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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to you under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.calcite.rex;
import org.apache.calcite.plan.RelOptPredicateList;
import org.apache.calcite.plan.RelOptUtil;
import org.apache.calcite.rel.RelCollation;
import org.apache.calcite.rel.RelCollations;
import org.apache.calcite.rel.RelFieldCollation;
import org.apache.calcite.rel.RelNode;
import org.apache.calcite.rel.RelWriter;
import org.apache.calcite.rel.externalize.RelWriterImpl;
import org.apache.calcite.rel.type.RelDataType;
import org.apache.calcite.rel.type.RelDataTypeField;
import org.apache.calcite.sql.SqlExplainLevel;
import org.apache.calcite.sql.fun.SqlStdOperatorTable;
import org.apache.calcite.sql.type.SqlTypeUtil;
import org.apache.calcite.util.Litmus;
import org.apache.calcite.util.Pair;
import org.apache.calcite.util.Permutation;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Ordering;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.util.AbstractList;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
/**
* A collection of expressions which read inputs, compute output expressions,
* and optionally use a condition to filter rows.
*
* Programs are immutable. It may help to use a {@link RexProgramBuilder},
* which has the same relationship to {@link RexProgram} as {@link StringBuffer}
* has to {@link String}.
*
*
A program can contain aggregate functions. If it does, the arguments to
* each aggregate function must be an {@link RexInputRef}.
*
* @see RexProgramBuilder
*/
public class RexProgram {
//~ Instance fields --------------------------------------------------------
/**
* First stage of expression evaluation. The expressions in this array can
* refer to inputs (using input ordinal #0) or previous expressions in the
* array (using input ordinal #1).
*/
private final List exprs;
/**
* With {@link #condition}, the second stage of expression evaluation.
*/
private final List projects;
/**
* The optional condition. If null, the calculator does not filter rows.
*/
private final RexLocalRef condition;
private final RelDataType inputRowType;
private final RelDataType outputRowType;
/**
* Reference counts for each expression, computed on demand.
*/
private int[] refCounts;
//~ Constructors -----------------------------------------------------------
/**
* Creates a program.
*
* The expressions must be valid: they must not contain common expressions,
* forward references, or non-trivial aggregates.
*
* @param inputRowType Input row type
* @param exprs Common expressions
* @param projects Projection expressions
* @param condition Condition expression. If null, calculator does not
* filter rows
* @param outputRowType Description of the row produced by the program
*/
public RexProgram(
RelDataType inputRowType,
List exprs,
List projects,
RexLocalRef condition,
RelDataType outputRowType) {
this.inputRowType = inputRowType;
this.exprs = ImmutableList.copyOf(exprs);
this.projects = ImmutableList.copyOf(projects);
this.condition = condition;
this.outputRowType = outputRowType;
assert isValid(Litmus.THROW, null);
}
//~ Methods ----------------------------------------------------------------
// REVIEW jvs 16-Oct-2006: The description below is confusing. I
// think it means "none of the entries are null, there may be none,
// and there is no further reduction into smaller common sub-expressions
// possible"?
/**
* Returns the common sub-expressions of this program.
*
* The list is never null but may be empty; each the expression in the
* list is not null; and no further reduction into smaller common
* sub-expressions is possible.
*/
public List getExprList() {
return exprs;
}
/**
* Returns an array of references to the expressions which this program is
* to project. Never null, may be empty.
*/
public List getProjectList() {
return projects;
}
/**
* Returns a list of project expressions and their field names.
*/
public List> getNamedProjects() {
return new AbstractList>() {
public int size() {
return projects.size();
}
public Pair get(int index) {
return Pair.of(
projects.get(index),
outputRowType.getFieldList().get(index).getName());
}
};
}
/**
* Returns the field reference of this program's filter condition, or null
* if there is no condition.
*/
public RexLocalRef getCondition() {
return condition;
}
/**
* Creates a program which calculates projections and filters rows based
* upon a condition. Does not attempt to eliminate common sub-expressions.
