morrySnow commented on code in PR #11802: URL: https://github.com/apache/doris/pull/11802#discussion_r950983767
########## fe/fe-core/src/main/java/org/apache/doris/nereids/rules/expression/rewrite/rules/TypeCoercion.java: ########## @@ -0,0 +1,180 @@ +// 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.doris.nereids.rules.expression.rewrite.rules; + +import org.apache.doris.nereids.annotation.Developing; +import org.apache.doris.nereids.rules.expression.rewrite.AbstractExpressionRewriteRule; +import org.apache.doris.nereids.rules.expression.rewrite.ExpressionRewriteContext; +import org.apache.doris.nereids.trees.expressions.BinaryOperator; +import org.apache.doris.nereids.trees.expressions.CaseWhen; +import org.apache.doris.nereids.trees.expressions.Cast; +import org.apache.doris.nereids.trees.expressions.Expression; +import org.apache.doris.nereids.trees.expressions.InPredicate; +import org.apache.doris.nereids.trees.expressions.typecoercion.ImplicitCastInputTypes; +import org.apache.doris.nereids.types.DataType; +import org.apache.doris.nereids.types.coercion.AbstractDataType; +import org.apache.doris.nereids.util.TypeCoercionUtils; + +import com.google.common.collect.Lists; + +import java.util.List; +import java.util.Optional; +import java.util.concurrent.atomic.AtomicInteger; +import java.util.stream.Collectors; + +/** + * a rule to add implicit cast for expressions. + * This class is inspired by spark's TypeCoercion. + */ +@Developing +public class TypeCoercion extends AbstractExpressionRewriteRule { + + // TODO: + // 1. DecimalPrecision Process + // 2. Divide process + // 3. String promote with numeric in binary arithmetic + // 4. Date and DateTime process + + public static final TypeCoercion INSTANCE = new TypeCoercion(); + + @Override + public Expression rewrite(Expression expr, ExpressionRewriteContext ctx) { + if (expr instanceof ImplicitCastInputTypes) { + return visitImplicitCastInputTypes(expr, ctx); + } else { + return super.rewrite(expr, ctx); + } + } + + // TODO: add other expression visitor function to do type coercion if necessary. + + @Override + public Expression visitBinaryOperator(BinaryOperator binaryOperator, ExpressionRewriteContext context) { + Expression left = rewrite(binaryOperator.left(), context); + Expression right = rewrite(binaryOperator.right(), context); + + return Optional.of(TypeCoercionUtils.canHandleTypeCoercion(left.getDataType(), right.getDataType())) + .filter(Boolean::booleanValue) + .map(b -> TypeCoercionUtils.findTightestCommonType(left.getDataType(), right.getDataType())) + .filter(Optional::isPresent) + .map(Optional::get) + .filter(ct -> binaryOperator.inputType().acceptsType(ct)) + .filter(ct -> !left.getDataType().equals(ct) || !right.getDataType().equals(ct)) + .map(commonType -> { + Expression newLeft = TypeCoercionUtils.castIfNotSameType(left, commonType); + Expression newRight = TypeCoercionUtils.castIfNotSameType(right, commonType); + return binaryOperator.withChildren(newLeft, newRight); + }) + .orElse(binaryOperator.withChildren(left, right)); + } + + @Override + public Expression visitCaseWhen(CaseWhen caseWhen, ExpressionRewriteContext context) { + List<Expression> rewrittenChildren = caseWhen.children().stream() + .map(e -> rewrite(e, context)).collect(Collectors.toList()); + CaseWhen newCaseWhen = caseWhen.withChildren(rewrittenChildren); + List<DataType> dataTypesForCoercion = newCaseWhen.dataTypesForCoercion(); + if (dataTypesForCoercion.size() <= 1) { + return newCaseWhen; + } + DataType first = dataTypesForCoercion.get(0); + if (dataTypesForCoercion.stream().allMatch(dataType -> dataType.equals(first))) { + return newCaseWhen; + } + Optional<DataType> optionalCommonType = TypeCoercionUtils.findWiderCommonType(dataTypesForCoercion); + return optionalCommonType + .map(commonType -> { + List<Expression> newChildren + = newCaseWhen.getWhenClauses().stream() + .map(wc -> wc.withChildren(wc.getOperand(), + TypeCoercionUtils.castIfNotSameType(wc.getResult(), commonType))) + .collect(Collectors.toList()); + newCaseWhen.getDefaultValue() + .map(dv -> TypeCoercionUtils.castIfNotSameType(dv, commonType)) + .ifPresent(newChildren::add); + return newCaseWhen.withChildren(newChildren); + }) + .orElse(newCaseWhen); + } + + @Override + public Expression visitInPredicate(InPredicate inPredicate, ExpressionRewriteContext context) { + List<Expression> rewrittenChildren = inPredicate.children().stream() + .map(e -> rewrite(e, context)).collect(Collectors.toList()); + InPredicate newInPredicate = inPredicate.withChildren(rewrittenChildren); + + if (newInPredicate.getOptions().stream().map(Expression::getDataType) + .allMatch(dt -> dt.equals(newInPredicate.getCompareExpr().getDataType()))) { + return newInPredicate; + } + Optional<DataType> optionalCommonType = TypeCoercionUtils.findWiderCommonType(newInPredicate.children() + .stream().map(Expression::getDataType).collect(Collectors.toList())); + + return optionalCommonType + .map(commonType -> { + List<Expression> newChildren = newInPredicate.children().stream() + .map(e -> TypeCoercionUtils.castIfNotSameType(e, commonType)) + .collect(Collectors.toList()); + return newInPredicate.withChildren(newChildren); + }) + .orElse(newInPredicate); + } + + /** + * Do implicit cast for expression's children. + */ + private Expression visitImplicitCastInputTypes(Expression expr, ExpressionRewriteContext ctx) { + ImplicitCastInputTypes implicitCastInputTypes = (ImplicitCastInputTypes) expr; + List<Expression> newChildren = Lists.newArrayListWithCapacity(expr.arity()); + AtomicInteger changed = new AtomicInteger(0); + for (int i = 0; i < implicitCastInputTypes.expectedInputTypes().size(); i++) { + newChildren.add(implicitCast(expr.child(i), implicitCastInputTypes.expectedInputTypes().get(i), ctx) + .map(e -> { + changed.incrementAndGet(); + return e; + }) + .orElse(expr.child(0)) + ); + } + if (changed.get() != 0) { + return expr.withChildren(newChildren); + } else { + return expr; + } + } + + /** + * Return Optional.empty() if we cannot do or do not need to do implicit cast. + */ + @Developing + private Optional<Expression> implicitCast(Expression input, AbstractDataType expected, + ExpressionRewriteContext ctx) { + Expression rewrittenInput = rewrite(input, ctx); + Optional<DataType> castDataType = TypeCoercionUtils.implicitCast(rewrittenInput.getDataType(), expected); + if (castDataType.isPresent() && !castDataType.get().equals(rewrittenInput.getDataType())) { + return Optional.of(new Cast(rewrittenInput, castDataType.get())); + } else { + // TODO: there maybe has performance problem, we need use ctx to save whether children is changed. Review Comment: good idea -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: commits-unsubscr...@doris.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: commits-unsubscr...@doris.apache.org For additional commands, e-mail: commits-h...@doris.apache.org
