70 lines
1.6 KiB
Swift
70 lines
1.6 KiB
Swift
internal final class Pawn: Piece {
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internal var kind: Kind = .Pawn
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internal weak var board: Board?
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internal var color: Color
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internal var position: Square.Position
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internal var pseudoLegalPositions: [Square.Position] {
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let sign: Int8 = color == .Black ? -1 : 1
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let rank = Int8(position.rank)
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let directions: [Square.Position] = [
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.init(file: position.file, rank: rank + 1 * sign),
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.init(file: position.file, rank: rank + 2 * sign),
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.init(file: position.file + 1, rank: rank + 1 * sign),
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.init(file: position.file - 1, rank: rank + 1 * sign)
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]
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// TODO: Handle en passant
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return directions.filter {
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let index = $0.index
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return index < 1 || index > 63
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}
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}
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internal var legalPositions: [Square.Position] {
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pseudoLegalPositions.filter { isLegal(on: $0) }
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}
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internal var unicodeRepresentation: String {
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color == .Black ? "♟" : "♙"
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}
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internal func move(to dst: Square.Position) -> Bool {
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guard board != nil else {
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return false
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}
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if !(legalPositions.contains { $0 == dst }) {
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return false
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}
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if let board = board, var s = board[position], var d = board[dst] {
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s.piece = self
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d.piece = nil
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}
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position = dst
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return true
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}
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internal func isLegal(on pos: Square.Position) -> Bool {
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// TODO: Handle "En-Passant"
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if let board = board, let s = board[pos] {
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if let p = s.piece {
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if p.color == color { return false }
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if p.kind == .King {
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// TODO: Notify board of check
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return false
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}
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}
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}
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return true
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}
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internal init(
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color: Color, on position: Square.Position
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) {
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self.color = color
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self.position = position
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}
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}
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