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share/endpoint/www/js/undo.js  view on Meta::CPAN

      // Note that this makes the loop skip line objects that have
      // been pulled into chains by lines before them.
      if (!temp(line.from)) return;

      var chain = [], curNode = line.from, safe = true;
      // Put any line objects (referred to by temp info) before this
      // one on the front of the array.
      while (true) {
        var curLine = temp(curNode);
        if (!curLine) {
          if (safe) break;
          else curLine = buildLine(curNode);
        }
        chain.unshift(curLine);
        setTemp(curNode, null);
        if (!curNode) break;
        safe = self.after(curNode);
        curNode = nextBR(curNode, "previous");
      }
      curNode = line.to; safe = self.before(line.from);
      // Add lines after this one at end of array.
      while (true) {
        if (!curNode) break;
        var curLine = temp(curNode);
        if (!curLine) {
          if (safe) break;
          else curLine = buildLine(curNode);
        }
        chain.push(curLine);
        setTemp(curNode, null);
        safe = self.before(curNode);
        curNode = nextBR(curNode, "next");
      }
      chains.push(chain);
    });

    return chains;
  },

  // Find the 'shadow' of a given chain by following the links in the
  // DOM nodes at its start and end.
  shadowChain: function(chain) {
    var shadows = [], next = this.after(chain[0].from), end = chain[chain.length - 1].to;
    while (true) {
      shadows.push(next);
      var nextNode = next.to;
      if (!nextNode || nextNode == end)
        break;
      else
        next = nextNode.historyAfter || this.before(end);
      // (The this.before(end) is a hack -- FF sometimes removes
      // properties from BR nodes, in which case the best we can hope
      // for is to not break.)
    }
    return shadows;
  },

  // Update the DOM tree to contain the lines specified in a given
  // chain, link this chain into the DOM nodes.
  applyChain: function(chain) {
    // Some attempt is made to prevent the cursor from jumping
    // randomly when an undo or redo happens. It still behaves a bit
    // strange sometimes.
    var cursor = select.cursorPos(this.container, false), self = this;

    // Remove all nodes in the DOM tree between from and to (null for
    // start/end of container).
    function removeRange(from, to) {
      var pos = from ? from.nextSibling : self.container.firstChild;
      while (pos != to) {
        var temp = pos.nextSibling;
        removeElement(pos);
        pos = temp;
      }
    }

    var start = chain[0].from, end = chain[chain.length - 1].to;
    // Clear the space where this change has to be made.
    removeRange(start, end);

    // Insert the content specified by the chain into the DOM tree.
    for (var i = 0; i < chain.length; i++) {
      var line = chain[i];
      // The start and end of the space are already correct, but BR
      // tags inside it have to be put back.
      if (i > 0)
        self.container.insertBefore(line.from, end);

      // Add the text.
      var node = makePartSpan(fixSpaces(line.text));
      self.container.insertBefore(node, end);
      // See if the cursor was on this line. Put it back, adjusting
      // for changed line length, if it was.
      if (cursor && cursor.node == line.from) {
        var cursordiff = 0;
        var prev = this.after(line.from);
        if (prev && i == chain.length - 1) {
          // Only adjust if the cursor is after the unchanged part of
          // the line.
          for (var match = 0; match < cursor.offset &&
               line.text.charAt(match) == prev.text.charAt(match); match++){}
          if (cursor.offset > match)
            cursordiff = line.text.length - prev.text.length;
        }
        select.setCursorPos(this.container, {node: line.from, offset: Math.max(0, cursor.offset + cursordiff)});
      }
      // Cursor was in removed line, this is last new line.
      else if (cursor && (i == chain.length - 1) && cursor.node && cursor.node.parentNode != this.container) {
        select.setCursorPos(this.container, {node: line.from, offset: line.text.length});
      }
    }

    // Anchor the chain in the DOM tree.
    this.linkChain(chain);
    return start;
  }
};