列挙型と列挙子名(文字列)または整数の相互変換(ジェネリックス版)

Record helper for enumeration

unit Unit2;

interface

uses
  TypInfo, SysUtils, SysConst;

type
  TEnumHelper = record
    class function TryGetEnumName<T: record>(Value: T; out S: String): Boolean; static;
    class function GetEnumName<T: record>(Value: T): String; static;
    class function TryGetEnumValue<T: record>(const Name: String; out Enum: T): Boolean; overload; static;
    class function GetEnumValue<T: record>(const Name: String): T; overload; static;
    class function TryGetEnumValue<T: record>(Value: Integer; out Enum: T): Boolean; overload; static;
    class function GetEnumValue<T: record>(Value: Integer): T; overload; static;
  end;

implementation

class function TEnumHelper.TryGetEnumName<T>(Value: T; out S: String): Boolean;
var
  P: PTypeInfo;
  IValue: Integer;
begin

  Result := False;
  S := '';

  P := TypeInfo(T);
  if (P = nil) or (P^.Kind <> tkEnumeration) then
  begin
    Exit;
  end;

  IValue := 0;
  Move(Value,IValue,SizeOf(T));
  S := TypInfo.GetEnumName(P,IValue);
  Result := True;

end;

class function TEnumHelper.GetEnumName<T>(Value: T): String;
var
  P: PTypeInfo;
  IValue: Integer;
begin

  P := TypeInfo(T);
  if (P = nil) or (P^.Kind <> tkEnumeration) then
  begin
    raise EInvalidOpException.CreateRes(@SVarNotImplemented);
  end;

  IValue := 0;
  Move(Value,IValue,SizeOf(T));
  Result := TypInfo.GetEnumName(P,IValue);

end;

class function TEnumHelper.TryGetEnumValue<T>(const Name: String; out Enum: T): Boolean;
var
  P: PTypeInfo;
  IValue: Integer;
begin

  Result := False;
  Enum := Default(T);

  P := TypeInfo(T);
  if (P = nil) or (P^.Kind <> tkEnumeration) then
  begin
    Exit;
  end;

  IValue := TypInfo.GetEnumValue(P,Name);

  with GetTypeData(P)^ do
  begin
    if (IValue < MinValue) or (IValue > MaxValue) then
    begin
      Exit;
    end;
  end;

  Move(IValue,Enum,SizeOf(T));
  Result := True;

end;

class function TEnumHelper.GetEnumValue<T>(const Name: String): T;
var
  P: PTypeInfo;
  IValue: Integer;
begin

  Result := Default(T);

  P := TypeInfo(T);
  if (P = nil) or (P^.Kind <> tkEnumeration) then
  begin
    raise EInvalidOpException.CreateRes(@SVarNotImplemented);
  end;

  IValue := TypInfo.GetEnumValue(P,Name);

  with GetTypeData(P)^ do
  begin
    if (IValue < MinValue) or (IValue > MaxValue) then
    begin
      raise ERangeError.CreateRes(@SRangeError);
    end;
  end;

  Move(IValue,Result,SizeOf(T));

end;

class function TEnumHelper.TryGetEnumValue<T>(Value: Integer; out Enum: T): Boolean;
var
  P: PTypeInfo;
begin

  Result := False;
  Enum := Default(T);

  P := TypeInfo(T);
  if (P = nil) or (P^.Kind <> tkEnumeration) then
  begin
    Exit;
  end;

  with GetTypeData(P)^ do
  begin
    if (Value < MinValue) or (Value > MaxValue) then
    begin
      Exit;
    end;
  end;

  Move(Value,Enum,SizeOf(T));
  Result := True;

end;

class function TEnumHelper.GetEnumValue<T>(Value: Integer): T;
var
  P: PTypeInfo;
begin

  Result := Default(T);

  P := TypeInfo(T);
  if (P = nil) or (P^.Kind <> tkEnumeration) then
  begin
    raise EInvalidOpException.CreateRes(@SVarNotImplemented);
  end;

  with GetTypeData(P)^ do
  begin
    if (Value < MinValue) or (Value > MaxValue) then
    begin
      raise ERangeError.CreateRes(@SRangeError);
    end;
  end;

  Move(Value,Result,SizeOf(T));

end;

end.