81 lines
1.7 KiB
Plaintext
81 lines
1.7 KiB
Plaintext
pub class Rc<T> : Drop, Copy
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class Inner<T>(t: T)
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mut count = 1
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end
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inner: &weak Inner = Null
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pub ctor(t: T)
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inner = Inner(t)
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end
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ctor(parent: &Self)
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parent.inner++
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inner = &weak parent.inner
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end
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pub fn copy() -> Self
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Self(self)
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end
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impl fn drop(self)
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if inner.upgrade() is Some(inner) then
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inner.count--
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if inner.count == 0 then
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drop inner
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end
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else
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throw Exception('rc.inner could not be converted from a weak reference')
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end
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end
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end
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class Game(player: Player) end
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class Player
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pub mut game: &weak Game = Null
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end
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fn circular()
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let player = Player()
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let game = Game(player)
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expectThrows(EmptyWeakReferenceException) {
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player.game.upgrade()
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}
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player.game = &weak game
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expectDoesNotThrow {
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player.game.upgrade()
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}
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end
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class Board
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pub fn flip()
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println 'Flipped!'
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end
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end
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class ChessGame(pub board: rc Board) end
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class ChessPlayer(pub board: rc Board) end
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fn getGameAndPlayer() -> (ChessGame, ChessPlayer)
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let board = rc Board() // Rc<Board> count is 1
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let game = ChessGame(board) // Rc<Board> copied, count is 2
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let player = ChessPlayer(board) // Rc<Board> copied, count is 3
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(game, player) // initial Rc<Board> dropped before fn return, count now 2
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end
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fn playChess()
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let (game, player) = getGameAndPlayer()
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// Rc<Board> count is 2
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let board = game.board // Copy, so count is now 3
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board.flip()
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drop board // count now 2
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drop game // count now 1
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drop player // count now 0, board memory finally dropped
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end |