Add require runtime import option

packages/babel-plugin-flow-runtime/README.md

@@ -61,6 +61,7 @@ The plugin supports the following options:
 - `assert` - Boolean, indicates whether types should be asserted at runtime. Defaults to `true` if `process.env.NODE_ENV === 'development'`, otherwise `false`.
 - `annotate` - Boolean, indicates whether object or function values that have type annotations should be decorated with those types at runtime. Defaults to `true`.
 - `libraryName` - String, indicates which runtime to use. Defaults to `flow-runtime`
+- `libraryImport` - String, either `import` or `require`, indicates how the runtime should be loaded. Defaults to `import`.
 
 
 If `assert` is `true`, the following code:

packages/babel-plugin-flow-runtime/src/ConversionContext.js

@@ -28,6 +28,7 @@ export default class ConversionContext {
 
   libraryName: string = 'flow-runtime';
   libraryId: string = 't';
+  libraryImport: string = 'import';
   shouldImport: boolean = true;
   shouldAssert: boolean = true;
   shouldWarn: boolean = false;

packages/babel-plugin-flow-runtime/src/__tests__/transform.test.js

@@ -25,4 +25,55 @@ describe('transform', () => {
       });
     }
   }
+
+  it('should support requiring the runtime library', () => {
+    testTransform(`
+      type User = {
+        id: number;
+        name: string;
+      };
+    `, {assert: true, annotate: false, libraryImport: 'require'}, `
+      const t = require("flow-runtime");
+
+      const User = t.type("User", t.object(
+        t.property("id", t.number()),
+        t.property("name", t.string())
+      ));
+    `);
+  });
+
+  it('should support requiring a custom runtime library', () => {
+    testTransform(`
+      type User = {
+        id: number;
+      };
+    `, {
+      assert: true,
+      annotate: false,
+      libraryName: './custom-flow-runtime',
+      libraryImport: 'require'
+    }, `
+      const t = require("./custom-flow-runtime");
+
+      const User = t.type("User", t.object(
+        t.property("id", t.number())
+      ));
+    `);
+  });
+
+  it('should reuse an existing required runtime binding', () => {
+    testTransform(`
+      const rt = require("flow-runtime");
+
+      type User = {
+        id: number;
+      };
+    `, {assert: true, annotate: false, libraryImport: 'require'}, `
+      const rt = require("flow-runtime");
+
+      const User = rt.type("User", rt.object(
+        rt.property("id", rt.number())
+      ));
+    `);
+  });
 });

packages/babel-plugin-flow-runtime/src/attachImport.js

@@ -6,12 +6,21 @@ import type {NodePath} from '@babel/traverse';
 
 export default function attachImport (context: ConversionContext, program: NodePath) {
 
-  const importDeclaration = t.importDeclaration(
-    [t.importDefaultSpecifier(t.identifier(context.libraryId))],
-    t.stringLiteral(context.libraryName)
-  );
-
-  importDeclaration.importKind = 'value';
+  const importDeclaration = context.libraryImport === 'require'
+    ? t.variableDeclaration('const', [
+      t.variableDeclarator(
+        t.identifier(context.libraryId),
+        t.callExpression(t.identifier('require'), [t.stringLiteral(context.libraryName)])
+      )
+    ])
+    : t.importDeclaration(
+      [t.importDefaultSpecifier(t.identifier(context.libraryId))],
+      t.stringLiteral(context.libraryName)
+    );
+
+  if (t.isImportDeclaration(importDeclaration)) {
+    importDeclaration.importKind = 'value';
+  }
 
   context.shouldImport = false;
 

packages/babel-plugin-flow-runtime/src/createConversionContext.js

@@ -12,6 +12,7 @@ export type Options = {
   // deprecated
   decorate?: boolean;
   libraryName?: string,
+  libraryImport?: string,
   optInOnly?: boolean;
 };
 
@@ -23,6 +24,10 @@ export default function createConversionContext (options: Options): ConversionCo
     context.libraryName = options.libraryName;
   }
 
+  if (options.libraryImport) {
+    context.libraryImport = options.libraryImport;
+  }
+
   context.optInOnly = options.optInOnly ? true : false;
 
   context.shouldAssert = options.assert === undefined

packages/babel-plugin-flow-runtime/src/firstPassVisitors.js

@@ -101,6 +101,20 @@ export default function firstPassVisitors (context: ConversionContext): Object {
       context.lastImportDeclaration = path;
     },
     VariableDeclarator (path: NodePath) {
+      const init = path.get('init');
+      const idPath = path.get('id');
+
+      if (
+        context.libraryImport === 'require' &&
+        idPath.isIdentifier() &&
+        init.isCallExpression() &&
+        init.get('callee').isIdentifier({name: 'require'}) &&
+        init.get('arguments.0').isStringLiteral({value: context.libraryName})
+      ) {
+        context.shouldImport = false;
+        context.libraryId = idPath.node.name;
+      }
+
       for (const id of findIdentifiers(path.get('id'))) {
         const {name} = id.node;
         context.defineValue(name, path);