From 64c96186da7f1fe50a1015edb77e97dea95b373f Mon Sep 17 00:00:00 2001
From: Pete Bacon Darwin <pete@bacondarwin.com>
Date: Mon, 24 Sep 2018 11:01:48 +0100
Subject: [PATCH] refactor(ivy): move ngcc `rootDirs` computation into a
 function (#26082)

PR Close #26082
---
 .../src/ngcc/src/packages/transformer.ts      | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/packages/compiler-cli/src/ngcc/src/packages/transformer.ts b/packages/compiler-cli/src/ngcc/src/packages/transformer.ts
index a1321ec155..455c03d122 100644
--- a/packages/compiler-cli/src/ngcc/src/packages/transformer.ts
+++ b/packages/compiler-cli/src/ngcc/src/packages/transformer.ts
@@ -62,14 +62,7 @@ export class Transformer {
     // Create the TS program and necessary helpers.
     // TODO : create a custom compiler host that reads from .bak files if available.
     const host = ts.createCompilerHost(options);
-    let rootDirs: string[]|undefined = undefined;
-    if (options.rootDirs !== undefined) {
-      rootDirs = options.rootDirs;
-    } else if (options.rootDir !== undefined) {
-      rootDirs = [options.rootDir];
-    } else {
-      rootDirs = [host.getCurrentDirectory()];
-    }
+    const rootDirs = this.getRootDirs(host, options);
     const entryPointFilePath = entryPoint[format];
     if (!entryPointFilePath) {
       throw new Error(
@@ -113,6 +106,16 @@ export class Transformer {
     writeMarkerFile(entryPoint, format);
   }
 
+  getRootDirs(host: ts.CompilerHost, options: ts.CompilerOptions) {
+    if (options.rootDirs !== undefined) {
+      return options.rootDirs;
+    } else if (options.rootDir !== undefined) {
+      return [options.rootDir];
+    } else {
+      return [host.getCurrentDirectory()];
+    }
+  }
+
   getHost(isCore: boolean, format: string, program: ts.Program, dtsMapper: DtsMapper):
       NgccReflectionHost {
     switch (format) {