portable gm_xpath

gm_xpath.js

//@original https://github.com/scriptish/scriptish/blob/master/extension/modules/api/sandboxScripts.js
//          を元にchrome上で動く用に改変
//@howto https://github.com/scriptish/scriptish/wiki/GM_xpath
//require        https://gist.github.com/54a5327db50607678b62.txt
//頭に@つけてuser.jsに書くと楽

if(typeof(GM_xpath) != "function"){
  function GM_xpath(details) {
    var contextNode, contextDocument, paths, resolver, namespace, result,path;
  
    if (typeof(details) == 'string') {
      details = { path: details }
    }
  
    contextNode = "node" in details ? details.node : document;
    if (!contextNode) {
      throw new Error("The value specified for node is invalid");
    }
  
    if (contextNode.ownerDocument) {
      contextDocument = contextNode.ownerDocument;
    }
    else if (contextNode.evaluate) {
      // contextNode is a Document already
      contextDocument = contextNode;
    }
    else {
      throw new Error("No owning document for the specified node. Make sure you pass a valid node!");
    }
  
    paths = details.paths || details.path;
    if (typeof(paths) == "string") {
      paths = [paths];
    }
  
    if (details.resolver) {
      if (typeof(details.resolver) == "string") {
        resolver = {lookupNamespaceURI: function(p){return details.resolver;}};
      }
      else if (typeof(details.resolver) == "function") {
        resolver = {lookupNamespaceURI: details.resolver};
      }
      else if (typeof(resolver.lookupNamespaceURI) == "function") {
        resolver = details.resolver;
      }
      else {
        throw new Error("resolver is invalid");
      }
    }
    else if (contextNode.namepaceURI) {
      namespace = contextNode.namespaceURI;
      resolver = {lookupNamespaceURI: function(p){return namespace;}};
    }
  
    if (details.all) {
      var rv = [], n;
      while (path = paths.shift()) {
        result = contextDocument.evaluate(
          path,
          contextNode,
          resolver,
          XPathResult.ORDERED_NODE_ITERATOR_TYPE,
          null
        );
        while (n = result.iterateNext()) {
          rv.push(n);
        }
      }
      return rv;
    }
  
    while (path = paths.shift()) {
       result = contextDocument.evaluate(
          path,
          contextNode,
          resolver,
          XPathResult.FIRST_ORDERED_NODE_TYPE,
          null
      ).singleNodeValue;
  
      if (result) {
        return result;
      }
    }
  
    return null;
  }
}