d3.map = function(object) {

var map = new d3_Map;

for (var key in object) map.set(key, object[key]);

return map;

};

function d3_Map() {}

d3_class(d3_Map, {

has: function(key) {

return d3_map_prefix + key in this;

},

get: function(key) {

return this[d3_map_prefix + key];

},

set: function(key, value) {

return this[d3_map_prefix + key] = value;

},

remove: function(key) {

key = d3_map_prefix + key;

return key in this && delete this[key];

},

keys: function() {

var keys = [];

this.forEach(function(key) { keys.push(key); });

return keys;

},

values: function() {

var values = [];

this.forEach(function(key, value) { values.push(value); });

return values;

},

entries: function() {

var entries = [];

this.forEach(function(key, value) { entries.push({key: key, value: value}); });

return entries;

},

forEach: function(f) {

for (var key in this) {

if (key.charCodeAt(0) === d3_map_prefixCode) {

f.call(this, key.substring(1), this[key]);

}

}

}

});

var d3_map_prefix = "\0", // prevent collision with built-ins

d3_map_prefixCode = d3_map_prefix.charCodeAt(0);