/// <summary>
/// Creates a database table binary data reader
/// </summary>
/// <param name="table">table</param>
/// <param name="handler">query handler</param>
public DbTableBinDataReader(DbTable table, DbQueryHandler handler = null)
: base(table, handler)
{
reader = new io.BinaryReader(io.File.OpenRead(Path));
//build column type translator
ColumnTypeSizes = Table.ColumnTypes.Select(t => t.GetSize()).ToArray();
}
/// <summary>
/// creates a database visualizer, must be disposed to release resources
/// </summary>
/// <param name="db">database</param>
/// <param name="query">parsed sql query</param>
/// <param name="options">visualize options</param>
public DbVisualizer(CsvDb db, DbQuery query, DbVisualize options = DbVisualize.Paged)
{
//reader = DbRecordReader.Create(db, query);
handler = new DbQueryHandler(db, query);
Options = options;
}
/// <summary>
/// free reader resources
/// </summary>
public void Dispose()
{
if (handler != null)
{
handler.Dispose();
handler = null;
}
}
/// <summary>
/// call generic class
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="handler"></param>
/// <param name="columnOperand"></param>
/// <param name="oper"></param>
/// <param name="constantOperand"></param>
/// <returns></returns>
IEnumerable <int> ExecuteColumnExpression <T>(DbQueryHandler handler,
DbQuery.ColumnOperand columnOperand, TokenType oper, DbQuery.ConstantOperand constantOperand)
where T : IComparable <T>
{
var executer = new DbQueryExpressionExecuter <T>(handler, columnOperand, oper, constantOperand);
return(executer.Execute().SelectMany(pair => pair.Value));
}
/// <summary>
/// Creates a database data table reader
/// </summary>
/// <param name="table">table</param>
/// <param name="handler">query handler</param>
internal DbTableDataReader(DbTable table, DbQueryHandler handler = null)
{
Handler = handler;
if ((Table = table) == null)
{
throw new ArgumentException("cannot read table data from undefined table");
}
//default to CSV
var extension = table.Database.IsBinary ? CsvDb.SchemaTableDataExtension : CsvDb.SchemaTableDefaultExtension;
//path to table data file
Path = io.Path.Combine(table.Database.BinaryPath, $"{Table.Name}.{extension}");
}
/// <summary>
/// Creates a database data table reader
/// </summary>
/// <param name="db">database</param>
/// <param name="table">table</param>
/// <param name="handler">query handler</param>
/// <returns></returns>
public static DbTableDataReader Create(CsvDb db, DbTable table, DbQueryHandler handler = null)
{
if (db == null || table == null)
{
return(null);
}
if ((db.Flags & DbSchemaConfigType.Binary) != 0)
{
return(new DbTableBinDataReader(table, handler));
}
else
{
return(new DbTableCsvDataReader(table, handler));
}
}
internal DbQueryExpressionExecuter(DbQueryHandler handler,
DbQuery.ColumnOperand columnOperand, TokenType oper, DbQuery.ConstantOperand constantOperand)
{
if (columnOperand == null || !(Operator = oper).IsComparison() || constantOperand == null ||
(Handler = handler) == null)
{
throw new ArgumentException($"cannot execute comparison expression");
}
//get the table column handler
Column = handler.Database.Index(columnOperand.Column.Hash);
// . handler.WhereColumns[columnOperand.Column.Hash];
//get the constant value to compare
Constant = constantOperand.Evaluate(null);
Reader = Handler.TableReaders.FirstOrDefault(r => r.Table == Column.Table);
if (Reader == null)
{
throw new ArgumentException($"could not resolve data table reader for column: {Column}");
}
}
/// <summary>
/// Creates a database table csv/text data reader
/// </summary>
/// <param name="table">table</param>
/// <param name="handler">query handler</param>
public DbTableCsvDataReader(DbTable table, DbQueryHandler handler = null)
: base(table, handler)
{
reader = new io.StreamReader(Path);
}
/// <summary>
/// Creates a database table data reader
/// </summary>
/// <param name="db">database</param>
/// <param name="tableName">table name</param>
/// <param name="handler">query handler</param>
/// <returns></returns>
public static DbTableDataReader Create(CsvDb db, string tableName, DbQueryHandler handler = null)
{
return(Create(db, db?.Table(tableName), handler));
}
