danny0405 commented on a change in pull request #1733: [CALCITE-3679] Allow lambda expressions in SQL queries URL: https://github.com/apache/calcite/pull/1733#discussion_r396054101
########## File path: core/src/main/java/org/apache/calcite/sql/fun/SqlLambdaOperator.java ########## @@ -0,0 +1,115 @@ +/* + * 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.sql.fun; + +import org.apache.calcite.rel.type.RelDataType; +import org.apache.calcite.sql.SqlCall; +import org.apache.calcite.sql.SqlCallBinding; +import org.apache.calcite.sql.SqlKind; +import org.apache.calcite.sql.SqlLambda; +import org.apache.calcite.sql.SqlLiteral; +import org.apache.calcite.sql.SqlNode; +import org.apache.calcite.sql.SqlNodeList; +import org.apache.calcite.sql.SqlOperandCountRange; +import org.apache.calcite.sql.SqlOperator; +import org.apache.calcite.sql.SqlOperatorBinding; +import org.apache.calcite.sql.SqlSyntax; +import org.apache.calcite.sql.SqlWriter; +import org.apache.calcite.sql.parser.SqlParserPos; +import org.apache.calcite.sql.type.InferTypes; +import org.apache.calcite.sql.type.OperandTypes; +import org.apache.calcite.sql.type.ReturnTypes; +import org.apache.calcite.sql.type.SqlOperandCountRanges; +import org.apache.calcite.sql.type.SqlTypeName; +import org.apache.calcite.sql.validate.SqlValidator; +import org.apache.calcite.sql.validate.SqlValidatorScope; + +public class SqlLambdaOperator extends SqlOperator { + + public static final SqlLambdaOperator INSTANCE = new SqlLambdaOperator(); + + //~ Instance fields -------------------------------------------------------- + + //~ Constructors ----------------------------------------------------------- + + /** + * Creates a SqlLambdaOperator. + */ + SqlLambdaOperator() { + super( + "->", + SqlKind.LAMBDA, + 32, + false, + ReturnTypes.ARG0_NULLABLE, + InferTypes.RETURN_TYPE, + OperandTypes.VARIADIC); + } + + //~ Methods ---------------------------------------------------------------- + + public SqlOperandCountRange getOperandCountRange() { + return SqlOperandCountRanges.any(); + } + + @Override public SqlSyntax getSyntax() { + return SqlSyntax.SPECIAL; + } + + public boolean checkOperandTypes( + SqlCallBinding callBinding, + boolean throwOnFailure) { + return true; + } + + public void unparse( + SqlWriter writer, + SqlCall call, + int leftPrec, + int rightPrec) { + final SqlWriter.Frame frame = writer.startList("", ""); + call.operand(0).unparse(writer, getLeftPrec(), getRightPrec()); + writer.sep(getName()); + + call.operand(1).unparse(writer, getLeftPrec(), getRightPrec()); + writer.endList(frame); + } + + @Override public void validateCall(SqlCall call, SqlValidator validator, + SqlValidatorScope scope, + SqlValidatorScope operandScope) { + validateOperands(validator, scope, call); + } + + public SqlCall createCall( + SqlLiteral functionQualifier, + SqlParserPos pos, + SqlNode... operands) { + assert functionQualifier == null; + assert operands.length == 2; + return new SqlLambda(pos, (SqlNodeList) operands[0], operands[1]); + } + + @Override public RelDataType deriveType( + SqlValidator validator, SqlValidatorScope scope, SqlCall call) { + return validateOperands(validator, scope, call); Review comment: Should implement the `checkOperandTypes` correctly to deduce the type, you can take `SqlCaseOperator` for a reference. ---------------------------------------------------------------- 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. For queries about this service, please contact Infrastructure at: [email protected] With regards, Apache Git Services
