/**
* 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.drill.exec.compile.sig;
import java.util.Collections;
import java.util.IdentityHashMap;
import java.util.List;
import java.util.Set;
import org.apache.drill.common.expression.BooleanOperator;
import org.apache.drill.common.expression.CastExpression;
import org.apache.drill.common.expression.ConvertExpression;
import org.apache.drill.common.expression.FunctionCall;
import org.apache.drill.common.expression.FunctionHolderExpression;
import org.apache.drill.common.expression.IfExpression;
import org.apache.drill.common.expression.LogicalExpression;
import org.apache.drill.common.expression.NullExpression;
import org.apache.drill.common.expression.SchemaPath;
import org.apache.drill.common.expression.TypedNullConstant;
import org.apache.drill.common.expression.ValueExpressions;
import org.apache.drill.common.expression.ValueExpressions.BooleanExpression;
import org.apache.drill.common.expression.ValueExpressions.DateExpression;
import org.apache.drill.common.expression.ValueExpressions.Decimal18Expression;
import org.apache.drill.common.expression.ValueExpressions.Decimal28Expression;
import org.apache.drill.common.expression.ValueExpressions.Decimal38Expression;
import org.apache.drill.common.expression.ValueExpressions.Decimal9Expression;
import org.apache.drill.common.expression.ValueExpressions.DoubleExpression;
import org.apache.drill.common.expression.ValueExpressions.IntervalDayExpression;
import org.apache.drill.common.expression.ValueExpressions.IntervalYearExpression;
import org.apache.drill.common.expression.ValueExpressions.LongExpression;
import org.apache.drill.common.expression.ValueExpressions.QuotedString;
import org.apache.drill.common.expression.ValueExpressions.TimeExpression;
import org.apache.drill.common.expression.ValueExpressions.TimeStampExpression;
import org.apache.drill.common.expression.visitors.ExprVisitor;
import com.google.common.collect.Lists;
public class ConstantExpressionIdentifier implements ExprVisitor<Boolean, IdentityHashMap<LogicalExpression, Object>, RuntimeException>{
static final org.slf4j.Logger logger = org.slf4j.LoggerFactory.getLogger(ConstantExpressionIdentifier.class);
private ConstantExpressionIdentifier(){}
/**
* Get a list of expressions that mark boundaries into a constant space.
* @param e
* @return
*/
public static Set<LogicalExpression> getConstantExpressionSet(LogicalExpression e){
IdentityHashMap<LogicalExpression, Object> map = new IdentityHashMap<>();
ConstantExpressionIdentifier visitor = new ConstantExpressionIdentifier();
if(e.accept(visitor, map) && map.isEmpty()){
// if we receive a constant value here but the map is empty, this means the entire tree is a constant.
// note, we can't use a singleton collection here because we need an identity set.
map.put(e, true);
return map.keySet();
}else if(map.isEmpty()){
// so we don't continue to carry around a map, we let it go here and simply return an empty set.
return Collections.emptySet();
}else{
return map.keySet();
}
}
private boolean checkChildren(LogicalExpression e, IdentityHashMap<LogicalExpression, Object> value, boolean transmitsConstant){
List<LogicalExpression> constants = Lists.newLinkedList();
boolean constant = true;
for(LogicalExpression child : e){
if(child.accept(this, value)){
constants.add(child);
}else{
constant = false;
}
}
// if one or more clauses isn't constant, this isn't constant. this also isn't a constant if it operates on a set.
