/*
 * 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.dialect.function;
import org.hibernate.type.StandardBasicTypes;

A SQLFunction implementation that emulates the ANSI SQL trim function on dialects which do not support the full definition. However, this function definition does assume the availability of ltrim, rtrim, and replace functions which it uses in various combinations to emulate the desired ANSI trim() functionality. 
Author:
Steve Ebersole/**
 * A {@link SQLFunction} implementation that emulates the ANSI SQL trim function
 * on dialects which do not support the full definition.  However, this function
 * definition does assume the availability of ltrim, rtrim, and replace functions
 * which it uses in various combinations to emulate the desired ANSI trim()
 * functionality.
 *
 * @author Steve Ebersole
 */
public class AnsiTrimEmulationFunction extends AbstractAnsiTrimEmulationFunction {
	
The default ltrim function name /**
	 * The default {@code ltrim} function name
	 */
	public static final String LTRIM = "ltrim";

	
The default rtrim function name /**
	 * The default {@code rtrim} function name
	 */
	public static final String RTRIM = "rtrim";

	
The default replace function name /**
	 * The default {@code replace} function name
	 */
	public static final String REPLACE = "replace";

	
The placeholder used to represent whitespace
/**
	 * The placeholder used to represent whitespace
	 */
	public static final String SPACE_PLACEHOLDER = "${space}$";

	
The SQLFunctionTemplate pattern for the trimming leading spaces
/**
	 * The SQLFunctionTemplate pattern for the trimming leading spaces
	 */
	public static final String LEADING_SPACE_TRIM_TEMPLATE = LTRIM + "(?1)";

	
The SQLFunctionTemplate pattern for the trimming trailing spaces
/**
	 * The SQLFunctionTemplate pattern for the trimming trailing spaces
	 */
	public static final String TRAILING_SPACE_TRIM_TEMPLATE = RTRIM + "(?1)";

	
The SQLFunctionTemplate pattern for the trimming both leading and trailing spaces
/**
	 * The SQLFunctionTemplate pattern for the trimming both leading and trailing spaces
	 */
	public static final String BOTH_SPACE_TRIM_TEMPLATE = LTRIM + "(" + RTRIM + "(?1))";

	
The SQLFunctionTemplate pattern for the trimming both leading and trailing spaces, with the optional FROM keyword.
Different because we need to skip the FROM keyword in the SQLFunctionTemplate processing
/**
	 * The SQLFunctionTemplate pattern for the trimming both leading and trailing spaces, with the optional FROM keyword.
	 * Different because we need to skip the FROM keyword in the SQLFunctionTemplate processing
	 */
	public static final String BOTH_SPACE_TRIM_FROM_TEMPLATE = LTRIM + "(" + RTRIM + "(?2))";

	
A template for the series of calls required to trim non-space chars from the beginning of text.

NOTE : essentially we:

replace all space chars with the text '${space}$'
replace all the actual replacement chars with space chars
perform left-trimming (that removes any of the space chars we just added which occur at the beginning of the text)
replace all space chars with the replacement char
replace all the '${space}$' text with space chars

/**
	 * A template for the series of calls required to trim non-space chars from the beginning of text.
	 * <p/>
	 * NOTE : essentially we:<ol>
	 * <li>replace all space chars with the text '${space}$'</li>
	 * <li>replace all the actual replacement chars with space chars</li>
	 * <li>perform left-trimming (that removes any of the space chars we just added which occur at the beginning of the text)</li>
	 * <li>replace all space chars with the replacement char</li>
	 * <li>replace all the '${space}$' text with space chars</li>
	 * </ol>
	 */
	public static final String LEADING_TRIM_TEMPLATE =
			REPLACE + "(" +
				REPLACE + "(" +
					LTRIM + "(" +
						REPLACE + "(" +
							REPLACE + "(" +
								"?1," +
								"' '," +
								"'" + SPACE_PLACEHOLDER + "'" +
							")," +
							"?2," +
							"' '" +
						")" +
					")," +
					"' '," +
					"?2" +
				")," +
				"'" + SPACE_PLACEHOLDER + "'," +
				"' '" +
			")";

	
A template for the series of calls required to trim non-space chars from the end of text.
 NOTE: essentially the same series of calls as outlined in LEADING_TRIM_TEMPLATE except that here, instead of left-trimming the added spaces, we right-trim them to remove them from the end of the text. /**
	 * A template for the series of calls required to trim non-space chars from the end of text.
	 * <p/>
	 * NOTE: essentially the same series of calls as outlined in {@link #LEADING_TRIM_TEMPLATE} except that here,
	 * instead of left-trimming the added spaces, we right-trim them to remove them from the end of the text.
	 */
	public static final String TRAILING_TRIM_TEMPLATE =
			REPLACE + "(" +
				REPLACE + "(" +
					RTRIM + "(" +
						REPLACE + "(" +
							REPLACE + "(" +
								"?1," +
								"' '," +
								"'" + SPACE_PLACEHOLDER + "'" +
							")," +
							"?2," +
							"' '" +
						")" +
					")," +
					"' '," +
					"?2" +
				")," +
				"'" + SPACE_PLACEHOLDER + "'," +
				"' '" +
			")";

