Data update

Task/Generator-Exponential/Delphi/generator-exponential.pas

@@ -0,0 +1,151 @@
+{Custom object forms basic generator}
+
+type TCustomGen = class(TObject)
+ private
+  FNumber: integer;
+  FExponent: integer;
+  FStart: integer;
+ protected
+   property Exponent: integer read FExponent write FExponent;
+ public
+   constructor Create; virtual;
+   procedure Reset;
+   function Next: integer; virtual;
+   procedure Skip(Count: integer);
+   property Start: integer read FStart write FStart;
+ end;
+
+{Child object specifically for generating Squares}
+
+type TSquareGen = class(TCustomGen)
+ public
+  constructor Create; override;
+  end;
+
+
+{Child object specifically for generating cubes}
+
+type TCubeGen = class(TCustomGen)
+ public
+  constructor Create; override;
+  end;
+
+{Child object specifically for filtering squares}
+
+type TFilterSquareGen = class(TSquareGen)
+ private
+  function IsCube(N: integer): boolean;
+ public
+  function Next: integer; override;
+  end;
+
+{ TCustomGen }
+
+constructor TCustomGen.Create;
+begin
+Start:=0;
+{Default to returning X^1}
+Exponent:=1;
+Reset;
+end;
+
+
+function TCustomGen.Next: integer;
+{Find next number in sequence}
+var I: integer;
+begin
+Result:=FNumber;
+{Raise to specified power}
+for I:=1 to FExponent-1 do Result:=Result * Result;
+{Get next base}
+Inc(FNumber);
+end;
+
+
+procedure TCustomGen.Reset;
+begin
+FNumber:=Start;
+end;
+
+
+procedure TCustomGen.Skip(Count: integer);
+{Skip specified number of items}
+var I: integer;
+begin
+for I:=1 to Count do Next;
+end;
+
+{ TSquareGen }
+
+constructor TSquareGen.Create;
+begin
+inherited;
+Exponent:=2;
+end;
+
+{ TCubeGen }
+
+constructor TCubeGen.Create;
+begin
+inherited;
+Exponent:=3;
+end;
+
+{ TFilterSquareGen }
+
+function TFilterSquareGen.IsCube(N: integer): boolean;
+{Test if number is perfect cube}
+var I: integer;
+begin
+I:=Round(Power(N,1/3));
+Result:=I*I*I = N;
+end;
+
+
+
+function TFilterSquareGen.Next: integer;
+begin
+{Gets inherited next square, rejects cubes}
+repeat Result:=inherited Next
+until not IsCube(Result);
+end;
+
+
+{-----------------------------------------------------------}
+
+procedure DoTest(Memo: TMemo; Gen: TCustomGen; SkipCnt: integer; Title: string);
+{Carry out TGenerators tests. "Gen" is a TCustomGen which is the parent of}
+{all generators. That means "DoTest" can work with any type of generator}
+var S: string;
+var I,V: integer;
+begin
+Gen.Reset;
+Gen.Skip(SkipCnt);
+Memo.Lines.Add(Title);
+S:='[';
+for I:=1 to 10 do S:=S+Format(' %d',[Gen.Next]);
+Memo.Lines.Add(S+']');
+end;
+
+
+
+procedure TestGenerators(Memo: TMemo);
+{Tests all three types of generators}
+var SquareGen: TSquareGen;
+var CubeGen: TCubeGen;
+var Filtered: TFilterSquareGen;
+begin
+SquareGen:=TSquareGen.Create;
+try
+CubeGen:=TCubeGen.Create;
+try
+Filtered:=TFilterSquareGen.Create;
+try
+DoTest(Memo,SquareGen,0,'Testing Square Generator');
+DoTest(Memo,CubeGen,0,'Testing Cube Generator');
+DoTest(Memo,Filtered,20,'Testing Squares with cubes removed');
+
+finally Filtered.Free; end;
+finally CubeGen.Free; end;
+finally SquareGen.Free; end;
+end;