if(!constant || !transmitsConstant){
for(LogicalExpression c: constants){
value.put(c, true);
}
}
return constant && transmitsConstant;
}
@Override
public Boolean visitFunctionCall(FunctionCall call, IdentityHashMap<LogicalExpression, Object> value){
throw new UnsupportedOperationException("FunctionCall is not expected here. "+
"It should have been converted to FunctionHolderExpression in materialization");
}
@Override
public Boolean visitFunctionHolderExpression(FunctionHolderExpression holder, IdentityHashMap<LogicalExpression, Object> value) throws RuntimeException {
return checkChildren(holder, value, !holder.isAggregating() && !holder.isRandom());
}
@Override
public Boolean visitBooleanOperator(BooleanOperator op, IdentityHashMap<LogicalExpression, Object> value) throws RuntimeException {
return checkChildren(op, value, true);
}
@Override
public Boolean visitIfExpression(IfExpression ifExpr, IdentityHashMap<LogicalExpression, Object> value){
return checkChildren(ifExpr, value, true);
}
@Override
public Boolean visitSchemaPath(SchemaPath path, IdentityHashMap<LogicalExpression, Object> value){
return false;
}
@Override
public Boolean visitIntConstant(ValueExpressions.IntExpression intExpr, IdentityHashMap<LogicalExpression, Object> value) throws RuntimeException {
return true;
}
@Override
public Boolean visitFloatConstant(ValueExpressions.FloatExpression fExpr, IdentityHashMap<LogicalExpression, Object> value) throws RuntimeException {
return true;
}
@Override
public Boolean visitLongConstant(LongExpression intExpr, IdentityHashMap<LogicalExpression, Object> value){
return true;
}
@Override
public Boolean visitDateConstant(DateExpression intExpr, IdentityHashMap<LogicalExpression, Object> value){
return true;
}
@Override
public Boolean visitDecimal9Constant(Decimal9Expression decExpr, IdentityHashMap<LogicalExpression, Object> value){
return true;
}
@Override
public Boolean visitTimeConstant(TimeExpression intExpr, IdentityHashMap<LogicalExpression, Object> value){
return true;
}
@Override
public Boolean visitDecimal18Constant(Decimal18Expression decExpr, IdentityHashMap<LogicalExpression, Object> value){
return true;
}
@Override
public Boolean visitIntervalYearConstant(IntervalYearExpression intExpr, IdentityHashMap<LogicalExpression, Object> value){
return true;
}
@Override
public Boolean visitDecimal28Constant(Decimal28Expression decExpr, IdentityHashMap<LogicalExpression, Object> value){
return true;
}
@Override
public Boolean visitIntervalDayConstant(IntervalDayExpression intExpr, IdentityHashMap<LogicalExpression, Object> value){
return true;
}
@Override
public Boolean visitTimeStampConstant(TimeStampExpression intExpr, IdentityHashMap<LogicalExpression, Object> value){
return true;
}
@Override
public Boolean visitDecimal38Constant(Decimal38Expression decExpr, IdentityHashMap<LogicalExpression, Object> value){
return true;
}
@Override
public Boolean visitDoubleConstant(DoubleExpression dExpr, IdentityHashMap<LogicalExpression, Object> value){
return true;
}
@Override
public Boolean visitBooleanConstant(BooleanExpression e, IdentityHashMap<LogicalExpression, Object> value){
return true;
}
@Override
public Boolean visitQuotedStringConstant(QuotedString e, IdentityHashMap<LogicalExpression, Object> value){
return true;
}
@Override
public Boolean visitCastExpression(CastExpression e, IdentityHashMap<LogicalExpression, Object> value)
throws RuntimeException {
return e.getInput().accept(this, value);
}
@Override
public Boolean visitUnknown(LogicalExpression e, IdentityHashMap<LogicalExpression, Object> value){
return checkChildren(e, value, false);
}
@Override
public Boolean visitNullConstant(TypedNullConstant e, IdentityHashMap<LogicalExpression, Object> value) throws RuntimeException {
return true;
}
@Override
public Boolean visitNullExpression(NullExpression e, IdentityHashMap<LogicalExpression, Object> value) throws RuntimeException {
return true;
}
@Override
public Boolean visitConvertExpression(ConvertExpression e,
IdentityHashMap<LogicalExpression, Object> value) throws RuntimeException {
return e.getInput().accept(this, value);
}
}