Support declare export statements (#5589)

* Add definition of declare export statements

* Add more codecoverage

packages/babel-generator/src/generators/flow.js

@@ -1,3 +1,5 @@
+import * as t from "babel-types";
+
 export function AnyTypeAnnotation() {
   this.word("any");
 }
@@ -20,17 +22,21 @@ export function NullLiteralTypeAnnotation() {
   this.word("null");
 }
 
-export function DeclareClass(node: Object) {
-  this.word("declare");
-  this.space();
+export function DeclareClass(node: Object, parent: Object) {
+  if (!t.isDeclareExportDeclaration(parent)) {
+    this.word("declare");
+    this.space();
+  }
   this.word("class");
   this.space();
   this._interfaceish(node);
 }
 
-export function DeclareFunction(node: Object) {
-  this.word("declare");
-  this.space();
+export function DeclareFunction(node: Object, parent: Object) {
+  if (!t.isDeclareExportDeclaration(parent)) {
+    this.word("declare");
+    this.space();
+  }
   this.word("function");
   this.space();
   this.print(node.id, node);
@@ -69,9 +75,11 @@ export function DeclareTypeAlias(node: Object) {
   this.TypeAlias(node);
 }
 
-export function DeclareVariable(node: Object) {
-  this.word("declare");
-  this.space();
+export function DeclareVariable(node: Object, parent: Object) {
+  if (!t.isDeclareExportDeclaration(parent)) {
+    this.word("declare");
+    this.space();
+  }
   this.word("var");
   this.space();
   this.print(node.id, node);
@@ -79,6 +87,57 @@ export function DeclareVariable(node: Object) {
   this.semicolon();
 }
 
+export function DeclareExportDeclaration(node: Object) {
+  this.word("declare");
+  this.space();
+  this.word("export");
+  this.space();
+  if (node.default) {
+    this.word("default");
+    this.space();
+  }
+
+  FlowExportDeclaration.apply(this, arguments);
+}
+
+export function DeclareExportAllDeclaration(node: Object) {
+  this.word("declare");
+  this.space();
+  this.word("export");
+  this.space();
+  this.token("*");
+  this.space();
+  this.word("from");
+  this.space();
+  this.print(node.source, node);
+  this.semicolon();
+}
+
+function FlowExportDeclaration(node: Object) {
+  if (node.declaration) {
+    const declar = node.declaration;
+    this.print(declar, node);
+    if (!t.isStatement(declar)) this.semicolon();
+  } else {
+    this.token("{");
+    if (node.specifiers.length) {
+      this.space();
+      this.printList(node.specifiers, node);
+      this.space();
+    }
+    this.token("}");
+
+    if (node.source) {
+      this.space();
+      this.word("from");
+      this.space();
+      this.print(node.source, node);
+    }
+
+    this.semicolon();
+  }
+}
+
 export function ExistsTypeAnnotation() {
   this.token("*");
 }

packages/babel-generator/test/fixtures/flow/declare-exports/actual.js

@@ -0,0 +1,24 @@
+declare export var foo
+declare export var foo;
+declare export function foo(): void
+declare export function foo(): void;
+declare export function foo<T>(): void;
+declare export function foo(x: number, y: string): void;
+declare export class A {}
+declare export class A<T> extends B<T> { x: number }
+declare export class A { static foo(): number; static x : string }
+declare export class A { static [ indexer: number]: string }
+declare export class A { static () : number }
+declare export class A mixins B<T>, C {}
+declare export default class A {}
+declare export default function foo(): void;
+declare export default string
+declare export * from 'asd';
+declare export { a, b };
+declare export {};
+declare export { c, d } from 'bar';
+
+declare module B {
+  declare export type B = {};
+  declare export interface Moon {}
+}

packages/babel-generator/test/fixtures/flow/declare-exports/expected.js

@@ -0,0 +1,24 @@
+declare export var foo;
+declare export var foo;
+declare export function foo(): void;
+declare export function foo(): void;
+declare export function foo<T>(): void;
+declare export function foo(x: number, y: string): void;
+declare export class A {}
+declare export class A<T> extends B<T> { x: number }
+declare export class A { static foo: () => number, static x: string, }
+declare export class A { static [indexer: number]: string }
+declare export class A { static (): number }
+declare export class A mixins B<T>, C {}
+declare export default class A {}
+declare export default function foo(): void;
+declare export default string;
+declare export * from 'asd';
+declare export { a, b };
+declare export {};
+declare export { c, d } from 'bar';
+
+declare module B {
+  declare export type B = {};
+  declare export interface Moon {}
+}

packages/babel-plugin-transform-flow-strip-types/test/fixtures/strip-types/strip-declare-exports/actual.js

@@ -0,0 +1,15 @@
+declare export var foo
+declare export var foo;
+declare export function foo(): void
+declare export function foo(): void;
+declare export function foo<T>(): void;
+declare export function foo(x: number, y: string): void;
+declare export class A {}
+declare export class A<T> extends B<T> { x: number }
+declare export class A { static foo(): number; static x : string }
+declare export class A { static [ indexer: number]: string }
+declare export class A { static () : number }
+declare export class A mixins B<T>, C {}
+declare export default class A {}
+declare export default function foo(): void;
+declare export default string

packages/babel-plugin-transform-flow-strip-types/test/fixtures/strip-types/strip-declare-statements/actual.js

@@ -14,3 +14,4 @@ declare type A = string
 declare type T<U> = { [k:string]: U }
 declare interface I { foo: string }
 declare interface I<T> { foo: T }
+declare module.exports: string;

packages/babel-types/src/definitions/flow.js

@@ -111,6 +111,22 @@ defineType("DeclareVariable", {
   },
 });
 
+defineType("DeclareExportDeclaration", {
+  visitor: ["declaration", "specifiers", "source"],
+  aliases: ["Flow", "FlowDeclaration", "Statement", "Declaration"],
+  fields: {
+    // todo
+  },
+});
+
+defineType("DeclareExportAllDeclaration", {
+  visitor: ["source"],
+  aliases: ["Flow", "FlowDeclaration", "Statement", "Declaration"],
+  fields: {
+    // todo
+  },
+});
+
 defineType("ExistsTypeAnnotation", {
   aliases: ["Flow"],
 });