adding game_of_life sample

dart/samples/webcomponents/game_of_life/components/components.dart

Index: dart/samples/webcomponents/game_of_life/components/components.dart
diff --git a/dart/samples/webcomponents/game_of_life/components/components.dart b/dart/samples/webcomponents/game_of_life/components/components.dart
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+// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+#library('game_of_life_components');
+
+#import('dart:html');
+#import('dart:math', prefix: 'Math');
+#import('package:dart-web-components/lib/js_polyfill/web_components.dart');
+
+/** Functions used to propogate a tick to cells. */
+typedef void Ping();
+
+// We've done things this way because we can't have default values for fields
+// inside a web component right now (see bug 4957).
+
+/** How big should the (square) board be by default? Measured in cells/side. */
+final int DEFAULT_GAME_SIZE = 40;
+
+/**
+ * How many pixels long is the side of a cell by default?
+ * (Note: must match the CSS!)
+ */
+final int DEFAULT_CELL_SIZE = 20;
+
+/** How many pixels from the game should the control panel be by default? */
+final int DEFAULT_PANEL_OFFSET = 20;
+
+/** How many milliseconds between steps by default? */
+final int DEFAULT_STEP_TIME = 1000;
+
+/** 
+ * Maps tag names to Dart constructors for components in this library.
+ * Singleton.
+ */
+Map<String, WebComponentFactory> get CTOR_MAP {
+  if (_CTOR_MAP == null) {
+    _CTOR_MAP = {
+      'x-cell' : () => new Cell.component(),
+      'x-control-panel' : () => new ControlPanel.component(),
+      'x-game-of-life' : () => new GameOfLife.component()
+    };
+  }
+  return _CTOR_MAP;
+}
+
+Map<String, WebComponentFactory> _CTOR_MAP;
+
+/** 
+ * If the importing code uses only the components in this library, 
+ * this function will do all necessary component initialization.
+ */
+void gameOfLifeComponentsSetup() {
+  initializeComponents((String name) => CTOR_MAP[name], true);
+}
+
+/**
+ * A single cell in the Game Of Life. Listens to a GameOfLife parent component
+ * to get a clock tick, and interacts on its neighbors on every tick to move the
+ * game one step forward.
+ */
+class Cell extends DivElementImpl implements WebComponent, Hashable {
+  Collection<Cell> neighbors;
+  ShadowRoot _root;
+  GameOfLife game;
+  bool aliveThisStep;
+  bool aliveNextStep;
+
+  // BEGIN AUTOGENERATED CODE
+  static WebComponentFactory _$constr;
+  factory Cell.component() {
+    if(_$constr == null) {
+      _$constr = () => new Cell._internal();
+    }
+    var t1 = new DivElement();
+    t1.attributes['is'] = 'x-cell';
+    rewirePrototypeChain(t1, _$constr, 'Cell');
+    return t1;
+  }
+
+  factory Cell() {
+    return manager.expandHtml('<div is="x-cell"></div>');
+  }
+
+  Cell._internal();
+  // END AUTOGENERATED CODE
+
+  void created(ShadowRoot root) {
+    _root = root;
+    neighbors = <Cell>[];
+    classes.add('cell');
+
+    // Cells start dead.
+    aliveThisStep = false;
+  }
+
+  void inserted() { }
+
+  /**
+   * Set up event listeners and populate [neighbors] by querying [game] for this
+   * cell's neighbors. Event listeners can be done here rather than dealt with
+   * in [inserted] and [removed] because cells will always be gc'd if removed
+   * from the DOM.
+   */
+  void bound() {
+    on.click.add((event) {
+      classes.toggle('alive');
+      aliveThisStep = !aliveThisStep;
+    });
+
+    game.on.step.add(step);
+    game.on.resolve.add(resolve);
+
+    // find neighbors
+    var parsedCoordinates = this.id.substring(1).split('y');
+    var x = Math.parseInt(parsedCoordinates[0]);
+    var y = Math.parseInt(parsedCoordinates[1]);
+    for (int dx = -1; dx <= 1; dx++) {
+      for (int dy = -1; dy <= 1; dy++) {
+        if (game.inGrid(x + dx, y + dy) && !(dx == 0 && dy == 0)) {
+          var neighbor = game._query('#x${x + dx}y${y + dy}');
+          neighbors.add(neighbor);
+        }
+      }
+    }
+  }
+
+  
+  void attributeChanged(String name, String oldValue, String newValue) { }
+
+  void removed() { }
+
+  /**
+   * Each turn of the game is broken into a step and a resolve. On a step, the
+   * cell queries its neighbors current states and decides whether or not will
+   * be alive or dead next turn.
+   */
+  void step() {
+    var numAlive = neighbors.filter((n) => n.aliveThisStep).length;
+    // We could compress this into one line, but it's clearer this way.
+    aliveNextStep = false;
+    if (aliveThisStep) {
+      if (numAlive == 2 || numAlive == 3) {
+        aliveNextStep = true;
+      }
+    } else {
+      if (numAlive == 3) {
+        aliveNextStep = true;
+      }
+    }
+  }
+
+  /**
+   * Each turn of the game is broken in a step and a resolve. On a resolve, the
+   * cell uses the information collected in the step phase to update its state
+   * and appearance -- black if alive this turn, white if dead this turn.
