/*
* Copyright 2004-2023 H2 Group. Multiple-Licensed under the MPL 2.0,
* and the EPL 1.0 (https://h2database.com/html/license.html).
* Initial Developer: H2 Group
*/
package org.h2.table;
import org.h2.command.query.Select;
import org.h2.expression.Expression;
import org.h2.expression.ExpressionColumn;
import org.h2.value.Value;
/**
* A column resolver is list of column (for example, a table) that can map a
* column name to an actual column.
*/
public interface ColumnResolver {
/**
* Get the table alias.
*
* @return the table alias
*/
default String getTableAlias() {
return null;
}
/**
* Get the column list.
*
* @return the column list
*/
Column[] getColumns();
/**
* Get the column with the specified name.
*
* @param name
* the column name, must be a derived name if this column
* resolver has a derived column list
* @return the column with the specified name, or {@code null}
*/
Column findColumn(String name);
/**
* Get the name of the specified column.
*
* @param column column
* @return column name
*/
default String getColumnName(Column column) {
return column.getName();
}
/**
* Returns whether this column resolver has a derived column list.
*
* @return {@code true} if this column resolver has a derived column list,
* {@code false} otherwise
*/
default boolean hasDerivedColumnList() {
return false;
}
/**
* Get the list of system columns, if any.
*
* @return the system columns or null
*/
default Column[] getSystemColumns() {
return null;
}
/**
* Get the row id pseudo column, if there is one.
*
* @return the row id column or null
*/
default Column getRowIdColumn() {
return null;
}
/**
* Get the schema name or null.
*
* @return the schema name or null
*/
default String getSchemaName() {
return null;
}
/**
* Get the value for the given column.
*
* @param column the column
* @return the value
*/
Value getValue(Column column);
/**
* Get the table filter.
*
* @return the table filter
*/
default TableFilter getTableFilter() {
return null;
}
/**
* Get the select statement.
*
* @return the select statement
*/
default Select getSelect() {
return null;
}
/**
* Get the expression that represents this column.
*
* @param expressionColumn the expression column
* @param column the column
* @return the optimized expression
*/
default Expression optimize(ExpressionColumn expressionColumn, Column column) {
return expressionColumn;
}
}