Reuse effective type roots code in language service

Author: riknoll

src/compiler/program.ts

@@ -168,22 +168,19 @@ namespace ts {
 
     const typeReferenceExtensions = [".d.ts"];
 
-    function getEffectiveTypeRoots(options: CompilerOptions, host: ModuleResolutionHost) {
+    export function getEffectiveTypeRoots(options: CompilerOptions, currentDirectory: string) {
         if (options.typeRoots) {
             return options.typeRoots;
         }
 
-        let currentDirectory: string;
         if (options.configFilePath) {
             currentDirectory = getDirectoryPath(options.configFilePath);
         }
-        else if (host.getCurrentDirectory) {
-            currentDirectory = host.getCurrentDirectory();
-        }
 
         if (!currentDirectory) {
             return undefined;
         }
+
         return map(defaultTypeRoots, d => combinePaths(currentDirectory, d));
     }
 
@@ -201,7 +198,7 @@ namespace ts {
             traceEnabled
         };
 
-        const typeRoots = getEffectiveTypeRoots(options, host);
+        const typeRoots = getEffectiveTypeRoots(options, host.getCurrentDirectory && host.getCurrentDirectory());
         if (traceEnabled) {
             if (containingFile === undefined) {
                 if (typeRoots === undefined) {
@@ -1061,7 +1058,7 @@ namespace ts {
         // Walk the primary type lookup locations
         const result: string[] = [];
         if (host.directoryExists && host.getDirectories) {
-            const typeRoots = getEffectiveTypeRoots(options, host);
+            const typeRoots = getEffectiveTypeRoots(options, host.getCurrentDirectory && host.getCurrentDirectory());
             if (typeRoots) {
                 for (const root of typeRoots) {
                     if (host.directoryExists(root)) {

src/services/services.ts

@@ -4846,17 +4846,10 @@ namespace ts {
                         result.push(createCompletionEntryForModule(moduleName, ScriptElementKind.externalModuleName));
                     }
                 }
-                else if (host.getDirectories && options.typeRoots) {
-                    const absoluteRoots = map(options.typeRoots, rootDirectory => {
-                        if (isRootedDiskPath(rootDirectory)) {
-                            return normalizePath(rootDirectory);
-                        }
-
-                        const basePath = options.project || host.getCurrentDirectory();
-                        return normalizePath(combinePaths(basePath, rootDirectory));
-                    });
-                    for (const absoluteRoot of absoluteRoots) {
-                        getCompletionEntriesFromDirectories(host, options, absoluteRoot, result);
+                else if (host.getDirectories) {
+                    const typeRoots = getEffectiveTypeRoots(options, host.getCurrentDirectory());
+                    for (const root of typeRoots) {
+                        getCompletionEntriesFromDirectories(host, options, root, result);
                     }
                 }