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diff --git a/popperjs/package/lib/dom-utils/getClippingRect.js.flow b/popperjs/package/lib/dom-utils/getClippingRect.js.flow
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+// @flow
+import type { ClientRectObject } from '../types';
+import type { Boundary, RootBoundary } from '../enums';
+import { viewport } from '../enums';
+import getViewportRect from './getViewportRect';
+import getDocumentRect from './getDocumentRect';
+import listScrollParents from './listScrollParents';
+import getOffsetParent from './getOffsetParent';
+import getDocumentElement from './getDocumentElement';
+import getComputedStyle from './getComputedStyle';
+import { isElement, isHTMLElement } from './instanceOf';
+import getBoundingClientRect from './getBoundingClientRect';
+import getParentNode from './getParentNode';
+import contains from './contains';
+import getNodeName from './getNodeName';
+import rectToClientRect from '../utils/rectToClientRect';
+import { max, min } from '../utils/math';
+
+function getInnerBoundingClientRect(element: Element) {
+  const rect = getBoundingClientRect(element);
+
+  rect.top = rect.top + element.clientTop;
+  rect.left = rect.left + element.clientLeft;
+  rect.bottom = rect.top + element.clientHeight;
+  rect.right = rect.left + element.clientWidth;
+  rect.width = element.clientWidth;
+  rect.height = element.clientHeight;
+  rect.x = rect.left;
+  rect.y = rect.top;
+
+  return rect;
+}
+
+function getClientRectFromMixedType(
+  element: Element,
+  clippingParent: Element | RootBoundary
+): ClientRectObject {
+  return clippingParent === viewport
+    ? rectToClientRect(getViewportRect(element))
+    : isElement(clippingParent)
+    ? getInnerBoundingClientRect(clippingParent)
+    : rectToClientRect(getDocumentRect(getDocumentElement(element)));
+}
+
+// A "clipping parent" is an overflowable container with the characteristic of
+// clipping (or hiding) overflowing elements with a position different from
+// `initial`
+function getClippingParents(element: Element): Array<Element> {
+  const clippingParents = listScrollParents(getParentNode(element));
+  const canEscapeClipping =
+    ['absolute', 'fixed'].indexOf(getComputedStyle(element).position) >= 0;
+  const clipperElement =
+    canEscapeClipping && isHTMLElement(element)
+      ? getOffsetParent(element)
+      : element;
+
+  if (!isElement(clipperElement)) {
+    return [];
+  }
+
+  // $FlowFixMe[incompatible-return]: https://github.com/facebook/flow/issues/1414
+  return clippingParents.filter(
+    (clippingParent) =>
+      isElement(clippingParent) &&
+      contains(clippingParent, clipperElement) &&
+      getNodeName(clippingParent) !== 'body' &&
+      (canEscapeClipping
+        ? getComputedStyle(clippingParent).position !== 'static'
+        : true)
+  );
+}
+
+// Gets the maximum area that the element is visible in due to any number of
+// clipping parents
+export default function getClippingRect(
+  element: Element,
+  boundary: Boundary,
+  rootBoundary: RootBoundary
+): ClientRectObject {
+  const mainClippingParents =
+    boundary === 'clippingParents'
+      ? getClippingParents(element)
+      : [].concat(boundary);
+  const clippingParents = [...mainClippingParents, rootBoundary];
+  const firstClippingParent = clippingParents[0];
+
+  const clippingRect = clippingParents.reduce((accRect, clippingParent) => {
+    const rect = getClientRectFromMixedType(element, clippingParent);
+
+    accRect.top = max(rect.top, accRect.top);
+    accRect.right = min(rect.right, accRect.right);
+    accRect.bottom = min(rect.bottom, accRect.bottom);
+    accRect.left = max(rect.left, accRect.left);
+
+    return accRect;
+  }, getClientRectFromMixedType(element, firstClippingParent));
+
+  clippingRect.width = clippingRect.right - clippingRect.left;
+  clippingRect.height = clippingRect.bottom - clippingRect.top;
+  clippingRect.x = clippingRect.left;
+  clippingRect.y = clippingRect.top;
+
+  return clippingRect;
+}