*
* @param projectExprs Project expressions
* @param conditionExpr Condition on which to filter rows, or null if rows
* are not to be filtered
* @param outputRowType Output row type
* @param rexBuilder Builder of rex expressions
* @return A program
*/
public static RexProgram create(
RelDataType inputRowType,
List projectExprs,
RexNode conditionExpr,
RelDataType outputRowType,
RexBuilder rexBuilder) {
return create(inputRowType, projectExprs, conditionExpr,
outputRowType.getFieldNames(), rexBuilder);
}
/**
* Creates a program which calculates projections and filters rows based
* upon a condition. Does not attempt to eliminate common sub-expressions.
*
* @param projectExprs Project expressions
* @param conditionExpr Condition on which to filter rows, or null if rows
* are not to be filtered
* @param fieldNames Names of projected fields
* @param rexBuilder Builder of rex expressions
* @return A program
*/
public static RexProgram create(
RelDataType inputRowType,
List projectExprs,
RexNode conditionExpr,
List fieldNames,
RexBuilder rexBuilder) {
if (fieldNames == null) {
fieldNames = Collections.nCopies(projectExprs.size(), null);
} else {
assert fieldNames.size() == projectExprs.size()
: "fieldNames=" + fieldNames
+ ", exprs=" + projectExprs;
}
final RexProgramBuilder programBuilder =
new RexProgramBuilder(inputRowType, rexBuilder);
for (int i = 0; i < projectExprs.size(); i++) {
programBuilder.addProject(projectExprs.get(i), fieldNames.get(i));
}
if (conditionExpr != null) {
programBuilder.addCondition(conditionExpr);
}
return programBuilder.getProgram();
}
// description of this calc, chiefly intended for debugging
public String toString() {
// Intended to produce similar output to explainCalc,
// but without requiring a RelNode or RelOptPlanWriter.
final RelWriterImpl pw =
new RelWriterImpl(new PrintWriter(new StringWriter()));
collectExplainTerms("", pw);
return pw.simple();
}
/**
* Writes an explanation of the expressions in this program to a plan
* writer.
*
* @param pw Plan writer
*/
public RelWriter explainCalc(RelWriter pw) {
return collectExplainTerms("", pw, pw.getDetailLevel());
}
public RelWriter collectExplainTerms(
String prefix,
RelWriter pw) {
return collectExplainTerms(
prefix,
pw,
SqlExplainLevel.EXPPLAN_ATTRIBUTES);
}
/**
* Collects the expressions in this program into a list of terms and values.
*
* @param prefix Prefix for term names, usually the empty string, but useful
* if a relational expression contains more than one program
* @param pw Plan writer
*/
public RelWriter collectExplainTerms(
String prefix,
RelWriter pw,
SqlExplainLevel level) {
final List inFields = inputRowType.getFieldList();
final List outFields = outputRowType.getFieldList();
assert outFields.size() == projects.size()
: "outFields.length=" + outFields.size()
+ ", projects.length=" + projects.size();
pw.item(prefix + "expr#0"
+ ((inFields.size() > 1) ? (".." + (inFields.size() - 1)) : ""),
"{inputs}");
for (int i = inFields.size(); i < exprs.size(); i++) {
pw.item(prefix + "expr#" + i, exprs.get(i));
}
// If a lot of the fields are simply projections of the underlying
// expression, try to be a bit less verbose.
int trivialCount = 0;
// Do not use the trivialCount optimization if computing digest for the
// optimizer (as opposed to doing an explain plan).
if (level != SqlExplainLevel.DIGEST_ATTRIBUTES) {
trivialCount = countTrivial(projects);
}
switch (trivialCount) {
case 0:
break;
case 1:
trivialCount = 0;
break;
default:
pw.item(prefix + "proj#0.." + (trivialCount - 1), "{exprs}");
break;
}
// Print the non-trivial fields with their names as they appear in the
// output row type.
for (int i = trivialCount; i < projects.size(); i++) {
pw.item(prefix + outFields.get(i).getName(), projects.get(i));
}
if (condition != null) {
pw.item(prefix + "$condition", condition);
}
return pw;
}
/**
* Returns the number of expressions at the front of an array which are
* simply projections of the same field.
