| /* |
| * 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.adapter.druid; |
| |
| import org.apache.calcite.rel.type.RelDataType; |
| import org.apache.calcite.rex.RexCall; |
| import org.apache.calcite.rex.RexLiteral; |
| import org.apache.calcite.rex.RexNode; |
| import org.apache.calcite.sql.SqlKind; |
| import org.apache.calcite.sql.SqlOperator; |
| import org.apache.calcite.sql.fun.SqlStdOperatorTable; |
| |
| import javax.annotation.Nullable; |
| |
| /** |
| * Converts Calcite SUBSTRING call to Druid Expression when possible. |
| */ |
| public class SubstringOperatorConversion implements DruidSqlOperatorConverter { |
| @Override public SqlOperator calciteOperator() { |
| return SqlStdOperatorTable.SUBSTRING; |
| } |
| |
| @Nullable |
| @Override public String toDruidExpression(RexNode rexNode, RelDataType rowType, |
| DruidQuery query) { |
| final RexCall call = (RexCall) rexNode; |
| final String arg = DruidExpressions.toDruidExpression( |
| call.getOperands().get(0), rowType, query); |
| if (arg == null) { |
| return null; |
| } |
| |
| final String startIndex; |
| final String length; |
| // SQL is 1-indexed, Druid is 0-indexed. |
| if (!call.getOperands().get(1).isA(SqlKind.LITERAL)) { |
| final String arg1 = DruidExpressions.toDruidExpression( |
| call.getOperands().get(1), rowType, query); |
| if (arg1 == null) { |
| // can not infer start index expression bailout. |
| return null; |
| } |
| startIndex = DruidQuery.format("(%s - 1)", arg1); |
| } else { |
| startIndex = DruidExpressions.numberLiteral( |
| RexLiteral.intValue(call.getOperands().get(1)) - 1); |
| } |
| |
| if (call.getOperands().size() > 2) { |
| //case substring from start index with length |
| if (!call.getOperands().get(2).isA(SqlKind.LITERAL)) { |
| // case it is an expression try to parse it |
| length = DruidExpressions.toDruidExpression( |
| call.getOperands().get(2), rowType, query); |
| if (length == null) { |
| return null; |
| } |
| } else { |
| // case length is a constant |
| length = DruidExpressions.numberLiteral(RexLiteral.intValue(call.getOperands().get(2))); |
| } |
| |
| } else { |
| //case substring from index to the end |
| length = DruidExpressions.numberLiteral(-1); |
| } |
| return DruidQuery.format("substring(%s, %s, %s)", arg, startIndex, length); |
| } |
| } |