+   */
+  void resolve() {
+    if (aliveNextStep) {
+      classes.add('alive');
+    } else {
+      classes.remove('alive');
+    }
+    aliveThisStep = aliveNextStep;
+  }
+
+}
+
+/** 
+ * A control panel for the Game of Life. Has start, stop, and step buttons which
+ * start the game, stop the game, and move the game one turn forward,
+ * respectively.
+ */
+class ControlPanel extends DivElementImpl implements WebComponent {
+  ShadowRoot _root;
+  GameOfLife game;
+
+  // BEGIN AUTOGENERATED CODE
+  static WebComponentFactory _$constr;
+  factory ControlPanel.component() {
+    if(_$constr == null) {
+      _$constr = () => new ControlPanel._internal();
+    }
+    var t1 = new DivElement();
+    t1.attributes['is'] = 'x-control-panel';
+    rewirePrototypeChain(t1, _$constr, 'ControlPanel');
+    return t1;
+  }
+
+  factory ControlPanel() {
+    return manager.expandHtml('<div is="x-control-panel"></div>');
+  }
+
+  ControlPanel._internal();
+  // END AUTOGENERATED CODE
+
+  void created(ShadowRoot root) {
+    _root = root;
+  }
+
+  void inserted() { }
+
+  /** 
+   * Sets up event listeners for the buttons. This must be done here rather than
+   * in [inserted] because the events must propogate up to [game].
+   */
+  void bound() { 
+    _root.query('#start').on.click.add((e) => game.run());
+    _root.query('#stop').on.click.add((e) => game.stop());
+    _root.query('#step').on.click.add((e) => game.step());
+  }
+
+  void attributeChanged(String name, String oldValue, String newValue) { }
+
+  void removed() { }
+}
+
+/** 
+ * A Game of Life component, containing an interactive implementation of
+ * Conway's Game of Life.
+ */
+class GameOfLife extends DivElementImpl implements WebComponent {
+
+  // Implementation Notes: The game consists of a control panel and a board
+  // composed of cells. Each cell is a web component, and the control panel is a
+  // web component. The top-level widget populates the board with cells and
+  // provides a clock tick to which the cells listen. It exposes API to stop and
+  // start that tick, which the control panel binds to its buttons. Aside
+  // from the tick, no state is maintained in the top level widget -- each cell
+  // maintains its own state and talks to its neighbors to move the game
+  // forward.
+
+  // TODO(samhop): implement wraparound on the board.
+  ShadowRoot _root;
+  GameOfLifeEvents on;
+  Timer timer;
+  int lastRefresh;
+  bool _stop;
+  StyleElement computedStyles;
+
+  // These cannot be initialized here right now -- see bug 4957.
+
+  /** How big should the (square) board be? Measured in cells/side. */
+  int GAME_SIZE;
+
+  /** How many pixels long is the side of a cell? (Note: must match the CSS!) */
+  int CELL_SIZE;
+
+  /** How many pixels from the game should the control panel be? */
+  int PANEL_OFFSET;
+
+  /** How many milliseconds between steps? */
+  int _stepTime;
+
+  void set stepTime(int time) {
+    _stepTime = time;
+  }
+
+  // BEGIN AUTOGENERATED CODE
+  static WebComponentFactory _$constr;
+  factory GameOfLife.component() {
+    if(_$constr == null) {
+      _$constr = () => new GameOfLife._internal();
+    }
+    var t1 = new DivElement();
+    t1.attributes['is'] = 'x-game-of-life';
+    rewirePrototypeChain(t1, _$constr, 'GameOfLife');
+    return t1;
+  }
+
+  factory GameOfLife() {
+    return manager.expandHtml('<div is="x-game-of-life"></div>');
+  }
+
+  GameOfLife._internal();
+  // END AUTOGENERATED CODE
+
+  /** On creation, initialize fields and then populate the game. */
+  void created(ShadowRoot root) {
+    _root = root;
+    on = new GameOfLifeEvents();
+    lastRefresh = 0;
+    
+    // At present we must do this initialization here -- see bug 4957.
+    GAME_SIZE = DEFAULT_GAME_SIZE;
+    CELL_SIZE = DEFAULT_CELL_SIZE;
+    PANEL_OFFSET = DEFAULT_PANEL_OFFSET;
+    _stepTime = DEFAULT_STEP_TIME;
+
+    _populate();
+  }
+
+  void inserted() { }
+
+  void attributeChanged(String name, String oldValue, String newValue) { }
+
+  void removed() { }
+
+  /** 
+   * Returns the results of querying on [selector] beneath [_root]. Needed by
+   * Cells to determine their neighbors.
+   */
+  _query(String selector) {
+    return _root.query(selector);
+  }
+
+  /** Stop ticking. */
+  void stop() {
+    _stop = true;
+  }
+
+  /** 
+   * Tick once, if it has been at least _stepTime milliseconds since the last
+   * tick. Then, if we haven't been told to stop, call set up a
+   * requestAnimationFrame callback to tick again.
