CodeSnip Old Code (SVN)

--- a/trunk/Src/USnipData.pas
+++ b/trunk/Src/USnipData.pas
@@ -1,9 +1,8 @@
 {
  * USnipData.pas
  *
- * Defines interface implemented by classes that access back end Code Snippets
- * database. Also implememts class that that registers factories that create
- * back end database access objects.
+ * Defines interface implemented by classes that read and write back end Code
+ * Snippets database. Also provides an exception class for data I/O errors.
  *
  * $Rev$
  * $Date$
@@ -113,14 +112,11 @@
 
 
 uses
-  // Delphi
-  SysUtils, Classes,
   // Project
-  UExceptions, UBaseObjects, USnippets, UIStringList;
+  UExceptions, USnippets, UIStringList;
 
 
 type
-
   {
   IDataReader:
     Interface that defines operations that must be implemented by objects that
@@ -228,102 +224,6 @@
   end;
 
   {
-  TDatabaseType:
-    Type of database. Used by readers so they know whether to access the
-    codesnip or user database.
-  }
-  TDatabaseType = (
-    dtMain,   // main CodeSnip database
-    dtUser    // user's database
-  );
-
-  {
-  TDataIOFactoryClass:
-    Class reference to TDataIOFactory classes.
-  }
-  TDataIOFactoryClass = class of TDataIOFactory;
-
-  {
-  TDataIOFactory:
-    Pure abstract base class for classes that create objects that implement
-    IDataReader or IDataWriter. Should not be directly overridden. Provided so
-    that TDataReadFactory and TDataWriterFactory can be used polymorphically.
-  }
-  TDataIOFactory = class(TNoConstructObject)
-  public
-    class function Instance(const DBType: TDatabaseType): IInterface;
-      virtual; abstract;
-  end;
-
-  {
-  TDataReaderFactory:
-    Pure abstract base class for classes that create objects that implement
-    IDataReader and can access either the CodeSnip of user database. Each data
-    reader object must provide a factory class that derives from this class and
-    that creates an instance of the IDataReader object in its Instance method.
-  }
-  TDataReaderFactory = class(TDataIOFactory)
-  public
-    class function Instance(const DBType: TDatabaseType): IInterface;
-      override; abstract;
-  end;
-
-  {
-  TDataWriterFactory:
-    Pure abstract base class for classes that create objects that implement
-    IDataWriter and can write the user database. Each data writer object must
-    provide a factory class that derives from this class and that creates an
-    instance of the IDataWriter object in its Instance method.
-  }
-  TDataWriterFactory = class(TDataIOFactory)
-  public
-    class function Instance(const DBType: TDatabaseType): IInterface;
-      override; abstract;
-  end;
-
-  {
-  TDataIOFactories:
-    Static class that enables factory classes for various database reader and
-    writer objects to be registered and instantiated. Factories are registered
-    with unique IDs. The class also permits the registered IDs to be listed and
-    a description to be returned.
-  }
-  TDataIOFactories = class(TNoConstructObject)
-  strict private
-    class function FindEntry(const ID: string): TObject;
-      {Finds an internal object that describes a specified factory.
-        @param ID [in] Unique string that identifies a factory class.
-        @return Reference to internal object that describes the factory or nil
-          if no factory is registered with ID.
-      }
-  public
-    class procedure RegisterFactory(const ID: string;
-      const FactoryClass: TDataIOFactoryClass);
-      {Registers a data reader or writer factory.
-        @param ID [in] Unique string identifying the factory.
-        @param FactoryClass [in] Factory's class reference.
-        @except EBug raised if factory with given ID is already registered.
-      }
-    class function CreateDataReader(const ID: string;
-      const DBType: TDatabaseType): IDataReader;
-      {Creates an instance of a registered data reader object.
-        @param ID [in] Identifies the factory class.
-        @param DBType [in] Type of database to read.
-        @return New data reader object instance.
-        @except EBug raised if no factory with given ID is registered.
-      }
-    class function CreateDataWriter(const ID: string;
-      const DBType: TDatabaseType): IDataWriter;
-      {Creates an instance of a registered data writer object.
-        @param ID [in] Identifies the factory class.
-        @param DBType [in] Type of database to write.
-        @return New data writer object instance.
-        @except EBug raised if no factory with given ID is registered.
-        @except EBug raised if dtMain is specified in DBType.
-      }
-  end;
-
-  {
   EDataIO:
     Class of exception raised by IDataReader and IDataWriter objects.
   }
@@ -332,131 +232,5 @@
 