*
* @param refs References
*/
private static int countTrivial(List refs) {
for (int i = 0; i < refs.size(); i++) {
RexLocalRef ref = refs.get(i);
if (ref.getIndex() != i) {
return i;
}
}
return refs.size();
}
/**
* Returns the number of expressions in this program.
*/
public int getExprCount() {
return exprs.size()
+ projects.size()
+ ((condition == null) ? 0 : 1);
}
/**
* Creates the identity program.
*/
public static RexProgram createIdentity(RelDataType rowType) {
return createIdentity(rowType, rowType);
}
/**
* 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 fields = rowType.getFieldList();
final List projectRefs = new ArrayList<>();
final List 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);
}
/**
* Returns the type of the input row to the program.
*
* @return input row type
*/
public RelDataType getInputRowType() {
return inputRowType;
}
/**
* Returns whether this program contains windowed aggregate functions
*
* @return whether this program contains windowed aggregate functions
*/
public boolean containsAggs() {
return RexOver.containsOver(this);
}
/**
* Returns the type of the output row from this program.
*
* @return output row type
*/
public RelDataType getOutputRowType() {
return outputRowType;
}
/**
* Checks that this program is valid.
*
* If fail is true, executes assert false, so
* will throw an {@link AssertionError} if assertions are enabled. If
* fail is false, merely returns whether the program is valid.
*
* @param litmus What to do if an error is detected
* @param context Context of enclosing {@link RelNode}, for validity checking,
* or null if not known
* @return Whether the program is valid
*/
public boolean isValid(Litmus litmus, RelNode.Context context) {
if (inputRowType == null) {
return litmus.fail(null);
}
if (exprs == null) {
return litmus.fail(null);
}
if (projects == null) {
return litmus.fail(null);
}
if (outputRowType == null) {
return litmus.fail(null);
}
// If the input row type is a struct (contains fields) then the leading
// expressions must be references to those fields. But we don't require
// this if the input row type is, say, a java class.
if (inputRowType.isStruct()) {
if (!RexUtil.containIdentity(exprs, inputRowType, litmus)) {
return litmus.fail(null);
}
// None of the other fields should be inputRefs.
for (int i = inputRowType.getFieldCount(); i < exprs.size(); i++) {
RexNode expr = exprs.get(i);
if (expr instanceof RexInputRef) {
return litmus.fail(null);
}
}
}
// todo: enable
// CHECKSTYLE: IGNORE 1
if (false && RexUtil.containNoCommonExprs(exprs, litmus)) {
return litmus.fail(null);
}
if (!RexUtil.containNoForwardRefs(exprs, inputRowType, litmus)) {
return litmus.fail(null);
}
if (!RexUtil.containNoNonTrivialAggs(exprs, litmus)) {
return litmus.fail(null);
}
final Checker checker =
new Checker(inputRowType, RexUtil.types(exprs), null, litmus);
if (condition != null) {
if (!SqlTypeUtil.inBooleanFamily(condition.getType())) {
return litmus.fail("condition must be boolean");
}
condition.accept(checker);
if (checker.failCount > 0) {
return litmus.fail(null);
}
}
for (RexLocalRef project : projects) {
project.accept(checker);
if (checker.failCount > 0) {
return litmus.fail(null);
}
}
for (RexNode expr : exprs) {
expr.accept(checker);
if (checker.failCount > 0) {
return litmus.fail(null);
}
}
return litmus.succeed();
}
/**
* Returns whether an expression always evaluates to null.
*
*
Like {@link RexUtil#isNull(RexNode)}, null literals are null, and
* casts of null literals are null. But this method also regards references
* to null expressions as null.
*
* @param expr Expression
* @return Whether expression always evaluates to null
*/
public boolean isNull(RexNode expr) {
switch (expr.getKind()) {
case LITERAL:
return ((RexLiteral) expr).getValue2() == null;
case LOCAL_REF:
RexLocalRef inputRef = (RexLocalRef) expr;
return isNull(exprs.get(inputRef.index));
case CAST:
return isNull(((RexCall) expr).operands.get(0));
default:
return false;
}
}
/**
* Fully expands a RexLocalRef back into a pure RexNode tree containing no
* RexLocalRefs (reversing the effect of common subexpression elimination).
