epubjs/books/accessible_epub_3-20121024.epub/stitcher.js

Render ePub documents in the browser, across many devices

var OReader = OReader || {};
OReader.Stitcher = {};

OReader.Stitcher.parsePart = function(partString) {
  var tokens = partString.split("["); // Split string into element and other
  var attributes = {};
  var part = {
    "string" : partString,
    "attributes" : attributes,
    "node" : tokens[0],
    "offset" : 1
  };
  var attrString;
  var re = /\@([^=]+)=[\'\"]([^\'^\"]+)[\'\"]/g;
  var match;

  // Part muight have additional information such as id or offset
  if(tokens[1]){
    // remove the last part
    attrString = tokens[1].replace(']', '');
    // If there is an offset it will be numerical
    if(!isNaN(parseFloat(attrString)) && isFinite(attrString)){ // is a number
      part.offset = parseInt(attrString);
    } else {
      // Run through string looking for @key=value paris
      do {
        match = re.exec(attrString);

        if (match) {
          // Add pairs to attributes object
          attributes[match[1]] = match[2];
        }
      } while (match);

    }
  }

  return part;
};

OReader.Stitcher.parseXpath = function(_xpath){
  // Split path into parts
  var parts = _xpath.substring(1).split("/");
  var xpath = [];

  // Parse each part and add to xpath array
  parts.forEach(function(part){
    var parsed = OReader.Stitcher.parsePart(part);
    xpath.push(parsed);
  });

  return xpath;
};

OReader.Stitcher.createElement = function(part, _doc){
  var doc = _doc || document;
  var element = doc.createElement(part.node);

  for (var attribute in part.attributes){
    if (part.attributes.hasOwnProperty(attribute)) {
      element.setAttribute(attribute, part.attributes[attribute]);
    }
  }

  return element;
};

OReader.Stitcher.rebuild = function(_xpath, doc, payload){

  var xpath = OReader.Stitcher.parseXpath(_xpath);
  var walked = [];
  var prevElement = doc.documentElement;
  var wrapper;
  var last = xpath.pop();
  var wrapperPresent = doc.evaluate(_xpath, doc, null, XPathResult.FIRST_ORDERED_NODE_TYPE, null).singleNodeValue;

  if(!wrapperPresent){
    // Create the terminal element
    wrapper = OReader.Stitcher.createElement(last, doc);

    // wrap the current payload in element
    while (payload.childNodes.length > 0) {
      if(payload.childNodes[0] != prevElement){
        wrapper.appendChild(payload.childNodes[0]);
      }
    }

  } else {
    // All elements in xpath already present in correct location
    return;
  }

  // Process xpath parts
  xpath.forEach(function(part){
    var present;
    var element;
    walked.push(part.string);

    // Check if part is present in DOM
    present = doc.evaluate("//"+walked.join('/'), doc, null, XPathResult.FIRST_ORDERED_NODE_TYPE, null).singleNodeValue;
    // console.log(present, walked.join('/'))
    if(!present) {
      
      // Create the element, add attributes
      element = OReader.Stitcher.createElement(part, doc);

      // Add to previously created element
      prevElement.appendChild(element);

      // Continue
      prevElement = element;

    } else {

      // Continue
      prevElement = present;
    
    }

  });
  
  // Add the wrapper last
  prevElement.appendChild(wrapper);

};