From 00c2def7bd944c580b7e25b4bb0a5b62555a3eb3 Mon Sep 17 00:00:00 2001
From: Patricio Palladino <email@patriciopalladino.com>
Date: Thu, 31 Jan 2019 16:10:06 -0300
Subject: [PATCH] Export lazy object and import to plugins

---
 package.json              |  1 +
 src/internal/util/lazy.ts | 24 ++++++++++++++++++++++++
 src/plugins.ts            |  1 +
 yarn.lock                 |  5 +++++
 4 files changed, 31 insertions(+)

diff --git a/package.json b/package.json
index 186af5fb79c..e26a1fb6c69 100644
--- a/package.json
+++ b/package.json
@@ -80,6 +80,7 @@
     "find-up": "^2.1.0",
     "fs-extra": "^7.0.1",
     "glob": "^7.1.3",
+    "import-lazy": "^3.1.0",
     "lodash": "^4.17.11",
     "mocha": "^5.1.1",
     "semver": "^5.6.0",
diff --git a/src/internal/util/lazy.ts b/src/internal/util/lazy.ts
index d1921eceadd..4c459858f8f 100644
--- a/src/internal/util/lazy.ts
+++ b/src/internal/util/lazy.ts
@@ -81,3 +81,27 @@ export function lazyObject<T extends object>(objectCreator: () => T): T {
     }
   });
 }
+
+/**
+ * This function is a lazy version of `require`. It imports a module
+ * synchronously, by creating a proxy that delays the actual `require` until
+ * the module is used.
+ *
+ * The disadvantage of using this technique is that the type information is
+ * lost. If done with enough care, this can be manually fixed.
+ *
+ * TypeScript doesn't emit `require` calls for modules that are imported only
+ * because of their types. So if one uses lazyImport along with a normal ESM
+ * import you can pass the module's type to this function.
+ *
+ * An example of this can be:
+ *
+ *   `import ModType from "mod";`
+ *   `const Mod = lazyImport<ModType>("mod");`
+ */
+export function lazyImport<ModuleT = any>(packageName: string): ModuleT {
+  const importLazy = require("import-lazy");
+  const lazyRequire = importLazy(require);
+
+  return lazyRequire(packageName);
+}
diff --git a/src/plugins.ts b/src/plugins.ts
index f98d4edad9b..1dd7f76cac0 100644
--- a/src/plugins.ts
+++ b/src/plugins.ts
@@ -4,3 +4,4 @@ export {
   readArtifact,
   readArtifactSync
 } from "./internal/artifacts";
+export { lazyObject, lazyImport } from "./internal/util/lazy";
diff --git a/yarn.lock b/yarn.lock
index 4d94b791257..e4c3943cef7 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -1772,6 +1772,11 @@ ieee754@^1.1.4:
   resolved "https://registry.yarnpkg.com/ieee754/-/ieee754-1.1.12.tgz#50bf24e5b9c8bb98af4964c941cdb0918da7b60b"
   integrity sha512-GguP+DRY+pJ3soyIiGPTvdiVXjZ+DbXOxGpXn3eMvNW4x4irjqXm4wHKscC+TfxSJ0yw/S1F24tqdMNsMZTiLA==
 
+import-lazy@^3.1.0:
+  version "3.1.0"
+  resolved "https://registry.yarnpkg.com/import-lazy/-/import-lazy-3.1.0.tgz#891279202c8a2280fdbd6674dbd8da1a1dfc67cc"
+  integrity sha512-8/gvXvX2JMn0F+CDlSC4l6kOmVaLOO3XLkksI7CI3Ud95KDYJuYur2b9P/PUt/i/pDAMd/DulQsNbbbmRRsDIQ==
+
 imurmurhash@^0.1.4:
   version "0.1.4"
   resolved "https://registry.yarnpkg.com/imurmurhash/-/imurmurhash-0.1.4.tgz#9218b9b2b928a238b13dc4fb6b6d576f231453ea"