* For example, program.expandLocalRef(program.getCondition())
* will return the expansion of a program's condition.
*
* @param ref a RexLocalRef from this program
* @return expanded form
*/
public RexNode expandLocalRef(RexLocalRef ref) {
return ref.accept(new ExpansionShuttle(exprs));
}
/** Splits this program into a list of project expressions and a list of
* filter expressions.
*
* Neither list is null.
* The filters are evaluated first. */
public Pair, ImmutableList> split() {
final List filters = new ArrayList<>();
if (condition != null) {
RelOptUtil.decomposeConjunction(expandLocalRef(condition), filters);
}
final ImmutableList.Builder projects = ImmutableList.builder();
for (RexLocalRef project : this.projects) {
projects.add(expandLocalRef(project));
}
return Pair.of(projects.build(), ImmutableList.copyOf(filters));
}
/**
* Given a list of collations which hold for the input to this program,
* returns a list of collations which hold for its output. The result is
* mutable and sorted.
*/
public List getCollations(List inputCollations) {
final List outputCollations = new ArrayList<>();
deduceCollations(
outputCollations,
inputRowType.getFieldCount(), projects,
inputCollations);
return outputCollations;
}
/**
* Given a list of expressions and a description of which are ordered,
* populates a list of collations, sorted in natural order.
*/
public static void deduceCollations(
List outputCollations,
final int sourceCount,
List refs,
List inputCollations) {
int[] targets = new int[sourceCount];
Arrays.fill(targets, -1);
for (int i = 0; i < refs.size(); i++) {
final RexLocalRef ref = refs.get(i);
final int source = ref.getIndex();
if ((source < sourceCount) && (targets[source] == -1)) {
targets[source] = i;
}
}
loop:
for (RelCollation collation : inputCollations) {
final List fieldCollations = new ArrayList<>(0);
for (RelFieldCollation fieldCollation : collation.getFieldCollations()) {
final int source = fieldCollation.getFieldIndex();
final int target = targets[source];
if (target < 0) {
continue loop;
}
fieldCollations.add(
fieldCollation.copy(target));
}
// Success -- all of the source fields of this key are mapped
// to the output.
outputCollations.add(RelCollations.of(fieldCollations));
}
outputCollations.sort(Ordering.natural());
}
/**
* Returns whether the fields on the leading edge of the project list are
* the input fields.
*
* @param fail Whether to throw an assert failure if does not project
* identity
*/
public boolean projectsIdentity(final boolean fail) {
final int fieldCount = inputRowType.getFieldCount();
if (projects.size() < fieldCount) {
assert !fail
: "program '" + toString()
+ "' does not project identity for input row type '"
+ inputRowType + "'";
return false;
}
for (int i = 0; i < fieldCount; i++) {
RexLocalRef project = projects.get(i);
if (project.index != i) {
assert !fail
: "program " + toString()
+ "' does not project identity for input row type '"
+ inputRowType + "', field #" + i;
return false;
}
}
return true;
}
/**
* Returns whether this program projects precisely its input fields. It may
* or may not apply a condition.
*/
public boolean projectsOnlyIdentity() {
if (projects.size() != inputRowType.getFieldCount()) {
return false;
}
for (int i = 0; i < projects.size(); i++) {
RexLocalRef project = projects.get(i);
if (project.index != i) {
return false;
}
}
return true;
}
/**
* Returns whether this program returns its input exactly.
*
* This is a stronger condition than {@link #projectsIdentity(boolean)}.
*/
public boolean isTrivial() {
return getCondition() == null && projectsOnlyIdentity();
}
/**
* Gets reference counts for each expression in the program, where the
* references are detected from later expressions in the same program, as
* well as the project list and condition. Expressions with references
* counts greater than 1 are true common sub-expressions.
