Move TypeForStyleKey from StyleSheetTypes to StyleSheet

Reviewed By: yungsters

Differential Revision: D7281362

fbshipit-source-id: 936d198e83dfbfc62449e82b5559a30bd57621c4

Libraries/StyleSheet/StyleSheet.js

@@ -20,6 +20,7 @@ const flatten = require('flattenStyle');
 import type {
   ____StyleSheetInternalStyleIdentifier_Internal as StyleSheetInternalStyleIdentifier,
   ____Styles_Internal,
+  ____DangerouslyImpreciseStyle_Internal,
   ____DangerouslyImpreciseStyleProp_Internal,
   ____ViewStyleProp_Internal,
   ____TextStyleProp_Internal,
@@ -66,6 +67,40 @@ export type ImageStyleProp = ____ImageStyleProp_Internal;
  */
 export type DangerouslyImpreciseStyleProp = ____DangerouslyImpreciseStyleProp_Internal;
 
+/**
+ * Utility type for getting the values for specific style keys.
+ *
+ * The following is bad because position is more restrictive than 'string':
+ * ```
+ * type Props = {position: string};
+ * ```
+ *
+ * You should use the following instead:
+ *
+ * ```
+ * type Props = {position: TypeForStyleKey<'position'>};
+ * ```
+ *
+ * This will correctly give you the type 'absolute' | 'relative'
+ */
+export type TypeForStyleKey<
+  +key: $Keys<____DangerouslyImpreciseStyle_Internal>,
+> = $ElementType<____DangerouslyImpreciseStyle_Internal, key>;
+
+/**
+ * WARNING: You probably shouldn't be using this type. This type is an object
+ * with all possible style key's and their values. Note that this isn't
+ * a safe way to type a style prop for a component as results from
+ * StyleSheet.create return an internal identifier, not an object of styles.
+ *
+ * If you want to type the style prop of a function, consider using
+ * ViewStyleProp, TextStyleProp, or ImageStyleProp.
+ *
+ * This should only be used by very core utilities that operate on an object
+ * containing any possible style value.
+ */
+export type DangerouslyImpreciseStyle = ____DangerouslyImpreciseStyle_Internal;
+
 let hairlineWidth = PixelRatio.roundToNearestPixel(0.4);
 if (hairlineWidth === 0) {
   hairlineWidth = 1 / PixelRatio.get();

Libraries/StyleSheet/StyleSheetTypes.js

@@ -213,7 +213,7 @@ export type ImageStyle = $ReadOnly<{|
   overlayColor?: string,
 |}>;
 
-export type DangerouslyImpreciseStyle = {
+export type ____DangerouslyImpreciseStyle_Internal = {
   ...$Exact<TextStyle>,
   +resizeMode?: 'contain' | 'cover' | 'stretch' | 'center' | 'repeat',
   +tintColor?: ColorValue,
@@ -231,7 +231,7 @@ type GenericStyleProp<+T> =
   | $ReadOnlyArray<GenericStyleProp<T>>;
 
 export type ____DangerouslyImpreciseStyleProp_Internal = GenericStyleProp<
-  $Shape<DangerouslyImpreciseStyle>,
+  $Shape<____DangerouslyImpreciseStyle_Internal>,
 >;
 export type ____ViewStyleProp_Internal = GenericStyleProp<
   $ReadOnly<$Shape<ViewStyle>>,
@@ -244,24 +244,5 @@ export type ____ImageStyleProp_Internal = GenericStyleProp<
 >;
 
 export type ____Styles_Internal = {
-  +[key: string]: $Shape<DangerouslyImpreciseStyle>,
+  +[key: string]: $Shape<____DangerouslyImpreciseStyle_Internal>,
 };
-
-/*
-Utility type get non-nullable types for specific style keys.
-Useful when a component requires values for certain Style Keys.
-So Instead:
-```
-type Props = {position: string};
-```
-You should use:
-```
-type Props = {position: TypeForStyleKey<'position'>};
-```
-
-This will correctly give you the type 'absolute' | 'relative' instead of the
-weak type of just string;
-*/
-export type TypeForStyleKey<
-  +key: $Keys<DangerouslyImpreciseStyle>,
-> = $ElementType<DangerouslyImpreciseStyle, key>;

Libraries/StyleSheet/flattenStyle.js

@@ -12,8 +12,10 @@
 
 var ReactNativePropRegistry;
 
-import type {DangerouslyImpreciseStyleProp} from 'StyleSheet';
-import type {DangerouslyImpreciseStyle} from 'StyleSheetTypes';
+import type {
+  DangerouslyImpreciseStyle,
+  DangerouslyImpreciseStyleProp,
+} from 'StyleSheet';
 
 function getStyle(style) {
   if (ReactNativePropRegistry === undefined) {