reactNativeUtils: Add helper type ViewStylePropWithout

Author: chrisbobbe

src/__flow-tests__/reactNativeUtils-test.js

@@ -0,0 +1,29 @@
+/* @flow strict-local */
+import type AnimatedValue from 'react-native/Libraries/Animated/nodes/AnimatedValue';
+import type { DimensionValue } from 'react-native/Libraries/StyleSheet/StyleSheetTypes';
+import type { ViewStyleProp } from 'react-native/Libraries/StyleSheet/StyleSheet';
+
+import type { IsSupertype } from '../generics';
+import type { ViewStylePropWithout } from '../reactNativeUtils';
+
+function test_ViewStylePropWithout() {
+  type ViewStyleNoHeight = ViewStylePropWithout<{|
+    height: DimensionValue,
+    minHeight: DimensionValue,
+    maxHeight: DimensionValue,
+  |}>;
+
+  // Is a subtype of ViewStyleProp
+  (s: ViewStyleNoHeight): ViewStyleProp => s;
+
+  // Accepts width-related attributes
+  (s: {| minWidth: 10, width: AnimatedValue, maxWidth: '100%' |}): ViewStyleNoHeight => s;
+
+  // Doesn't accept height-related attributes
+  // $FlowExpectedError[incompatible-return]
+  (s: {| minHeight: 10 |}): ViewStyleNoHeight => s;
+  // $FlowExpectedError[incompatible-return]
+  (s: {| height: AnimatedValue |}): ViewStyleNoHeight => s;
+  // $FlowExpectedError[incompatible-return]
+  (s: {| maxHeight: '100%' |}): ViewStyleNoHeight => s;
+}

src/reactNativeUtils.js

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+/* @flow strict-local */
+
+// eslint-disable-next-line id-match
+import type { ____ViewStyle_Internal } from 'react-native/Libraries/StyleSheet/StyleSheetTypes';
+
+import type { BoundedDiff } from './generics';
+
+// A copy of the same-named type in
+// node_modules/react-native/Libraries/StyleSheet/StyleSheetTypes.js, for
+// use in ViewStylePropWithout, below.
+type GenericStyleProp<+T> = null | void | T | false | '' | $ReadOnlyArray<GenericStyleProp<T>>;
+
+/**
+ * `View`'s style prop, but without the style attributes defined in T.
+ */
+// RN's type for `View`'s style prop is `ViewStyleProp` in
+// node_modules/react-native/Libraries/StyleSheet/StyleSheet.js; our
+// implementation builds on a copy of that.
+export type ViewStylePropWithout<T: { ... }> = GenericStyleProp<
+  // Uses unsound $Shape just because the upstream type does, and we're
+  // copying that.
+  $ReadOnly<$Shape<BoundedDiff<____ViewStyle_Internal, T>>>,
+>;