swift - The Flyweight Pattern

client:

let ss1 = Spreadsheet();

ss1.setValue(Coordinate(col: "A",row: 1),value: 100);

ss1.setValue(Coordinate(col: "J",row: 20),value: 200);

println("SS1 Total: (ss1.total)");

let ss2 = Spreadsheet();

ss2.setValue(Coordinate(col: "F",row: 10),value: 200);

ss2.setValue(Coordinate(col: "G",row: 23),value: 250);

println("SS2 Total: (ss2.total)");

println("Cells created: (1300 + ss1.grid.count + ss2.grid.count)");

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

pattern:

//1

func == (lhs: Coordinate,rhs: Coordinate) -> Bool {

return lhs.col == rhs.col && lhs.row == rhs.row;

}

class Coordinate : Hashable,Printable {

let col:Character;

let row:Int;

init(col:Character,row:Int) {

self.col = col; self.row = row;

}

var hashValue: Int {

return description.hashValue;

}

var description: String {

return "(col)(row)";

}

}

class Cell {

var coordinate:Coordinate;

var value:Int;

init(col:Character,row:Int,val:Int) {

self.coordinate = Coordinate(col: col,row: row);

self.value = val;

}

}

class Spreadsheet {

var grid:Flyweight;

init() {

grid = FlyweightFactory.createFlyweight();

}

func setValue(coord: Coordinate,value:Int) {

grid[coord] = value;

}

var total:Int {

return grid.total;

}

}

//2

import Foundation;

protocol Flyweight {

subscript(index:Coordinate) -> Int? { get set };

var total:Int { get };

var count:Int { get };

}

extension Dictionary {

init(setupFunc:(() -> [(Key,Value)])) {

self.init();

for item in setupFunc() {

self[item.0] = item.1;

}

}

}

class FlyweightFactory {

class func createFlyweight() -> Flyweight {

return FlyweightImplementation(extrinsic: extrinsicData);

}

private class var extrinsicData:[Coordinate: Cell] {

get {

struct singletonWrapper {

static let singletonData = Dictionary<Coordinate,Cell> (

setupFunc: {() in

var results = [(Coordinate,Cell)]();

let letters:String = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";

var stringIndex = letters.startIndex;

let rows = 50;

do {

let colLetter = letters[stringIndex];

stringIndex = stringIndex.successor();

for rowIndex in 1 ... rows {

let cell = Cell(col: colLetter,row: rowIndex,

val: rowIndex);

results.append((cell.coordinate,cell));

}

} while (stringIndex != letters.endIndex);

return results;

}

);

}

return singletonWrapper.singletonData;

}

}

}

class FlyweightImplementation : Flyweight {

private let extrinsicData:[Coordinate: Cell];

private var intrinsicData:[Coordinate: Cell];

private let queue:dispatch_queue_t;

private init(extrinsic:[Coordinate: Cell]) {

self.extrinsicData = extrinsic;

self.intrinsicData = Dictionary<Coordinate,Cell>();

self.queue = dispatch_queue_create("dataQ",DISPATCH_QUEUE_CONCURRENT);

}

subscript(key:Coordinate) -> Int? {

get {

var result:Int?;

dispatch_sync(self.queue,{() in

if let cell = self.intrinsicData[key] {

result = cell.value;

} else {

result = self.extrinsicData[key]?.value;

}

});

return result;

}

set (value) {

if (value != nil) {

dispatch_barrier_sync(self.queue,{() in

self.intrinsicData[key] = Cell(col: key.col,

row: key.row,val: value!);

});

}

}

}

var total:Int {

var result = 0;

dispatch_sync(self.queue,{() in

result = reduce(self.extrinsicData.values,0,{total,cell in

if let intrinsicCell = self.intrinsicData[cell.coordinate] {

return total + intrinsicCell.value;

} else {

return total + cell.value

}

});

});

return result;

}

var count:Int {

var result = 0;

dispatch_sync(self.queue,{() in

result = self.intrinsicData.count;

});

return result;

}

}

（编辑：李大同）

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