WIP - add extractor, generate snippet_data

node_modules/babel-preset-fbjs/plugins/dev-declaration.js

@@ -0,0 +1,45 @@
+/**
+ * Copyright (c) 2013-present, Facebook, Inc.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+'use strict';
+
+module.exports = function(babel) {
+  const t = babel.types;
+
+  // We can't construct an identifier with a type annotation all in 1 fell swoop
+  // so we have to create & mutate, then pass along.
+  const DEV_IDENTIFIER = t.identifier('__DEV__');
+  DEV_IDENTIFIER.typeAnnotation = t.typeAnnotation(t.booleanTypeAnnotation());
+  const DEV_DECLARATION = t.declareVariable(
+    DEV_IDENTIFIER
+  );
+
+  return {
+    pre() {
+      this.usesDEV = false;
+    },
+
+    visitor: {
+      Identifier: {
+        enter(path, file) {
+          this.usesDEV = this.usesDEV || path.isIdentifier({name: '__DEV__'});
+        },
+      },
+
+      Program: {
+        exit(path, file) {
+          if (!this.usesDEV) {
+            return;
+          }
+
+          // Add the declaration at the front of the body if we've used __DEV__.
+          path.node.body.unshift(DEV_DECLARATION);
+        },
+      },
+    },
+  };
+};