Metacat

// Copyright 2005 Google Inc.

// All Rights Reserved

//

// An XML parse and a minimal DOM implementation that just supportes

// the subset of the W3C DOM that is used in the XSLT implementation.

//

// References: 

//

// [DOM] W3C DOM Level 3 Core Specification

//       <http://www.w3.org/TR/2004/REC-DOM-Level-3-Core-20040407/>.

//

// 

// Author: Steffen Meschkat <mesch@google.com>

// NOTE: The split() method in IE omits empty result strings. This is

// utterly annoying. So we don't use it here.

// Resolve entities in XML text fragments. According to the DOM

// specification, the DOM is supposed to resolve entity references at

// the API level. I.e. no entity references are passed through the

// API. See "Entities and the DOM core", p.12, DOM 2 Core

// Spec. However, different browsers actually pass very different

// values at the API.

//

function xmlResolveEntities(s) {

  var parts = stringSplit(s, '&');

  var ret = parts[0];

  for (var i = 1; i < parts.length; ++i) {

    var rp = stringSplit(parts[i], ';');

    if (rp.length == 1) {

      // no entity reference: just a & but no ;

      ret += parts[i];

      continue;

    }

    var ch;

    switch (rp[0]) {

      case 'lt': 

        ch = '<';

        break;

      case 'gt': 

        ch = '>';

        break;

      case 'amp': 

        ch = '&';

        break;

      case 'quot': 

        ch = '"';

        break;

      case 'apos': 

        ch = '\'';

        break;

      case 'nbsp': 

        ch = String.fromCharCode(160);

        break;

      default:

        // Cool trick: let the DOM do the entity decoding. We assign

        // the entity text through non-W3C DOM properties and read it

        // through the W3C DOM. W3C DOM access is specified to resolve

        // entities. 

        var span = window.document.createElement('span');

        span.innerHTML = '&' + rp[0] + '; ';

        ch = span.childNodes[0].nodeValue.charAt(0);

    }

    ret += ch + rp[1];

  }

  return ret;

}

// Parses the given XML string with our custom, JavaScript XML parser. Written

// by Steffen Meschkat (mesch@google.com).

function xmlParse(xml) {

  Timer.start('xmlparse');

  var regex_empty = /\/$/;

  // See also <http://www.w3.org/TR/REC-xml/#sec-common-syn> for

  // allowed chars in a tag and attribute name. TODO(mesch): the

  // following is still not completely correct.

  var regex_tagname = /^([\w:-]*)/;

  var regex_attribute = /([\w:-]+)\s?=\s?('([^\']*)'|"([^\"]*)")/g;

  var xmldoc = new XDocument();

  var root = xmldoc;

  // For the record: in Safari, we would create native DOM nodes, but

  // in Opera that is not possible, because the DOM only allows HTML

  // element nodes to be created, so we have to do our own DOM nodes.

  // xmldoc = document.implementation.createDocument('','',null);

  // root = xmldoc; // .createDocumentFragment();

  // NOTE(mesch): using the DocumentFragment instead of the Document

  // crashes my Safari 1.2.4 (v125.12).

  var stack = [];

  var parent = root;

  stack.push(parent);

  var x = stringSplit(xml, '<');

  for (var i = 1; i < x.length; ++i) {

    var xx = stringSplit(x[i], '>');

    var tag = xx[0];

    var text = xmlResolveEntities(xx[1] || '');

    if (tag.charAt(0) == '/') {

      stack.pop();

      parent = stack[stack.length-1];

    } else if (tag.charAt(0) == '?') {

      // Ignore XML declaration and processing instructions

    } else if (tag.charAt(0) == '!') {

      // Ignore notation and comments

    } else {

      var empty = tag.match(regex_empty);

      var tagname = regex_tagname.exec(tag)[1];

      var node = xmldoc.createElement(tagname);

      var att;

      while (att = regex_attribute.exec(tag)) {

        var val = xmlResolveEntities(att[3] || att[4] || '');

        node.setAttribute(att[1], val);

      }

      if (empty) {

        parent.appendChild(node);

      } else {

        parent.appendChild(node);

        parent = node;

        stack.push(node);

      }

    }

    if (text && parent != root) {

      parent.appendChild(xmldoc.createTextNode(text));

    }

  }

  Timer.end('xmlparse');

  return root;

}

// Our W3C DOM Node implementation. Note we call it XNode because we

// can't define the identifier Node. We do this mostly for Opera,

// where we can't reuse the HTML DOM for parsing our own XML, and for

// Safari, where it is too expensive to have the template processor

// operate on native DOM nodes.

function XNode(type, name, value, owner) {

  this.attributes = [];

  this.childNodes = [];

  XNode.init.call(this, type, name, value, owner);

}

// Don't call as method, use apply() or call().

XNode.init = function(type, name, value, owner) {

  this.nodeType = type - 0;

  this.nodeName = '' + name;

  this.nodeValue = '' + value;

  this.ownerDocument = owner;

  this.firstChild = null;

  this.lastChild = null;

  this.nextSibling = null;

  this.previousSibling = null;

  this.parentNode = null;

}

XNode.unused_ = [];

XNode.recycle = function(node) {

  if (!node) {

    return;

  }

  if (node.constructor == XDocument) {

    XNode.recycle(node.documentElement);

    return;

  }

  if (node.constructor != this) {

    return;

  }

  XNode.unused_.push(node);

  for (var a = 0; a < node.attributes.length; ++a) {

    XNode.recycle(node.attributes[a]);

  }

  for (var c = 0; c < node.childNodes.length; ++c) {

    XNode.recycle(node.childNodes[c]);

  }

  node.attributes.length = 0;

  node.childNodes.length = 0;

  XNode.init.call(node, 0, '', '', null);

