How to use

org.apache.calcite.rex.RexProgram

constructor

/**
 * Creates a program that projects its input fields but with possibly
 * different names for the output fields.
 */
public static RexProgram createIdentity(
  RelDataType rowType,
  RelDataType outputRowType) {
 if (rowType != outputRowType
   && !Pair.right(rowType.getFieldList()).equals(
     Pair.right(outputRowType.getFieldList()))) {
  throw new IllegalArgumentException(
    "field type mismatch: " + rowType + " vs. " + outputRowType);
 }
 final List<RelDataTypeField> fields = rowType.getFieldList();
 final List<RexLocalRef> projectRefs = new ArrayList<>();
 final List<RexInputRef> refs = new ArrayList<>();
 for (int i = 0; i < fields.size(); i++) {
  final RexInputRef ref = RexInputRef.of(i, fields);
  refs.add(ref);
  projectRefs.add(new RexLocalRef(i, ref.getType()));
 }
 return new RexProgram(rowType, refs, projectRefs, null, outputRowType);
}

/**
 * Creates a program that projects its input fields but with possibly
 * different names for the output fields.
 */
public static RexProgram createIdentity(
  RelDataType rowType,
  RelDataType outputRowType) {
 if (rowType != outputRowType
   && !Pair.right(rowType.getFieldList()).equals(
     Pair.right(outputRowType.getFieldList()))) {
  throw new IllegalArgumentException(
    "field type mismatch: " + rowType + " vs. " + outputRowType);
 }
 final List<RelDataTypeField> fields = rowType.getFieldList();
 final List<RexLocalRef> projectRefs = new ArrayList<>();
 final List<RexInputRef> refs = new ArrayList<>();
 for (int i = 0; i < fields.size(); i++) {
  final RexInputRef ref = RexInputRef.of(i, fields);
  refs.add(ref);
  projectRefs.add(new RexLocalRef(i, ref.getType()));
 }
 return new RexProgram(rowType, refs, projectRefs, null, outputRowType);
}

return new RexProgram(
  inputRowType,
  exprList,

return new RexProgram(
  inputRowType,
  exprList,

public RexProgram copyOf(RexProgram program) {
 return new RexProgram(
  copyOf(program.getInputRowType()),
  copyRexNodes(program.getExprList()),
  Lists.transform(program.getProjectList(), COPY_REX_LOCAL_REF),
  (RexLocalRef) copyOf(program.getCondition()),
  copyOf(program.getOutputRowType())
 );
}

new RexProgram(
  inputRowType, exprs, projectRefs, conditionRef, outputRowType);

new RexProgram(
  inputRowType, exprs, projectRefs, conditionRef, outputRowType);

new RexProgram(
  rel.getRowType(),
  exprList,

new RexProgram(
  rel.getRowType(),
  exprList,

 public RelNode accept(RexShuttle shuttle) {
  List<RexNode> oldExprs = program.getExprList();
  List<RexNode> exprs = shuttle.apply(oldExprs);
  List<RexLocalRef> oldProjects = program.getProjectList();
  List<RexLocalRef> projects = shuttle.apply(oldProjects);
  RexLocalRef oldCondition = program.getCondition();
  RexNode condition;
  if (oldCondition != null) {
   condition = shuttle.apply(oldCondition);
   assert condition instanceof RexLocalRef
     : "Invalid condition after rewrite. Expected RexLocalRef, got "
     + condition;
  } else {
   condition = null;
  }
  if (exprs == oldExprs
    && projects == oldProjects
    && condition == oldCondition) {
   return this;
  }
  return copy(traitSet, getInput(),
    new RexProgram(program.getInputRowType(),
      exprs,
      projects,
      (RexLocalRef) condition,
      program.getOutputRowType()));
 }
}

 public RelNode accept(RexShuttle shuttle) {
  List<RexNode> oldExprs = program.getExprList();
  List<RexNode> exprs = shuttle.apply(oldExprs);
  List<RexLocalRef> oldProjects = program.getProjectList();
  List<RexLocalRef> projects = shuttle.apply(oldProjects);
  RexLocalRef oldCondition = program.getCondition();
  RexNode condition;
  if (oldCondition != null) {
   condition = shuttle.apply(oldCondition);
   assert condition instanceof RexLocalRef
     : "Invalid condition after rewrite. Expected RexLocalRef, got "
     + condition;
  } else {
   condition = null;
  }
  if (exprs == oldExprs
    && projects == oldProjects
    && condition == oldCondition) {
   return this;
  }
  return copy(traitSet, getInput(),
    new RexProgram(program.getInputRowType(),
      exprs,
      projects,
      (RexLocalRef) condition,
      program.getOutputRowType()));
 }
}