1 // TODO data(null) for clearing data?

     2 d3_selectionPrototype.data = function(data, join) {

     3   var enter = [],

     4       update = [],

     5       exit = [];

     6 

     7   function bind(group, groupData) {

     8     var i,

     9         n = group.length,

    10         m = groupData.length,

    11         n0 = Math.min(n, m),

    12         n1 = Math.max(n, m),

    13         updateNodes = [],

    14         enterNodes = [],

    15         exitNodes = [],

    16         node,

    17         nodeData;

    18 

    19     if (join) {

    20       var nodeByKey = {},

    21           keys = [],

    22           key,

    23           j = groupData.length;

    24 

    25       for (i = -1; ++i < n;) {

    26         key = join.call(node = group[i], node.__data__, i);

    27         if (key in nodeByKey) {

    28           exitNodes[j++] = node; // duplicate key

    29         } else {

    30           nodeByKey[key] = node;

    31         }

    32         keys.push(key);

    33       }

    34 

    35       for (i = -1; ++i < m;) {

    36         node = nodeByKey[key = join.call(groupData, nodeData = groupData[i], i)];

    37         if (node) {

    38           node.__data__ = nodeData;

    39           updateNodes[i] = node;

    40           enterNodes[i] = exitNodes[i] = null;

    41         } else {

    42           enterNodes[i] = d3_selection_dataNode(nodeData);

    43           updateNodes[i] = exitNodes[i] = null;

    44         }

    45         delete nodeByKey[key];

    46       }

    47 

    48       for (i = -1; ++i < n;) {

    49         if (keys[i] in nodeByKey) {

    50           exitNodes[i] = group[i];

    51         }

    52       }

    53     } else {

    54       for (i = -1; ++i < n0;) {

    55         node = group[i];

    56         nodeData = groupData[i];

    57         if (node) {

    58           node.__data__ = nodeData;

    59           updateNodes[i] = node;

    60           enterNodes[i] = exitNodes[i] = null;

    61         } else {

    62           enterNodes[i] = d3_selection_dataNode(nodeData);

    63           updateNodes[i] = exitNodes[i] = null;

    64         }

    65       }

    66       for (; i < m; ++i) {

    67         enterNodes[i] = d3_selection_dataNode(groupData[i]);

    68         updateNodes[i] = exitNodes[i] = null;

    69       }

    70       for (; i < n1; ++i) {

    71         exitNodes[i] = group[i];

    72         enterNodes[i] = updateNodes[i] = null;

    73       }

    74     }

    75 

    76     enterNodes.update

    77         = updateNodes;

    78 

    79     enterNodes.parentNode

    80         = updateNodes.parentNode

    81         = exitNodes.parentNode

    82         = group.parentNode;

    83 

    84     enter.push(enterNodes);

    85     update.push(updateNodes);

    86     exit.push(exitNodes);

    87   }

    88 

    89   var i = -1,

    90       n = this.length,

    91       group;

    92   if (typeof data === "function") {

    93     while (++i < n) {

    94       bind(group = this[i], data.call(group, group.parentNode.__data__, i));

    95     }

    96   } else {

    97     while (++i < n) {

    98       bind(group = this[i], data);

    99     }

   100   }

   101 

   102   var selection = d3_selection(update);

   103   selection.enter = function() { return d3_selection_enter(enter); };

   104   selection.exit = function() { return d3_selection(exit); };

   105   return selection;

   106 };

   107 

   108 function d3_selection_dataNode(data) {

   109   return {__data__: data};

   110 }