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.sql2rel;
  
  import org.apache.calcite.rex.RexLiteral;
  import org.apache.calcite.rex.RexNode;
  import org.apache.calcite.sql.SqlCall;
  import org.apache.calcite.sql.SqlIntervalQualifier;
  import org.apache.calcite.sql.SqlLiteral;
  import org.apache.calcite.sql.SqlNode;
  
  /**
   * Converts expressions from {@link SqlNode} to {@link RexNode}.
   */
  public interface SqlNodeToRexConverter {
    //~ Methods ----------------------------------------------------------------
  
    /**
     * Converts a {@link SqlCall} to a {@link RexNode} expression.
     */
    RexNode convertCall(
        SqlRexContext cx,
        SqlCall call);
  
    /**
     * Converts a {@link SqlLiteral SQL literal} to a
     * {@link RexLiteral REX literal}.
     *
     * <p>The result is {@link RexNode}, not {@link RexLiteral} because if the
     * literal is NULL (or the boolean Unknown value), we make a <code>CAST(NULL
     * AS type)</code> expression.
     */
    RexNode convertLiteral(
        SqlRexContext cx,
        SqlLiteral literal);
  
    /**
     * Converts a {@link SqlIntervalQualifier SQL Interval Qualifier} to a
     * {@link RexLiteral REX literal}.
     */
    RexLiteral convertInterval(
        SqlRexContext cx,
        SqlIntervalQualifier intervalQualifier);
  }
  