*
* @return array of reference counts; the ith element in the returned array
* is the number of references to getExprList()[i]
*/
public int[] getReferenceCounts() {
if (refCounts != null) {
return refCounts;
}
refCounts = new int[exprs.size()];
ReferenceCounter refCounter = new ReferenceCounter();
RexUtil.apply(refCounter, exprs, null);
if (condition != null) {
refCounter.visitLocalRef(condition);
}
for (RexLocalRef project : projects) {
refCounter.visitLocalRef(project);
}
return refCounts;
}
/**
* Returns whether an expression is constant.
*/
public boolean isConstant(RexNode ref) {
return ref.accept(new ConstantFinder());
}
public RexNode gatherExpr(RexNode expr) {
return expr.accept(new Marshaller());
}
/**
* Returns the input field that an output field is populated from, or -1 if
* it is populated from an expression.
*/
public int getSourceField(int outputOrdinal) {
assert (outputOrdinal >= 0) && (outputOrdinal < this.projects.size());
RexLocalRef project = projects.get(outputOrdinal);
int index = project.index;
while (true) {
RexNode expr = exprs.get(index);
if (expr instanceof RexCall
&& ((RexCall) expr).getOperator()
== SqlStdOperatorTable.IN_FENNEL) {
// drill through identity function
expr = ((RexCall) expr).getOperands().get(0);
}
if (expr instanceof RexLocalRef) {
index = ((RexLocalRef) expr).index;
} else if (expr instanceof RexInputRef) {
return ((RexInputRef) expr).index;
} else {
return -1;
}
}
}
/**
* Returns whether this program is a permutation of its inputs.
*/
public boolean isPermutation() {
if (projects.size() != inputRowType.getFieldList().size()) {
return false;
}
for (int i = 0; i < projects.size(); ++i) {
if (getSourceField(i) < 0) {
return false;
}
}
return true;
}
/**
* Returns a permutation, if this program is a permutation, otherwise null.
*/
public Permutation getPermutation() {
Permutation permutation = new Permutation(projects.size());
if (projects.size() != inputRowType.getFieldList().size()) {
return null;
}
for (int i = 0; i < projects.size(); ++i) {
int sourceField = getSourceField(i);
if (sourceField < 0) {
return null;
}
permutation.set(i, sourceField);
}
return permutation;
}
/**
* Returns the set of correlation variables used (read) by this program.
*
* @return set of correlation variable names
*/
public Set getCorrelVariableNames() {
final Set paramIdSet = new HashSet<>();
RexUtil.apply(
new RexVisitorImpl(true) {
public Void visitCorrelVariable(
RexCorrelVariable correlVariable) {
paramIdSet.add(correlVariable.getName());
return null;
}
},
exprs,
null);
return paramIdSet;
}
/**
* Returns whether this program is in canonical form.
*
* @param litmus What to do if an error is detected (program is not in
* canonical form)
* @param rexBuilder Rex builder
* @return whether in canonical form
*/
public boolean isNormalized(Litmus litmus, RexBuilder rexBuilder) {
final RexProgram normalizedProgram = normalize(rexBuilder, null);
String normalized = normalizedProgram.toString();
String string = toString();
if (!normalized.equals(string)) {
final String message = "Program is not normalized:\n"
+ "program: {}\n"
+ "normalized: {}\n";
return litmus.fail(message, string, normalized);
}
return litmus.succeed();
}
/**
* Creates a simplified/normalized copy of this program.
*
* @param rexBuilder Rex builder
* @param simplify Simplifier to simplify (in addition to normalizing),
* or null to not simplify
* @return Normalized program
*/
public RexProgram normalize(RexBuilder rexBuilder, RexSimplify simplify) {
// Normalize program by creating program builder from the program, then
// converting to a program. getProgram does not need to normalize
// because the builder was normalized on creation.
assert isValid(Litmus.THROW, null);
final RexProgramBuilder builder =
RexProgramBuilder.create(rexBuilder, inputRowType, exprs, projects,
condition, outputRowType, true, simplify);
return builder.getProgram(false);
}
@Deprecated // to be removed before 2.0
public RexProgram normalize(RexBuilder rexBuilder, boolean simplify) {
final RelOptPredicateList predicates = RelOptPredicateList.EMPTY;
return normalize(rexBuilder, simplify
? new RexSimplify(rexBuilder, predicates, false, RexUtil.EXECUTOR)
: null);
}
//~ Inner Classes ----------------------------------------------------------
/**
* Visitor which walks over a program and checks validity.
