function describeNativeComponentFrame()

in fixtures/legacy-jsx-runtimes/react-17/cjs/react-jsx-dev-runtime.development.js [350:501]

• 88 lines of code
• 31 McCabe index (conditional complexity)

function describeNativeComponentFrame(fn, construct) {
  // If something asked for a stack inside a fake render, it should get ignored.
  if (!fn || reentry) {
    return '';
  }

  {
    var frame = componentFrameCache.get(fn);

    if (frame !== undefined) {
      return frame;
    }
  }

  var control;
  reentry = true;
  var previousPrepareStackTrace = Error.prepareStackTrace; // $FlowFixMe It does accept undefined.

  Error.prepareStackTrace = undefined;
  var previousDispatcher;

  {
    previousDispatcher = ReactCurrentDispatcher.current; // Set the dispatcher in DEV because this might be call in the render function
    // for warnings.

    ReactCurrentDispatcher.current = null;
    disableLogs();
  }

  try {
    // This should throw.
    if (construct) {
      // Something should be setting the props in the constructor.
      var Fake = function () {
        throw Error();
      }; // $FlowFixMe


      Object.defineProperty(Fake.prototype, 'props', {
        set: function () {
          // We use a throwing setter instead of frozen or non-writable props
          // because that won't throw in a non-strict mode function.
          throw Error();
        }
      });

      if (typeof Reflect === 'object' && Reflect.construct) {
        // We construct a different control for this case to include any extra
        // frames added by the construct call.
        try {
          Reflect.construct(Fake, []);
        } catch (x) {
          control = x;
        }

        Reflect.construct(fn, [], Fake);
      } else {
        try {
          Fake.call();
        } catch (x) {
          control = x;
        }

        fn.call(Fake.prototype);
      }
    } else {
      try {
        throw Error();
      } catch (x) {
        control = x;
      }

      fn();
    }
  } catch (sample) {
    // This is inlined manually because closure doesn't do it for us.
    if (sample && control && typeof sample.stack === 'string') {
      // This extracts the first frame from the sample that isn't also in the control.
      // Skipping one frame that we assume is the frame that calls the two.
      var sampleLines = sample.stack.split('\n');
      var controlLines = control.stack.split('\n');
      var s = sampleLines.length - 1;
      var c = controlLines.length - 1;

      while (s >= 1 && c >= 0 && sampleLines[s] !== controlLines[c]) {
        // We expect at least one stack frame to be shared.
        // Typically this will be the root most one. However, stack frames may be
        // cut off due to maximum stack limits. In this case, one maybe cut off
        // earlier than the other. We assume that the sample is longer or the same
        // and there for cut off earlier. So we should find the root most frame in
        // the sample somewhere in the control.
        c--;
      }

      for (; s >= 1 && c >= 0; s--, c--) {
        // Next we find the first one that isn't the same which should be the
        // frame that called our sample function and the control.
        if (sampleLines[s] !== controlLines[c]) {
          // In V8, the first line is describing the message but other VMs don't.
          // If we're about to return the first line, and the control is also on the same
          // line, that's a pretty good indicator that our sample threw at same line as
          // the control. I.e. before we entered the sample frame. So we ignore this result.
          // This can happen if you passed a class to function component, or non-function.
          if (s !== 1 || c !== 1) {
            do {
              s--;
              c--; // We may still have similar intermediate frames from the construct call.
              // The next one that isn't the same should be our match though.

              if (c < 0 || sampleLines[s] !== controlLines[c]) {
                // V8 adds a "new" prefix for native classes. Let's remove it to make it prettier.
                var _frame = '\n' + sampleLines[s].replace(' at new ', ' at ');

                {
                  if (typeof fn === 'function') {
                    componentFrameCache.set(fn, _frame);
                  }
                } // Return the line we found.


                return _frame;
              }
            } while (s >= 1 && c >= 0);
          }

          break;
        }
      }
    }
  } finally {
    reentry = false;

    {
      ReactCurrentDispatcher.current = previousDispatcher;
      reenableLogs();
    }

    Error.prepareStackTrace = previousPrepareStackTrace;
  } // Fallback to just using the name if we couldn't make it throw.


  var name = fn ? fn.displayName || fn.name : '';
  var syntheticFrame = name ? describeBuiltInComponentFrame(name) : '';

  {
    if (typeof fn === 'function') {
      componentFrameCache.set(fn, syntheticFrame);
    }
  }

  return syntheticFrame;
}