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.plan.RelOptTable;
  import org.apache.calcite.rel.RelNode;
  import org.apache.calcite.rel.type.RelDataType;
  import org.apache.calcite.rex.RexNode;
  import org.apache.calcite.schema.ColumnStrategy;
  import org.apache.calcite.sql.SqlFunction;
  
  import org.checkerframework.checker.nullness.qual.Nullable;
  
  import java.util.List;
  import java.util.function.BiFunction;
  
  /**
   * InitializerExpressionFactory supplies default values for INSERT, UPDATE, and NEW.
   */
  public interface InitializerExpressionFactory {
    //~ Methods ----------------------------------------------------------------
  
    /**
     * Whether a column is always generated. If a column is always generated,
     * then non-generated values cannot be inserted into the column.
     *
     * @see #generationStrategy(RelOptTable, int)
     *
     * @deprecated Use {@code c.generationStrategy(t, i) == VIRTUAL
     * || c.generationStrategy(t, i) == STORED}
     */
    @Deprecated // to be removed before 2.0
    boolean isGeneratedAlways(
        RelOptTable table,
        int iColumn);
  
    /**
     * Returns how a column is populated.
     *
     * @param table   the table containing the column
     * @param iColumn the 0-based offset of the column in the table
     *
     * @return generation strategy, never null
     *
     * @see RelOptTable#getColumnStrategies()
     */
    ColumnStrategy generationStrategy(
        RelOptTable table,
        int iColumn);
  
    /**
     * Creates an expression which evaluates to the default value for a
     * particular column.
     *
     * <p>If the default value comes from a un-validated {@link org.apache.calcite.sql.SqlNode},
     * make sure to invoke {@link InitializerContext#validateExpression} first before you actually
     * do the conversion with method {@link InitializerContext#convertExpression}.
     *
     * @param table   the table containing the column
     * @param iColumn the 0-based offset of the column in the table
     * @param context Context for creating the expression
     *
     * @return default value expression
     */
    RexNode newColumnDefaultValue(
        RelOptTable table,
        int iColumn,
        InitializerContext context);
  
    /**
     * Creates a hook function to customize the relational expression right after the column
     * expressions are converted. Usually the relational expression is a projection
     * above a table scan.
     *
     * @return a hook function to transform the relational expression
     * right after the column expression conversion to a customized one
     *
     * @see #newColumnDefaultValue(RelOptTable, int, InitializerContext)
     */
    @Nullable BiFunction<InitializerContext, RelNode, RelNode> postExpressionConversionHook();
  
    /**
     * Creates an expression which evaluates to the initializer expression for a
     * particular attribute of a structured type.
     *
     * @param type            the structured type
     * @param constructor     the constructor invoked to initialize the type
     * @param iAttribute      the 0-based offset of the attribute in the type
     * @param constructorArgs arguments passed to the constructor invocation
     * @param context Context for creating the expression
     *
     * @return default value expression
     */
    RexNode newAttributeInitializer(
        RelDataType type,
        SqlFunction constructor,
        int iAttribute,
        List<RexNode> constructorArgs,
        InitializerContext context);
  }
  