Roll Observatory packages and add a roll script

charted/lib/selection/selection_scope.dart

-/*
- * Copyright 2014 Google Inc. All rights reserved.
- *
- * Use of this source code is governed by a BSD-style
- * license that can be found in the LICENSE file or at
- * https://developers.google.com/open-source/licenses/bsd
- */
-
-part of charted.selection;
-
-/** SelectionScope represents a scope for all the data and DOM operations. */
-class SelectionScope {
-  Expando _associations = new Expando();
-  Expando<Map<String, Pair<Function, bool>>> _listeners = new Expando();
-  Element _root;
-
-  /** Creates a new selection scope with document as the root. */
-  SelectionScope() {
-    _root = document.documentElement;
-  }
-
-  /**
-   * Creates a new selection scope with the first element matching
-   * [selector] as the root.
-   */
-  SelectionScope.selector(String selector) {
-    if (selector == null || selector.isEmpty ){
-      throw new ArgumentError('Selector cannot be empty');
-    }
-    _root = document.querySelector(selector);
-  }
-
-  /**
-   * Creates a new selection scope with the passed [element] as [root].
-   * Charted assumes that the element is already part of the DOM.
-   */
-  SelectionScope.element(Element element) {
-    if (element == null) {
-      throw new ArgumentError('Root element for SelectionScope cannot be null');
-    }
-    _root = element;
-  }
-
-  /**
-   * Returns the [root] element for this scope.
-   * All [Selection]s and elements created using the Charted API,
-   * are created as descendants of root.
-   */
-  Element get root => _root;
-
-  /*
-   * Current event for which a callback is being called.
-   */
-  Event event;
-
-  /** Returns the stored for the given [element]. */
-  datum(Object element) => element == null ? null : _associations[element];
-
-  /** Associates data to the given [element]. */
-  associate(Object element, datum) =>
-      datum != null ? _associations[element] = datum : null;
-
-  /**
-   * Creates a new [Selection] containing the first element matching
-   * [selector].  If no element matches, the resulting selection will
-   * have a null element.
-   */
-  Selection select(String selector) =>
-      new _SelectionImpl.single(selector: selector, scope: this);
-
-  /**
-   * Creates a new [Selection] containing all elements matching [selector].
-   * If no element matches, the resulting selection will not have any
-   * elements in it.
-   */
-  Selection selectAll(String selector) =>
-      new _SelectionImpl.all(selector:selector, scope:this);
-
-  /**
-   * Creates a new [Selection] containing [elements].  Assumes that
-   * all the given elements are descendants of [root] in DOM.
-   */
-  Selection selectElements(List<Element> elements) =>
-      new _SelectionImpl.elements(elements, this);
-
-  /**
-   * Appends a new element to [root] and creates a selection containing
-   * the newly added element.
-   */
-  Selection append(String tag) {
-    var element = Namespace.createChildElement(tag, _root);
-    root.children.add(element);
-
-    return selectElements([element]);
-  }
-}