/**
* It returns an original column name if it is aliased column reference. Otherwise, it will return
* NULL.
*/
public String checkAndGetIfAliasedColumn(String name) {
Expr expr = getExpr(name);
if (expr != null && expr.getType() == OpType.Column) {
ColumnReferenceExpr column = (ColumnReferenceExpr) expr;
if (!column.getCanonicalName().equals(name)) {
return column.getCanonicalName();
}
}
return null;
}
@Override
public Expr visitColumnReference(
ExprNormalizedResult ctx, Stack<Expr> stack, ColumnReferenceExpr expr)
throws PlanningException {
// normalize column references.
if (!expr.hasQualifier()) {
if (ctx.block.namedExprsMgr.contains(expr.getCanonicalName())) {
NamedExpr namedExpr = ctx.block.namedExprsMgr.getNamedExpr(expr.getCanonicalName());
return new ColumnReferenceExpr(namedExpr.getAlias());
} else {
String normalized = ctx.plan.getNormalizedColumnName(ctx.block, expr);
expr.setName(normalized);
}
}
return expr;
}