse, factory );
				}
				else if ( leading ) {
					return resolveLeadingTrimFunction().render( argumentType, argsToUse, factory );
				}
				else {
					return resolveTrailingTrimFunction().render( argumentType, argsToUse, factory );
				}
			}
		}
	}

	/**
	 * Resolve the function definition which should be used to trim both leading and trailing spaces.
	 * <p/>
	 * In this form, the imput arguments is missing the <tt>FROM keyword.
	 *
	 * @return The sql function
	 */
	protected abstract SQLFunction resolveBothSpaceTrimFunction();

	/**
	 * Resolve the function definition which should be used to trim both leading and trailing spaces.
	 * <p/>
	 * The same as {#link resolveBothSpaceTrimFunction} except that here the<tt>FROM is included and
	 * will need to be accounted for during {@link SQLFunction#render} processing.
	 * 
	 * @return The sql function
	 */
	protected abstract SQLFunction resolveBothSpaceTrimFromFunction();

	/**
	 * Resolve the function definition which should be used to trim leading spaces.
	 *
	 * @return The sql function
	 */
	protected abstract SQLFunction resolveLeadingSpaceTrimFunction();

	/**
	 * Resolve the function definition which should be used to trim trailing spaces.
	 *
	 * @return The sql function
	 */
	protected abstract SQLFunction resolveTrailingSpaceTrimFunction();

	/**
	 * Resolve the function definition which should be used to trim the specified character from both the
	 * beginning (leading) and end (trailing) of the trim source.
	 *
	 * @return The sql function
	 */
	protected abstract SQLFunction resolveBothTrimFunction();

	/**
	 * Resolve the function definition which should be used to trim the specified character from the
	 * beginning (leading) of the trim source.
	 *
	 * @return The sql function
	 */
	protected abstract SQLFunction resolveLeadingTrimFunction();

	/**
	 * Resolve the function definition which should be used to trim the specified character from the
	 * end (trailing) of the trim source.
	 *
	 * @return The sql function
	 */
	protected abstract SQLFunction resolveTrailingTrimFunction();
}

Other Hibernate examples (source code examples)

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