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;
  
  import org.apache.calcite.rel.type.RelDataType;
  import org.apache.calcite.sql.parser.SqlParserPos;
  import org.apache.calcite.sql.validate.SqlValidator;
  import org.apache.calcite.util.Litmus;
  
  /**
   * A <code>SqlTypeNameSpec</code> is a type name specification that allows user to
   * customize sql node unparsing and data type deriving.
   *
   * <p>To customize sql node unparsing, override the method
   * {@link #unparse(SqlWriter, int, int)}.
   *
   * <p>To customize data type deriving, override the method
   * {@link #deriveType(SqlValidator)}.
   */
  public abstract class SqlTypeNameSpec {
    private final SqlIdentifier typeName;
    private final SqlParserPos pos;
  
    /**
     * Creates a {@code SqlTypeNameSpec}.
     *
     * @param name Name of the type
     * @param pos  Parser position, must not be null
     */
    protected SqlTypeNameSpec(SqlIdentifier name, SqlParserPos pos) {
      this.typeName = name;
      this.pos = pos;
    }
  
    /**
     * Derive type from this SqlTypeNameSpec.
     *
     * @param validator The sql validator
     * @return the {@code RelDataType} instance, throws exception if we could not
     *         deduce the type
     */
    public abstract RelDataType deriveType(SqlValidator validator);
  
    /** Writes a SQL representation of this spec to a writer. */
    public abstract void unparse(SqlWriter writer, int leftPrec, int rightPrec);
  
    /** Returns whether this spec is structurally equivalent to another spec. */
    public abstract boolean equalsDeep(SqlTypeNameSpec spec, Litmus litmus);
  
    public SqlParserPos getParserPos() {
      return pos;
    }
  
    public SqlIdentifier getTypeName() {
      return typeName;
    }
  }
  