} // parseJoinItem()
private SelectItem findSelectItem(String token, FromItem[] joinTables)
{
// first look in the original query
SelectItemParser selectItemParser = new SelectItemParser(_query, false);
SelectItem result = selectItemParser.findSelectItem(token);
if (result == null)
{
// fail over and try with the from items available in the join that
// is being built.
Query temporaryQuery = new Query().from(joinTables);
selectItemParser = new SelectItemParser(temporaryQuery, false);
result = selectItemParser.findSelectItem(token);
if (result == null)
{
throw new QueryParserException("Not capable of parsing ON token: " + token);
}
// set the query on the involved query parts (since they have been
// temporarily moved to the searched query).
result.setQuery(_query);
}
return(result);
} // findSelectItem()
} // parse()
/**
* Finds/creates a SelectItem based on the given expression. Unlike the
* {@link #parse(String, String)} method, this method will not actually add
* the selectitem to the query.
*
* @param expression
* @return
*
* @throws MultipleSelectItemsParsedException
* if an expression yielding multiple select-items (such as "*")
* was passed in the expression
*/
public SelectItem findSelectItem(String expression) // throws MultipleSelectItemsParsedException
{
if ("*".Equals(expression))
{
throw new MultipleSelectItemsParsedException(null);
}
if ("COUNT(*)".Equals(expression, StringComparison.CurrentCultureIgnoreCase))
{
return(SelectItem.getCountAllItem());
}
String unmodifiedExpression = expression;
bool functionApproximation;
FunctionType function;
int startParenthesis = expression.IndexOf('(');
if (startParenthesis > 0 && expression.EndsWith(")"))
{
functionApproximation = (expression.StartsWith(SelectItem.FUNCTION_APPROXIMATION_PREFIX));
String functionName = expression.Substring(
(functionApproximation ? SelectItem.FUNCTION_APPROXIMATION_PREFIX.Length : 0), startParenthesis);
function = FunctionTypeFactory.get(functionName.ToUpper());
if (function != null)
{
expression = expression.Substring(startParenthesis + 1, expression.Length - 1).Trim();
if (function is CountAggregateFunction && "*".Equals(expression))
{
SelectItem select_item = SelectItem.getCountAllItem();
select_item.setFunctionApproximationAllowed(functionApproximation);
return(select_item);
}
}
}
else
{
function = null;
functionApproximation = false;
}
String columnName = null;
FromItem fromItem = null;
// attempt to find from item by cutting up the string in prefix and
// suffix around dot.
{
int splitIndex = expression.LastIndexOf('.');
while (fromItem == null && splitIndex != -1)
{
String prefix = expression.Substring(0, splitIndex);
columnName = expression.Substring(splitIndex + 1);
fromItem = _query.getFromClause().getItemByReference(prefix);
splitIndex = expression.LastIndexOf('.', splitIndex - 1);
}
}
if (fromItem == null)
{
if (_query.getFromClause().getItemCount() == 1)
{
fromItem = _query.getFromClause().getItem(0);
columnName = expression;
}
else
{
fromItem = null;
columnName = null;
}
}
if (fromItem != null)
{
if ("*".Equals(columnName))
{
throw new MultipleSelectItemsParsedException(fromItem);
}
else if (fromItem.getTable() != null)
{
Column column = fromItem.getTable().getColumnByName(columnName);
int offset = -1;
while (function == null && column == null)
{
// check for MAP_VALUE shortcut syntax
offset = columnName.IndexOf('.', offset + 1);
if (offset == -1)
{
break;
}
String part1 = columnName.Substring(0, offset);
column = fromItem.getTable().getColumnByName(part1);
if (column != null)
{
String part2 = columnName.Substring(offset + 1);
return(new SelectItem(new MapValueFunction(), new Object[] { part2 }, column, fromItem));
}
}
if (column != null)
{
SelectItem select_item = new SelectItem(function, column, fromItem);
select_item.setFunctionApproximationAllowed(functionApproximation);
return(select_item);
}
}
else if (fromItem.getSubQuery() != null)
{
Query subQuery = fromItem.getSubQuery();
SelectItem subQuerySelectItem = new SelectItemParser(subQuery, _allowExpressionBasedSelectItems)
.findSelectItem(columnName);
if (subQuerySelectItem == null)
{
return(null);
}
return(new SelectItem(subQuerySelectItem, fromItem));
}
}
// if the expression is alias of some select item defined return that
// select item
SelectItem aliasSelectItem = MetaModelHelper.getSelectItemByAlias(_query, unmodifiedExpression);
if (aliasSelectItem != null)
{
return(aliasSelectItem);
}
if (_allowExpressionBasedSelectItems)
{
SelectItem select_item = new SelectItem(function, expression, null);
select_item.setFunctionApproximationAllowed(functionApproximation);
return(select_item);
}
return(null);
} // findSelectItem()
