morrySnow commented on code in PR #11630: URL: https://github.com/apache/doris/pull/11630#discussion_r941967031
########## fe/fe-core/src/main/java/org/apache/doris/nereids/rules/expression/rewrite/rules/SimplifyCastRule.java: ########## @@ -0,0 +1,97 @@ +// 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.rules.expression.rewrite.AbstractExpressionRewriteRule; +import org.apache.doris.nereids.rules.expression.rewrite.ExpressionRewriteContext; +import org.apache.doris.nereids.trees.expressions.Cast; +import org.apache.doris.nereids.trees.expressions.Expression; +import org.apache.doris.nereids.trees.expressions.StringLiteral; +import org.apache.doris.nereids.types.DataType; +import org.apache.doris.nereids.types.IntegralType; +import org.apache.doris.nereids.types.NumericType; + +import java.util.Optional; + + +/** + * Rewrite rule of simplify CAST expression. + * Remove redundant cast like + * - cast(1 as int) -> 1. + * Merge cast like + * - cast(cast(1 as bigint) as string) -> cast(1 as string). + */ +public class SimplifyCastRule extends AbstractExpressionRewriteRule { + + public static SimplifyCastRule INSTANCE = new SimplifyCastRule(); + + @Override + public Expression visitCast(Cast origin, ExpressionRewriteContext context) { + return simplify(origin) + .map(simplifiedExpr -> { + if (simplifiedExpr instanceof Cast) { + return rewrite(simplifiedExpr, context); + } + return simplifiedExpr; + }) + .orElse(origin); + } + + private Optional<Expression> simplify(Cast cast) { + Expression source = cast.left(); + StringLiteral type = cast.right(); + + // remove redundant cast + // CAST(value as type), value is type + if (cast.getDataType().equals(source.getDataType())) { + return Optional.of(source); + } + // CAST(CAST()) -> CAST() + if (source instanceof Cast) { + Cast innerCast = (Cast) source; + if (check(innerCast.getDataType(), cast.getDataType()) + && check(innerCast.getDataType(), source.getDataType())) { + return Optional.of(new Cast(innerCast.left(), type)); + } + return simplify(innerCast).map(inner -> + new Cast(inner, type) + ); + } + + return Optional.empty(); + } + + // It after remove redundant cast. so left.class != right.class + // We forbidden subclass of NumericType convert other subclass of NumericType, + // except subclass of IntegralType can mutual conversion. + private boolean check(DataType left, DataType right) { + // int, bigint ... can mutual conversion. + if (left instanceof IntegralType && right instanceof IntegralType) { + return true; + } + + // We forbidden subclass of NumericType convert to other subclass of NumericType, + if (!(left instanceof NumericType) || (!(right instanceof NumericType))) { + return true; + } + + // It after remove redundant cast. so left.class != right.class + // So we don't need to return left.class == right.class + return false; Review Comment: ```suggestion // We forbidden subclass of NumericType convert to other subclass of NumericType, if (left instanceof NumericType && right instanceof NumericType) { return false; } // It after remove redundant cast. so left.class != right.class // So we don't need to return left.class == right.class return true; ``` ########## fe/fe-core/src/main/java/org/apache/doris/nereids/rules/expression/rewrite/rules/SimplifyCastRule.java: ########## @@ -0,0 +1,97 @@ +// 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.rules.expression.rewrite.AbstractExpressionRewriteRule; +import org.apache.doris.nereids.rules.expression.rewrite.ExpressionRewriteContext; +import org.apache.doris.nereids.trees.expressions.Cast; +import org.apache.doris.nereids.trees.expressions.Expression; +import org.apache.doris.nereids.trees.expressions.StringLiteral; +import org.apache.doris.nereids.types.DataType; +import org.apache.doris.nereids.types.IntegralType; +import org.apache.doris.nereids.types.NumericType; + +import java.util.Optional; + + +/** + * Rewrite rule of simplify CAST expression. + * Remove redundant cast like + * - cast(1 as int) -> 1. + * Merge cast like + * - cast(cast(1 as bigint) as string) -> cast(1 as string). + */ +public class SimplifyCastRule extends AbstractExpressionRewriteRule { + + public static SimplifyCastRule INSTANCE = new SimplifyCastRule(); + + @Override + public Expression visitCast(Cast origin, ExpressionRewriteContext context) { + return simplify(origin) + .map(simplifiedExpr -> { + if (simplifiedExpr instanceof Cast) { + return rewrite(simplifiedExpr, context); + } + return simplifiedExpr; + }) + .orElse(origin); + } + + private Optional<Expression> simplify(Cast cast) { + Expression source = cast.left(); + StringLiteral type = cast.right(); + + // remove redundant cast + // CAST(value as type), value is type + if (cast.getDataType().equals(source.getDataType())) { + return Optional.of(source); + } + // CAST(CAST()) -> CAST() + if (source instanceof Cast) { + Cast innerCast = (Cast) source; + if (check(innerCast.getDataType(), cast.getDataType()) + && check(innerCast.getDataType(), source.getDataType())) { + return Optional.of(new Cast(innerCast.left(), type)); + } + return simplify(innerCast).map(inner -> + new Cast(inner, type) + ); + } + + return Optional.empty(); + } + + // It after remove redundant cast. so left.class != right.class + // We forbidden subclass of NumericType convert other subclass of NumericType, + // except subclass of IntegralType can mutual conversion. + private boolean check(DataType left, DataType right) { + // int, bigint ... can mutual conversion. + if (left instanceof IntegralType && right instanceof IntegralType) { + return true; + } + + // We forbidden subclass of NumericType convert to other subclass of NumericType, Review Comment: add some example to explain why forbidden this situation -- This is an automated message from the Apache Git Service. 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