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[CALCITE-4099] Unify Strong.Policy and NullPolicy #4630

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[CALCITE-4099] Unify Strong.Policy and NullPolicy #4630

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4 changes: 4 additions & 0 deletions core/src/main/java/org/apache/calcite/adapter/enumerable/NullPolicy.java
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Original file line number Diff line number Diff line change
Expand Up @@ -38,5 +38,9 @@ public enum NullPolicy {
ANY,
/** If the first argument is null, return null. */
ARG0,
/** Never returns null no matter the values of the arguments. */
NEVER,
/** Returns null under certain conditions that depend entirely on the operator/function.
* Operators using this policy have custom rules for when to return null.*/
NONE
}
41 changes: 28 additions & 13 deletions core/src/main/java/org/apache/calcite/adapter/enumerable/RexImpTable.java
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Expand Up @@ -1138,9 +1138,9 @@ void populate2() {
define(NOT_SUBMULTISET_OF, NotImplementor.of(subMultisetImplementor));

define(COALESCE, new CoalesceImplementor());
define(CAST, new CastImplementor());
define(SAFE_CAST, new CastImplementor());
define(TRY_CAST, new CastImplementor());
define(CAST, new CastImplementor(NullPolicy.STRICT));
define(SAFE_CAST, new CastImplementor(NullPolicy.SEMI_STRICT));
define(TRY_CAST, new CastImplementor(NullPolicy.SEMI_STRICT));

define(REINTERPRET, new ReinterpretImplementor());
define(CONVERT, new ConvertImplementor());
Expand Down Expand Up @@ -1539,6 +1539,20 @@ public TableFunctionCallImplementor get(final SqlWindowTableFunction operator) {
}
}

/**
* Returns the NullPolicy for the specified operator.
*
* @param operator the operator
* @return the NullPolicy for the specified operator, or null if a policy is undefined.
*/
public @Nullable NullPolicy getPolicy(SqlOperator operator) {
final RexCallImplementor implementor = get(operator);
if (implementor instanceof AbstractRexCallImplementor) {
return ((AbstractRexCallImplementor) implementor).nullPolicy;
}
return null;
}

static Expression optimize(Expression expression) {
return expression.accept(new OptimizeShuttle());
}
Expand Down Expand Up @@ -3644,8 +3658,8 @@ private static Expression implementRecurse(RexToLixTranslator translator,

/** Implementor for the SQL {@code CAST} operator. */
private static class CastImplementor extends AbstractRexCallImplementor {
CastImplementor() {
super("cast", NullPolicy.STRICT, false);
CastImplementor(NullPolicy nullPolicy) {
super("cast", nullPolicy, false);
}

@Override Expression implementSafe(final RexToLixTranslator translator,
Expand Down Expand Up @@ -4392,6 +4406,7 @@ private List<Expression> unboxIfNecessary(final List<Expression> argValueList) {
switch (nullPolicy) {
case STRICT:
case SEMI_STRICT:
case NEVER:
return Util.transform(argValueList,
AbstractRexCallImplementor::unboxExpression);
case ARG0:
Expand Down Expand Up @@ -4544,7 +4559,7 @@ private static class LogicalOrImplementor extends AbstractRexCallImplementor {
*/
private static class LogicalNotImplementor extends AbstractRexCallImplementor {
LogicalNotImplementor() {
super("logical_not", NullPolicy.NONE, true);
super("logical_not", NullPolicy.STRICT, true);
}

@Override Expression implementSafe(final RexToLixTranslator translator,
Expand Down Expand Up @@ -4714,7 +4729,7 @@ private static class PiImplementor extends AbstractRexCallImplementor {
/** Implementor for the {@code IS FALSE} SQL operator. */
private static class IsFalseImplementor extends AbstractRexCallImplementor {
IsFalseImplementor() {
super("is_false", NullPolicy.STRICT, false);
super("is_false", NullPolicy.NEVER, false);
}

@Override Expression getIfTrue(Type type, final List<Expression> argValueList) {
Expand All @@ -4730,7 +4745,7 @@ private static class IsFalseImplementor extends AbstractRexCallImplementor {
/** Implementor for the {@code IS NOT FALSE} SQL operator. */
private static class IsNotFalseImplementor extends AbstractRexCallImplementor {
IsNotFalseImplementor() {
super("is_not_false", NullPolicy.STRICT, false);
super("is_not_false", NullPolicy.NEVER, false);
}

@Override Expression getIfTrue(Type type, final List<Expression> argValueList) {
Expand All @@ -4746,7 +4761,7 @@ private static class IsNotFalseImplementor extends AbstractRexCallImplementor {
/** Implementor for the {@code IS NOT NULL} SQL operator. */
private static class IsNotNullImplementor extends AbstractRexCallImplementor {
IsNotNullImplementor() {
super("is_not_null", NullPolicy.STRICT, false);
super("is_not_null", NullPolicy.NEVER, false);
}