*/
static class Checker extends RexChecker {
private final List internalExprTypeList;
/**
* Creates a Checker.
*
* @param inputRowType Types of the input fields
* @param internalExprTypeList Types of the internal expressions
* @param context Context of the enclosing {@link RelNode},
* or null
* @param litmus Whether to fail
*/
Checker(RelDataType inputRowType,
List internalExprTypeList, RelNode.Context context,
Litmus litmus) {
super(inputRowType, context, litmus);
this.internalExprTypeList = internalExprTypeList;
}
/** Overrides {@link RexChecker} method, because {@link RexLocalRef} is
* is illegal in most rex expressions, but legal in a program. */
@Override public Boolean visitLocalRef(RexLocalRef localRef) {
final int index = localRef.getIndex();
if ((index < 0) || (index >= internalExprTypeList.size())) {
++failCount;
return litmus.fail(null);
}
if (!RelOptUtil.eq(
"type1",
localRef.getType(),
"type2",
internalExprTypeList.get(index), litmus)) {
++failCount;
return litmus.fail(null);
}
return litmus.succeed();
}
}
/**
* A RexShuttle used in the implementation of
* {@link RexProgram#expandLocalRef}.
*/
static class ExpansionShuttle extends RexShuttle {
private final List exprs;
ExpansionShuttle(List exprs) {
this.exprs = exprs;
}
public RexNode visitLocalRef(RexLocalRef localRef) {
RexNode tree = exprs.get(localRef.getIndex());
return tree.accept(this);
}
}
/**
* Walks over an expression and determines whether it is constant.
*/
private class ConstantFinder extends RexUtil.ConstantFinder {
@Override public Boolean visitLocalRef(RexLocalRef localRef) {
final RexNode expr = exprs.get(localRef.index);
return expr.accept(this);
}
@Override public Boolean visitOver(RexOver over) {
return false;
}
@Override public Boolean visitCorrelVariable(RexCorrelVariable correlVariable) {
// Correlating variables are constant WITHIN A RESTART, so that's
// good enough.
return true;
}
}
/**
* Given an expression in a program, creates a clone of the expression with
* sub-expressions (represented by {@link RexLocalRef}s) fully expanded.
*/
private class Marshaller extends RexVisitorImpl {
Marshaller() {
super(false);
}
public RexNode visitInputRef(RexInputRef inputRef) {
return inputRef;
}
public RexNode visitLocalRef(RexLocalRef localRef) {
final RexNode expr = exprs.get(localRef.index);
return expr.accept(this);
}
public RexNode visitLiteral(RexLiteral literal) {
return literal;
}
public RexNode visitCall(RexCall call) {
final List newOperands = new ArrayList<>();
for (RexNode operand : call.getOperands()) {
newOperands.add(operand.accept(this));
}
return call.clone(call.getType(), newOperands);
}
public RexNode visitOver(RexOver over) {
return visitCall(over);
}
public RexNode visitCorrelVariable(RexCorrelVariable correlVariable) {
return correlVariable;
}
public RexNode visitDynamicParam(RexDynamicParam dynamicParam) {
return dynamicParam;
}
public RexNode visitRangeRef(RexRangeRef rangeRef) {
return rangeRef;
}
public RexNode visitFieldAccess(RexFieldAccess fieldAccess) {
final RexNode referenceExpr =
fieldAccess.getReferenceExpr().accept(this);
return new RexFieldAccess(
referenceExpr,
fieldAccess.getField());
}
}
/**
* Visitor which marks which expressions are used.
*/
private class ReferenceCounter extends RexVisitorImpl {
ReferenceCounter() {
super(true);
}
public Void visitLocalRef(RexLocalRef localRef) {
final int index = localRef.getIndex();
refCounts[index]++;
return null;
}
}
}
// End RexProgram.java