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* to you under the Apache License, Version 2.0 (the
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* Unless required by applicable law or agreed to in writing, software
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package org.apache.drill.exec.planner.physical.visitor;
import com.google.common.collect.Lists;
import net.hydromatic.optiq.tools.RelConversionException;
import org.apache.drill.common.exceptions.DrillRuntimeException;
import org.apache.drill.exec.expr.fn.FunctionImplementationRegistry;
import org.apache.drill.exec.planner.physical.DrillFlattenPrel;
import org.apache.drill.exec.planner.physical.Prel;
import org.apache.drill.exec.planner.physical.ProjectPrel;
import org.apache.drill.exec.planner.physical.visitor.BasePrelVisitor;
import org.apache.drill.exec.planner.types.RelDataTypeDrillImpl;
import org.apache.drill.exec.planner.types.RelDataTypeHolder;
import org.eigenbase.rel.ProjectRelBase;
import org.eigenbase.rel.RelShuttleImpl;
import org.apache.drill.exec.planner.sql.DrillOperatorTable;
import org.eigenbase.rel.ProjectRel;
import org.eigenbase.rel.RelNode;
import org.eigenbase.reltype.RelDataTypeFactory;
import org.eigenbase.reltype.RelDataTypeField;
import org.eigenbase.reltype.RelDataTypeFieldImpl;
import org.eigenbase.reltype.RelRecordType;
import org.eigenbase.rex.RexBuilder;
import org.eigenbase.rex.RexCall;
import org.eigenbase.rex.RexLiteral;
import org.eigenbase.rex.RexNode;
import org.eigenbase.sql.SqlFunction;
import org.eigenbase.sql.SqlOperator;
import org.eigenbase.util.NlsString;
import java.util.ArrayList;
import java.util.List;
public class RewriteProjectToFlatten extends BasePrelVisitor<Prel, Object, RelConversionException> {
RelDataTypeFactory factory;
DrillOperatorTable table;
public RewriteProjectToFlatten(RelDataTypeFactory factory, DrillOperatorTable table) {
super();
this.factory = factory;
this.table = table;
}
@Override
public Prel visitPrel(Prel prel, Object value) throws RelConversionException {
List<RelNode> children = Lists.newArrayList();
for(Prel child : prel){
child = child.accept(this, null);
children.add(child);
}
return (Prel) prel.copy(prel.getTraitSet(), children);
}
@Override
public Prel visitProject(ProjectPrel node, Object unused) throws RelConversionException {
ProjectPrel project = node;
List<RexNode> exprList = new ArrayList<>();
boolean rewrite = false;
List<RelDataTypeField> relDataTypes = new ArrayList();
int i = 0;
RexNode flatttenExpr = null;
for (RexNode rex : project.getChildExps()) {
RexNode newExpr = rex;
if (rex instanceof RexCall) {
RexCall function = (RexCall) rex;
String functionName = function.getOperator().getName();
int nArgs = function.getOperands().size();
if (functionName.equalsIgnoreCase("flatten") ) {
rewrite = true;
if (function.getOperands().size() != 1) {
throw new RelConversionException("Flatten expression expects a single input.");
}
newExpr = function.getOperands().get(0);
RexBuilder builder = new RexBuilder(factory);
flatttenExpr = builder.makeInputRef( new RelDataTypeDrillImpl(new RelDataTypeHolder(), factory), i);
}
}
relDataTypes.add(project.getRowType().getFieldList().get(i));
i++;
exprList.add(newExpr);
}
if (rewrite == true) {
// TODO - figure out what is the right setting for the traits
Prel newChild = ((Prel)project.getInput(0)).accept(this, null);
ProjectPrel newProject = new ProjectPrel(node.getCluster(), project.getTraitSet(), newChild, exprList, new RelRecordType(relDataTypes));
DrillFlattenPrel flatten = new DrillFlattenPrel(project.getCluster(), project.getTraitSet(), newProject, flatttenExpr);
return flatten;
}
Prel child = ((Prel)project.getChild()).accept(this, null);
return new ProjectPrel(node.getCluster(), project.getTraitSet(), child, exprList, new RelRecordType(relDataTypes));
}
}