@Override Expression getIfTrue(Type type, final List<Expression> argValueList) {
Expand All @@ -4762,7 +4777,7 @@ private static class IsNotNullImplementor extends AbstractRexCallImplementor {
/** Implementor for the {@code IS NOT TRUE} SQL operator. */
private static class IsNotTrueImplementor extends AbstractRexCallImplementor {
IsNotTrueImplementor() {
super("is_not_true", NullPolicy.STRICT, false);
super("is_not_true", NullPolicy.NEVER, false);
}

@Override Expression getIfTrue(Type type, final List<Expression> argValueList) {
Expand All @@ -4778,7 +4793,7 @@ private static class IsNotTrueImplementor extends AbstractRexCallImplementor {
/** Implementor for the {@code IS NULL} SQL operator. */
private static class IsNullImplementor extends AbstractRexCallImplementor {
IsNullImplementor() {
super("is_null", NullPolicy.STRICT, false);
super("is_null", NullPolicy.NEVER, false);
}

@Override Expression getIfTrue(Type type, final List<Expression> argValueList) {
Expand All @@ -4794,7 +4809,7 @@ private static class IsNullImplementor extends AbstractRexCallImplementor {
/** Implementor for the {@code IS NOT DISTINCT FROM} SQL operator. */
private static class IsNotDistinctFromImplementor extends AbstractRexCallImplementor {
IsNotDistinctFromImplementor() {
super("is_not_distinct_from", NullPolicy.NONE, false);
super("is_not_distinct_from", NullPolicy.NEVER, false);
}

@Override public RexToLixTranslator.Result implement(final RexToLixTranslator translator,
Expand Down Expand Up @@ -4840,7 +4855,7 @@ private static class IsNotDistinctFromImplementor extends AbstractRexCallImpleme
/** Implementor for the {@code IS TRUE} SQL operator. */
private static class IsTrueImplementor extends AbstractRexCallImplementor {
IsTrueImplementor() {
super("is_true", NullPolicy.STRICT, false);
super("is_true", NullPolicy.NEVER, false);
}

@Override Expression getIfTrue(Type type, final List<Expression> argValueList) {
Expand Down
59 changes: 50 additions & 9 deletions core/src/main/java/org/apache/calcite/plan/Strong.java
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Expand Up @@ -16,6 +16,7 @@
*/
package org.apache.calcite.plan;

import org.apache.calcite.adapter.enumerable.NullPolicy;
import org.apache.calcite.rex.RexCall;
import org.apache.calcite.rex.RexFieldAccess;
import org.apache.calcite.rex.RexInputRef;
Expand All @@ -35,6 +36,8 @@
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Iterables;

import org.checkerframework.checker.nullness.qual.Nullable;

import java.util.ArrayList;
import java.util.EnumMap;
import java.util.List;
Expand Down Expand Up @@ -116,6 +119,7 @@ public static Policy policy(SqlKind kind) {
* Returns how to deduce whether a particular {@link RexNode} expression is null,
* given whether its arguments are null.
*/
@Deprecated
public static Policy policy(RexNode rexNode) {
if (rexNode instanceof RexCall) {
return policy(((RexCall) rexNode).getOperator());
Expand All @@ -127,13 +131,28 @@ public static Policy policy(RexNode rexNode) {
* Returns how to deduce whether a particular {@link SqlOperator} expression is null,
* given whether its arguments are null.
*/
@Deprecated
public static Policy policy(SqlOperator operator) {
if (operator.getStrongPolicyInference() != null) {
return operator.getStrongPolicyInference().get();
}
return MAP.getOrDefault(operator.getKind(), Policy.AS_IS);
}

/**
* Returns the {@link NullPolicy} for a given {@link SqlKind}.
*
* @param kind SqlKind
* @return NullPolicy or null if not defined
*/
public static @Nullable NullPolicy nullPolicy(SqlKind kind) {
Policy p = MAP.get(kind);
if (p != null) {
return p.nullPolicy();
}
return null;
}

/**
* Returns whether a given expression is strong.
*
Expand Down Expand Up @@ -207,14 +226,17 @@ private boolean anyNotTrue(List<RexNode> operands) {
* expressions, and you may override methods to test hypotheses such as
* "if {@code x} is null, is {@code x + y} null? */
public boolean isNull(RexNode node) {
final Policy policy = policy(node);
switch (policy) {
case NOT_NULL:
return false;
case ANY:
return anyNull(((RexCall) node).getOperands());
default:
break;
if (node instanceof RexCall) {
RexCall call = (RexCall) node;
final NullPolicy policy = call.getOperator().getNullPolicy();
switch (policy) {
case NEVER:
return false;
case STRICT:
return anyNull(call.getOperands());
default:
break;
}
}

switch (node.getKind()) {
Expand Down Expand Up @@ -383,6 +405,7 @@ private static Map<SqlKind, Policy> createPolicyMap() {

/** How whether an operator's operands are null affects whether a call to
* that operator evaluates to null. */
@Deprecated
public enum Policy {
/** This kind of expression is never null. No need to look at its arguments,
* if it has any. */
Expand All @@ -397,6 +420,24 @@ public enum Policy {
ANY,

/** This kind of expression may be null. There is no way to rewrite. */
AS_IS,
AS_IS;