+   */
+  void _increment(int time) {
+    if (new Date.now().millisecondsSinceEpoch - lastRefresh >= _stepTime) {
+      on.step.forEach((f) => f());
+      on.resolve.forEach((f) => f());
+      lastRefresh = new Date.now().millisecondsSinceEpoch;
+    }
+    if (!_stop) {
+       window.requestAnimationFrame(_increment);
+    }
+  }
+
+  /** Start the game. */
+  void run() {
+    _stop = false;
+    window.requestAnimationFrame(_increment);
+  }
+
+  /** 
+   * Move the game one step forward. If the game was running, stop the game
+   * beforehand.
+   */
+  void step() {
+    _stop = true;
+    _increment(null);
+  }
+
+  /** 
+   * Fill the game board with cells, position them appropriately, position the 
+   * control panel, and bind all subcomponents.
+   */
+  void _populate() {
+    // set up position styles
+    computedStyles = new StyleElement();
+    _root.nodes.add(computedStyles);
+    var computedStylesBuffer = new StringBuffer(); 
+    _forEachCell((i, j) =>  _addPositionId(computedStylesBuffer, i, j));
+
+    // position the control panel
+    var panelStyle = 
+        '''
+        #panel {
+          top: ${CELL_SIZE * GAME_SIZE + PANEL_OFFSET}px;
+          left: ${PANEL_OFFSET}px;
+        }
+        ''';
+    computedStylesBuffer.add('${computedStyles.innerHTML}\n$panelStyle');
+
+    computedStyles.innerHTML = computedStylesBuffer.toString();
+
+    // add cells
+    _forEachCell((i, j) {
+      var cell = new Cell();
+      cell.game = this;
+      cell.id = _generatePositionString(i, j);
+      _root.nodes.add(cell);
+    });
+
+    // bind the control panel
+    var controlPanel = _root.query('div[is="x-control-panel"]');
+    controlPanel.game = this;
+    controlPanel.bound();
+
+    // TODO(samhop): fix webcomponents.dart so that attributes are preserved.
+    _root.query('div').id = 'panel';
+
+    // TODO(samhop) fix webcomponents.dart so we don't have to do this
+    _root.queryAll('.cell').forEach((cell) => cell.bound());
+  }
+
+  /** 
+   * Calls f exactly once on all pairs (i, j) for ints i, j between 0 and
+   * [GAME_SIZE] - 1, inclusive.
+   */
+  void _forEachCell(f) {
+    for (var i = 0; i < GAME_SIZE; i++) {
+      for (var j = 0; j < GAME_SIZE; j++) {
+        f(i, j);
+      }
+    }
+  }
+  
+  /**
+   * Appends correct cell positioning information for cell ([i], [j]) to [curr].
+   */
+  String _addPositionId(StringBuffer curr, int i, int j) =>
+      curr.add(
+      '''
+      #${_generatePositionString(i, j)} {
+        left: ${CELL_SIZE * i}px;
+        top: ${CELL_SIZE * j}px;
+      }
+      ''');
+
+  /** Returns the cell id corresponding to ([i], [j]). */
+  String _generatePositionString(int i, int j) => 'x${i}y${j}';
+
+  /** 
+   * Is the coordinate ([x],[y]) in the game grid, given the current
+   * [GAME_SIZE]?
+   */
+  bool inGrid(x, y) =>
+    (x >=0 && y >=0 && x < GAME_SIZE && y < GAME_SIZE);
+
+  /** 
+   * Set cell ([i],[j])'s aliveness to [alive]. Throws an
+   * IllegalArgumentException if ([i],[j]) is not a valid cell (i.e. if it is
+   * outside of the grid).
+   */
+  void setAliveness(int i, int j, bool alive) {
+    _validateGridPosition(i, j);
+    _query('#${_generatePositionString(i, j)}').aliveThisStep = alive;
+  }
+
+  /**
+   * Is cell ([i], [j]) currently alive? Throws an IllegalArgumentException if
+   * ([i], [j]) is not a valid cell (i.e. it is outside the grid).
+   */
+  bool isAlive(int i, int j) {
+    _validateGridPosition(i, j);
+    return _query('#${_generatePositionString(i,j)}').aliveThisStep;
+  }
+
+  /** Throw an IllegalArgumentException if ([i], [j]) is not a valid cell. */
+  void _validateGridPosition(int i, int j) {
+    if (i < 0 || j < 0 || !inGrid(i,j)) {
+      throw new IllegalArgumentException('(${i}, ${j}) is a bad coordinate');
+    }
+    assert(inGrid(i,j) && i >= 0 && j >= 0);
+  }
+}
+
+/** Events container for a GameOfLife. */
+class GameOfLifeEvents implements Events {
+  List<Ping> _step_list;
+  List<Ping> _resolve_list;
+
+  GameOfLifeEvents() 
+      : _step_list = <Ping>[],
+        _resolve_list = <Ping>[];
+
+  List<Ping> get step => _step_list;
+  List<Ping> get resolve => _resolve_list;
+}