Fix stale separator props and expose CellRenderer refs

Reviewed By: sahrens

Differential Revision: D5554920

fbshipit-source-id: 4b6ebc88603afeb642b2860c6069f28cb415d8be

Libraries/Lists/SectionList.js

@@ -129,7 +129,7 @@ type OptionalProps<SectionT: SectionBase<any>> = {
   /**
    * Used to extract a unique key for a given item at the specified index. Key is used for caching
    * and as the react key to track item re-ordering. The default extractor checks item.key, then
-   * falls back to using the index, like react does. Note that this sets keys for each item, but 
+   * falls back to using the index, like react does. Note that this sets keys for each item, but
    * each overall section still needs its own key.
    */
   keyExtractor: (item: Item, index: number) => string,

Libraries/Lists/VirtualizedList.js

@@ -94,6 +94,11 @@ type OptionalProps = {
    */
   inverted?: ?boolean,
   keyExtractor: (item: Item, index: number) => string,
+  /**
+   * Each cell is rendered using this element. Can be a React Component Class,
+   * or a render function. Defaults to using View.
+   */
+  CellRendererComponent?: ?ReactClass<any>,
   /**
    * Rendered when the list is empty. Can be a React Component Class, a render function, or
    * a rendered element.
@@ -442,6 +447,7 @@ class VirtualizedList extends React.PureComponent<OptionalProps, Props, State> {
     inversionStyle: ?StyleObj,
   ) {
     const {
+      CellRendererComponent,
       ItemSeparatorComponent,
       data,
       getItem,
@@ -461,6 +467,7 @@ class VirtualizedList extends React.PureComponent<OptionalProps, Props, State> {
       }
       cells.push(
         <CellRenderer
+          CellRendererComponent={CellRendererComponent}
           ItemSeparatorComponent={ii < end ? ItemSeparatorComponent : undefined}
           cellKey={key}
           fillRateHelper={this._fillRateHelper}
@@ -1155,6 +1162,7 @@ class VirtualizedList extends React.PureComponent<OptionalProps, Props, State> {
 
 class CellRenderer extends React.Component {
   props: {
+    CellRendererComponent?: ?ReactClass<any>,
     ItemSeparatorComponent: ?ReactClass<*>,
     cellKey: string,
     fillRateHelper: FillRateHelper,
@@ -1214,6 +1222,7 @@ class CellRenderer extends React.Component {
 
   render() {
     const {
+      CellRendererComponent,
       ItemSeparatorComponent,
       fillRateHelper,
       item,
@@ -1234,12 +1243,25 @@ class CellRenderer extends React.Component {
         : this.props.onLayout;
     // NOTE: that when this is a sticky header, `onLayout` will get automatically extracted and
     // called explicitly by `ScrollViewStickyHeader`.
+    const itemSeparator =
+      ItemSeparatorComponent &&
+      <ItemSeparatorComponent {...this.state.separatorProps} />;
+    if (!CellRendererComponent) {
+      return (
+        <View style={inversionStyle} onLayout={onLayout}>
+          {element}
+          {itemSeparator}
+        </View>
+      );
+    }
     return (
-      <View onLayout={onLayout} style={inversionStyle}>
+      <CellRendererComponent
+        {...this.props}
+        style={inversionStyle}
+        onLayout={onLayout}>
         {element}
-        {ItemSeparatorComponent &&
-          <ItemSeparatorComponent {...this.state.separatorProps} />}
-      </View>
+        {itemSeparator}
+      </CellRendererComponent>
     );
   }
 }

Libraries/Lists/VirtualizedSectionList.js

@@ -373,22 +373,24 @@ class VirtualizedSectionList<SectionT: SectionBase> extends React.PureComponent<
   };
 }
 
+type ItemWithSeparatorProps = {
+  LeadingSeparatorComponent: ?ReactClass<*>,
+  SeparatorComponent: ?ReactClass<*>,
+  cellKey: string,
+  index: number,
+  item: Item,
+  onUpdateSeparator: (cellKey: string, newProps: Object) => void,
+  prevCellKey?: ?string,
+  renderItem: Function,
+  section: Object,
+  leadingItem: ?Item,
+  leadingSection: ?Object,
+  trailingItem: ?Item,
+  trailingSection: ?Object,
+};
+
 class ItemWithSeparator extends React.Component {
-  props: {
-    LeadingSeparatorComponent: ?ReactClass<*>,
-    SeparatorComponent: ?ReactClass<*>,
-    cellKey: string,
-    index: number,
-    item: Item,
-    onUpdateSeparator: (cellKey: string, newProps: Object) => void,
-    prevCellKey?: ?string,
-    renderItem: Function,
-    section: Object,
-    leadingItem: ?Item,
-    leadingSection: ?Object,
-    trailingItem: ?Item,
-    trailingSection: ?Object,
-  };
+  props: ItemWithSeparatorProps;
 
   state = {
     separatorProps: {
@@ -435,6 +437,27 @@ class ItemWithSeparator extends React.Component {
     },
   };
 
+  componentWillReceiveProps(props: ItemWithSeparatorProps) {
+    this.setState(state => ({
+      separatorProps: {
+        ...this.state.separatorProps,
+        leadingItem: props.item,
+        leadingSection: props.leadingSection,
+        section: props.section,
+        trailingItem: props.trailingItem,
+        trailingSection: props.trailingSection,
+      },
+      leadingSeparatorProps: {
+        ...this.state.leadingSeparatorProps,
+        leadingItem: props.leadingItem,
+        leadingSection: props.leadingSection,
+        section: props.section,
+        trailingItem: props.item,
+        trailingSection: props.trailingSection,
+      },
+    }));
+  }
+
   updateSeparatorProps(newProps: Object) {
     this.setState(state => ({
       separatorProps: {...state.separatorProps, ...newProps},