function flip()

in js/bootstrap.bundle.js [2745:2862]
99 lines of code
25 McCabe index (conditional complexity)

  function flip(_ref) {
    var state = _ref.state,
        options = _ref.options,
        name = _ref.name;

    if (state.modifiersData[name]._skip) {
      return;
    }

    var _options$mainAxis = options.mainAxis,
        checkMainAxis = _options$mainAxis === void 0 ? true : _options$mainAxis,
        _options$altAxis = options.altAxis,
        checkAltAxis = _options$altAxis === void 0 ? true : _options$altAxis,
        specifiedFallbackPlacements = options.fallbackPlacements,
        padding = options.padding,
        boundary = options.boundary,
        rootBoundary = options.rootBoundary,
        altBoundary = options.altBoundary,
        _options$flipVariatio = options.flipVariations,
        flipVariations = _options$flipVariatio === void 0 ? true : _options$flipVariatio,
        allowedAutoPlacements = options.allowedAutoPlacements;
    var preferredPlacement = state.options.placement;
    var basePlacement = getBasePlacement(preferredPlacement);
    var isBasePlacement = basePlacement === preferredPlacement;
    var fallbackPlacements = specifiedFallbackPlacements || (isBasePlacement || !flipVariations ? [getOppositePlacement(preferredPlacement)] : getExpandedFallbackPlacements(preferredPlacement));
    var placements = [preferredPlacement].concat(fallbackPlacements).reduce(function (acc, placement) {
      return acc.concat(getBasePlacement(placement) === auto ? computeAutoPlacement(state, {
        placement: placement,
        boundary: boundary,
        rootBoundary: rootBoundary,
        padding: padding,
        flipVariations: flipVariations,
        allowedAutoPlacements: allowedAutoPlacements
      }) : placement);
    }, []);
    var referenceRect = state.rects.reference;
    var popperRect = state.rects.popper;
    var checksMap = new Map();
    var makeFallbackChecks = true;
    var firstFittingPlacement = placements[0];

    for (var i = 0; i < placements.length; i++) {
      var placement = placements[i];

      var _basePlacement = getBasePlacement(placement);

      var isStartVariation = getVariation(placement) === start;
      var isVertical = [top, bottom].indexOf(_basePlacement) >= 0;
      var len = isVertical ? 'width' : 'height';
      var overflow = detectOverflow(state, {
        placement: placement,
        boundary: boundary,
        rootBoundary: rootBoundary,
        altBoundary: altBoundary,
        padding: padding
      });
      var mainVariationSide = isVertical ? isStartVariation ? right : left : isStartVariation ? bottom : top;

      if (referenceRect[len] > popperRect[len]) {
        mainVariationSide = getOppositePlacement(mainVariationSide);
      }

      var altVariationSide = getOppositePlacement(mainVariationSide);
      var checks = [];

      if (checkMainAxis) {
        checks.push(overflow[_basePlacement] <= 0);
      }

      if (checkAltAxis) {
        checks.push(overflow[mainVariationSide] <= 0, overflow[altVariationSide] <= 0);
      }

      if (checks.every(function (check) {
        return check;
      })) {
        firstFittingPlacement = placement;
        makeFallbackChecks = false;
        break;
      }

      checksMap.set(placement, checks);
    }

    if (makeFallbackChecks) {
      // `2` may be desired in some cases – research later
      var numberOfChecks = flipVariations ? 3 : 1;

      var _loop = function _loop(_i) {
        var fittingPlacement = placements.find(function (placement) {
          var checks = checksMap.get(placement);

          if (checks) {
            return checks.slice(0, _i).every(function (check) {
              return check;
            });
          }
        });

        if (fittingPlacement) {
          firstFittingPlacement = fittingPlacement;
          return "break";
        }
      };

      for (var _i = numberOfChecks; _i > 0; _i--) {
        var _ret = _loop(_i);

        if (_ret === "break") break;
      }
    }

    if (state.placement !== firstFittingPlacement) {
      state.modifiersData[name]._skip = true;
      state.placement = firstFittingPlacement;
      state.reset = true;
    }
  } // eslint-disable-next-line import/no-unused-modules