{
* UInitialLetter.pas
*
* Defines a record that encapsulates an upper case Unicode character.
*
* $Rev$
* $Date$
*
* This unit was originally named UAlphabet.pas.
*
* ***** 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 UInitialLetter.pas
*
* The Initial Developer of the Original Code is Peter Johnson
* (http://www.delphidabbler.com/).
*
* Portions created by the Initial Developer are Copyright (C) 2009-2011 Peter
* Johnson. All Rights Reserved.
*
* Contributor(s)
* NONE
*
* ***** END LICENSE BLOCK *****
}
unit UInitialLetter;
interface
type
/// <summary>
/// Record that encapsulates an upper case Unicode character.
/// </summary>
TInitialLetter = record
strict private
var fLetter: Char; // Value of letter property
public
/// Initialises record with given character, which is forced to upper case.
constructor Create(ALetter: Char);
/// Upper case letter
property Letter: Char read fLetter;
/// Compares two letters. Returns -ve if Left < Right, 0 if equal and +ve
/// if Left > Right
class function Compare(const Left, Right: TInitialLetter): Integer; static;
/// Casts a TInitialLetter to a character.
class operator Implicit(const R: TInitialLetter): Char;
/// Test for equality of two records
class operator Equal(const L1, L2: TInitialLetter): Boolean;
/// Test for equality of a record and a char. Case of char is ignored.
class operator Equal(const L: TInitialLetter; const C: Char): Boolean;
/// Test for equality of a char and a record. Case of char is ignored.
class operator Equal(const C: Char; const L: TInitialLetter): Boolean;
end;
implementation
uses
// Delphi
Character,
// Project
UStrUtils;
{ TInitialLetter }
class function TInitialLetter.Compare(const Left, Right: TInitialLetter):
Integer;
begin
Result := StrCompareText(Left.Letter, Right.Letter);
end;
constructor TInitialLetter.Create(ALetter: Char);
begin
fLetter := TCharacter.ToUpper(ALetter);
end;
class operator TInitialLetter.Equal(const L1, L2: TInitialLetter): Boolean;
begin
Result := Compare(L1, L2) = 0;
end;
class operator TInitialLetter.Equal(const L: TInitialLetter;
const C: Char): Boolean;
begin
Result := L = TInitialLetter.Create(C);
end;
class operator TInitialLetter.Equal(const C: Char;
const L: TInitialLetter): Boolean;
begin
Result := TInitialLetter.Create(C) = L;
end;
class operator TInitialLetter.Implicit(const R: TInitialLetter): Char;
begin
Result := R.Letter;
end;
end.
