content: /*
   * 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.config.NullCollation;
  import org.apache.calcite.sql.SqlCall;
  import org.apache.calcite.sql.SqlDialect;
  import org.apache.calcite.sql.SqlNode;
  import org.apache.calcite.sql.SqlWriter;
  import org.apache.calcite.sql.fun.SqlLibraryOperators;
  import org.apache.calcite.sql.parser.SqlParserPos;
  import org.apache.calcite.util.RelToSqlConverterUtil;
  
  import org.checkerframework.checker.nullness.qual.Nullable;
  
  /**
   * A <code>SqliteSqlDialect</code> implementation for the SQLite database.
   */
  public class SqliteSqlDialect extends SqlDialect {
  
    public static final SqlDialect.Context DEFAULT_CONTEXT = SqlDialect.EMPTY_CONTEXT
        .withDatabaseProduct(SqlDialect.DatabaseProduct.DUCKDB)
        .withIdentifierQuoteString("\"")
        // Refer to document: https://sqlite.org/datatype3.html
        .withNullCollation(NullCollation.LOW);
  
    public static final SqlDialect DEFAULT = new SqliteSqlDialect(DEFAULT_CONTEXT);
  
    /** Creates a SqliteSqlDialect. */
    public SqliteSqlDialect(SqlDialect.Context context) {
      super(context);
    }
  
    @Override public boolean supportsAliasedValues() {
      return false;
    }
  
    @Override public void unparseOffsetFetch(SqlWriter writer, @Nullable SqlNode offset,
        @Nullable SqlNode fetch) {
      unparseFetchUsingLimit(writer, offset, fetch);
    }
  
    @Override public void unparseCall(SqlWriter writer, SqlCall call,
        int leftPrec, int rightPrec) {
      switch (call.getKind()) {
      case CHAR_LENGTH:
        SqlCall lengthCall = SqlLibraryOperators.LENGTH
            .createCall(SqlParserPos.ZERO, call.getOperandList());
        super.unparseCall(writer, lengthCall, leftPrec, rightPrec);
        break;
      case TRIM:
        RelToSqlConverterUtil.unparseTrimLR(writer, call, leftPrec, rightPrec);
        break;
      case POSITION:
        final SqlWriter.Frame frame = writer.startFunCall("INSTR");
        writer.sep(",");
        call.operand(1).unparse(writer, leftPrec, rightPrec);
        writer.sep(",");
        call.operand(0).unparse(writer, leftPrec, rightPrec);
        writer.endFunCall(frame);
        break;
      default:
        super.unparseCall(writer, call, leftPrec, rightPrec);
      }
    }
  
  }
  