Roll Observatory packages and add a roll script

charted/lib/layout/src/hierarchy_layout.dart

-/*
- * Copyright 2015 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.layout;
-
-typedef int SortFunction(HierarchyNode a, HierarchyNode b);
-typedef List ChildrenAccessor(HierarchyNode node);
-typedef num ValueAccessor(HierarchyNode node);
-
-/**
- * The hierarchy layout is an abstract layout that is not used directly, but
- * instead allows code sharing between multiple hierarchical layouts such as:
- * Cluster, Pack, Partition, Tree, and Treemap layout.
- */
-abstract class HierarchyLayout<T extends HierarchyNode> {
-  static const ROOT_ROW_INDEX = -1;
-  SortFunction sortFunction = hierarchySort;
-  ChildrenAccessor childrenAccessor = hierarchyChildren;
-  ValueAccessor valueAccessor = hierarchyValue;
-
-  /// Returns the list of HierarchyNode constructed from the given data and
-  /// parentColumn and valueColumn which is used to construct the hierarchy.
-  /// The returned list of nodes contains the hierarchy with root being the
-  /// first element its children in depth first order.
-  List<T> layout(List rows, int parentColumn, int labelColumn,
-      int valueColumn) {
-    List<HierarchyNode> nodeList = [];
-    for (var row in rows) {
-      nodeList.add(createNode(row[labelColumn], row[valueColumn], 0));
-    }
-
-    for (var i = 0; i < rows.length; i++) {
-      int parentRow = rows[i][parentColumn];
-      if (parentRow == ROOT_ROW_INDEX) continue;
-      var currentNode = nodeList[i];
-      var parentNode = nodeList[parentRow];
-      (parentNode.children.isEmpty) ? parentNode.children = [currentNode] :
-          parentNode.children.add(currentNode);
-      currentNode.parent = parentNode;
-      currentNode.depth = parentNode.depth + 1;
-      for (var child in currentNode.children) {
-        child.depth += 1;
-      }
-    }
-
-    // Reorder the list so that root is the first element and the list contains
-    // the hierarchy of nodes in depth first order.
-    var hierarchyNodeList = [];
-    var root = nodeList.where((e) => e.depth == 0).elementAt(0);
-    var children = [root];
-    while (children.length > 0) {
-      var node = children.removeLast();
-      children.addAll(node.children);
-      hierarchyNodeList.add(node);
-    }
-
-    return hierarchyNodeList;
-  }
-
-  T createNode(label, value, depth);
-
-  /// Default accessor method for getting the list of children of the node.
-  static List hierarchyChildren(HierarchyNode node) => node.children;
-
-  /// Default accessor method for getting the value of the node.
-  static num hierarchyValue(HierarchyNode node) => node.value;
-
-  /// Default sorting method for comparing node a and b.
-  static int hierarchySort(HierarchyNode a, HierarchyNode b) =>
-      b.value - a.value;
-
-}
-
-abstract class HierarchyNode {
-  /// The parent node, or null for the root.
-  HierarchyNode parent = null;
-
-  /// The list of children nodes, or null for leaf nodes.
-  List children = [];
-
-  /// The label to show for each block of hierarchy
-  String label = '';
-
-  /// The node value, as returned by the value accessor.
-  dynamic value;
-
-  /// The depth of the node, starting at 0 for the root.
-  int depth = 0;
-}