{
* UNulDataReader.pas
*
* Implements a do nothing data reader for use when a database does not exist.
*
* v1.0 of 31 Aug 2008 - Original version.
*
*
* ***** BEGIN LICENSE BLOCK *****
*
* Version: MPL 1.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (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.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License for
* the specific language governing rights and limitations under the License.
*
* The Original Code is UNulDataReader.pas
*
* The Initial Developer of the Original Code is Peter Johnson
* (http://www.delphidabbler.com/).
*
* Portions created by the Initial Developer are Copyright (C) 2008 Peter
* Johnson. All Rights Reserved.
*
* ***** END LICENSE BLOCK *****
}
unit UNulDataReader;
interface
implementation
uses
// Project
USnipData, USnippets, UIStringList;
type
{
TNulDataReader:
A do nothing data reader used when a database does not exist.
}
TNulDataReader = class(TInterfacedObject,
IDataReader
)
public
{ IDataReader methods }
function DatabaseExists: Boolean;
{Checks if the database exists. This method is always called first. No
other methods are called if this method returns false.
@return Always returns True. It always can read a do-nothing database.
}
function GetAllCatNames: IStringList;
{Gets names of all categories in database.
@return Empty string list.
}
procedure GetCatProps(const Cat: string; var Props: TCategoryData);
{Gets properties of a category.
@param Cat [in] Name of required category.
@param Props [in/out] Empty properties passed in. Unchanged.
}
function GetCatRoutines(const Cat: string): IStringList;
{Gets names of all routines in a category.
@param Cat [in] Name of category containing routines.
@return Empty list.
}
procedure GetRoutineProps(const Routine: string; var Props: TRoutineData);
{Gets properties of a routine. These are the fields of the routine's
record in the routines "table".
@param Routine [in] Name of required routine.
@param Props [in/out] Empty properties passed in. Unchanged.
}
function GetRoutineXRefs(const Routine: string): IStringList;
{Gets list of all routines that are cross referenced by a routine.
@param Routine [in] Name of routine we need cross references for.
@return Empty list.
}
function GetRoutineDepends(const Routine: string): IStringList;
{Gets list of all routines on which a given routine depends.
@param Routine [in] Name of required routine.
@return Empty list.
}
function GetRoutineUnits(const Routine: string): IStringList;
{Gets list of all units referenced by a routine.
@param Routine [in] Name of required routine.
@return Empty list.
}
end;
{
TNulDataReaderFactory:
Static factory class that creates an instance of the TNulDataReader object.
This class is registered with the TDataIOFactories class. Designed for use
when one of the databases is missing.
}
TNulDataReaderFactory = class sealed(TDataReaderFactory)
public
class function Instance(const DBType: TDatabaseType): IInterface; override;
{Creates instance of object that supports IDataReader.
@param DBType [in] Type of database to be read: main or user.
@return Instance of data reader object.
}
end;
{ TNulDataReader }
function TNulDataReader.DatabaseExists: Boolean;
{Checks if the database exists. This method is always called first. No other
methods are called if this method returns false.
@return Always returns True. It always can read a do-nothing database.
}
begin
Result := True;
end;
function TNulDataReader.GetAllCatNames: IStringList;
{Gets names of all categories in database.
@return Empty string list.
}
begin
Result := TIStringList.Create;
end;
procedure TNulDataReader.GetCatProps(const Cat: string;
var Props: TCategoryData);
{Gets properties of a category.
@param Cat [in] Name of required category.
@param Props [in/out] Empty properties passed in. Unchanged.
}
begin
// Do nothing
end;
function TNulDataReader.GetCatRoutines(const Cat: string): IStringList;
{Gets names of all routines in a category.
@param Cat [in] Name of category containing routines.
@return Empty list.
}
begin
Result := TIStringList.Create;
end;
function TNulDataReader.GetRoutineDepends(const Routine: string): IStringList;
{Gets list of all routines on which a given routine depends.
@param Routine [in] Name of required routine.
@return Empty list.
}
begin
Result := TIStringList.Create;
end;
procedure TNulDataReader.GetRoutineProps(const Routine: string;
var Props: TRoutineData);
{Gets properties of a routine. These are the fields of the routine's record in
the routines "table".
@param Routine [in] Name of required routine.
@param Props [in/out] Empty properties passed in. Unchanged.
}
begin
// Do nothing
end;
function TNulDataReader.GetRoutineUnits(const Routine: string): IStringList;
{Gets list of all units referenced by a routine.
@param Routine [in] Name of required routine.
@return Empty list.
}
begin
Result := TIStringList.Create;
end;
function TNulDataReader.GetRoutineXRefs(const Routine: string): IStringList;
{Gets list of all routines that are cross referenced by a routine.
@param Routine [in] Name of routine we need cross references for.
@return Empty list.
}
begin
Result := TIStringList.Create;
end;
{ TNulDataReaderFactory }
class function TNulDataReaderFactory.Instance(
const DBType: TDatabaseType): IInterface;
{Creates instance of object that supports IDataReader.
@param DBType [in] Type of database to be read: main or user.
@return Instance of data reader object.
}
begin
Result := TNulDataReader.Create;
end;
initialization
// Register the data reader factory
TDataIOFactories.RegisterFactory('NulDataReader', TNulDataReaderFactory);
end.
