Function makeChangeFromHistory

samples/common/codehighlight/codemirror.js:5300–5372

(doc, type, allowSelectionOnly)

  // Revert a change stored in a document's history.
  function makeChangeFromHistory(doc, type, allowSelectionOnly) {
    var suppress = doc.cm && doc.cm.state.suppressEdits;
    if (suppress && !allowSelectionOnly) { return }

    var hist = doc.history, event, selAfter = doc.sel;
    var source = type == "undo" ? hist.done : hist.undone, dest = type == "undo" ? hist.undone : hist.done;

    // Verify that there is a useable event (so that ctrl-z won't
    // needlessly clear selection events)
    var i = 0;
    for (; i < source.length; i++) {
      event = source[i];
      if (allowSelectionOnly ? event.ranges && !event.equals(doc.sel) : !event.ranges)
        { break }
    }
    if (i == source.length) { return }
    hist.lastOrigin = hist.lastSelOrigin = null;

    for (;;) {
      event = source.pop();
      if (event.ranges) {
        pushSelectionToHistory(event, dest);
        if (allowSelectionOnly && !event.equals(doc.sel)) {
          setSelection(doc, event, {clearRedo: false});
          return
        }
        selAfter = event;
      } else if (suppress) {
        source.push(event);
        return
      } else { break }
    }

    // Build up a reverse change object to add to the opposite history
    // stack (redo when undoing, and vice versa).
    var antiChanges = [];
    pushSelectionToHistory(selAfter, dest);
    dest.push({changes: antiChanges, generation: hist.generation});
    hist.generation = event.generation || ++hist.maxGeneration;

    var filter = hasHandler(doc, "beforeChange") || doc.cm && hasHandler(doc.cm, "beforeChange");

    var loop = function ( i ) {
      var change = event.changes[i];
      change.origin = type;
      if (filter && !filterChange(doc, change, false)) {
        source.length = 0;
        return {}
      }

      antiChanges.push(historyChangeFromChange(doc, change));

      var after = i ? computeSelAfterChange(doc, change) : lst(source);
      makeChangeSingleDoc(doc, change, after, mergeOldSpans(doc, change));
      if (!i && doc.cm) { doc.cm.scrollIntoView({from: change.from, to: changeEnd(change)}); }
      var rebased = [];

      // Propagate to the linked documents