 implementation
 
-
-uses
-  // Delphi
-  Contnrs, Windows {for inlining};
-
-
-var
-  // Private global object storing registered data reader factory classes
-  PvtFactoryClasses: TObjectList;
-
-
-type
-
-  {
-  TDataFactoryEntry:
-    Class that records information about a registered data reader factory.
-  }
-  TDataFactoryEntry = class(TObject)
-  public
-    ID: string;
-      {ID of factory}
-    FactoryClass: TDataIOFactoryClass;
-      {Class reference to static factory class}
-  end;
-
-
-{ TDataIOFactories }
-
-class function TDataIOFactories.CreateDataReader(const ID: string;
-  const DBType: TDatabaseType): IDataReader;
-  {Creates an instance of a registered data reader object.
-    @param ID [in] Identifies the factory class.
-    @param DBType [in] Type of database to read.
-    @return New data reader object instance.
-    @except EBug raised if no factory with given ID is registered.
-  }
-var
-  Entry: TObject; // entry representing the the required factory
-begin
-  Entry := FindEntry(ID);
-  if not Assigned(Entry) then                              // ** do not localise
-    raise EBug.Create(ClassName + '.CreateDataReader: ID not found');
-  // Create instance of data reader object using required factory
-  Result := (Entry as TDataFactoryEntry).FactoryClass.Instance(DBType)
-    as IDataReader;
-end;
-
-class function TDataIOFactories.CreateDataWriter(const ID: string;
-  const DBType: TDatabaseType): IDataWriter;
-  {Creates an instance of a registered data writer object.
-    @param ID [in] Identifies the factory class.
-    @param DBType [in] Type of database to write.
-    @return New data writer object instance.
-    @except EBug raised if no factory with given ID is registered.
-    @except EBug raised if dtMain is specified in DBType.
-  }
-var
-  Entry: TObject; // entry representing the the required factory
-begin
-  Entry := FindEntry(ID);
-  if not Assigned(Entry) then                              // ** do not localise
-    raise EBug.Create(ClassName + '.CreateDataWriter: ID not found');
-  if DBType = dtMain then                                  // ** do not localise
-    raise EBug.Create(ClassName + '.CreateDataWriter: ID can''t be mtMain');
-  // Create instance of data writer object using required factory
-  Result := (Entry as TDataFactoryEntry).FactoryClass.Instance(DBType)
-    as IDataWriter;
-end;
-
-class function TDataIOFactories.FindEntry(const ID: string): TObject;
-  {Finds an internal object that describes a specified factory.
-    @param ID [in] Unique string that identifies a factory class.
-    @return Reference to internal object that describes the factory or nil if no
-      factory is registered with ID.
-  }
-var
-  Idx: Integer; // loops thru list of registered factories
-begin
-  Result := nil;
-  for Idx := 0 to Pred(PvtFactoryClasses.Count) do
-  begin
-    if AnsiSameText(
-      (PvtFactoryClasses[Idx] as TDataFactoryEntry).ID, ID
-    ) then
-    begin
-      Result := PvtFactoryClasses[Idx];
-      Break;
-    end;
-  end;
-end;
-
-class procedure TDataIOFactories.RegisterFactory(const ID: string;
-  const FactoryClass: TDataIOFactoryClass);
-  {Registers a data reader or writer factory.
-    @param ID [in] Unique string identifying the factory.
-    @param FactoryClass [in] Factory's class reference.
-    @except EBug raised if factory with given ID is already registered.
-  }
-var
-  Entry: TDataFactoryEntry; // entry representing the the required factory
-begin
-  // Check if factory with given ID registered already
-  if Assigned(FindEntry(ID)) then
-    raise EBug.Create(                                     // ** do not localise
-      ClassName + '.RegisterFactory: factory already registered'
-    );
-  // Create entry for new factory
-  Entry := TDataFactoryEntry.Create;
-  Entry.ID := ID;
-  Entry.FactoryClass := FactoryClass;
-  // Add entry to list
-  PvtFactoryClasses.Add(Entry);
-end;
-
-
-initialization
-
-// Create factory class registration list
-PvtFactoryClasses := TObjectList.Create(True);
-
-
-finalization
-
-// Free registration list
-FreeAndNil(PvtFactoryClasses);
-
 end.