}

XNode.create = function(type, name, value, owner) {

  if (XNode.unused_.length > 0) {

    var node = XNode.unused_.pop();

    XNode.init.call(node, type, name, value, owner);

    return node;

  } else {

    return new XNode(type, name, value, owner);

  }

}

XNode.prototype.appendChild = function(node) {

  // firstChild

  if (this.childNodes.length == 0) {

    this.firstChild = node;

  }

  // previousSibling

  node.previousSibling = this.lastChild;

  // nextSibling

  node.nextSibling = null;

  if (this.lastChild) {

    this.lastChild.nextSibling = node;

  }

  // parentNode

  node.parentNode = this;

  // lastChild

  this.lastChild = node;

  // childNodes

  this.childNodes.push(node);

}

XNode.prototype.replaceChild = function(newNode, oldNode) {

  if (oldNode == newNode) {

    return;

  }

  for (var i = 0; i < this.childNodes.length; ++i) {

    if (this.childNodes[i] == oldNode) {

      this.childNodes[i] = newNode;

      var p = oldNode.parentNode;

      oldNode.parentNode = null;

      newNode.parentNode = p;

      p = oldNode.previousSibling;

      oldNode.previousSibling = null;

      newNode.previousSibling = p;

      if (newNode.previousSibling) {

        newNode.previousSibling.nextSibling = newNode;

      }

      p = oldNode.nextSibling;

      oldNode.nextSibling = null;

      newNode.nextSibling = p;

      if (newNode.nextSibling) {

        newNode.nextSibling.previousSibling = newNode;

      }

      if (this.firstChild == oldNode) {

        this.firstChild = newNode;

      }

      if (this.lastChild == oldNode) {

        this.lastChild = newNode;

      }

      break;

    }

  }

}

XNode.prototype.insertBefore = function(newNode, oldNode) {

  if (oldNode == newNode) {

    return;

  }

  if (oldNode.parentNode != this) {

    return;

  }

  if (newNode.parentNode) {

    newNode.parentNode.removeChild(newNode);

  }

  var newChildren = [];

  for (var i = 0; i < this.childNodes.length; ++i) {

    var c = this.childNodes[i];

    if (c == oldNode) {

      newChildren.push(newNode);

      newNode.parentNode = this;

      newNode.previousSibling = oldNode.previousSibling;

      oldNode.previousSibling = newNode;

      if (newNode.previousSibling) {

        newNode.previousSibling.nextSibling = newNode;

      }

      newNode.nextSibling = oldNode;

      if (this.firstChild == oldNode) {

        this.firstChild = newNode;

      }

    }

    newChildren.push(c);

  }

  this.childNodes = newChildren;

}

XNode.prototype.removeChild = function(node) {

  var newChildren = [];

  for (var i = 0; i < this.childNodes.length; ++i) {

    var c = this.childNodes[i];

    if (c != node) {

      newChildren.push(c);

    } else {

      if (c.previousSibling) {

        c.previousSibling.nextSibling = c.nextSibling;

      }

      if (c.nextSibling) {

        c.nextSibling.previousSibling = c.previousSibling;

      }

      if (this.firstChild == c) {

        this.firstChild = c.nextSibling;

      }

      if (this.lastChild == c) {

        this.lastChild = c.previousSibling;

      }

    }

  }

  this.childNodes = newChildren;

}

XNode.prototype.hasAttributes = function() {

  return this.attributes.length > 0;

}

XNode.prototype.setAttribute = function(name, value) {

  for (var i = 0; i < this.attributes.length; ++i) {

    if (this.attributes[i].nodeName == name) {

      this.attributes[i].nodeValue = '' + value;

      return;

    }

  }

  this.attributes.push(new XNode(DOM_ATTRIBUTE_NODE, name, value));

}

XNode.prototype.getAttribute = function(name) {

  for (var i = 0; i < this.attributes.length; ++i) {

    if (this.attributes[i].nodeName == name) {

      return this.attributes[i].nodeValue;

    }

  }

  return null;

}

XNode.prototype.removeAttribute = function(name) {

  var a = [];

  for (var i = 0; i < this.attributes.length; ++i) {

    if (this.attributes[i].nodeName != name) {

      a.push(this.attributes[i]);

    }

  }

  this.attributes = a;

}

function XDocument() {

  XNode.call(this, DOM_DOCUMENT_NODE, '#document', null, this);

  this.documentElement = null;

}

XDocument.prototype = new XNode(DOM_DOCUMENT_NODE, '#document');

XDocument.prototype.clear = function() {

  XNode.recycle(this.documentElement);

  this.documentElement = null;

}

XDocument.prototype.appendChild = function(node) {

  XNode.prototype.appendChild.call(this, node);

  this.documentElement = this.childNodes[0];

}

XDocument.prototype.createElement = function(name) {

  return XNode.create(DOM_ELEMENT_NODE, name, null, this);

}

XDocument.prototype.createDocumentFragment = function() {

  return XNode.create(DOM_DOCUMENT_FRAGMENT_NODE, '#document-fragment',

                    null, this);

}

XDocument.prototype.createTextNode = function(value) {

  return XNode.create(DOM_TEXT_NODE, '#text', value, this);

}

XDocument.prototype.createAttribute = function(name) {

  return XNode.create(DOM_ATTRIBUTE_NODE, name, null, this);

}

XDocument.prototype.createComment = function(data) {

  return XNode.create(DOM_COMMENT_NODE, '#comment', data, this);

}

XNode.prototype.getElementsByTagName = function(name, list) {

  if (!list) {

    list = [];

  }

  if (this.nodeName == name) {

    list.push(this);

  }

  for (var i = 0; i < this.childNodes.length; ++i) {

    this.childNodes[i].getElementsByTagName(name, list);

  }

  return list;

}