Add support for out-of-tree platform plugins (#20825)

Summary:
This pull request adds the ability for a platform developer to provide a `"haste"` key under the `"rnpm"` key in their `package.json` which allows the packager to pick up that platform's javascript files. The intent is to remove the need to have custom platforms hardcoded in. This is inspired by the `"jest": { "haste": {} }` key used by jest.

For example, React Native Dom would have an entry like:

```json
{
  "rnpm": {
    "haste": {
      "providesModuleNodeModules": [
        "react-native-dom"
      ],
      "platforms": [
        "dom"
      ]
    }
  }
}
```

Support for more keys (path blacklists perhaps?) could be added in the future.

This succeeds #20662, as per a discussion I had with matthargett.

I've got an open discussion over here as well: react-native-community/discussions-and-proposals#21
Pull Request resolved: facebook/react-native#20825

Differential Revision: D9596429

Pulled By: hramos

fbshipit-source-id: a02f0da0bea8870bdc45d55e23da8ccbc36249f2

core/findPlugins.js

@@ -47,36 +47,61 @@ const findPlatformsInPackage = pjson => {
   return path.join(pjson.name, pjson.rnpm.platform);
 };
 
+const getEmptyPluginConfig = () => ({
+  commands: [],
+  platforms: [],
+  haste: {
+    platforms: [],
+    providesModuleNodeModules: [],
+  },
+});
+
+const findHasteConfigInPackageAndConcat = (pjson, haste) => {
+  if (!pjson.rnpm || !pjson.rnpm.haste) {
+    return;
+  }
+  let pkgHaste = pjson.rnpm.haste;
+
+  if (pkgHaste.platforms) {
+    haste.platforms = haste.platforms.concat(pkgHaste.platforms);
+  }
+
+  if (pkgHaste.providesModuleNodeModules) {
+    haste.providesModuleNodeModules = haste.providesModuleNodeModules.concat(
+      pkgHaste.providesModuleNodeModules,
+    );
+  }
+};
+
 const findPluginInFolder = folder => {
   const pjson = readPackage(folder);
 
   if (!pjson) {
-    return {commands: [], platforms: []};
+    return getEmptyPluginConfig();
   }
 
   const deps = union(
     Object.keys(pjson.dependencies || {}),
     Object.keys(pjson.devDependencies || {}),
   );
 
-  return deps.reduce(
-    (acc, pkg) => {
-      let commands = acc.commands;
-      let platforms = acc.platforms;
-      if (isRNPMPlugin(pkg)) {
-        commands = commands.concat(pkg);
-      }
-      if (isReactNativePlugin(pkg)) {
-        const pkgJson = readPackage(path.join(folder, 'node_modules', pkg));
-        if (pkgJson) {
-          commands = commands.concat(findPluginsInReactNativePackage(pkgJson));
-          platforms = platforms.concat(findPlatformsInPackage(pkgJson));
-        }
+  return deps.reduce((acc, pkg) => {
+    let commands = acc.commands;
+    let platforms = acc.platforms;
+    let haste = acc.haste;
+    if (isRNPMPlugin(pkg)) {
+      commands = commands.concat(pkg);
+    }
+    if (isReactNativePlugin(pkg)) {
+      const pkgJson = readPackage(path.join(folder, 'node_modules', pkg));
+      if (pkgJson) {
+        commands = commands.concat(findPluginsInReactNativePackage(pkgJson));
+        platforms = platforms.concat(findPlatformsInPackage(pkgJson));
+        findHasteConfigInPackageAndConcat(pkgJson, haste);
       }
-      return {commands: commands, platforms: platforms};
-    },
-    {commands: [], platforms: []},
-  );
+    }
+    return {commands: commands, platforms: platforms, haste: haste};
+  }, getEmptyPluginConfig());
 };
 
 /**
@@ -89,5 +114,11 @@ module.exports = function findPlugins(folders) {
   return {
     commands: uniq(flatten(plugins.map(p => p.commands))),
     platforms: uniq(flatten(plugins.map(p => p.platforms))),
+    haste: {
+      platforms: uniq(flatten(plugins.map(p => p.haste.platforms))),
+      providesModuleNodeModules: uniq(
+        flatten(plugins.map(p => p.haste.providesModuleNodeModules)),
+      ),
+    },
   };
 };

core/index.js

@@ -70,11 +70,11 @@ const defaultConfig = {
   hasteImplModulePath: require.resolve('../../jest/hasteImpl'),
 
   getPlatforms(): Array<string> {
-    return ['ios', 'android', 'windows', 'web', 'dom'];
+    return ['ios', 'android', 'native', ...plugins.haste.platforms];
   },
 
   getProvidesModuleNodeModules(): Array<string> {
-    return ['react-native', 'react-native-windows', 'react-native-dom'];
+    return ['react-native', ...plugins.haste.providesModuleNodeModules];
   },
 };
 
@@ -132,9 +132,17 @@ async function getCliConfig(): Promise<RNConfig> {
   );
 
   config.transformer.assetRegistryPath = ASSET_REGISTRY_PATH;
-  config.resolver.hasteImplModulePath = config.resolver.hasteImplModulePath || defaultConfig.hasteImplModulePath;
-  config.resolver.platforms = config.resolver.platforms || defaultConfig.getPlatforms();
-  config.resolver.providesModuleNodeModules = config.resolver.providesModuleNodeModules || defaultConfig.getProvidesModuleNodeModules();
+  config.resolver.hasteImplModulePath =
+    config.resolver.hasteImplModulePath || defaultConfig.hasteImplModulePath;
+  config.resolver.platforms = config.resolver.platforms
+    ? config.resolver.platforms.concat(defaultConfig.getPlatforms())
+    : defaultConfig.getPlatforms();
+  config.resolver.providesModuleNodeModules = config.resolver
+    .providesModuleNodeModules
+    ? config.resolver.providesModuleNodeModules.concat(
+        defaultConfig.getProvidesModuleNodeModules(),
+      )
+    : defaultConfig.getProvidesModuleNodeModules();
 
   return {...defaultRNConfig, ...config};
 }