//$Id: ClauseParser.java 4907 2004-12-08 00:24:14Z oneovthafew $
package org.hibernate.hql.classic;
import org.hibernate.QueryException;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
/**
* Parses the Hibernate query into its constituent clauses.
*/
public class ClauseParser implements Parser {
private Parser child;
private List selectTokens;
private boolean cacheSelectTokens = false;
private boolean byExpected = false;
private int parenCount = 0;
public void token(String token, QueryTranslatorImpl q) throws QueryException {
String lcToken = token.toLowerCase();
if ( "(".equals( token ) ) {
parenCount++;
}
else if ( ")".equals( token ) ) {
parenCount--;
}
if ( byExpected && !lcToken.equals( "by" ) ) {
throw new QueryException( "BY expected after GROUP or ORDER: " + token );
}
boolean isClauseStart = parenCount == 0; //ignore subselect keywords
if ( isClauseStart ) {
if ( lcToken.equals( "select" ) ) {
selectTokens = new ArrayList();
cacheSelectTokens = true;
}
else if ( lcToken.equals( "from" ) ) {
child = new FromParser();
child.start( q );
cacheSelectTokens = false;
}
else if ( lcToken.equals( "where" ) ) {
endChild( q );
child = new WhereParser();
child.start( q );
}
else if ( lcToken.equals( "order" ) ) {
endChild( q );
child = new OrderByParser();
byExpected = true;
}
else if ( lcToken.equals( "having" ) ) {
endChild( q );
child = new HavingParser();
child.start( q );
}
else if ( lcToken.equals( "group" ) ) {
endChild( q );
child = new GroupByParser();
byExpected = true;
}
else if ( lcToken.equals( "by" ) ) {
if ( !byExpected ) throw new QueryException( "GROUP or ORDER expected before BY" );
child.start( q );
byExpected = false;
}
else {
isClauseStart = false;
}
}
if ( !isClauseStart ) {
if ( cacheSelectTokens ) {
selectTokens.add( token );
}
else {
if ( child == null ) {
throw new QueryException( "query must begin with SELECT or FROM: " + token );
}
else {
child.token( token, q );
}
}
}
}
private void endChild(QueryTranslatorImpl q) throws QueryException {
if ( child == null ) {
//null child could occur for no from clause in a filter
cacheSelectTokens = false;
}
else {
child.end( q );
}
}
public void start(QueryTranslatorImpl q) {
}
public void end(QueryTranslatorImpl q) throws QueryException {
endChild( q );
if ( selectTokens != null ) {
child = new SelectParser();
child.start( q );
Iterator iter = selectTokens.iterator();
while ( iter.hasNext() ) {
token( ( String ) iter.next(), q );
}
child.end( q );
}
byExpected = false;
parenCount = 0;
cacheSelectTokens = false;
}
}
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