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.rex;
  
  import org.apache.calcite.sql.SqlLiteral;
  import org.apache.calcite.sql.SqlNode;
  import org.apache.calcite.sql.SqlWindow;
  
  /**
   * Representation of different kinds of exclude clause in window functions.
   */
  public enum RexWindowExclusion {
    EXCLUDE_NO_OTHER("EXCLUDE NO OTHER"),
    EXCLUDE_CURRENT_ROW("EXCLUDE CURRENT ROW"),
    EXCLUDE_TIES("EXCLUDE TIES"),
    EXCLUDE_GROUP("EXCLUDE GROUP");
  
    private final String sql;
  
    RexWindowExclusion(String sql) {
      this.sql = sql;
    }
  
    @Override public String toString() {
      return sql;
    }
  
    /**
     * Creates a window exclusion from a {@link SqlNode}.
     *
     * @param node SqlLiteral of the exclusion clause
     * @return RexWindowExclusion
     */
    public static RexWindowExclusion create(SqlNode node) {
      SqlLiteral exclude = (SqlLiteral) node;
      if (SqlWindow.isExcludeCurrentRow(exclude)) {
        return EXCLUDE_CURRENT_ROW;
      }
      if (SqlWindow.isExcludeNoOthers(exclude)) {
        return EXCLUDE_NO_OTHER;
      }
      if (SqlWindow.isExcludeGroup(exclude)) {
        return EXCLUDE_GROUP;
      }
      if (SqlWindow.isExcludeTies(exclude)) {
        return EXCLUDE_TIES;
      }
      throw new AssertionError("Unexpected Exclusion clause");
    }
  }
  