Function parse

tools/utils/parse-stack.js:17–57

(err)

// return anything past that function. We call this the "user portion"
// of the stack.
export function parse(err) {
  const stack = err.stack;
  if (typeof stack !== "string") {
    return {};
  }

  // at least the first line is the exception
  const frames = stack.split("\n").slice(1)
    // longjohn adds lines of the form '---' (45 times) to separate
    // the trace across async boundaries. It's not clear if we need to
    // separate the trace in the same way we do for future boundaries below
    // (it's not clear that that code is still useful either)
    // so for now, we'll just remove such lines
    .filter(f => ! f.match(/^\-{45}$/));
  
  // "    - - - - -"
  // This is something added when you throw an Error through a Future. The
  // stack above the dashes is the stack of the 'wait' call; the stack below
  // is the stack inside the fiber where the Error is originally
  // constructed.
  // XXX This code assumes that the stack trace can only be split once. It's not
  // clear whether this can happen multiple times.
  const indexOfFiberSplit = frames.indexOf('    - - - - -');

  if (indexOfFiberSplit === -1) {
    // This is a normal stack trace, not a split fiber stack trace
    return {
      outsideFiber: parseStackFrames(frames)
    }
  }

  // If this is a split stack trace from a future, parse the frames above and
  // below the split separately.
  const outsideFiber = parseStackFrames(frames);
  const insideFiber = parseStackFrames(frames.slice(indexOfFiberSplit + 1));

  return {
    insideFiber,
    outsideFiber
  };
}

// Decorator. Mark the point at which a stack trace returned by
// parse() should stop: no frames earlier than this point will be