/*
* 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 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</tt>
* function itself.
* <p/>
* Follows the <a href="http://en.wikipedia.org/wiki/Template_method_pattern">template</a> 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> <right paren>
//
// <trim operands> ::=
// [ [ <trim specification> ] [ <trim character> ] FROM ] <trim source>
//
// <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 );
}
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 );
}
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"
// should leading trim-characters be trimmed?
boolean leading = true;
// should trailing trim-characters be trimmed?
boolean trailing = true;
// the trim-character (what is to be trimmed off?)
String trimCharacter;
// the trim-source (from where should it be trimmed?)
String trimSource;
// potentialTrimCharacterArgIndex = 1 assumes that a
// trim-specification has been specified. we handle the
// exception to that explicitly
int potentialTrimCharacterArgIndex = 1;
final String firstArg = (String) args.get( 0 );
if ( "leading".equalsIgnoreCase( firstArg ) ) {
trailing = false;
}
else if ( "trailing".equalsIgnoreCase( firstArg ) ) {
leading = false;
}
else if ( "both".equalsIgnoreCase( firstArg ) ) {
// nothing to do here
}
else {
potentialTrimCharacterArgIndex = 0;
}
final 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 );
}
}
final List<String> argsToUse = new ArrayList<String>();
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</tt> 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</tt> 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();
}