	
A template for the series of calls required to trim non-space chars from both the beginning and the end of text.
 NOTE: again, we have a series of calls that is essentially the same as outlined in LEADING_TRIM_TEMPLATE except that here we perform both left (leading) and right (trailing) trimming. /**
	 * A template for the series of calls required to trim non-space chars from both the beginning and the end of text.
	 * <p/>
	 * NOTE: again, we have a series of calls that is essentially the same as outlined in {@link #LEADING_TRIM_TEMPLATE}
	 * except that here we perform both left (leading) and right (trailing) trimming.
	 */
	public static final String BOTH_TRIM_TEMPLATE =
			REPLACE + "(" +
				REPLACE + "(" +
					LTRIM + "(" +
						RTRIM + "(" +
							REPLACE + "(" +
								REPLACE + "(" +
									"?1," +
									"' '," +
									"'" + SPACE_PLACEHOLDER + "'" +
								")," +
								"?2," +
								"' '" +
							")" +
						")" +
					")," +
					"' '," +
					"?2" +
				")," +
				"'" + SPACE_PLACEHOLDER + "'," +
				"' '" +
			")";

	private final SQLFunction leadingSpaceTrim;
	private final SQLFunction trailingSpaceTrim;
	private final SQLFunction bothSpaceTrim;
	private final SQLFunction bothSpaceTrimFrom;

	private final SQLFunction leadingTrim;
	private final SQLFunction trailingTrim;
	private final SQLFunction bothTrim;

	
Constructs a new AnsiTrimEmulationFunction using LTRIM, RTRIM, and REPLACE respectively. 
See Also:
AnsiTrimEmulationFunction(String, String, String)/**
	 * Constructs a new AnsiTrimEmulationFunction using {@link #LTRIM}, {@link #RTRIM}, and {@link #REPLACE}
	 * respectively.
	 *
	 * @see #AnsiTrimEmulationFunction(String,String,String)
	 */
	public AnsiTrimEmulationFunction() {
		this( LTRIM, RTRIM, REPLACE );
	}

	
Constructs a trim() emulation function definition using the specified function calls.
Params:
ltrimFunctionName – The left trim function to use.
rtrimFunctionName – The right trim function to use.
replaceFunctionName – The replace function to use./**
	 * Constructs a <tt>trim()</tt> emulation function definition using the specified function calls.
	 *
	 * @param ltrimFunctionName The <tt>left trim</tt> function to use.
	 * @param rtrimFunctionName The <tt>right trim</tt> function to use.
	 * @param replaceFunctionName The <tt>replace</tt> function to use.
	 */
	public AnsiTrimEmulationFunction(String ltrimFunctionName, String rtrimFunctionName, String replaceFunctionName) {
		leadingSpaceTrim = new SQLFunctionTemplate(
				StandardBasicTypes.STRING,
				LEADING_SPACE_TRIM_TEMPLATE.replaceAll( LTRIM, ltrimFunctionName )
		);

		trailingSpaceTrim = new SQLFunctionTemplate(
				StandardBasicTypes.STRING,
				TRAILING_SPACE_TRIM_TEMPLATE.replaceAll( RTRIM, rtrimFunctionName )
		);

		bothSpaceTrim = new SQLFunctionTemplate(
				StandardBasicTypes.STRING,
				BOTH_SPACE_TRIM_TEMPLATE.replaceAll( LTRIM, ltrimFunctionName )
						.replaceAll( RTRIM, rtrimFunctionName )
		);

		bothSpaceTrimFrom = new SQLFunctionTemplate(
				StandardBasicTypes.STRING,
				BOTH_SPACE_TRIM_FROM_TEMPLATE.replaceAll( LTRIM, ltrimFunctionName )
						.replaceAll( RTRIM, rtrimFunctionName )
		);

		leadingTrim = new SQLFunctionTemplate(
				StandardBasicTypes.STRING,
				LEADING_TRIM_TEMPLATE.replaceAll( LTRIM, ltrimFunctionName )
						.replaceAll( RTRIM, rtrimFunctionName )
						.replaceAll( REPLACE,replaceFunctionName )
		);

		trailingTrim = new SQLFunctionTemplate(
				StandardBasicTypes.STRING,
				TRAILING_TRIM_TEMPLATE.replaceAll( LTRIM, ltrimFunctionName )
						.replaceAll( RTRIM, rtrimFunctionName )
						.replaceAll( REPLACE,replaceFunctionName )
		);

		bothTrim = new SQLFunctionTemplate(
				StandardBasicTypes.STRING,
				BOTH_TRIM_TEMPLATE.replaceAll( LTRIM, ltrimFunctionName )
						.replaceAll( RTRIM, rtrimFunctionName )
						.replaceAll( REPLACE,replaceFunctionName )
		);
	}

	
{@inheritDoc}
/**
	 * {@inheritDoc}
	 */
	@Override
	protected SQLFunction resolveBothSpaceTrimFunction() {
		return bothSpaceTrim;
	}

	
{@inheritDoc}
/**
	 * {@inheritDoc}
	 */
	@Override
	protected SQLFunction resolveBothSpaceTrimFromFunction() {
		return bothSpaceTrimFrom;
	}

	
{@inheritDoc}
/**
	 * {@inheritDoc}
	 */
	@Override
	protected SQLFunction resolveLeadingSpaceTrimFunction() {
		return leadingSpaceTrim;
	}

	
{@inheritDoc}
/**
	 * {@inheritDoc}
	 */
	@Override
	protected SQLFunction resolveTrailingSpaceTrimFunction() {
		return trailingSpaceTrim;
	}

	
{@inheritDoc}
/**
	 * {@inheritDoc}
	 */
	@Override
	protected SQLFunction resolveBothTrimFunction() {
		return bothTrim;
	}

	
{@inheritDoc}
/**
	 * {@inheritDoc}
	 */
	@Override
	protected SQLFunction resolveLeadingTrimFunction() {
		return leadingTrim;
	}

	
{@inheritDoc}
/**
	 * {@inheritDoc}
	 */
	@Override
	protected SQLFunction resolveTrailingTrimFunction() {
		return trailingTrim;
	}
}