Function clearEmptySpans

src/codemirror.js:6454–6462

(spans)

  // Remove spans that are empty and don't have a clearWhenEmpty
  // option of false.
  function clearEmptySpans(spans) {
    for (var i = 0; i < spans.length; ++i) {
      var span = spans[i];
      if (span.from != null && span.from == span.to && span.marker.clearWhenEmpty !== false)
        spans.splice(i--, 1);
    }
    if (!spans.length) return null;
    return spans;
  }

  // Used for un/re-doing changes from the history. Combines the
  // result of computing the existing spans with the set of spans that