Function changeLine

src/codemirror.js:4796–4803

(doc, handle, changeType, op)

  // returning the number and optionally registering the line as
  // changed.
  function changeLine(doc, handle, changeType, op) {
    var no = handle, line = handle;
    if (typeof handle == "number") line = getLine(doc, clipLine(doc, handle));
    else no = lineNo(handle);
    if (no == null) return null;
    if (op(line, no) && doc.cm) regLineChange(doc.cm, no, changeType);
    return line;
  }

  // Helper for deleting text near the selection(s), used to implement
  // backspace, delete, and similar functionality.