/**
* Returns the corresponding {@link NullPolicy}.
*
* @return the corresponding NullPolicy
*/
NullPolicy nullPolicy() {
switch (this) {
case NOT_NULL:
return NullPolicy.NEVER;
case ANY:
return NullPolicy.STRICT;
case CUSTOM:
case AS_IS:
default:
return NullPolicy.NONE;
}
}
}
}
34 changes: 18 additions & 16 deletions core/src/main/java/org/apache/calcite/rex/RexSimplify.java
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Expand Up @@ -16,6 +16,7 @@
*/
package org.apache.calcite.rex;

import org.apache.calcite.adapter.enumerable.NullPolicy;
import org.apache.calcite.avatica.util.TimeUnit;
import org.apache.calcite.avatica.util.TimeUnitRange;
import org.apache.calcite.plan.RelOptPredicateList;
Expand Down Expand Up @@ -1158,10 +1159,10 @@ private RexNode simplifyIs(RexCall call, RexUnknownAs unknownAs) {
if (hasCustomNullabilityRules(a.getKind())) {
return null;
}
switch (Strong.policy(a)) {
case NOT_NULL:
switch (policy(a)) {
case NEVER:
return rexBuilder.makeLiteral(true);
case ANY:
case STRICT:
// "f" is a strong operator, so "f(operand0, operand1) IS NOT NULL"
// simplifies to "operand0 IS NOT NULL AND operand1 IS NOT NULL"
final List<RexNode> operands = new ArrayList<>();
Expand All @@ -1177,16 +1178,11 @@ private RexNode simplifyIs(RexCall call, RexUnknownAs unknownAs) {
}
}
return RexUtil.composeConjunction(rexBuilder, operands);
case CUSTOM:
default:
switch (a.getKind()) {
case LITERAL:
return rexBuilder.makeLiteral(!((RexLiteral) a).isNull());
default:
throw new AssertionError("every CUSTOM policy needs a handler, "
+ a.getKind());
}
case AS_IS:
default:
return null;
}
}
Expand All @@ -1213,10 +1209,10 @@ private RexNode simplifyIs(RexCall call, RexUnknownAs unknownAs) {
if (hasCustomNullabilityRules(a.getKind())) {
return null;
}
switch (Strong.policy(a)) {
case NOT_NULL:
switch (policy(a)) {
case NEVER:
return rexBuilder.makeLiteral(false);
case ANY:
case STRICT:
// "f" is a strong operator, so "f(operand0, operand1) IS NULL" simplifies
// to "operand0 IS NULL OR operand1 IS NULL"
final List<RexNode> operands = new ArrayList<>();
Expand All @@ -1230,7 +1226,6 @@ private RexNode simplifyIs(RexCall call, RexUnknownAs unknownAs) {
}
}
return RexUtil.composeDisjunction(rexBuilder, operands, false);
case AS_IS:
default:
return null;
}
Expand All @@ -1246,11 +1241,11 @@ private static void validateStrongPolicy(RexNode rexNode) {
if (hasCustomNullabilityRules(rexNode.getKind())) {
return;
}
switch (Strong.policy(rexNode)) {
case NOT_NULL:
switch (policy(rexNode)) {
case NEVER:
assert !rexNode.getType().isNullable();
break;
case ANY:
case STRICT:
List<RexNode> operands = ((RexCall) rexNode).getOperands();
if (rexNode.getType().isNullable()) {
assert operands.stream()
Expand All @@ -1267,6 +1262,13 @@ private static void validateStrongPolicy(RexNode rexNode) {
}
}

private static NullPolicy policy(RexNode node) {
if (node instanceof RexCall) {
return ((RexCall) node).getOperator().getNullPolicy();
}
return NullPolicy.NONE;
}

/**
* Returns {@code true} if specified {@link SqlKind} has custom nullability rules which
* depend not only on the nullability of input operands.
Expand Down
22 changes: 22 additions & 0 deletions core/src/main/java/org/apache/calcite/sql/SqlOperator.java
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Expand Up @@ -16,6 +16,8 @@
*/
package org.apache.calcite.sql;

import org.apache.calcite.adapter.enumerable.NullPolicy;
import org.apache.calcite.adapter.enumerable.RexImpTable;
import org.apache.calcite.linq4j.Ord;
import org.apache.calcite.plan.Strong;
import org.apache.calcite.rel.type.RelDataType;
Expand Down Expand Up @@ -1033,10 +1035,30 @@ public <R> void acceptCall(
* @see Strong
*/
@Pure
@Deprecated
public @Nullable Supplier<Strong.Policy> getStrongPolicyInference() {
return null;
}

/**
* Returns the null policy for this operator.
*
* @return the null policy for this operator
*/
public NullPolicy getNullPolicy() {
NullPolicy p = RexImpTable.INSTANCE.getPolicy(this);
if (p != null) {
return p;
}
p = Strong.nullPolicy(getKind());
if (p != null) {
assert p == NullPolicy.NONE
: p + " policy is only defined via SqlKind for " + this.getName();
return p;
}
return NullPolicy.NONE;
}

/**
* Returns whether this is a safe operator.
*
Expand Down
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