import “../core/ns”; import “selection”;

d3_selectionPrototype.attr = function(name, value) {

if (arguments.length < 2) {

  // For attr(string), return the attribute value for the first node.
  if (typeof name === "string") {
    var node = this.node();
    name = d3.ns.qualify(name);
    return name.local
        ? node.getAttributeNS(name.space, name.local)
        : node.getAttribute(name);
  }

  // For attr(object), the object specifies the names and values of the
  // attributes to set or remove. The values may be functions that are
  // evaluated for each element.
  for (value in name) this.each(d3_selection_attr(value, name[value]));
  return this;
}

return this.each(d3_selection_attr(name, value));

};

function d3_selection_attr(name, value) {

name = d3.ns.qualify(name);

// For attr(string, null), remove the attribute with the specified name.
function attrNull() {
  this.removeAttribute(name);
}
function attrNullNS() {
  this.removeAttributeNS(name.space, name.local);
}

// For attr(string, string), set the attribute with the specified name.
function attrConstant() {
  this.setAttribute(name, value);
}
function attrConstantNS() {
  this.setAttributeNS(name.space, name.local, value);
}

// For attr(string, function), evaluate the function for each element, and set
// or remove the attribute as appropriate.
function attrFunction() {
  var x = value.apply(this, arguments);
  if (x == null) this.removeAttribute(name);
  else this.setAttribute(name, x);
}
function attrFunctionNS() {
  var x = value.apply(this, arguments);
  if (x == null) this.removeAttributeNS(name.space, name.local);
  else this.setAttributeNS(name.space, name.local, x);
}

return value == null
    ? (name.local ? attrNullNS : attrNull) : (typeof value === "function"
    ? (name.local ? attrFunctionNS : attrFunction)
    : (name.local ? attrConstantNS : attrConstant));

}