core/src/main/java/org/apache/calcite/sql/dialect/StarRocksSqlDialect.java

/*
 * 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.dialect;

import org.apache.calcite.avatica.util.TimeUnitRange;
import org.apache.calcite.config.NullCollation;
import org.apache.calcite.rel.type.RelDataType;
import org.apache.calcite.sql.SqlAbstractDateTimeLiteral;
import org.apache.calcite.sql.SqlAlienSystemTypeNameSpec;
import org.apache.calcite.sql.SqlCall;
import org.apache.calcite.sql.SqlDataTypeSpec;
import org.apache.calcite.sql.SqlDialect;
import org.apache.calcite.sql.SqlLiteral;
import org.apache.calcite.sql.SqlNode;
import org.apache.calcite.sql.SqlWriter;
import org.apache.calcite.sql.fun.SqlFloorFunction;
import org.apache.calcite.sql.parser.SqlParserPos;
import org.apache.calcite.sql.type.SqlTypeName;

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

import static org.apache.calcite.util.RelToSqlConverterUtil.unparseHiveTrim;

/**
 * A <code>SqlDialect</code> implementation for the StarRocks database.
 */
public class StarRocksSqlDialect extends MysqlSqlDialect {

  public static final SqlDialect.Context DEFAULT_CONTEXT = SqlDialect.EMPTY_CONTEXT
      .withDatabaseProduct(SqlDialect.DatabaseProduct.STARROCKS)
      .withIdentifierQuoteString("`")
      .withNullCollation(NullCollation.LOW);

  public static final SqlDialect DEFAULT = new StarRocksSqlDialect(DEFAULT_CONTEXT);

  /**
   * Creates a StarRocksSqlDialect.
   */
  public StarRocksSqlDialect(Context context) {
    super(context);
  }

  @Override public boolean supportsGroupByWithRollup() {
    return false;
  }

  @Override public boolean supportsTimestampPrecision() {
    return false;
  }

  @Override public boolean supportsApproxCountDistinct() {
    return true;
  }

  @Override public void unparseCall(SqlWriter writer, SqlCall call, int leftPrec, int rightPrec) {
    switch (call.getKind()) {
    case ARRAY_VALUE_CONSTRUCTOR:
      final SqlWriter.Frame arrayFrame = writer.startList("[", "]");
      for (SqlNode operand : call.getOperandList()) {
        writer.sep(",");
        operand.unparse(writer, leftPrec, rightPrec);
      }
      writer.endList(arrayFrame);
      break;
    case MAP_VALUE_CONSTRUCTOR:
      writer.keyword(call.getOperator().getName());
      final SqlWriter.Frame mapFrame = writer.startList("{", "}");
      for (int i = 0; i < call.operandCount(); i++) {
        String sep = i % 2 == 0 ? "," : ":";
        writer.sep(sep);
        call.operand(i).unparse(writer, leftPrec, rightPrec);
      }
      writer.endList(mapFrame);
      break;
    case TRIM:
      unparseHiveTrim(writer, call, leftPrec, rightPrec);
      break;
    case FLOOR:
      if (call.operandCount() != 2) {
        super.unparseCall(writer, call, leftPrec, rightPrec);
        return;
      }
      final SqlLiteral timeUnitNode = call.operand(1);
      final TimeUnitRange timeUnit = timeUnitNode.getValueAs(TimeUnitRange.class);
      SqlCall newCall =
          SqlFloorFunction.replaceTimeUnitOperand(call, timeUnit.name(),
              timeUnitNode.getParserPosition());
      SqlFloorFunction.unparseDatetimeFunction(writer, newCall, "DATE_TRUNC", false);
      break;
    default:
      super.unparseCall(writer, call, leftPrec, rightPrec);
      break;
    }
  }

  @Override public @Nullable SqlNode getCastSpec(RelDataType type) {
    switch (type.getSqlTypeName()) {
    case TIMESTAMP:
      return new SqlDataTypeSpec(
          new SqlAlienSystemTypeNameSpec(
              "DATETIME",
              type.getSqlTypeName(),
              SqlParserPos.ZERO),
          SqlParserPos.ZERO);
    default:
      return super.getCastSpec(type);
    }
  }

  @Override public void unparseDateTimeLiteral(SqlWriter writer,
      SqlAbstractDateTimeLiteral literal, int leftPrec, int rightPrec) {
    if (literal.getTypeName() == SqlTypeName.TIMESTAMP) {
      writer.literal("DATETIME '" + literal.toFormattedString() + "'");
    } else {
      super.unparseDateTimeLiteral(writer, literal, leftPrec, rightPrec);
    }
  }

}