Create a gist now

Instantly share code, notes, and snippets.

What would you like to do?
If expression
(*
* If expression - ternary operator like C.
*
* HOW TO USE
* 1. uses uIfExp;
* 2. IfExp<TYPE>(BooleanValue) - TRUE_VALUE or FALSE_VALUE
* or
* IfExp<TYPE>(BooleanValue).ThenElse(TRUE_VALUE, FALSE_VALUE);
*
* EXAMPLE
* Writeln(IfExp<String>(1 > 0) - 'true' or 'false');
* Writeln(IfExp<Integer>(1 > 3) - 100 or -100);
* Writeln(IfExp<Double>('a' > 'c').ThenElse(0.1, 0.2));
*
* Programmed by HOSOKAWA Jun / twitter: @pik
*)
unit uIfExp;
interface
uses
System.Rtti;
type
IfExp<T> = record
private class var
FValue: Boolean;
FThen: TValue;
public
class operator Implicit(const AValue: Boolean): IfExp<T>;
class operator Subtract(
const ALeft: IfExp<T>;
const ARight: TValue): IfExp<T>;
class operator BitwiseOr(const ALeft: IfExp<T>; const ARight: TValue): T;
class function ThenElse(const AThen, AElse: T): T; static; inline;
end;
implementation
{ IfThen<T> }
class operator IfExp<T>.BitwiseOr(
const ALeft: IfExp<T>;
const ARight: TValue): T;
begin
if (FValue) then
Result := FThen.AsType<T>
else
Result := ARight.AsType<T>;
end;
class operator IfExp<T>.Implicit(const AValue: Boolean): IfExp<T>;
begin
FValue := AValue;
end;
class operator IfExp<T>.Subtract(
const ALeft: IfExp<T>;
const ARight: TValue): IfExp<T>;
begin
FThen := ARight;
end;
class function IfExp<T>.ThenElse(const AThen, AElse: T): T;
begin
if (FValue) then
Result := AThen
else
Result := AElse;
end;
end.
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment